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Rule

What type of heat gun should be used for a heat gun oven?  I went the cheap route. A furnace flue hung horizontally on chains. With a Sears professional heat gun stuck in one end. The heat gun end is too hot,  the other end is too cold, but the middle is just right. I flip the strips every couple minutes, and take them out when I get that hot resin smell with just a hint of smoke. They have just started to change color at that point, and come out a bit darker than untreated cane. They are probably on the light side of most heat treatment methods, but it seems to work. Before treating, bound strips will retain a slight bend when flexed, after heat they snap right into a straight line. I believe that my best test is to flex the cane. If it does not feel right, it goes back in for another 10 minutes until I get the right feel.

I have heard nothing but great things about the double tube oven, but I have little capability for working with sheet metal. OK, I hate the stuff.   (Jeff Schaeffer)

    I use a modified version of Frank Neunemann vertical heat gun oven with a Wagner heat gun from Wallyworld and have nothing but praise for it!  (Shawn Pineo)

Rule

I just finished completing my Neunemann style oven.  I use a heat gun that has a high setting of 1000 degrees.  I tried out my oven and could only get I up to 300 degrees after running the gun full boar for 45 minutes.  I was trying it outdoors because I will need the clearance to get the rod sections in.  I was wondering if insulation might help.  (Tim Stoltz)

    I had the same problem with my heat gun oven so I now use it on its side. That added almost 75 degrees to my internal temperatures when set up upright.

    Insulation also helps a lot (that added about 110 degrees), but as I mentioned a few days ago, I haven't been using insulation recently. The extra temperature I got from using it sideways was enough.  (Tim Klein)

      Using the oven horizontally should also reduce the load on the heat gun motor.  Heat wants to rise.  That's why Hot Air Balloons go up.  That's why chimneys work.  When trying to blow hot air down into a vertical oven pipe, you are fighting the natural tendency for heat to rise.  This puts more of a load on the motor causing it to work harder.

      30 years ago, I was working on a furnace project and my boss wanted to know why I had a larger blower motor on a downflow furnace than on an upflow furnace.  He wouldn't accept this concept until I setup both furnaces side by side and proved it to him. The smaller motor used on the upflow furnace would not provide the same airflow on the downflow furnace.

      The Horizontal furnace of the series used the same motor as the upflow furnace.

      Adding an upward pointing elbow to the outlet will also help.  This helps to pull air through the oven.  The opening for the heat gun should be on the bottom side of the oven.  Thus the air travels along heating the outlet tube which is attached to the inside top of the larger tube and then exits through that smaller outlet tube containing the strips. Thus the smaller outlet tube gets heated twice. Once by the hot air passing over the outside of the smaller outlet tube and then through the inside of the tube.  (Dick Fuhrman)

        This is exactly how my oven is set up and you've confirmed my reasoning behind laying it on its side.

        One other thing I noticed is that the temperature seems quite a bit more even than when I used it vertically. My theory is that the hottest air (that directly out of the air gun) is balanced with the coolest air (the air that is exiting the chamber after traveling the longest distance). On the far end, two roughly equal temperatures that have traveled half their routed distance, are very similar to this balanced high and low at the business end.  (Tim Klein)

Rule

Can anyone point me to plans simple heat gun driven oven?  I can find descriptions but I'm a little slow and would like some pretty pictures or drawings.  (Lee Orr)

    Here is a good link to the design I used.  (Tim Stoltz)

      I'd suggest using insulated pipe though.  I made one with ordinary heat duct and it only gets to about 310°.  Insulation will cost me as much as the insulated pipe, so I think I'll just make another.  (Neil Savage)

        I have used the heat gun oven for about three years now and have had no problems using it at 370 degrees for 30 minutes.  This creates a nice light brown tone to the rod section.  The heat gun that I am using is a Sears Industrial Heat gun and you can adjust the temperature on a scale from 0 to 15.  I set mine at about 10.5 to reach and hold 370 degrees.  It is very quick to bring the temperature up to 370 by setting the dial to 15 for a few minutes and then backing it off to 10.5.  If you want a lighter shade of brown you could shorten the time you leave the section in the oven.  Since I have started using the heat gun oven I have not had any problems with sets catching fish up to 4 pounds.

        I covered the heat duct with foil backed insulation and have two thermometers inserted in the duct, one at the top and one at the bottom.  There has only been a difference of one or two degrees between the top and bottom since I started using this oven.  (Tom Peters)

        I wrapped mine in batting designed for attics. I use it only outside, it smelled the first time I used it, and it's as ugly as dog vomit.  It also readily runs up to 390F and I've been using it for about 5 years with no other problems. I think the roll of Kraft-faced insulation ran me about $15. I used continuous wrapping ties (Read - -"wire") to hold it on.  If you're starting out, get the best you can; if you already have something that just won't hold the heat, well....  (Art Port)

          There was a cane rodmaking display at the Midwest FF Expo this year and their heat gun oven was made of double or triple wall stove pipe.  I'm not sure which.  5' of "Metalbestos" pipe is $18 at the local Home Depot and a roll of insulation is about the same, so.  (Neil Savage)

Rule

I have made a heat gun oven as per Frank Neunemann but am having problems getting an even temperature. The top of the oven, where the heat gun is placed, gets significantly hotter than the bottom and remains so. I think the problem may be that I increased the size of the outer pipe to 150 mm diameter (from the 125 mm specified) and this is probably inhibiting the movement of air through the oven? I have tried insulating the pipe but to no effect.

