Official Luthiers Forum!

Looking for some help here and direction. Last week I bent a pair of sides of waterfall bubinga that I purchased a couple of years ago from the Zootman. Of course, it is beautiful. I bent similar to rosewood on the bender I purchased from John Hall. The first side, I bent wrapping it in craft paper, spritzed fairly heavy, and bent fairly slowly. Bent it on a 14 Taylor style mold. When I removed it, there was significant uneven bending. What I mean is: on every 'wave' of the figure it would bend more, and in between would create a 'flat' spot. This repeated very regular with the figure pattern. I was able to even it out 'some'
with the hand bending iron, but not satisfactory. The second side, I used aluminum foil to wrap the side in with a small amoung of spritzing. Basicall the same results. I use spring steel slats and my sandwich from top to bottom is: blanket, slat, wood, slat. Is there any hope for these sides, or any advice for a future bend, I have one more set. I don't have any pictures of it at this time. Thanks ahead of time for your help! Tom Harbin
PS: With the other set, I might look for someone to farm this out to and pay to have it bent for me. I have had no trouble with most of the other woods I have used, rosewoods, magogany (some figure), a set of the 'brain' looking sapele, walnut.

JJ might weigh in here, he has bent this stuff, or you can try a PM.

Hi Tom - Yep JJ had probably the same wood also from Uncle Bob at RC Tonewoods and he was able to bend it. I don't know if JJ was using Super Soft II back then but I think that he is now and this is probably what he will advise you to try.

Thanks guys, hope JJ checks in here!

Good luck... I never could get that stuff to bend well. No matter what I did it had facets in it.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

True bubinga waterfall figure is flatsawn with wide, rolling non-specific grain undulations. It does retain it's figure thru several degrees of radial, however. That can be a bit frustrating bending for sure.

If I can't correct the first set, please watch the auctions for another set for sale! Tom

If I can't correct the first set, please watch the auctions for another set for sale! Tom

Hello boys! I just arrived home...Now I know why my ears were sure buzzing during the trip!

I have indeed bent this wood and it's really not that hard...it's getting the surfaces flat that create the additional effort. I started out at a thickness of .090"

1) Spritz both surfaces with SuperSoft2 and allow to dry overnight
2) Wrap in craft paper and spritz the paper with distilled water
3) Bend in a Fox Bender at 300-325F...at around 225F, crank the waist to about 1/2" of the bottom
4) Set the lower bout and upper bout and final seat the waist
5) Turn off heat at 315F and allow to cool to RT
6) Heat to 300F and allow to cool again

Now it's time to sand and scrape the inner surface flat and even. Then it's time to glue in the neck and tail blocks.

The outside will have undulations and I waited until the top and back were glued up. Start sanding and scraping until smooth and even and only then even think about routing for bindings.

Here's a pic of what you're shooting for.

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JJ
Napa, CA
http://www.DonohueGuitars.com

JJ: very nice! and thanks. What do you think, Would it help at all to rebend after spraying with SS 2? I'm going to try, nothing to lose! Tom

The problem tom is it will be hard to get the proper support fom your slats now that the wood has been bent but with care it might help.

For future referance waterfall quilt some curl figuring will often display this issue. It called faciting and as you have likely assumed it due to the ratical change in the grain structure and direction in these types of figuring. SSII is a great help but with these figures you likely have to do some scaraping to get things perfecty smooth.

Tom sorry to hear you are having problems with the WF Bubinga. Most of the sets were QS to rift sawn but this figure is indeed difficult to bend. JJ's suggestions are very good and his guitar looks and sounds great in person. Keeping about a 1/2" to 5/8" to crank down at the waist after the lower and upper bouts are bent helps to increase the tension on the slats. I think I would start at .080 to .085. Also important to leave in the bender overnite to insure that the side is good and dry. You may still have some faceting but it should be minimized.

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Beautiful and unusual tone woods at a reasonable price.
http://www.rctonewoods.com/RCT_Store
The Zootman
1109 Military Rd.
Kenmore, NY 14217
(716) 874-1498

Bob: thank you! That wood is drop dead gorgeous and certainly worthy of the term Zoot.
Talk to you soon! tom

I've now come to expect this faceting when bending curly woods and just deal with the sanding, scraping and leveling. I've experienced similar results not only with the WFB but also with Curly Cherry and Sapele. I guess it's a small price to pay for using highly figured zoot. If I were selling these, I'd charge a good bit extra for the considerable labor of smoothing it all out.

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JJ
Napa, CA
http://www.DonohueGuitars.com

I just bent 3 sets without much trouble. A book that I read recommended less water and a temp of 340 degrees. When I use the beautiful bees wing set I intend to go very thin and use the double side technique Bogdanovich describes in "Classical Guitar Building" with western red cedar for the inner wood. Any comments?

