Author Topic: Vacuum Kiln?  (Read 943 times)

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Offline SDBurntStick

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Vacuum Kiln?
« on: February 28, 2022, 04:16:45 pm »
Anyone have any experience with vacuum drying wood?  Just curious if this has been applied for bow staves by anyone on the forum.  Seems promising and a quick way to dry wood without checking.  Not exactly primitive but looks interesting.

https://youtu.be/-I9DygHrLCo (-S

Offline bassman211

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Re: Vacuum Kiln?
« Reply #1 on: February 28, 2022, 05:04:46 pm »
No ,but I tried kiln drying Amish wagon wheel hickory staves once. That didn't work out very well. If you go to utube, and look up the fire hardening method by Doug Shannon, and Thad Beckham, and now Clay Hayes you will see them make a Fresh cut sapling to a finished bow in a couple of days. Little cost with good results, and it does work.

Offline SDBurntStick

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Re: Vacuum Kiln?
« Reply #2 on: February 28, 2022, 06:08:30 pm »
I was more thinking this could be done on woods like Osage that take a long time to season.  I finally found some osage that I was able to cut and now it's just a matter of me having the patience to wait for the staves to dry and season.  I do really like the white woods for being able to cut and have a working bow in a short period of time.

Offline Hamish

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Re: Vacuum Kiln?
« Reply #3 on: February 28, 2022, 06:24:31 pm »
I wouldn't go putting a nice osage stave in a vacuum dryer without doing some tests first.

I would also consider what the stave will do as its dying, eg reflexing, twisting? Does it need to be strapped to a form?

Osage really doesn't take too long to get a shooting bow if you want to rush it, conventionally. You need to get it to floor tillered size, a little wide at the tips. Shellac the back well to stop the chance of it checking.
Staves only take a long time to dry if they're left as a quartered stave, with lots of waste wood.

You can steam it whilst green and that will dry it out very quickly, and you can put a reflex in at the same time.

Then you have the heatbox option too. You can bring a stave that has lost most of the moisture, but not fully seasoned, down to ideal moisture.

Dean Torges book Hunting the Osage Bow details the entire procedure.

Offline SDBurntStick

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Re: Vacuum Kiln?
« Reply #4 on: February 28, 2022, 08:57:31 pm »
I would also consider what the stave will do as its dying, eg reflexing, twisting? Does it need to be strapped to a form?

I would think that would be a concern regardless.  The internal tensions of the wood will show up during any type of drying but I think the idea here is that the release of the moisture from the wood is at the same rate throughout unlike heating or naturally releasing moisture.

Under vacuum the moisture may release more consistently.  I thought the idea was interesting so just curious if anyone had experience with it.

Offline Hamish

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Re: Vacuum Kiln?
« Reply #5 on: February 28, 2022, 11:46:39 pm »
 
 
"I would think that would be a concern regardless. " Yes it is, but you made no mention of what you would do, it sounded like you were just going to stick your primo stave in and hope for the best. That's not a good option without knowing the potential  risks and how to combat them, so I just wanted to bring it to your attention, before you took the plunge.

It is definitely an interesting idea. You might have to be the pioneer when it comes to how suitable the process is for bow staves, and different species of wood.
Its an area that might yield good results, but it would need a fair bit of research.

I haven't heard of it in old methods from the pre fibreglass golden era of archery. I do remember at least one article that mentioned the idea of infusing green bow staves with PEG polyethylene glycol solution( no vacuum necesaary). Woodturners use it to turn green wood. I don't know if they actually tried it with staves. It would quickly allow the wood to season without degrade. Not sure if it would have a positive or negative effect on set, or cast.
From the same era pressure treating timber, to increase the density, and strength of lumber was also suggested. It seems to work best with softwoods, and was using successfully to create extra strong, and durable arrow shafts.
Once again I can't remember any successful results for bow staves. Fibreglass backing and facing became the standard for archery bows and the industry and they lost interest in further research down these avenues. (so there may  be some promise for wood bows in these areas of research.)

bownarra

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Re: Vacuum Kiln?
« Reply #6 on: March 01, 2022, 02:06:47 am »
I'd follow what Hamish said regarding quick drying :)
Osage doesn't take long to dry out if reduced to a stave-sized blank and not a log!