Does anyone have a possible solution or should I just scrap it? one possibility I have been contemplating is to insert a third pipe into the heat-gun hole with holes/slots in it. the holes could increase in size/number towards the bottom of the pipe? I am just not sure whether it would work at all or how to determine the progression of holes/slots.  (Stephen Dugmore)

    Two things: First, shoot your heat gun into the bottom and let it come out the top. Second, find some high temperature insulation and insulate the oven. There will be a world of difference. (Timothy Troester)

    I found the best thing I ever did with my heat gun oven was to stop using it and get a mica strip oven. I had a rod full of strips burst into flames using my heat gun oven, and no matter how I watched it, it was dangerous at best. There is no middle ground between flaming with a torch and a pipe (ALA Ralph Moon and George Barnes) and the mica strip in my opinion. I would do one or the other instead of the heat gun.  (Bob Maulucci)

      What sort of (low cost) thermostat do you suggest for building a mica oven?  (Scott Wolfe)

        I have a Bret Reiter oven, and to be honest I have no idea. All I know is that it works like a charm. It is invaluable around here for heat treating, curing glue, and drying strips. Built like a tank.  (Bob Maulucci)

        One out of an old oven that has been junked. I find mine works quite well even though there is some overshoot on the temperatures.  (Jack Follweiler)

        I don't use one.  When the oven is hot enough, I unplug the thing. Need more heat? Plug it back in.  Maybe I will get ambitious and install a switch someday, but it works as is.

        I use three candy thermometers to monitor temps.  I got them from "Bed Bath and Beyond"  or "Linens and Things" I forget which.   Ten bucks for the dial model, twenty for the nifty digital model.  (Joe Handwerker)

    I have made the oven described on Frank's site after using the very basic single tube.  The double version is better but not perfect.  I just swap the strips around half way through and the results seem OK.  Patience in letting it all warm up is rewarded as is judicious local insulation.

    Could always ask the original designer?  (Gary Marshall)

      The oven I made I had the same problem. Solved it by replacing the tube the heat gun fits in with an exhaust pipe that was a foot or so long and splitting it and opening it up. I turned it away from the middle 3" pipe so the hot air was not impinging on the 3" pipe. I monitor the heat in 3 places and it is within a few degrees.  (Dave Norling)

    I've used the third pipe for the heat gun to blow into, with holes like a gas burner. I also mounted the oven horizontal. I think size of pipe is OK, if the heat gun has enough airflow and pressure to move air through the oven. I think it would be easier for the gun to move air through the oven if it is mounted horizontal. You'll have to build a rack for the rod sections to lay on.  (David Dziadosz)

    Without actually seeing your oven, but assuming it resembles Neunemann's design, I would expect the exterior pipe temperature to be dangerous to touch, if your gun is reaching 1000 degrees F. Adding sufficient insulation would protect your exposed body parts as well as providing more uniform temperature thru the unit. Mine works quite well but I also reverse the blanks at about 2/3 way thru the cooking cycle. I did find that particular attention had to be made at the joint between my inner pipes because the hot air was short cycling at this point rather than going to the bottom 0f the outer pipe. I preheat my oven to 350-375 using the high setting of my gun and then maintain the temperature at reduced setting as required. No hi-tech thermostats, just a long turkey cooker thermometer. For my limited floor space, the vertical oven is ideal, and technically capable of producing good results.  (Lee Koeser)

    What I am about to write might not be as easy to implement in your part of the world, but I built a heat gun oven in January for about $40 US plus the $50 B&D heat gun and was not happy with the ability to get up to temperature on rods 1-4. So I shelved it and built a 54 inch mica strip oven (60 inches overall) per the specs in Wayne Cattanach's book for about $110, and on the very first use this weekend I wished I had not spent time and money tweaking the heat gun pipe (at first figuring that there are multiple uses for the heat gun). After some help with thermostat wiring from Larry Blan on the list, I can get and hold a 350 to 400 degree temperature now with the mica strip.  It might have a hot spot or two yet to uncover if I am not watching or waiting, but using a long 650 watt mica strip (54 inches) and flipping the cane end over end appears to work, at least the first time.   When researching the tips it seemed that most frustration with heat strip ovens came from those who did not use a mica strip that ran the length of the duct.

    One can usually buy the 6 x 10 and 8 x 10 ductwork pieces off the shelf at an HVAC metal supply house, for $27 US in my city at this time. Add $5 or $6 for a couple 8 x 10 end caps.  If you don't like the price quoted on the phone, ask again.  I got a very strange variety of ductwork pricing every time I spoke to a different clerk at the same place. One fellow advised me to use a piece of 2 x 4 lumber to bend the 6 x 10 pieces, in order to screw together a 6 x 8 inch duct, which worked and then allowed for one inch duct board or furnace board insulation in between the ducts. The supply house had a wet piece of 1 inch duct board in the trash, which went home to dry for free.  (Paul Franklyn)

Rule

I'm looking to see if anyone has plans for a heat treating oven.  I've been using my mentor's but I'd like to have my own. Any suggestions?   (Wayne Caron)

    I'm partial to the heat gun type.  I used 5" double wall gas vent pipe for the outside and 3" single wall dryer vent pipe for the inner pipe.   Made the stand from some 3/4" plywood scraps I had.  I found a cap to press fit the bottom & used pop rivets to connect the inner pipe to the outer.  The top is cut out of a piece of 1/8" aluminum I had.  I have a Milwaukee heat gun, variable temp one speed.  A gun with digital control would be nice, but this is what I have.  I found a digital thermometer that goes to 390 degrees F.  The whole thing excluding the heat gun cost about $35.00.  I followed the basic plan in "The Best of the Planing Form"  Volume 1 & I had 375 degrees in 10 minutes in a cold basement when I shut it down.  Don't want to heat treat any hotter than that anyway.

    DO NOT get the VERY expensive triple wall pipe for zero clearance fireplaces.  My pipe just has an air space between the 2 walls.  The outside is hot enough you don't want to touch it, but it won't do serious damage if you get careless (unless you grab it.)  It would definitely remind you not to do that.  (Neil Savage)

Rule

I purchased the components for my oven with a heating strip in mind. Outside diameter hot air duct 7" and inner duct 6" with high temp insulation between. I planned a center baffle extending to within 3" of each end with a 2" feed pipe extending to within a foot of the far end. When I found the elements either to expensive or not readily available locally I decided to go with a vertical heat gun oven. It has now occurred to me that the inner chamber might be to large to be effectively heated with a heat gun. What would be the optimum size for the inner duct on a heat gun driven oven. I can easily cut the ducting down to the correct size. Also, would this type of oven remain effective horizontally if the inner chamber was smaller?  (Wayne Kifer)

    Why not just put a damper in the end of the 6" so you can have more control? The big difference in vertical would be, better flow of heat around your strips than horizontal. (Al Owen)

Rule

I've purchased all that I need to make the Heat gun oven except for the insulation that goes on the outside.

