I just finished heat treating a set of strips for a 2/2 7'6" rod. I tried something a little different, that I saw on the list. After rough planing, I then planed the strips to .025" over final dimension (I did not soak the strips first). I also hollowed out about two inches of the butt end of the butt section. Just enough to insert the sensor from my Fluke electronic thermometer. I had the oven preheated to 375°f and planned 9 minutes. for the butt section and 7 1/2 min. for the tips. After this amount of time the core temp of the butt section was about 240°. I let it go to see how long it would take for the core temp to reach oven temp. After 15 minutes. it still only read about 345°. I started getting nervous and put it out.  I use a heat gun oven that I built myself. I use two sensors on my thermometer and the temp stays fairly constant though out the oven. Always before, I heat treated the sections after rough planing, before any tapering. I've have seen a lot of heat treating recipes and often wondered how much heat got to the core in that amount of time or if all of the moisture has been driven out.

I'm sure someone has tried this, but for the short amount of time that I have been on the list,  have not seen anything on this subject. When heat treating rod sections, shouldn't the heat treating temp reach the core? Like I said, this time I'm only .025" over final dimensions and the enamel removed. I know the outer layers of fibers have been treated, but shouldn't they be treated to the core?  (David Dziadosz)

I would suggest you get a hold of a set of M-D's fixtures.  He and I use the same basic heat treat regimen, because our ovens are pretty much identical.  We put the strips attached to the fixtures in a cold oven, turn it on with a set point of 350 degrees.  Once it reaches that temp, we hold it for 30 minutes.  At the 30 minute point we set the set point to 225 degrees, hold that for an hour, pull the fixtures/strips out of the oven, let 'em cool down, take the string off, and "viola"  done deal.  I would think the strips get much more even heating, due both to being strung into the fixtures, and because of the ramp up time to get to 350 degrees.  Plus, the fixtures do tend to hold the heat better, and it takes a while for them to cool down.  Just ask M-D.....  ;^}  (Mark Wendt)

I looked at his fixtures at the SRG, and thought they were the cats meow. My oven hangs horizontally, I used a small rack for the cane to slide into a 2" tube. I didn't think three of his fixtures would fit in it at one time (for a 2/2 rod), also I would have to modify my binder for the larger diameter fixtures. Otherwise I would of snatched up a set.  Sounds like your recipe is for soaked strips. These were planed dry.  (David Dziadosz)

They do work great.  With the same type of oven as mine, I would think you could probably use the same regimen, soaked or unsoaked. The drying stage is just to squeeze the last available bit of moisture out of the cane that you can.  Realize that the temperature control in an oven like mine or M-D's is a lot tighter than with a heat gun or thermostat controlled heating elements.  What I mean to say is, the PID controllers we use are thermostats, but they have the technology to keep the oven set point temperature ± 1 degree F, even with the oven door open.  This was a heat treating regimen that M-D worked out specifically for these types of ovens, and it works very well.   Not sure  how well  it would  work in a non-PID, non-convective oven.  Nope, no financial interest, just a happy customer of a very good friend.  (Mark Wendt)

Since it was Mark who suggested it ;o). . . . The fixtures (gizmos for Harry Boyd. It's a Louisiana thing, y'all) allow the heat to enter along all three sides of the strips, simultaneously, thus defeating the insulative nature of the bamboo. Bamboo, like most all cellulose, is highly insulative. Then we have the added benefit of straighter strips owing to the  bound bundle being as straight as it could ever be, plus you now have the ability to heat treat only one, two, three, etc., strips at a time, should that be necessary.  (Martin-Darrell)

Heat treating is confusing to a lot of rodmakers. I believe so because of the lack of "break testing" done on their cane. Try a regime of heat treating that sound reasonable and then break the strips. What you want is no quick snapping and what you do want is stiff cane that break with a good amount of force and splinters into long fingers.  Now as for the internal temp of cane reaching the external temp of the oven, think about it like this: When cooking a turkey the oven is set at 400 degrees but the turkey is done at 170 degrees. If the turkey reached the oven temp it would be charcoal the same goes for cane.  (Adam Vigil)

This discussion got me wondering.  We want even heating in the sticks, when heat treating.  To achieve this, some folks turn their sticks part way through, or use a fixture.  However, following the turkey analogy, a smaller turkey requires less time to cook than a larger one (which may require less time per pound, but that's another story...).  If the rod is already tapered to it's final shape, if not it's final dimensions, then the distal ends of the sections will be smaller than the proximal ends.  Won't this result in uneven heating?  I was thinking that it might result in too much cooking for the smaller part of the bamboo, or not enough for larger ends.  Or is the taper not significant enough to have an effect on the heating of the cane.  (Jason Swan)

This is the first time that I've tried tapering the strips before heat treating. Always before I would plane the strips to a straight 60°. I split the tip strips smaller than the butt strips to eliminate excess planing. So, I heat treat the tips for a shorter period of time. I'm guessing that the layer of power fibers is fairly constant throughout the culm and the closer to the pith, the softer the fibers are anyway. So even though you're not heating to the core the densest fibers on the outside are being treated. Maybe this is why some are having good results with tapering the strips before heat treating.  (David Dziadosz)

