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Heat Treating - Overtreating


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Rule

I recently overdid the heat treating on some cane. I build nodeless and heat-treat in the kitchen oven.  A couple of sections of culm stayed in a bit too long and went to a chocolate brown color instead of the usual honey, some of the enamel bubbled slightly.  They were brownest next to the enamel and pretty well through the wall of the cane.  They still seemed to flex OK so I went ahead will milling them on my Morgan Mill.  Shaving came off the strips as usual.  As I worked I noted that in the dark areas some fibers along the edge were coming loose from the rest of the strip, yet they still seemed to flex OK.  I pinch one of the strips hard between my fingers and rolled it and the matrix holding the power fibers together disintegrated leaving just the fibers connected to normal cane at each end (they had been burnt only in the middle of a strip where they had been over the oven element).  It looked a bit like two paintbrushes joined at the bristles.  I broke a couple of strips in the dark and in the normally colored sections and both left long fibers.  It was an interesting demonstration of what happens to cane when it is heat-treated to too great an extent.  (Bill Lamberson)

    I too just cooked some cane to its darkest form. The thing about this was the cane was about 5+ years aged, and I used the same temps & time as with my newer cane. Has anyone found that aged cane generally cooks faster than non-aged cane?  (Chad Wigham)

      What I have experienced is if cane is real dry it will darken faster than cane that has been exposed to moisture.  As I soak my strips now I go through a drying regime before the strips are heat treated and come out with strips that look the same from one batch to the next.  (Tony Spezio)

        Would you care to elaborate on your technique for those of us who want to do the same as you. (Larry Puckett)

          I soak my strips for five to six days. Displace the nodes, do some straightening.

          The sweeps can be taken out without heat. Bevel the 60 degrees and from there partial taper all strips. The strips are drying out on the outside but still wet inside. The strips are then wrapped in MD's fixtures with the pith side out.  Not a commercial but this is one of the best things in rodmaking to come along. I made two brackets to hold the three fixtures together, each fixture holds six strips. The whole assembly is put in the oven that is preheated to 100-120* F. The door on the oven is left cracked open at the top. The strips are left in the oven for a hour or two then I check for moisture with a mirror.

          If moisture is still coming out of the top of the oven, the mirror will fog up. When the mirror does not fog up any more I assume the strips are dry enough to heat treat. The assembly is removed from the oven and cooled. The strips are now rewrapped with the enamel side up and heat treated. I did not mention the strips are about as straight as you can get them. The strips are then heat treated for 12 minuets @ 375 F, removed from the fixtures and final planed. I try to do heat treating, final planing and gluing in one session before the strips can absorb any moisture.  After the glue is set for 18 to 20 hours, the sticks are scraped, sanded and heat set using the fixtures again. After heat set for four hours the sticks are removed and while still warm given a coat of Tung Varnish to seal them.

          All the final sanding and additional coats are done when each coat is dry enough to sand.  (Tony Spezio)

      It seems reasonable that it might.  Boiling the moisture in the cane is going to absorb heat until it is largely removed.  Once the moisture and perhaps other volatiles are gone I would expect the temperature to rise and other chemical changes, the caramelization process, to occur.  The color change takes place pretty quickly once it starts.  If the cane is dry to begin with, the drying phase of the process would be likely to occur more quickly and the chemical changes to begin earlier in the process, so if left the same amount of time it would overcook.

      There is good logic to using a regimen consisting of a long period of a low temperature (say 200 degrees) drying phase, followed by a higher temperature (say 375 degrees) tempering (for lack of a better word) phase.  The drying phase would equalize the dryness of all cane whether "green" or relatively dry, and then the higher temperature would take care of the subsequent chemical changes.  I know that some do it this way, and I will probably join them.  (Bill Lamberson)

    I believe that's pretty much what's happening in the drying/heat treating regime that M-D and I use in our convection ovens.  He can probably expound more on it than I can, since he developed it through experimentation.  We put the strips, bundled onto the fixtures he designed, into the cold oven.  Then we use a set point of 350 degrees, and let the oven come up to the temperature with the strips inside, hold it for thirty minutes at 350, the adjust the set point down to 225, and hold that for an hour.  I think the 225 point just removes any residual moisture that may have been trapped in the strips.  Using the oven this way, I have gotten a pretty uniform golden honey brown color on all  my  strips  so far.   I probably  wouldn't attempt  this in a non-convection, non-PID controlled oven, since the heating may not be as uniform throughout the oven.  I've laid the strips from the current rod I'm working on alongside two previous rods, and the coloration is so close the difference is virtually undetectable.  (Mark Wendt)

      I agree with Mark completely that this regimen should not be attempted without benefit of both a convection oven and a PID process controller. I think you'd find some very crispy strips indeed, otherwise.  (Martin-Darrell)