The guys at Home Depot couldn't give me any temperature ratings on the fiberglass stuff, so I was wondering what you guys would suggest.  (Ren Monllor)

    I used the fiberglass from Home Depot and it works just fine.  In addition, I wrapped it with wire in a spiral to hold it to the oven then I slid the next size pipe over it and capped the whole thing with a duct end on both ends to help seal it.

    Mine works just great!  I even got a digital thermometer at the local grocery store for 9 bucks..    (Dave Gerich)

    Look for a new house going up or a big remodel job. Talk to the Heating and Cooling guys. They ought to have 2" Duct Wrap. It comes in rolls 4" wide and either 50' or 75' long. You don't need a whole roll. Just enough to wrap your oven. You might even get them to staple it on for you and tape the seam. That is what I would do.  (Dick Fuhrman)

    I used the stuff from Home Depot that looks similar to bubble wrap with foil covering on each side. Cost was reasonable and it will come in various size rolls which should leave you with minimal waste. I attached it to the oven using foil tape. It is probably pushing the stuff at the temperatures the oven reaches, but it does not melt and does a good job of insulating. I can get my oven to about 380 degrees or more.

    By the way, this is my second heat gun oven. The first one used an inner tube of 3" sheet metal tubing. I was unable to get even temps the full length of the oven. Varied by up to 30 degrees. In my second oven I used a 1 1/2" ID galvanized fence post for the inner tube. The outer sheet metal tube is 4" diameter. In order to make it stand by itself I got an 8" to 4" reducing connection and put a cap over the larger end and put the 4" oven tube into it. I use an inexpensive 1500 watt variable temperature heat gun by Black and Decker. I believe it also came from Home Depot. I have holes drilled into the inner tube at about 4" from each end and in the center for a candy thermometer to monitor the temperature.

    Once it heats up it holds an even temperature its entire length. I don't even swap the splines end for end half way through the treatment. In both cases I pop riveted the inner tube to the inside wall of the larger tube. I did not try to center it in the larger tube. Despite the small size of the fence pipe it is easy to hang four sections at once in this oven, although if you are using the heat treating MD fixtures sold by Harry Boyd I doubt you  could get more than two sections at once in the oven.

    Got my plans from Frank Neunemann's web site. If you haven't seen it is under the articles section.

    I am firmly convinced that the smaller size of the outer tube coupled with the mass of the fence post inner tube is what makes this oven work as well as it does.  (Steve Shelton)

    Go to a heating and cooling supplier. Ask for high temp insulation for wrapping pipes. The house insulation is not rated for that sort of heat. I had to buy 2 4' sections. at the time they were 30 dollars apiece. I needed 6'.  (Timothy Troester)

    When I made my oven I picked up some ceramic insulation that they use to wrap stainless steel chimney installations with.  I don't remember the exact temp rating, but I do remember that it was rated well above my stove output or what I'd have the temp set to for heat treating bamboo.  (Wayne Daley)

      I finished the oven this past Sunday and it works beautifully. It heated up to 410 degrees and held a steady temperature of 375 degrees  ±1 degree.

      I am still working on the plane forms, believe it or not, and I should have those complete soon. I made a new planning tool and I'm coming along a little better/quicker with the forms, I had no idea it would take this long to make them, but the bottom line is, " I'm making them" and they are coming out nice.

      I purchased three 9 1/2 block  planes on eBay and reworked the soles. Sharpened the plane blades using Scary Sharp System, and ordered bamboo from Demarest yesterday.

      I've been studying taper design with the help of Bob Norwood, and getting a bunch of input from guys on the type rods I'd like to produce. It's neat as I'm starting to feel like I'm seeing progress.

      I know I don't post a whole hell of a lot on the list. Half the time I don't even know what to ask or how to ask it, but I do know this, if it weren't the you guys on this list, I would be no this near to fulfilling my 25+ years dream.  (Ren Monllor)

    I just use a water heater blanket and cut it to fit.  You can get it at any of the home improvement stores.  They are cheap and will handle the heat without any problem.  (Mike Brown)

Rule

Ahh, ovens...

Mine's as simple as it gets. A heat gun on a horizontal tube. Very hi-tech! LOL No additional chambers, just blow hot air over the sticks. Now..my oven suffers from the 'sags' from using it hanging it from the ceiling over the years. Kinda dips in the middle, like me! The gun is variable speed, let's you dial it in pretty quickly and reliably, but air flow is way more important to hitting your numbers on this thing than just turning the knob to the approximate spot on the dial. The better the flow of air, the hotter it gets. If I want to fine tune (toon) this thing I raise or lower the front end. If I lower the front end it gets cooler, raise the front end and it gets hotter. Counterintuitive? Prolly! Lowering the front end would make one think that it will hold more hot air in the 'chamber' thus increasing the temps. The opposite is what happens. The gun tries to keep pushing hot air in but the venturi's (SP? LOL) at the nozzle allow air to push back out of the tube under back pressure. Raising the front of my tube allows air to flow easily out of the tube and warm a small section of the shop.

On a side note...yeah you knew there might be one...I used to kill bugs for a living. 30 damn years. I was lucky enough (if you think that killing bugs for a living is lucky) to get in on the ground floor of using 500,000 BTU heaters. It WAS fun! This was done by placing these propane fueled heaters at various places around the house as well as ducting hot air into strategic areas of the interior of the house. It was all about convection. Placement of heaters and fans to circulate the air.  One thing I noticed time and again was that it was WAY easier to get up to temps when it was raining, foggy, or simply misty. When I inquired to various seemingly knowledgeable sources as to why, I was told that moisture holds and conducts heat way better than drier air does. Stick yer finger in boiling water and 212 degree air and see which hurts for longer.

