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Sep 22, 2023 - 6:10:13 PM
1346 posts since 11/10/2022

Has anyone used an autoclave or simple vacuum chamber to build laminate rims? or block (gut feeling is autoclave wouldnt help block rims as much)

Some big name guitar manufactures autoclave guitars in a claim it ages the wood, then charge premiums. Any thoughts?

I have access to some very expensive aerospace claves and was thinking of giving it a go.

I used to autoclave resins until i learned a cheap sonic vibrator with heat control worked just as good. The autoclaves I have access to mainly cure laminated aerospace materials...boy do they remove air and are capable of incredible heat if needed.

Sep 22, 2023 - 9:15:47 PM
likes this

Bill Rogers (Moderator)


27576 posts since 6/25/2005

Wouldn’t the heat break down the glue joints?

Sep 22, 2023 - 10:10:34 PM

5293 posts since 5/29/2011

I wonder how close the process would be to torrefaction, the process of baking wood to remove excess moisture. Instruments made of torrefied wood tend to sell for a little more than those built by the normal means.

Sep 23, 2023 - 4:36:42 AM

15668 posts since 6/29/2005

Certainly is an interesting thought.  Knowing nothing about autoclaves, I did some research and saw ones that look like something between a pressure cooker and a house painter's pressure pot.

I have used a pressure pot to pressure cure epoxy and urethane parts. and they work for that, likewise as a vacuum chamber.

Are you thinking of putting slats of wood into an autoclave to steam them, then doing the lamination itself in some kind of form?

Sep 23, 2023 - 5:29:47 AM
Players Union Member



17294 posts since 8/30/2006

I haven't used an autoclave to perform mischief since 1967.You mentioned the removal of air and I suppose any and all void, I totally support an autoclave with obvious heat control if that's all you have.

Since you mentioned moving forward to simpler heat controlled sonic vibrator as an alternative, then I concur that simpler is better. Working simple is hard, difficult and employs the most noggin in the least amount of time; mostly accidental and usually beautiful.

I am a big Formula One fan where carbon fiber autoclaves used excessive heat and pressure to obtain results necessary to produce needed quality control and light weight; until McLaren published that by experimenting with heat and pressure parameters resulted in temperatures as low as the high 200's F. and pressures much lower to cook carbon fiber components to the same safety and QC meaning low void with fiber sheets cross laminated for strength, then cooked to perfection in much less time and trouble with much greater environmental disturbance like emphyczema (sp) for autoclave operators.
Ping used high pressure/temp autoclaves up here and began to subcontract F-16 parts right close to Luke and Edwards.

I assume many other aerospace companies then went the way of advanced F1 technology. Like the Chinese and Russians and now the Indians.

I disconcur about the marketed advantages of Torrefication to make a latitudinal "brick" rim make better music by removing water from the wood.
It is mummification in my opinion.  And they do sound better, but vintaging is so much nicer for resale.  

So I really support the use of vibrations to wake wood up, especially Earl Scruggs use of "Hi-Fi" speakers to reawaken his banjos after storing them in his cases. I hear cows like country music and rats like rock and roll. Some research about what Earl played for his banjos is then needed to see what he used. Banjo?

I use big band music in my shop because their ain't no symphonic bluegrass orchestras, nor anything like that yet. Appalachian Spring by Copeland still gives too much credit to those egotistical fiddlers. "Rocky Top" with Earl and a few others as soloists are close but no synchronic yet. It's too difficult with so many different right hands playing the "same."
"Orphan Girl" by Crooked Still w Cello are the best I jam with to wake wood up.  The Cranberries get jammed to.

I don't support the use of vibrators on top of new instruments to make them sound like old instruments like Jackson Browne and so many other trend followers.

I think playing the instruments is the better way and allows them to speak with each other and sing instead of humming to each other.

I was a Medical Equipment Repairman MOS 208.5 in Germany from 64-67.  I was assigned to a 400 cot Evac hospital with about 1 half dozen Hueys.  You've seen MASH with 50 beds and one chopper.  OK then we had real surgeons and real babes for nurses and real whiskey and a still @ 220v.

So the Korean veterans would wait until the IG was over and having gone to "town" and purchased a few fresh chickens and borrowed some fresh asparagus from the edges of the German farmer's fields and walked in the dark over to the German taverns for some beer to marinate the chickens in.

See the difficult part was showing up out in the country with fatigues on in different parts of the country at night.  They hate Russians, you see.

So then we would fire up the kerosene (diesel) powered autoclaves and cook those chicks I mean chickens and asparagus to perfection so we didn't have to eat Army chow on an aluminum tray on the fender of a deuce and a half in the rain. It's misappropriation and the beer, too.  No names just miss demanners, I mean misdemeanors.  And the autoclaves were perfectly innocent and sterile.  Some fire extinguishers were guilty of chilling beer, but they were "cool."