        You are right, I tried to dry and heat treat at the same time and got some dark brown strips. I set the oven for 375 F put the assembly with wet strips in and let it come up to temp. When it got to 375 F I timed my 12 minutes. The strips were overcooked.  (Tony Spezio)

      Is there noticeable change between the end of the 350 degree phase and the end of the 225 degree phase?  I would argue (without much conviction since I don't have any data) that the 225 degree phase should be first, then 350.  I would expect much moisture to be left after a half hour at 350.  Have you weighed a strip before and after the 225 phase?  (Bill Lamberson)

        I don't know for certain, since the strips don't leave the oven during the cool down phase to 225.  I haven't weighed a strip, since I don't have a scale accurate enough for such light weights.  M-D, could you weigh in (pun intended...) on the reasoning of the process?  (Mark Wendt)

          By putting the strips into the oven upon initial startup, the strips and fixtures all acclimate at the same rate, at the same temperature. The reasoning behind this was that the strips and the moisture they contained would all heat evenly, helping to evacuate the moisture more evenly and easily. It takes approximately 40 minutes for my oven to come to temperature so this allows time for moisture to escape. I have noticed however that no steam is present, coming from the strips, until the oven reaches around 300°, and that none is escaping at 225°, though one may feel the increased humidity level inside the oven at temperatures between 225° and 325°. Above that the heat is too great to sustain the moisture level, and it must escape the oven. The total time in my oven for the entire regimen, as outlined by Mark in a previous post, is 2 hr., 10 min. It takes approx. 40 minutes for my oven to reach 350°, from the ambient temperature, so this allows ample time for the moisture to come to heat and begin to move. I suppose that in this respect the 225° phase does come first, but to answer Bill's question, I don’t know, as I never removed a strip just to weigh it at that point.  (Martin-Darrell)

            How does a beginner know if the cane has been over cooked? What properties can I look for.  (Scott Wolfe)

              Color tells you a lot regarding the cooked state of the cane. Milward demonstrated that a color change to the cane was detrimental to it, however I wonder just how critical this is to a trout rod, as it seems there's very little that we do to the bamboo in the heat-treating/flaming process that results in catastrophic rod failure. Now, for larger rods I do not flame, and I'm careful to give the best heat treatment I can without compromising the bamboo, or at least what I assume is not compromising it based upon what little testing I do to each strip after it's been cooked. The finished rods also seem to bear this out.

              Bob Nunley once told of cooking strips to the point of deep brown, yet made a rod from it anyway just to see what would happen. At last report, the rod was still doing fine.  (Martin-Darrell)

      What is a PID controlled oven and is it possible to convert my Cattanach oven to this and what would it cost me? Is there some one I can get to do this or are there ovens for sale that are already PID controlled?  (Patrick Coffey)

        A PID (Proportional-Integral-Derivative - phew!!!) controller is a high falutin' thermostat that uses fuzzy logic to stabilize temperature.  With the right setup (insulation, air flow, etc.), and the appropriate PID controller, you can keep the temps inside the oven ± 1 degree.  Not sure how much improvement you would see in a non-convection oven versus a convection oven, but at least the temperature near where the thermocouple would be located would stay within that 1 degree variance.  The beauty of the convection ovens is that the moving air mass inside the oven is constantly moving from the side where the elements are to the other side where the cane is cooking, so the air mass tend to have a somewhat stable temperature throughout the oven,  since the air mass is constantly moving past the thermocouple, the PID controller and it's associated thermocouple are sensitive enough, and have the computer logic built in to it to be able to adjust fractions of a degree temperature wise the overall oven temp to hold it within the tolerances.  The first time you fire up the oven, you set the PID controller to auto-tune itself to the set point, and then it determines how many times per period of time it has to activate the relay to turn on current to the heating elements.  After that, you just let the computer do it's work.  I can even open the oven door, and leave it open, and not notice more than 1 degree of variance.  In fact, when I'm going through the initial phase of the regimen I posted before, I open the door to let the steam escape between 275 and 300 degrees, and the PID controller will compensate, keeping the temperature climbing to the set point.  The controllers run about $230 for the 1/16 DIN size, which is what M-D and I use.  (Mark Wendt)

          What kind of an oven do you have?  I am using a simple electric element in the bottom of a well-designed box, well insulated that can easily keep the temperature as close to 375 degrees. as I want (or lesser temperatures for gluing).  To control temp. I have used two ordinary contact type thermostats installed through the top of the sheet metal oven shell that seem to record temperatures fairly accurately.  (David Parker)