So, my question to all youse heat gunners is - have any of you ever misted any water into the venturi to increase the heat carrying capacity of the air?  All this just to ask a one line question. Sheesh...  (Mike Shay)

    I haven't.  However (isn't there always a "however"?) the idea of the oven is to drive the moisture out of the cane.  Maybe there's enough, at least initially, that it wouldn't make any difference?  Just a thought...  (Neil Savage)

      I KNEW someone would say that! I should have figured it would be you! LOL ;^)>

      Yes, of course, the idea is to drive off moisture. I'm thinkin' (scary eh?) that the little bit of moisture added to hot,

      quickly moving air wouldn't be imparted to the bamboo. It's not like you'd be saturating the bamboo, rather saturating the air, which is flowing over and moving right out the end of the tube.

      I don't know!

      It's just a thought that has been bouncing around the great emptiness. All this is premised on what took 8 to 10 hours of work when heating houses was cut to 6 or less when it was wet outside. Thank god, because all you could do was sit in the wet and wait.  (Mike Shay)

        I guess I wasn't clear with my thought.  I was thinking that there might be plenty of moisture from the cane and that adding more would have little or no effect, at least early in the heat treating process.  As the cane dries and gives off less moisture itself, adding some might be more useful.  (Neil Savage)

          Maybe there would be plenty of moisture from the bamboo, I don't know! To me "plenty" of moisture only appears at the end of flaming when the scuz bubbles at the end of the culm. Yes, 'scuz' is a technical term... That's not to say that moisture isn't leaving until it gets to the end of the culm.

          This really doesn't have anything to do with how much moisture leaves the bamboo per se, rather how much heat the air can hold at any given time.  Apparently moisture laden air can hold more heat than 'dry' air.  If it is simply 'hot' air that makes the changes happen, 'wet' air may actually be able to do the job faster as long as it keeps moving along. Keeping in mind that it is the heat, not the humidity! LOL

          I'm just tossing this out to y'all.

          I'm WAY open to suggestions!  (Mike Shay)

            It would be an interesting experiment.  You'd need some way to add the moisture and some way to tell if the cane dried sooner.  If you're adding water to the air, would that come out as steam even after the cane was dry?  I guess you could tell by the smell?  (Neil Savage)

              You need to look at what heat treating and drying are really trying to accomplish.  When we raise the heat to a certain temperature, there's a couple of things that are going to happen.  First, we're going to lower the relative humidity of the air surrounding the piece that we are drying/heat treating.  The second thing that's going to happen is once the temperature reaches a certain point, chemical changes start happening in the piece that's being heat treated.

              Since the relative humidity is lowered in air with a given amount of moisture by raising the temperature, we are able to "suck" the moisture from the piece that's being dried.  Adding additional moisture to the air while we are trying to dry the piece will only prolong the drying regimen, since the air will not be able to absorb the moisture from the cane as readily because the air will have a higher relative humidity.

              Once the chemical changes take place, adding moisture to the air probably won't make a hill of beans difference.  (Mark Wendt)

                Good point Mark!  (Neil Savage)

            You sorta gots it backwards.  Hot air will absorb more moisture than cold air, and the higher the heat for a given amount of moisture,  the lower the relative humidity.  Now, if'n you were squirting Buttwiper into yer heating chamber, you might see some adverse reactions.  You really don't wanna go there...   ;-)  (Mark Wendt)

              Yes, my thinking cap is beer powered. I was using the larger set of straws that came with a warning label on the cap. It also warned against women not really looking as good as they might appear.

              I'm glad to have stirred up a bit of conversation but I realize that my particular oven is unsuitable for this (or possibly any kind of) test.

              Any moisture that I could mist into the pipe is simply going to be blown right out the end of the tube with NO chance of heating up. After all, the tempering is done in a matter of minutes anyway. My oven runs longest when heat setting glue, 3 freaking hours!

              But...it's always good to hear from my brothers and listen to them shoot me down! LOL

              I'm just sayin'! (Mike Shay)

                I think you might have been thinking about how warmness "feels."  Consider this, would you feel warmer at 90º  in Phoenix,  or 90º in Atlanta?  Dry air never feels quite as warm as humid air does, and a little bit of humidity will tend to make moderate temperatures more comfortable to the human body.  (Mark Wendt)

                  This is cuz you sweat don’t work in Atlanta Mark!  (Doug Easton)

                    Don't work very well in the DC Metro area either.  98º, & 98% humidity.  (Mark Wendt)

                      Well, I wouldn't feel cool at either place! It's 90 damn degrees! Don't succumb to the brain-washing that the Phoenix Chamber of Commerce spews out. 120* is freaking hot. I don't care how much moisture is in the air!

                      My drunkin' thoughts were based on somewhat 'empirical'  evidence. (Yes, I have stuck my finger in boiling water, haven't you? How would you  know if  dinner  was done?) Heating up hunks of wood (the largest pieces we could find in the most difficult areas to reach) to a temp considered lethal to the poor little creatures. Yes, after ruthlessly killing them for so many years, I feel a certain amount of compassion for them. And they're still winning the war, enough of that.

                      Seems as though wood when attached to say a piece of concrete (think of a 6"X8" girder attached to a concrete pier) in the substructure, is very hard to get to lethal temps. The core of the wood must be heated hot enough to kill. The concrete is just a big heat sink. It sucks heat right out of the wood. Think, if you will, of a mudsill sitting on a concrete foundation. Almost impossible to heat. Set up time for this work would be from 2-4 hours. The actual heating would take 8-10 hours and tear down and repacking the trucks would be another 2 or 3 hours. That's a LONG damn day! Where's my straw, I know it's here somewhere?

                      All I was thinking was that the actual time spent heating these pieces of wood would be almost cut in half in inclement weather.

                      Now don't get me wrong...I don't think that spending 20 minutes to temper some bamboo is just too long to wait. I don't think 3 damn hours to set glue is too long. OK, yes I do...