Steve

Obviously everyone has their own approach to bending....... but I think this problem is a fine argument for using solid male/female forms for bending. I feel they give you less faceting to begin with...especially if you bring everything down very tight and go through a few heat/cool cycles. Those aggravating facets have more chance of 'giving in'. Solid forms also let you check results....then respritz as indicated, rewrap, and carefully place the sandwich back onto the male form. Apply pressure with the female cauls and hit it again with a cycle or two...basically taking up where you left off. I agree wholeheartedly that the slats in the Fox system do not provide sufficient support for this. Solid forms and my high tech blanket system (rapid, even, very accurate controlled heat) is a combination that sure is hard to beat (IMHO )

Tom

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"By the hand of one man".......
Doc's Stringed Instruments, Doc's Mandolins
http://www.docsmandolins.com

I think 2-part solid forms would provide less support than Fox bender slats. The 2-part forms do not provide full support until the side is completely bent, and the two forms have totally engaged, whereas bender slats support the wood throughout the bending process. And the facets are created during the bending process. The support provided by the steel slats is the real key to the success of the Fox bender. Now if you used steel slats with your 2-part form you would have full support and probably the best of both worlds.

Barry I was going to say exactly the same thing. One issue with a positive negative form is there is no way to use as a cutaway unless you have a hinged section for a cutaway upper bout. Besides most faceting is caused de to radical grain direction changes.

The best method I have ever seen is impractical for 99.9899% of us and that is ammonia gas bending. Where the wood is exposed to high levels of ammonia gas that temporarily plasticizes the wood fiber then the gas is evacuated and the wood quickly recovers. But this requires extremely specialized air tight equipment and gas storage and I assume permits to use.

Tom (mandomaniac) uses blued spring steel slats on both sides of his bending sandwich. Everything is supported fully "during the ride." A bunch of luthiers have Tom's silicone heat blanket system, and are achieving superb results. Most (inlcluding my only two bends so far) have bent using the typical, individual clamping cauls over the sandwich on top of a solid male bending form. Tom has shown some very impressive bends, including extremely tight mandolin cutaways, using solid forms inside and out. (I believe he has done some with individual cauls as well.)

Tom is a bright, knowledgeable, witty, and likable guy. FWIW, I can tell you that Tom is not theorizing, he is passing on his knowledge from his experience. Note that he is addressing "this" problem (faceting in some figured woods), and not recommending that all bending needs to be done (or will benefit from) exterior solid bending molds.

Dennis

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Dennis Leahy
Duluth, MN, USA
7th Sense Multimedia

Wowza...you'd a thunk I proposed the earth was round!

In the interest of those that might be open to pondering this approach to the problem, some clarification seems in order....

First...it appears we have terminology differences. When I consider a Fox style bender, I think of the 'slats' as the steel cross rails joining the two sides of the form. The thin sheets of steel on either (or preferably both) faces of the side to bent I do not call slats. I call these shimstock, and they indeed are DEFINITELY a major factor in bending successfully. They do indeed support the wood when it is away from the form in the initial stages of the bend.

Second....My point was the final shape of the side is affected by the support it has in the final stage of bending. That time when it is pressed against the shape of the form. The wood is still plastic at this point (or should be!) and small variation in the form will definitely appear in the wood. I might add that I feel this matters of BOTH faces of the side. I completely agree that the facets in 'difficult' woods are due to the grain....but if the final pressures those areas see cause the facet to bend just a hair more ....well....less facets!

I feel the Fox bender has open spaces between each crossrail where it relies only on the shimstock to support the inside face of the bend. On the outside, there is only the shimstock and a waist caul. Solid forms are just that....solid. There are no gaps. When you bring the male and female tightly together with a plastic side between (yes....with steel shimstock on each face!) ....WYSIWYG !!!!

Now ..obviously....the female form must be 'strategically divided' to enable you to even use it!
There are any number of ways....from hinges to simply using the divided sections as individual cauls that still act as a solid female form when brought down into final position.
It can be done with cutaway sections as well.

In any case.....hopefully that adds some clarity. Solid forms are cheap and easy to make. Might be worth a try.....

Tom

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"By the hand of one man".......
Doc's Stringed Instruments, Doc's Mandolins
http://www.docsmandolins.com

I have Tom's system and made my own solid forms - I have had great success in bending cherry and mahogany (I know, both relatively easy to bend) and will be trying some figured bubinga soon. I have the solid female cauls - one in the waist section, one each over the upper and lower bouts - and some straight cauls that bolt in at the bottom of each end -

Never had a problem bending yet...but I'm still a newbie

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Mitch