            I built a true convection oven, through the help of M-D, and using Don Andersen's basic set of plans.  There are two chambers in my oven, one for the rack that holds the cane and the thermocouple, and the other chamber that holds 2 850 watt heating elements, and a 1/4 hp driven (through pulleys) fan that's enshrouded by a 6" diameter duct.  The fan blows down one side, over the heating elements, around a radiused piece of sheet metal, through the cane cooking side, back around through the fan side.  Each corner of the box has the radiused piece of sheet metal to smoothly direct the air around the box.  You can see pictures of the oven throughout it's construction phases here.  The beauty of convection ovens is there will be no hot or cool spots anywhere in the oven, due the circulating air mass, something that's darned near impossible to achieve with a non-convection oven.  (Mark Wendt)

              I've gotten more consistent heat in my Cattanach style ever since I put in a steel plate between the heating elements and the wire rack (thanks to whoever suggested it on the list). The 1/4" thick steel plate (which only cost me about $9) fits tight in my oven (width and length wise), absorbs the heat and helps distribute it more evenly throughout the oven (like a brick pizza oven).  I track the temperature at three different spots in my oven and while it isn't exactly the same at all three spots it is a whole lot better than I was getting without the steel plate.   However, I have often thought about adding a fan at the far end of my oven to assist in the movement of the air inside the oven.  (Bob Williams)

                Actually, the PID controller is just a nice thing to have, since it will manage the temperature so well.  However, I think most folks would see an improvement in the repeatability and consistency just by using a convection system in their ovens.  It ensures truly even heating throughout.  I could put a thermometer any where in the cane chamber, and the temp would be identical.  The PID controller is just icing on the cake.  Heck, Don Anderson's ovens were built with a stove thermostat, I believe, and he's reported great results.  My PID controller was gotten 'cause I happened to listen to a smooth talking character, who now happens to be one of my best buds. ;^)  (Mark Wendt)

Rule

Fellow rodmakers ...lend me your thoughts.  I made yet another newbie mistake, or maybe it would be better described as a STUPID mistake, and I'd like to get some opinions.  I was showing rod #4 (ready for reel seat mounting) to an acquaintance and he asked "How strong can something so delicate be?"  Of course I felt obligated to demonstrate and grabbed the tip section and gave it a healthy flex. Snap!  That was the STUPID mistake.  Now comes the  question - It seems to me that the tip should not have snapped, but even more disturbing is that it did not splitter the way I would have expected, with the bamboo fibers flaring.  Rather it snapped like a piece of  wood - straight across.  Does this indicate I might have overcooked the cane sticks and they became brittle?  (The break did not happen at a node.)  Once the section was broken (it snapped about 12" from the tip), I purposely broke it in several more places to see if the same type of fracture would occur.  Some spots splintered, as I would have expected, but others broke clean across.  (Tom Key)

    As you surmise you have a bad piece of cane, or more accurately a bad section of cane rod.

    Healthy undamaged bamboo should have long splinters. A clean break means structurally compromised cane.  Overcooking is certainly a possibility. . .though I'm sure there are others.  (Chris Obuchowski)

    Ed Berg, among others have done some quantitative test with heat treating cane.  Ed's test was relatively simple but pointed out a the relationship between temperature, time, and cane failure.  Ed builds nodeless rods and treats the pieces prior to gluing.  They cast quite nice, and are exceptionally straight given that they are hand planed, and hand bound, as well as very well finished.

    I cannot remember exactly what he found about over heat treating and under heat treating.  (Greg Shockley)

    My first thought is that you did this test too soon after the cane was heat treated, and it was still dry and brittle. It takes a couple months after heat treatment for the sections to come into full equilibrium with the atmosphere, and probably a couple more if the rod is varnished. Too much moisture is no good, but that does not imply that "0" is any good, either. Having said that, let me also say that after reading Milward and Schott on this topic, I did back off my own heat treating a bit, where I used to cook to a medium brown, I now go for just the slightest color change, a look that I like anyway. I would also suggest that after you split your strips, that you test bend every internodal area to seek out areas of weakness. If you find a spongy area, reject the strip.  (Tom Smithwick)

      It sounds as if you over heated/tempered the cane. How did you heat treat, and by what method and time did you use?   (Bruce Herndon)

    I am guessing that you over cooked the cane and it became too brittle in local spots. What was your cooking regime - time and temp; color of the cooked cane; oven temp distribution, etc.. ? Just my thought.  (Frank Paul)

      I was not in my office for a while, but I do think I can provide some hands on information here.

      I use local cane, and I always test my culms before using them. Sometimes, most culms are OK, sometimes, I have to dump almost all. My cane if cheap, so I don't really care. My test is exactly what you experienced. I take a strip of a culm and break it. If I see lots of spiky stringy fibers parting with difficulty, its a good culm. If it snaps like a dry stick, its a bad culm. There are in betweens naturally, and some go some stay.

      I also grill my cane on a BBQ. On the hot coals. It flames and colours in cloudy browns and sometimes almost black. And of course, when I am grilling my cane sometimes, something happens, I leave the cane 'just a second' unattended and it bursts into flames. Then it is really charred and burned. Sometimes it is still OK for a rod, and again my test is a breaking test. When the cane is really black and charred, it still breaks 'stringy'; When totally burned, it just crumbles. So, I don't really know where some people think that overheating it would make a piece of cane break clean as opposed to breaking in fibers. My cane doesn't...