                      BRB...beer...

                      Where was I? Sorry to youse sensitive folks in GB...

                      Yeah...three hours to heat set glue drives me nuts! Certainly there are other benefits to heating the glued sections. It does, after all, drive out what little remaining moisture might be in the sections.

                      So, are you saying that hot wet air can't possibly pick up still more moisture? That the air isn't as hot as the thermocouple says it is? Don't know myself! I ain't no freaking weatherman! Wish I was though. Then I could be on TV.  (Mike Shay)

                        Well, I was talking Phoenix winter weather...   ;-)

                        Only by accident, only by accident.  That's what fermometers are for.  You got concrete in yer oven?  Must be one heavy son of a gun...  That's why we insulate our ovens, so the cooler outside air doesn't suck the heat from the inside.  Look at it this way - three hours to cook some glue gives ya more time for more beer!

                        No, hot air will absorb moisture until it reaches it's saturation point.  But, the closer and closer it gets to the saturation point, the less and less the air will be able to readily absorb the moisture.  So, you can do one of two things - raise the temperature, or release the moisture.   (Mark Wendt)

                        Mike's a living, breathing, walking example of what you guys are discussing, he lives in the dessert, absorbs lost of liquid (BEER) and sweats it out - Equilibrium.  (Pete Van Schaack)

    When I was a young man, I worked for a company that made wood furniture for schools, hospitals, clinics, libraries, and laboratories. Green lumber was placed in kilns to dry and come to uniform moisture content. Steam was injected into these kilns to achieve drying and ideal wood moisture content.  I guess at any temperature and humidity level the ideal moisture level would be reached. At the moment however, I'll stick to very dry bamboo by using dry heat even if it's not the most efficient heat transfer medium. ($.02 worth)  (Lee Koeser)

Rule

My buddy who owns a large metal fab shop is selling his business leaving me without access to an oven - guess it's time to build my own.  Due to limited horizontal space, and a heat gun stable that has grown to four, the obvious design is a vertical oven using a heat gun.  Since joining this list one year ago I remember at least two designs of this configuration discussed, but thinking I would have oven privileges I failed to keep those threads.  OK, enough of the set-up, are there any generous souls out there who would be willing to help a newbie out with plans - I hate reinventing the wheel.  Of course the more detailed the plans the better as I tend to subscribe to the KISS theory - which is more in keeping with my mind set and abilities.  (Tom Key)

    Well, let's see.  You got a small tube inside a big tube. Attach the small tube to the wall of the big tube with sheet metal screws. The big tube is a little longer than the smaller tube. It has to be enough larger than the small tube enough to get the nose of your heat gun into the space left over.  My Big tube is 6" sheet metal duct.  The small tube is 4" sheet metal duct.  That leaves a 2" space that is large enough to take a hole that the nose of my heat gun fits through (barely).  The gun end is capped with a premade duct cap (6" diameter) and permanently attached to the big tube.  Your bamboo strips go in the small tube and sit on some chicken wire spacer to keep them off the metal tube.

    The other end of the big tube is capped with the same type of 6" diameter cap but left loose to get the strips in and out. This is where the smaller tube does not go all the way to the end of the big tube.  Cut the smaller tube about 2" shorter than the big tube. Make a handle for this end so you can get it on and off easily.

    The idea is that the heat gun shoots hot air down the space and around the corner where there's about a 2" gap left and then out the smaller tube where you have your bamboo rough strips cooking.

    I had to wrap some insulation around the outer tube so I could get the temperature up to 375 degrees F.   It probably is not the correct insulation to use since it smells when I'm using the oven.

    I seem to remember someone saying that they couldn't get the vertical oven quite up to temp so they use it horizontally.   No problem then. I use mine in the horizontal mode.  It works fine.   I use two candy thermometers to check the heat. One stuck through a small hole in the far end and another that sits in the exhaust end.   It will typically show around a 10 degree variance from the hot end to the exhaust.  (Larry Swearingen)

      I used "pop rivets" to connect the two.  No sharp points inside if I can help it!  (Neil Savage)

      If you make a few rods a year it is a great solution. inexpensive and efficient. I suggest that you use an insulated stove pipe for the outer tube. I don't need to put insulation around the outside my oven. there are two kinds of insulated pipe; a fairly thinly insulated (reasonably priced) and heavily insulated pipe which you can use right next to wood structures (obscenely expensive). The reasonably priced kind works fine.

      One note of caution. Use meat thermometers to monitor temperature and do not leave the oven unattended when you are cooking cane.  (Doug Easton)

        A meat thermometer doesn't go up to 375 degrees.  Only around 200 degrees.  I do like my meat well done but nowhere near 375 degrees.   {:>)

        You need a candy thermometer.  They usually go up to 400 degrees.  (Larry Swearingen)

          Those electronic ones go to 394 F - can't figure out why they ALL go to 394; guess there's only one chip out there that's usable!  (Art Port)

            The Polder electronic thermos you can by at Target go to 392 degrees - so maybe there’s two chips!  (Tom Vagell)

              I may have to apologize - I THOUGHT it was 394, but it may have been (probably, in fact WAS) 392!

              As Billy Eckstein used to sing "I Apaw-lah-gize". Lets see the hands of all who recall THAT song now!  (Art Port)

            My thermometer goes to 392 and then says HIGH....... Not really helpful.  (Barry Janzen)

              I don't heat treat above 320. Usually I am heat treating strips that have already been flamed. I guess I like my cane rare.  (Doug Easton)

            That is what started all this worry over temps......my last 3/2 rod pulled the temps down to 300 degrees and I had to treat for 45 minutes. Thought that was too cool to work. Guess time will tell.  (Barry Janzen)

              That is what started all this worry over temps

              A long time ago, I worked for a company that had to heat cure some epoxy assembled parts at around 200°. They built a plywood box, and powered it with heat lamps. They controlled temperature by opening and closing vents at the top of the box. It worked pretty well, as I recall.  (Tom Smithwick)

              I have done my rods in my bookcase hotbox at 220 for 3 hours. By that time you can just start to smell the cane fumes. BTW, these are blanks that I have just glues wrapped and let stand for 24 hours. I use four 100 watt light bulbs and this takes me to just 220 when I seal any leaks with duck tape. This procedure has worked for me for 10 years, never have any problems with my rods and best of all it's cheap and simple, you know the KISS method.  (Bob Norwood)

Rule

I have had problems recently with my heat gun oven......Harry gave me some tips but I still have some questions.