So that's why I totally support your use of autoclaves to gently pursue the curing of laminated rims without damaging any innocent lammies.

See the attached video. from my home page.

Aside:  (  Joshua fought a battle at Jehrico, this much is historically correct.

1. The Lamb Ram Sheep horns began to blow :  That's the Bass

2. The Trumpets began to sound:  There's the Treble

3. Joshua commanded the People to Shout:  There's the chaotic dissonance.


So Joshua used Hi Tech with simple nothings just laying around, like good luthiers use what is at hand, and poetic language was all they had Oops.

I'm a rolling stone,  if there ain't no tracks, I go off road with my 12" ROUND THING ON A STICK.

Have a great weekend Not Yoda.

Sep 23, 2023 - 11:47:51 AM

1346 posts since 11/10/2022

I had a few thoughts. One is on resin. There are a few choices to use resin used on aero radomes to bind the wood instead of glue. Some advantages if cured properly are the wood would never delaminate, the rim would be very impact resistant, rim would withstand fire if completely covered after finish, rim would last a very long time.

But these resins need cured at high temps, thus the autoclave.

I thought I would take the wood rim strips and do several steam, bend, steam , bend cycles in autoclave using POSITIVE pressure.helps things bend.

Then glue the laminates and place in a steel form\clamp and autoclave with NEGATIVE pressure(vacuum) under a mild temperature vs time profile. This Should take out most moisture.

Then finish the rim with stain. Coat entire rim with epoxy and do another autoclave cycle.

I may end up with a deadly weapon instead of something easily machined. Who knows how a rim this hardened would sound...


use traditional glue under this process using much lower temps inside the autoclave

Autoclaves are basically cure and\or test chambers where pressure and temps are controlled over time. Some polymers and resins require complex temp\pressure cycles over days to cure\form right. You can control the cooling rate.

But i have no experience with aging wood at high temps and pressures. Maybe someone does?

The resins are in a family of composites called polyimides, for your reading pleasure.

Sep 23, 2023 - 11:52 AM



921 posts since 8/13/2015

Clamps work purdy good…


Sep 23, 2023 - 2:42:39 PM
Players Union Member



17294 posts since 8/30/2006

Thank you for the clamps comment

Yoda, no one has taken laminating rims forward to any degree lately.

Don't the community take this lightly: the last phase in this musical development that is uniquely American and world enabled and copied is bluegrass which is like the Irish immigrants in "The Streets of New York." The early immigrants take on the new immigrants entitled by their entrenchment, not their so-called heritage. We all walked out of Africa.

So making steps to use new technology with "older" concepts is evolution just letting the river flow around immoveable objections like clamp divots.
I think the new kind of lammies' sound would also depend on how many grain fibers per square inch and the nature of that particular tree, plank and place in each plank. In other words it might just become possible to accurately voice a rim.
I am one who hears voice in rims and can demonstrate that with the same hardware. and identical set up.
The same equations do not take into account the living, playing banjo.
A 3/4" thick 3-ply bluegrass block has the separate laminations manipulated so nobody cuts the outside lamination completely away to get the necessary 10-3/4" O.D.   But you already know that.
I like this.

Edited by - Helix on 09/23/2023 14:49:50

Sep 23, 2023 - 3:08:23 PM



23233 posts since 7/6/2005

Try it. Then you can give us a full report, so we'll ALL know!

Sep 23, 2023 - 5:19:17 PM

15668 posts since 6/29/2005

I'd love to see how you do it!

Traditional catalyzed laminating glues need temperatures higher than 70F.  I cure the glue in my rims over 100F.  The autoclave might be a great way to cure at a high temp

I still don't see how the laminations would be clamped, but I'm sure you have figured that out.  I'm hoping you'll show pictures when you do this.

Sep 23, 2023 - 8:42:41 PM
Players Union Member



17294 posts since 8/30/2006

By vacuum and "adjustable heat" no scorching.

Sep 24, 2023 - 6:30:35 AM

140 posts since 5/31/2009

If you can find a use, great. Im not sure what you would be trying to accomplish. Better tone? Stability? Durability/longevity? Simply a different way of doing things?

It doesn't seem you are doing the whole "solution in search of a problem" thing, so good on ya.

Tou might read up on stabilized wood. A lot of knife handles use it. Geoffrey Ellis uses it in aome of his wooden flutes. Maybe the process will give you ideas on how to utilize your equipment for banjos. Good luck!

Sep 24, 2023 - 8:29:18 AM

1346 posts since 11/10/2022

Rube Goldberg approaches are mainly for fun. Fun is the key ingredient to my hobbies.

These are also not my autoclaves. At over 2 million each I am only "thinking about giving it a go". Last year, We made carbon fiber knives in them and auctioned them off for charity. The claves are heavily used except at year end plant shutdow. We are just brainstorming things we could make in that 2 week December window.

Another feller wants to make airless atv tires. Scaled down versions of those already made for hum vees.

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