      I think you had a bad piece of cane to start with and heat it or BBQ it or use it as it is, it will always snap as a dry stick. Test your culms before you use them...  (Geert Poorteman)

    In my question posted yesterday (see above) I failed to tell that the culm was flamed to a nice dark caramel color then heat treated in an industrial oven at 350 for 15 minutes.  I think this is very important information I should have added to help give those of you who are responding a better picture of my cooking process.  Once again, I value your input in the hope I will not waste so much effort on future rods, and have a better end product.  (Tom Key)

      You should have only flamed the rod as you described. It sounds like by moving on to the oven for 350 degrees for 15 minutes, the cane was over cooked.

      When you did your flaming, did you notice any moisture or resins exiting the cane at each end?  (Bruce Herndon)

      I think if you flamed to that extent, you do not require any more heat there after.  (Gary Nicholson)

        Not that I have anything new to add but My unscientific findings were exactly as Gary's.

        A couple of makers, well known, (expensive rods) have their culms baked in a powder coating oven until they are deep brown all the way through. I tested and used one of these culms and although the pith was almost completely cooked out the bamboo still broke as strings.

        I think that Milwards research is valid, but I think there was an agenda in place that caused him to skew his conclusions.

        I have a rod that I cooked the cane at 400 deg. for 23 min. I still have it and it works just fine. I won't do it again, but it was a good test. Cooking to those levels certainly does the cane no good, but it does make a stiff rod.

        You didn't mentioned how you flamed Tom?

        I flame and bake. As a matter of process constancy, if you flame you have an unknown or uneven amount of tempering (if you believe that flaming tempers the cane) so in order to normalize the cane I temper it in an oven to bring it to a reproducible known.

        The reproducible rod itself is the result of consistent processes, not one of artistry.

        Cane will break clean around the nodes if you heat straighten it. Do I still do it, yes.

        I think you had a bad culm. Or it could be the flaming technique.  (Jerry Foster)

      You overcooked the stuff. Heat treatment is a cumulative process and you probably gave it enough for 2 rods. Do some test strips and find a heat treatment regimen that works with your equipment without crisping the cane.  (Larry Puckett)

        I was going to put it that tersely, but the necessary courage was not in me that night!  I also think that he may have had some slightly duff cane, like we all do from time to time.  (Robin Haywood)

    If you've been following the comments made by others regarding my "cracked cane" question, you know there is a range of opinions.  My biggest concern was the straight across break in a couple of spots, so the idea of flexing each strip between nodes after splitting makes good sense.  That being said, I'm also pretty sure I cooked the hell out of the strips in the attempt to make sure they would not take a set - a problem I fought with my first three rods. (That mystery was solved after I had already cooked the strips to "well done.") So far I don't feel too bad about my failures since none of the rods have been sold.  I'm sure I will continue to make mistakes for some time to come, but I hope to reach a state of enlightenment some time soon.  For now I will resharpen my plane iron, pre-flex all the strips, and cut down on my heating routine - I love that caramel color!  I'll let you know how my next attempt turns out.  Thanks to all who were willing to give their opinion on this conundrum.  (Tom Key)

      You are right not to feel bad about mistakes. It's the mistakes we make and what we learn from them that makes the learning curve shrink. If you change your process and don't quite get the caramel color you are looking for, I'd recommend purchasing a jar of Jeff Fultz’s cane browntoner. Easy to use and you can go from a light honey color all the way to a rich FE Thomas type browntone. No financial interest of course, I'm just satisfied with the product.  (Will Price)

Rule

I've built a number of Para 15's that I use WF6's & DT6's on to fish and land rainbows well over 5 lbs. This isn't about bragging - it's just the way it is when you live where few do and get to travel to be best water in N. America.

The first 3 I built all suffered the same malady - a set about 15>25" from the tip. All were tempered @ 350F for 15 minutes in a convection oven. The last rod was an experiment in deep flaming. Well I got carried away and toasted the sucker a tad much. Then after I got to final, I tempered it some more @ 350F for 12 minutes. The object of the experiment was to see if the rod would take the punishment. So far - so good. The rod is as straight as the day it was built and over the past 2 years has probably landed 50 or more rainbows over 5 lbs. I'd expected the rod to break around the ferrule point like other rods I'd seem with darker colours.

The flaming resulted in the cane not planing as well as normal with slight amounts of "crumbling" going on where it seemed like the lignin had lost the adhesion to the cane fibers. Still, it lives.

I temper after final planing and compensate 1% in the numbers for shrinkage.