How do you heat treat glued strips and keep them flat? What do you put in the tube to (horizontal style) that is flat?

Does the horizontal design  work as well or better than the vertical?

What can be done to fine tune the temp? My heat gun has 12 settings but still it moves 30+ degrees for each setting and keeping the magic numbers is tough.  Suggestions?   (Barry Janzen)

    As regards your questions:

    1.  You don't heat treat glued strips. Heat treat them before final planing. The use of MD Fixtures during heat treating will help straighten sweeps but not crooks at nodes. Follow up with Harry B. regarding MD Fixtures. He has the only franchise selling them.

    2. I have no idea. I use a vertical oven. Hanging strips should stay straight, horizontal strips may assume the shape of the bed on which they are laying. If bound to MD Fixtures they should be no less straight and probably come out more straight than before treating.

    3. The one thing I found which fine tuned the temp was to make my inner pipe of a cyclone fence post. It is steel, approximately 5/64" thick walls which when heated to temperature maintain a very consistent temperature from one end to the other. My first oven used an inner pipe of thin stove pipe and was quite inconsistent. Your heat gun output will govern what final temperatures are available in your oven, but the use of a thick walled inner pipe will yield consistent temperature from end to end. You can test with your heat gun and determine what temperatures are available to you and then adjust the length of time you heat treat to get an acceptable result. Or, you can buy another heat gun with infinitely variable temperature control to achieve the same end.

    You can either change the temperature or the time of exposure to heat treat your cane as long as the oven will heat to a point acceptable to getting the job done.  (Steve Shelton)

      I would make two additional points.  For the inner pipe you can use inexpensive double walled furnace vent pipe.  My 60" piece of double walled pipe was less than $20 in October of '07.

      For heat setting epoxy glues, you can to the fixtures to keep things straight.  Obviously, bind the glued strips together into a hexagon first, then bind butt sections mid sections into channels on the fixture.  Binding tip sections to the fixtures can be done, but it's tricky.

      And there is always the danger you will glue the sections to the fixtures.  Been there, done that.  One good whack against the workbench solved the problem.  (Harry Boyd)

        Why not just rearrange your setup so that the oven is vertical instead of horizontal? That would eliminate some of your issues with a shelf since you can hang the sections in the inner pipe instead of laying them on a shelf.  (Larry Puckett)

          Mine is vertical unless it is in storage. Then it rests in rope cradles attached to the ceiling.  (Steve Shelton)

        Maybe I should just make another oven. One that is shorter and vertical for heat setting my glue to 200 degrees and just hang the sections in that. The other oven would be more like yours setup horizontally and I could just insert the fixtures and heat treat away with double walls and insulation galore. Probably another simple oven would cost less than $20 for the pipe.  (Barry Janzen)

      You don't heat treat glued strips. Heat treat them before final planing. The use of MD Fixtures during heat treating will help straighten sweeps but not crooks at nodes.

      I am heating strips in M-D fixtures. My question is about heating glued strips to cure my Epon glue. I need to keep them straight and heat at 200 degrees. My low setting was heating to around 175 and the next setting was over 220.

      Problems are numerous.......

      M-D fixtures are hard to place in my vertical oven while running. I have to remove the gun and tilt it over to insert the fixtures to heat treat strips. Hence the reason for asking about a horizontal setup.

      With a horizontal setup......insertion of strips in fixtures would be easy, but then I would need a flat surface to lay glued sections for setting of the glue. Maybe I just need two ovens.

      Another problem is the fine tuning of the temps. My gun has 6+ settings but no fine tuning. Has anyone tried an adjustable vent in the out pipe to release excess heat to fine tune things?  (Barry Janzen)

        If my memory serves (it doesn't always) you can heat set for a longer time at a lower temperature.  Also, I'd think a heat gun oven for heat setting could be made from single wall pipe without a problem.  My original oven (single wall) got to about 295 degrees using my heat gun.  I had some single wall left from a remodeling project, and being cheap I intended using it to make my oven.  When I found it didn't get hot enough I trekked to the local Lowes and got the double wall I'm using now.  (Neil Savage)

      I've been using a heat gun oven for several years and your finding on the temp variation mirrors mine. I have several guns and all of them rise over time, some slower than others, but ALL. Perhaps due to the metal absorbing heat and making the gun more "efficient"?  I found quickly on that you can't turn the gun off and on, as the turning on begins with MUCH lowered temps and actually cools the oven down before reheating! So, since the bake time isn't that long, I stand over the oven and remove and replace the gun as the temp rises, dropping it slowly, but returning it quickly to spec. I use one of those electronic thermometers, available at Target for $20, with the alarms on them and they seem to be doing all right for me.

      I like the idea of the fence post, but question if it's needed if you're blowing the heat through the duct with the gun??  (Art Port)

        Exactly my experience. I don't use a heavy inner pipe, My temps are very even from bottom to top however they do slowly rise. I just watch or set the alarm and dial the heat gun down. My whole cycle is only about 30 minutes, so it's no problem for me.  (Doug Easton)

        I also find that the air flow needs to stay constant. Removing the gun for just a second seems to upset the temps as well. (Barry Janzen)

          Regarding the vertical oven.

