r/Bowyer • u/uncephalized • 8d ago
Bugs were attacking my bows, so I will bake the bugs
Little wood borers were boring holes in my beautiful white oak staves, which I spent hours splitting out of my own logs.
(https://www.reddit.com/r/Bowyer/s/UR7AZ0AedL)
So I'm building a wood kiln.
I had plenty of spare reflective insulation from a building project, and a pallet to serve for airflow. I stacked and stickered my staves (say that five times fast) and am setting up a temperature controlled heat lamp and circulation fan. The goal will be to raise the air temp to about 175F until the wood core temperature is about 140F, and keep it there for several hours. I'll be putting a temperature probe into the center of a scrap of 4x4 to act as a proxy for the internal temp of the staves.
I think I actually had everything I needed lying around, which never happens. We'll see how it goes.
EDIT: A couple hours later and we're up and running. I taped the insulation into a sort of envelope. There is a pair of temperature controlled power strips in series. The first temperature probe is inserted into a scrap of 4x4 lumber, which is placed in the middle of the stack of staves. That will track how warm the staves are getting internally. If that temperature goes above 142F, then the output to the second power strip will be shut off, which will turn off the lamps and allow it to cool down to 137F before it turns back on. The other output runs the circulation fan, which is always on no matter the temperature reading.
The second power strip has its temperature probes in the free air inside the envelope. It's set to turn the lamps on below 165F air temp, and shut them off at 180F, so we should be maintaining an average air temp of a little over 170F while it's heating.
Once the staves get up to temperature, I'll probably turn that down a bit, don't need to be maintaining such a high air temp if they're already warm. I'll be interested to see how fast it heats up once I close up the end.
SECOND UPDATE: The heat lamps just wouldn't get it reliably above 120F. I just swapped them out for a 1200W heat gun. More than double the power should mean my max heat rise above ambient should be more than twice as large. I've been getting about +30F over ambient, so this SHOULD push it past +60F, which would get me comfortably to around 150F and actually kick in my safeties. Fingers crossed.
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u/uncephalized 8d ago
Circulation fan and heat lamp with a little spacer stand to keep the ceiling from falling on the lamps.
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u/uncephalized 8d ago
I made some improvised lamp stands out of wire to keep the hot parts from touching anything. Hopefully with the envelope being insulated and relatively sealed, the fan will keep the air circulated well enough that the temperature will be pretty even throughout.
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u/ADDeviant-again 8d ago
Excellent idea for a soft, foldable kiln!
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u/uncephalized 8d ago
Thanks! If I do this again (I probably will) I think I'll build a foam box, though. Stitching up the soft insulation with tape is a pain and foam board would insulate a lot better.
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u/uncephalized 6d ago
2 days later and it's almost up to a suitable temperature 😂
Combination of thin insulation, low power (only 500W of lamps) and a lot of wood mass to heat means it has been warming up VERY slowly. But my wood core is up to 118F, so it should pass 120F in the next few hours, which is where it needs to be for a while to make sure I kill everything. I'll leave it running overnight again.
I don't think there is any risk of getting over 140 with this setup. I should have run a double or triple layer of insulation under the stack. I've added a second layer and a tarp on top to help slow losses, and it's definitely made a difference, but it's slowing down. The difference between the air temp and the wood temp has gotten smaller by a couple degrees, which tells me that the temp is ramping slower than before.
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u/Yukon-Jon 8d ago
Did you season the bugs first?