Anybody else overcooked and seen the same result?  (Don Anderson)

    My favorite way is to flame, blister that glasslike coating off the enamel, bundle roughed strips and bake 350 degrees for 12 minutes. I haven't seen a problem with set. There was one rod that I did not flame and baked 18 minutes at 350 degrees to a bright yellow that would end the day with a set. The owner of the rod would put the rod in a bind over night and the set would be gone the next day. I have offered to replace the rod but the guy will not give up the rod. He says it is his "funnest rod."  (Timothy Troester)

    If memory serves, PY used a gas ring that produced very dark rods, if necessary.  The only dark rod I've ever had break was one that received close to your rod's 'punishment,' and it divided neatly around the ferrule pin.  One of the pieces that had to be remade was cut off and used as a guide-wrapping thread gantry (if you'll allow that usage).  The thread comes off the spool and runs thru the tiptop.  Although it bends noticeably, dozens (hundreds?)of guide wraps have left it straight as the proverbial die.  Sorry I don't have more relevant observations to report.  (Steve Yasgur)

    I too have a couple of rods I've made that were crispy crittered (one of them a ten foot 3 wt.) and I use them here on Florida Largemouth.  No problems yet. As a matter of fact, I'm really liking the 10 footer more and more.  (Ren Monllor)

    I have one I call "The Toasted Quad". Over cooked by mistake. Still staying together.

    Feels real crispy.  (Tony Spezio)

Rule

I left a set of strips in the oven for two hours so they were AT TEMP for a good while.  Upon cooling, I performed a bend and break test on a couple.  The strips flexed and flexed until they finally splintered.  They were tough as hell, not brittle and, as you say, slightly darker.  (Al Baldauski)

    There may be something in that Al.

    Mike Montagne advocated heat treating at 140 degrees for 24 hours. I have not tried it because I use a heat gun oven but would be very interested to hear if someone else has.  (Steve Dugmore)

      That's not heat treating, that's more along the lines of kiln drying.  (Mark Wendt)

        Yes - but quite intense kiln drying and maybe that's actually a good, possibly even 'better', way to go. I don't know. As I say I haven't tried it but it apparently worked for Mike Montagne and his rods are apparently not the worse for it.  (Steve Dugmore)

          140 degrees isn't really intense.  Normal kiln dried lumber reaches temperatures of 170 to 180 degrees.  Kiln drying is used for reducing moisture content in green wood.  No matter how long you kiln dry lumber, it will eventually go back to the state where it's in equilibrium with the attendant humidity.  By the time we actually get our cane, split/saw it, it's been pretty well air dried.  It's moisture content will change with the level of humidity.  Drying at 140 degrees will lower the moisture content, but it will eventually work it's way back to the previous levels depending on the ambient humidity.  The only way to effectively lower the moisture content permanently is to reach that temperature where the chemical change in the lignin occurs, so that it's impossible for the moisture content to reach it's previous levels.

          You could leave the cane in the oven for a week, a month, a year, or for a very long time at 140 degrees.  The minute you take it out and it starts cooling, it will work it's way back to the previous moisture content levels.  (Mark Wendt)

      And further to the point - Mike Montagne heated the culms when split in half and with dams removed i.e. before final splitting. The thinking being the heating 'opens up' the culm increasing the effective diamater and thus making for a flatter curvature on the enamel, which is a plus for making quads.  (Steve Dugmore)

        It was a nice theory, but I haven't seen anything in the literature that corroborated that, nor is anybody else a proponent of that.  If it did, it was probably pretty minuscule, and if left, would probably tend to "close" back up.  (Mark Wendt)

          Not sure I agree. The check splits in the culms I have, that were exposed to heat under my sheet metal roof, have definitely widened and not returned.  (Steve Dugmore)

            Maybe so.  But how much of a change in the real radius did you see?  Or was it just the splits opening further?  The splits opening further don't necessarily change the true radius of the culm, though the widening of the split would change the effective diameter, though only due to the gap widening.  (Mark Wendt)

              We need Dr. Schott to do some more tests with his electron microscope and find what really polymerizes. The starch/cellulose/lignin?

              I'll wait for an an engineer type to take you up on the change the effective diameter but not the true radius thing. hehee. Sounds like lawyer talk...a difference without a distinction.  (Jerry Foster)

                Effective diameter versus true radius?  Easy enough to explain.  Lets say you very carefully split the culm into four pieces, and inserted an expanding mandrel in between.  Hold the four pieces in position on the mandrel with rubber bands so they don't move.  Now, expand the mandrel. You changed the effective diameter of the culm, but you really haven't changed the true radius on the existing strips.  This is what widening of a check split does.  I don't know from first hand experience how much flattening would occur from heat causing the 1/4 or 1/2 culm pieces. Maybe a little, maybe a lot.  Just questioning how effective that technique is, is all.  Maybe it's good.  (Mark Wendt)