          What is stopping you using the vertical pipe with the heat gun at the base, simply pointing the gun straight up the tube. And hanging the rod  sections from the top?  (Gary Nicholson)

            Some of this may be tradition, but I think the original Idea was that the natural movement of heated air is upward against gravity and therefore one wants to force the hottest air (directly out of the heat gun) downward and let the air in the smaller tube rise via convection.  (Doug Easton)

              I actually just use a 6 ft piece of 1 1/2" aluminum tubing that's a tight fit on the end of my heat gun. I just let rest on my work bench. It heats up to 325 F in about a min and then cycles off and on every 6 seconds to maintain that setting. I just slide the strips in the far end butt end first, stuck in an aluminum cigar tube to protect the ends that are nearest the heat gun from burning or heating up too much. I like to keep the ends at least 2ft from the heat gun so if I'm doing longer sections I'll add an additional piece of pipe to move the heat gun back more. I use a candy thermometer to double check my temps at the open end of the tube and adjust my heater control to maintain the temperature. I do 12 minutes for butts, 10 for mids and 8 minutes for tips. So far it seems to work just fine for me and it's a lot easier to store.  (Ken Paterson)

              Part of the engineering too is that the large outer duct will circumferentially warm the smaller inner duct to help stabilize the temps (plus more metal mass, bigger heat sink, more uniform temps with less variability). At the bottom turn, you end up with turbulent forces which mix the air into a more uniform temp,  you also end up with a "counter current heat exchange" mechanism (hottest part of the big tube is at the top next to the theoretically colder inner tube, and the hottest inner tube at the bottom next to the coldest part of the ot tube exchange heat for a "zero sum" gradient).

              My vertical heat gun oven has very little temp variability from top to bottom.  (Chris Obuchowski)

                I put a heat sink at the bottom of mine. I cast a 3" thick slab of concrete at the bottom of the big tube. It also helps keep my vertical oven vertical. Yes, there is a countercurrent distribution with the higher temperature coming down from  the top of the big tube warming the lower temperature air coming up the smaller tube. My oven also has no measurable temp gradient (using a meat thermometer). I heat treat at 320-325 F for 15-20 minutes after drying at 225 for 30 minutes I have heat treated tapered strips bound with thread.  (Doug Easton)

    I've never tried a vertical oven. Mine is horizontal with a distinct bend/sag in the middle. A rat wire cage bed will stay more than straight enough to keep the sections from sagging.

    My oven is hung from the ceiling and is raised out of the way and lowered via pulleys. The pulleys MAY solve your fine tuning problem.

    My gun is a variable speed. no distinct settings, simply a dial you can bump a bit if you want to raise or lower the temp. I can fine tune the temps by raising or lowering one end of the oven rather than fussing with the gun.

    If the open end of the oven is lower than the gun, the temps drop. If I push the open end higher than the gun, the temps rise.

    It's just about convection and the moving of hot air. Moving air heats, stagnant air cools. At least in my experience!  (Mike Shay)

      Thanks for that tip.....maybe a tilting, horizontal oven would allow the temp adjustment I am looking for. Will have to explore that.  (Barry Janzen)

    I used a heat gun oven for several years and a couple dozen rods and it worked is about all I can say about it. It was in a pretty much constant state of evolution trying to get it to work to my satisfaction, which it never did, though it got the job done. I finally had a semiretired heating contractor I knew make me an insulated square box 5' long and straightened out a hot plate element and rewired the controls to it. It worked so much better I can't even put it on a scale of 1-10, the control let me set a temperature and the element kept if within a tolerable range either side of that temp. I used this set up for several more years and another couple dozen rods until a friend of mine upgraded his oven and sent me his old mica strip heater, which also works like a champ wired to the same hot plate control. Moral of this long winded story, save yourselves a lot of aggravation and go with something more useful than a heat gun oven, you'll spend a little money, but will be glad you did.  (John Channer)

      If I live long enough to make several dozen rods at one or two a year, my doctor is going to be surprised!  (Neil Savage)

      Thanks for the suggestions.  However, I am now confused! I good friend and notable member here said his mica strip burned out and he went back to the heat gun oven and has loved it ever since. Much easier to work and cheaper to operate. I guess to each his own.  (Barry Janzen)

        Couldn't tell you what happened, but it seems very typical of rodmaking, what works fine for one of us doesn't work at all for another, go figure.  (John Channer)

Rule

I am finally starting to acquire tools and make as many items as possible to keep the initial startup cost more feasible.  Does anyone know of a source that  has step by step directions, pictures, as well as a parts list for a relatively inexpensive/easily constructed heat gun oven? (Ron Delesky)

    I'd suggest double wall "gas vent" pipe for the oven shell.  Single wall didn't get hot enough for me.  The double wall comes in 5' sections too and doesn't require insulating the outside.  There are pictures of mine on Todd's site under "contraptions".  (Neil Savage)

    You can get into it really cheap if you use the KISS method. I built a hot box - and oven by using a old book case w/ form/aluminum insulation inside and for the door. Use 4 100 light bulbs, one for the hot box and all of them for the oven, which gets up to 220 degrees for 3 hours and does a great job of heating the bamboo and setting the glue at the same time.  (Bob Norwood)

    You need to be on here.  (Gary Nicholson)

Rule

I am going to build a Neunemann style heat gun oven as recommended by others, but placing it vertically will be a problem due to clearance issues to get the rod sections in.  Can it be utilized horizontally without making changes to the design?  I will ultimately be using a 5' section of 5" diameter double wall pipe for the outer shell without additional insulation, and a 3" diameter single wall for the inner portion.  Any ideas concerning what type of material could be used to construct a shelf to place the rod sections on?  (Ron Delesky)

    Here's what I did,  I went to ACE and bought some plumbers tape, you know the stuff used to hang pipe, (metal with holes in it) and I hung my oven up. You can also use wire or chain if you please. One thing that I found very important is that you need to have the heat gun on the side of the interior pipe, if you put it on the bottom you will get a hot spot in the middle! I went to Home Depot and bought a vent section in the siding department I think it was 8 - 10 ft. aluminum with lots of holes in it, you will know it when you see it, this makes a great shelf.