I believe you are correct. I used to rough taper the splines before heat treating but no more!  (Marty DeSapio)

That's one of the reasons I don't plane a preliminary taper into the strips before I heat treat.  I figured I'd want to have all the variables the same for a given regimen.  (Mark Wendt)

That seems safest.  I'm curious to know what others, who do plane a preliminary taper, have found out.  (Jason Swan)

This is my line of reasoning, as well, but there are those on this list who taper first, then heat-treat, who don’t seem to have problems with their rods. Bob Milward does it this way. So? Beats me. I'm  still  sticking  with  my  original  premise.  (Martin-Darrell)

I once tried planing down to .020" over final dimensions before heat treating & ended up "overcooking" two different sets of tip strips - they broke off in the binder when gluing. I finally got a good tip section for the rod by planing a 60 degree angle in the strips & leaving them at about .200" That seems to be the best method for me & it's what I've done ever since.  (Tom Bowden)

Now you are thinking. You are correct and I personally heat treat untapered strips wanting to achieve consistent treatment. Thin areas come to temp much quicker then thick areas. Those who do heat treat tapered strips and achieve good results are working off experience many of us do not have.  (Adam Vigil)

I use a "stove pipe" oven and heat gun for heat treating also. A while back I got lazy and  forgot to closely watch the temperature. It got up to 400 degrees for about 5 minutes and that was all it took to really "brown" my preliminary planed butt and tip. I didn't finish this rod for fear that it was "TOO" brittle to hold up. My preferred time/temp is 350 degrees maximum for 20 minutes starting cold.  (Don Greife)

When you say "starting cold" and "for 20 minutes". What type of heat source do you have?  I use a heat gun with a rheostat element control. It takes a long time to bring the oven up to temp. but the temp is more even through out the oven. I can set the rheostat and let the oven warms more evenly. I have used a heat gun that had only high/low settings and couldn't regulate the temp. very good. Temperature difference from end to end, and was too much and set point differential was way too much. I used smaller diameter pipes thinking it would build up static pressure and would move the air through the oven better. I figured if the pipe was too large the air flow would just peter out at the end of the pipe the the heat would just drift out of the exhaust pipe. Causing uneven oven temps.

Most all regimens I have seen are, heat the oven to a certain temperature and then put the sections in for so many minutes. Even if the core is not brought up to oven temp, the outer layer of fibers are being treated and that's what counts. The closer to the pith the less dense or softer the fibers are and maybe they don't need as much treating. I would think that higher temps. for shorter time would temper the fibers better than at lower temps. for longer periods of time.  (David Dziadosz)

Are there any thoughts - of course there are - as to heat treating the sticks after the nodes have been pressed and flattened, but before soaking and rough planing?  The reason I ask is that it seems if the drying step can be removed between rough and finish planing it would save time.  If I remember correctly, some builders even re-hydrate between tempering and finish planing, so I do not see that soaking after heat treating is an issue.  (Tom Key)

I've nearly always experienced a second round of straightening after soaking since a slight residual "kink" always seems to want to reinstate itself in the water. (Especially when you use a hand mill, since you want them as straight as possible.) So, I would think the time saved in the planing process is lost to a second round of straightening... JMHO...  (Mike St. Clair)

I was reading Bamboo in the Laboratory, and was interested to read that it took about 20 days for much of the water to be regained and the shrinkage to be reversed (depending on ambient air conditions).  Do you all wait that long to start planing after heat treating, or do you wait a few days and then plane?  If one planes and glues rather quickly, will the glued up sticks stop much of the water absorption as compared to just strips laying there?  (Louis Devos)

I've found over the years that if I start planing right after heat treating, the planing "feels" to be a lot harder.  If I let the sticks set for a day or to, and they start stabilizing with the humidity, the planing seems to go a lot easier.  I've noticed the difference in situations where I've had to replace a spline due to fat finger planing, or because a hidden flaw showed up during planing, and replacing it with a recently heat treated spline.  There was a noticeable difference in the ease of planing the older splines than the new one.  (Mark Wendt)

After heat treatment, I weighed the strips and watched for weight increase. After about 2 days, they were no longer gaining weight. Still, I added 2 days to be sure.  (Don Anderson)

Gluing up won’t stop moisture absorption but it will slow it down a lot.  How much I don’t know.  I do know that if you measure a freshly heat treated section and compare it to a re-humidified section you will find a growth of about 4%, more or less depending on the time of year (RH in your shop).  So if you don’t wait for moisture equilibrium you’ll wind up with a rod one or two weights heavier than you expected.  You can accelerate moisture uptake by placing the strips in a PVC tube with some water in the bottom but not toughing the strips.  Leave them in there for a day, take them out and let them stand for two days in open air and they will be VERY close to you ambient humidity.  (Al Baldauski)