                  If there is only one check split and it increases in size then surely the radius of the culm has to have increased or there has to be a fold introduced somewhere? The latter is unlikely. It is certainly not visible.  (Steve Dugmore)

        I have to agree that this happens to a certain extent.  We all see it when we flame a piece of bamboo with a check split in it.  The  split starts  out being  1/4" wide  and ends  up  being 1-1/2 inches wide.  So what's happening  Well, IMHO, and no research or data to back this up, just a "gut" feeling (and I have a pretty big gut these days), is ...   The majority of the moisture is being held by the bamboo in the most dense area;  the power fiber pack close to the surface of the cane.  The pith, while spongy, holds very little moisture compared to the rest of the bamboo.  So when we flame it, we are, whether by design or accident, removing a lot of unbound moisture and some of the bound moisture.  When this happens,  surface of the bamboo, I THINK, actually shrinks, so we get this drastic widening of the check split, and yes, I think a little bet larger radius on the bamboo, although I've never measured to see if it's significant.  It would be interesting  know how much the radius changes.  Someone go burn some cane with a big torch, do light medium and heavy flaming and let me know!  I'm going to be too buys stalking the lake and rivers between now and Tuesday, but I'd really like to know the answer.

        I've seriously thought about having my flat cutter that I shave the cutting bed on my new CNC miller, resharpened to a 1-3/4" radius to give the bamboo a more stable base. But, that may be going overboard...  Kind of like putting a Side Saddle on a Hog, ya know.  Who's gonna ride it?  (Bob Nunley)

          "resharpened to a 1-3/4" radius to give the bamboo a more stable base."

          Actually that sounds like a VERY good idea.  Not the hog saddle though. In theory at least.  No need to flatten the rounds then or remove ANY power fiber.  You'd still need to remove the enamel though.

          BTW my memory of what happens is the the culm doesn't just open the split but it sort of open out and flattens a bit.  I usually split the culms before I flame them and it is more obvious what is happening then.  (Larry Swearingen)

          Yabut, when you're flaming, you're generally applying heat to one side only, which is causing that side to shrink more than the other because of the heat differential.  I just don't see that effect being great enough to effectively flatten the radius enough for it to make that much of a difference especially in the narrow width of the strips we use, whether quad, penta, hex or any other cross section.  We typically use what, 1 1/2" - 2" diameter culms?  How wide are the rough strips cut for quads, which to me would seem to be the ones that would benefit the most from the flattening of the radius.  I'll play around in some cad drawings later today to see if I can plot the differences that would show up with the flattening of the radius.  I'll use 3/8" wide strips. Think that would cover the width of the majority of the strips we use?  (Mark Wendt)

            By your own advocacy of shooting for the finest tolerances achievable, why not this one even if it is miniscule? i.e. Why not heat treat a half culm rather than strips?  (Steve Dugmore)

              Because I'm not defining my final tolerances yet at the heat treating stage.  It's still rough material at this point.  How much do you take off when you plane the enamel?  How much do you take off when you sand your blank after glue up?

              I would bet dollars to donuts that you sand off in those steps far outweighs whatever radius delta you might gain by that method.  Can you guarantee equal amounts of radius change each time you do this?  (Mark Wendt)

          I've seriously thought about having my flat cutter that I shave the cutting bed on my new CNC miller, resharpened to a 1-3/4" radius to give the bamboo a more stable base

          Interestingly enough Mike Montagne did exactly that. He advocated using a flat cutter but tilting the milling head/bed to get the desired radius.  (Steve Dugmore)

            Montagne was cutting his pattern boards on an end mill, so it was no biggie just to tilt the head and run the pattern through and you can get any kind of radius you want, but some simple math dealing with the diameter of the mill and the angle of tilt to get a desired radius.

            With mine, it will actually be a little easier. My cutting bed is CPVC sheet and I use a flat milling cutter mounted on the spindle on my machine to shave the bed level. Since my bed does not have a taper in it and the taper is generated my movement of my spindle slide (Z axis) then I can simply have one mill cutter cut at a 1.00" or so radius and I don't think the CPVC sheet will EVER dull it. I'll be able to use it from now on.

            As for different diameter culms, when you look at the difference in the arc  on a 0.85" Radius and a 1.00" radius, which will cover most of the bamboo we'll every use. I think we could get way out of hand with the radiused cutter either forcing us, meaning those who want to do this, to either have a collection of radiused cutters, or to be selective more about the diameter of the bamboo. I think as long as a "Reasonable" facsimile of the average radius is represented on the bed then it will be fine. Actually, most people running mills do NOT worry about this and just shave their beds flat. I know some mighty fine rods come from makers who use flat beds rather than radiused beds.... so I may be just wasting time and $150 bucks or so, but hey... wouldn't be the first time for me to waste either!!!  (Bob Nunley)