    Arguello, Joe Shop

    (Joe Arguello)

    I use mine horizontally. I put a platform inside made out of hardware cloth (1/4" rat screen). I have added another layer of single wall pipe to the outside of the  basic design and put fiberglass insulation sandwiched between that pipe and the main body of the oven. I heat treat in my garage and store the oven standing vertically in a corner. I have an old salvaged wooden door and two collapsible saw horses (Home Depot) for a table.  (Steve Weiss)

    I too have built a heat gun oven that was inexpensive to build and very effective. My gun rest on top of a 6 inch pipe with a 3 inch pipe riveted inside for the cane. I did  make a concrete base with Quikrete for safety of tipping over and a cap with holes for the gun and cane pipe. Also have 2 thermometers top and bottom that stay amazingly close during heating. Duct insulation is wrapped around the entire oven with heat resistant tape. (Jeff Volner)

Rule

Help!  I built a vertical oven using Frank Neunemann's plans and using double wall stove pipe.  I've got a good quality Milwaukee heat gun that claims to put out 1100 degrees F, but so far I have not been able to get the oven temp about 354 degrees.  For those of you who use this type of heat gun oven, is that about what I should expect, or do I need to do some time tuning.  I've even considered making it into a two gun oven.  Also, how long do you heat treat if you use this type of oven - flamed and unflamed time and temp.  (Tom Key)

    I used double wall stovepipe around a single wall pipe, insulation in between the two. I run it horizontally, the trick is to run the inlet tube for the heat gun (section of rod tube) along the side of the oven, this keeps the heat surprisingly even throughout. Here is a pic including storage/usage set up. I hung it from the channel that the rollers of the garage door run in. Hope this helps.  (Joe Arguello)

    Arguello, Joe Shop

      354 is enough.

      Joe, I'm jealous of your shop, lathe, air compressor, but so clean?

      You must have what nowadays are called issues....  (Henry Mitchell)

        As Paul Harvey used to say, "And now the rest of the story!"

        That picture was taken when I first moved in and was setting up the shop, as you can see the wall isn't even finished as far as the insulation. Now that doesn't mean I don't have issues, but that is why the shop was so clean.  (Joe Arguello)

          Ahem.  Then we need to see a "present" shot of the workshop. Can you still walk through it Joe?  (Mark Wendt)

            Well, it's not bad. Years ago when I bought my Bridgeport, the guy who delivered it had his roll back trailer in the driveway and we were letting the Bridgeport down and trying to figure out the best place for it. Just as luck would have it my wife got home from work! She took one look at the size of my new toyl and looked into the garage and simply stated "all I want to say is that I park my car in that garage!" then she walked into the house. Mike and I looked at each other and in unison said "let’s put it in that corner over there " Well she still parks in the garage so I have to keep the shop garage clean. Some women are so unreasonable!

            Actually I am very lucky, I have a wife who supports my every effort, and there have been times that a friend of mine and I have been playing working in the shop and forget how the time is slipping by. She will come out with a couple of sandwiches and say "you boys better eat something" She treats all my friends very well. I really don't know how I got so lucky!  (Joe Arguello)

              We are both lucky in that department.  When my wife found out I had been using the money I had been saving to buy my drift boat with to pay for other things she told me in no uncertain terms that I was to not do that & I was to buy my boat.

              I have never used my regular paycheck for my hobbies & she does not like me using my hobby money for real life things, though I do on occasion & this is why my boat does not have a motor yet.

              When I had my fly shop I always felt sorry for the poor saps who had to have their stuff shipped to their office so the wife would not know about it.

              Part of my shop is in my garage too & she only asks that I clean up when I am done & make sure she can get the car in.  (Bret Reiter)

    I'm just using single wall pipe with regular house insulation wrapped around it.  It's no problem getting over 400 degrees.  It has three temp probes (cheap candy thermometers) and stays within about 10 degrees of each other.

    The biggest difference is that it's horizontal.

    The biggest problem is that it's horizontal. 

    It does take up a lot of space and is always in the way.  Works good though.  (Bruce Johns)

      I use a single wall horizontal gun oven too. Consider placing the oven on pulleys. Raise it to the ceiling when you aren't using it and use the pulleys to raise and lower the front end of the oven when in use. Lower the front end and it restricts air flow and lowers temps. Raise the front end and air flows easier and hotter temps. You can fine tune it by just raising or lowering the front end a few inches or less.  (Mike Shay)

        Well, there you have it. We've heard of desert coolers, now we know what a desert heater is!  (Larry Blan)

          Yes it worked quite well this summer. I lowered the end of the oven and it only got to 117° F in the shop this summer. Beats the holy hell out of 120.  (Mike Shay)

    Thanks to all of you heat gun oven owners who responded to my request of how to increase the heat.  Now that helped me solve that problem I'd like to ask about heat levels and time you use.  I like to flame my cane for the darker look, so what heat should I use and for how long.  (Tom Key)

      Flamed or not I heat treat for 15 minutes at 350 degrees.   (Joe Arguello)

Rule

Sometimes you win. I have a heat strip oven, I was unhappy with the hot spots. I built a new vertical  oven, I used two 4" insulated  stove pipes with two elbows at the bottom, I put the heat strip in a 4"  pipe with a fan blowing the heat down and up the other 4" pipe. The fan I used was a muffin type fan that was too strong, I had to increase the setting on the thermostat higher, the probe temp never got hot enough to shut the heat off, oven temp varied 2 or 3 degrees at the most. That’s with a cheap oven thermostat. (Larry Downey)

    I received several e-mails requesting clarification on the oven, I use Epon for glue up and heat treat at 190 to 200 degrees. the oven consists of two insulated stove pipes 4" in diameter with two elbow pipes at the bottom, I put the heat strip  in one pipe and the heat sensor in the other, the fan being to strong blows cool air over the heat strip preventing it from reaching temp. when I set the thermostat at 200 degrees the pipe with the bamboo strips in it reached only about 90 degrees. I kept readjusting the thermostat until the temp was about 195 degrees. the thermostat setting ended up being 300 degrees, the heat sensor never got above 195 degrees therefore it never shut the heat of and the temp stayed constant. I Know it's as clear as mud. Hope it helps anyway.  (Larry Downey)

Rule

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