              Regarding cutting a concave radius on your pattern board:  I was remembering that I used to have trouble getting my angles right when roughing because the curved enamel side would throw things off in the planing forms.  So I started by filing a very small flat in the middle of the curve so that the strip would lay better in the groove.  I didn't file the flat all the way across the strip because I didn't want to lose any more power fiber than I had too.  I don't know, you may not have that problem in your taper mill.  Now that I think about it you may have. If your strip rocks on the radius the 60° V wouldn't be correct against the enamel side.  Although that would probably only be evident on the larger Butt end strips.  Or if you made Quad rods that could be a problem too. Just the usual over thinking of things that happens so often on this List.  (Larry Swearingen)

              If you radius the bed then at what point of the radius do you use to zero your mill?  If you say the bottom of the radius, then wouldn't any strip with a radius larger than your bed radius not touch the bottom and throw off your dimensions?  Maybe not enough to matter, just a thought.  (Rick Hodges)

          You know Bob you just may be on to something here. I remember some of the list members making some derogatory comments to Darryl Hayashida about his radical flaming/heat treating regiman. One list member even called him an idiot. He never owned or used an oven and flamed his bamboo from the pith side because he preferred blond rods. I believe most of us have seen the pics he posted of his method where he actually set the pith on fire until it was charred and the "sap" could clearly be seen oozing heavily out the end of the half culm. This method of flaming would keep the most direct heat away from the power fibers near the enamel. Darryl also mentioned that his rods had not taken a set even though they were fished heavily. I have no way to prove it but would think that he was reaching high enough temps to get the chemical change in the lignin that everyone strives for with their heat treating.

          While I am thoroughly enjoying all this activity on the list I can't help but think that if our departed friend John Channer were still around we would have heard, "We are building fishing poles! Just how hard do you want to make this?"  (Will Price)

            For the 6 of the last 8 rods I've built I followed Darryll's method and flamed the pith side of the culms with great success and probably will continue to do so on future blond rods.  I've never been happy with my mica strip oven and even tried to convert it to a PID controlled convection oven without much success.  A few months ago I got one of the Harry Boyd/Bob Nunley heat gun ovens but have not used it yet.  However, I expect it will be much better than my mica strip oven.  Since I don't build commercially, consistency isn't as important to me.   (Bob Williams)

    This is a Great Thread!

    The subject of lower temperature and Longer time appears to have merit, I will say that both Payne and Leonard "cooked" for an extended period of time. 24 hrs in one case and over 50 hrs in the other. One flame browned first, the other did not. They both achieved good results as do various builders today -- just look at all the different methods people use and they all seem to produce fine rods.

    Someone needs to do a study on this longer/lower temp method.  (James (JED) Dempsey)

      Reading some of this makes me think that there are several ways to achieve good results. In the name of consistancy, I think you should pick a way that works for you and stick with it. This may be arrived at by the tools you have on hand! Don't need to break the bank!

      Remember this?  (Joe Arguello)

        You educated folk sure make things complex, what with all those big words. I've always referred to this as 'run what ya brung'. That did precede 'measure it with a micrometer, mark it with a crayon and cut it with an axe' by some few years, of course.  (Larry Blan)

    I wonder that nobody brings up all the testing Milward has made about the heat treating issue and written in his book.

    For example he writes in his first book. " I have a a personal bias against naked flam heat treatment. It produced for me, one of the worst rods I have ever scrapped. Despite brown tone and a fast taper; it was soft actioned and took a set any way you cared to bend it. The reason I suspect is that the bamboo carried a lot of moister and that the hot flame burnt the skin with really affecting the inner layers adequately."  (Olaf Kundrus)

      I remember reading that section.  Don't remember whether he heat treated after flaming or not though.  I heat treat all my strips, flamed or blonde.  (Mark Wendt)

        In Milward's Second edition, he disparages flaming cane completely.  In fact, his assertion is that any heating treatment that results in anything more than an "amber" color will permanently damage the cane.  His tests show that while these browner rods may be faster/stiffer at the outset, they break down alarmingly quickly compared to rods heated to much lighter colors and take sets far more readily.  He also refers to work done by one Wolfram Schott, something that has appeared here recently ("Bamboo in the Laboratory").  But of all the heat treating regimens out there, he reserves his severest criticism (more like disgust) for flaming of the enamel side. He says nothing about flaming from the pith side, ala Hayashida.  Never having seen a copy of the first edition, I can't compare the two, so I don't know how much of this is new.  He does give an ideal time and temperature according to his tests, which are very well done and quite convincing.  I hesitate to give away too much in the way of detail, not wanting to get into any trouble or hurt the guy's sales.  That may be, Olaf, the reason not much has been said.  At least to this point.  (Bob Brockett)

          Welp, all I can say is the same thing that I said when this discussion came up 2-3 years ago. First I'll say that there is no change in Milwards feelings on this subject since the first book. Second I'll say there is no change in my feelings either. If Milward and Schott are right then Paul Young was wrong. Out of all the "old master" classics I have had in my hands I have yet to see a Paul Young rod with a set. They haven't broken down after 50-60 years of fishing either. Same for rods made by Bob Summers. I own a heavily flamed rod made by E.W. Edwards that is over 90 years old and still straight and highly fishable. Ron Kusse also flamed deeply.  Either these fellows fly along with blind luck on their side or Milward is wrong in his opinion (and he is entitled to his opinion, I'm just pointing out empirical evidence that disproves his opinion). It's hard to argue with evidence that you can hold in your hand! I could go on and on with more examples but the point has been made by what has already been said.

          Believe what you choose.  (Will Price)

          Now we have Milward's book saying flaming is bad.  With all these discussions we are having I can only wonder one thing: AM I DOING ANYTHING RIGHT?????  I am about ready to hang it up and go strictly plastic.  At least I know they won't take a set, break down from the flaming, humidity won't affect them, they won't delaminate, and they will be perfect clones to each other. Last but not least: They won't have any character.

          Never thought I would long for the off topic post(s), that piss us all off.  At least I don't have to ponder my inferior methods when I read them ;)  (Pete Emmel)

            Don't despair Pete. At least not until your rods start having problems. And plastic rods will occasionally take sets(ask Mike Brooks), they don't break down from flaming because they MELT before they have a chance to break down,  and while I haven't seen it in graphite yet, I have seen fiberglass rods that have delaminated.  (Will Price)

              I had a graphite rod once that essentially delaminated. It collapsed like a bent straw and folded right up just in front of the cork. I talked to a composites expert about it and his opinion (as I recall) there was too little resin in the matrix. It was on a rod that I built from a blank. Fortunately the blank was covered by a warranty. However I had to build up the rod again with the replacement blank.  (Joe Hudock)

            Guess I should add to that earlier post that I have no means for quantifying anything Milward has written.  My intent was merely to pass along a generalization of his assertions to those who haven't seen it in response to Olaf's post.  Right?  Wrong?  I have no idea.  I've got plenty of already flamed culms out there and I'd still do it again, since sometimes I just like the look.  My guess is you'd have to fish hell out of any of them to experience any of the things Milward found in his tests.  So that's what I intend to do: fish hell out of them and let all those little chips fall where they may!  (Bob Brockett)

              I'm just yanking the list's chain. I only build plastic when a customer orders plastic. There is no way I would ever give up God's gift to fly fishing.... Bamboo.    We all have our way of building rods.  Add our opinions in with our egos and there are bound to be testy responses to all these topics.  I guess we can add to the list.   Never discuss religion, politics and now Bamboo LOL.

              My way may not be the best way, but its my way and it works for me.  I never think less of another builder because their way is not my way.  Like I've said before we have everything from the anal engineers to the laid back artist building rods.  Funny thing is all the rods do what they are suppose to do:  Catch fish and give the user extreme pleasure.

              Guess I  did something right on my last customer rod.  He said he was laying out every inch of fly line with it.  And he is extremely happy with the rod.  That's good enough for me.

              Now everybody hit the shop and hand plane, machine plane or whittle some bamboo on 1,5,6 inch centers.  Heck eyeball it for that matter ;).  (Pete Emmel)

                Ya left me out.   My  machine don't plane, it saws...  ;-)  It's funny, you see the same kinds of arguments on metal machining bulletin boards where the old time manual machinists bump up against the CNC machinists.  Funny thing is, most the the very good CNC machinists are also very good manual machinists.  Same goes I'm pretty sure with the fellas on the list here that are purty good CNC guys.  You have to have a good understanding of cane rods to turn out good rods either hand planing or by machine.  Either way, hand planing or machining, the old computer axiom holds true - Garbage in, garbage out.  I'd like to think all the knowledge I've gained over the years of hand planing were a huge help in the design of my machine.  I don't believe there's any way in the world I could have designed my machine to do what I wanted it to do without knowing what I was looking for in a strip ready to glue up.

                The software out there doesn't design the tapers.  Folks using the software still have to have an inkling of what goes into making a good taper for a given length, line weight, and type of fishing/casting the end user is going to want or need.  The software just obviates the need for reems of paper and hours bending over a slide rule or calculator to do the equations.  And what's the point of endlessly doing the same equation over and over again per inch of rod length.  Oh yeah, I forgot, some folks are dead set against the "inch" theory...  But I digress.

                Doesn't matter if you hand plane, or use a machine.   It's still the maker that does the work, and the blood (for Nunley), sweat (for the rest of us) and elbow grease that makes the final product that delivers the rod to the customer's hands, and that big sh*t eating grin he/she gets when he/she casts it for the first time makes it all worth while.  Well, that and the check in hand too...  (Mark Wendt)

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