Bending Figured Woods - Maple

[Prostheta]

What are the relative differences between bending flamed, quilted and birdseye maple for ~1.0mm-1.5mm sides in terms of grain orientation, amount of spritzing required and spring back? Which more likely to split (flame, IIRC) when bending, and which require more "babying", less/more water, higher/lower temp, etc? I understand that flame is more prevalent on quartered, and quilted on flat sawn which I guess would have an effect.

I have a decision to make on which figure to use for the sides of a semi-hollow i'm making which has had the small radii designed out, but this is my first adventure into the world of bending woods. I don't have any hardwood scrap in the right thickness to practice on unfortunately, although if there is a good "break in" wood to learn from, I would appreciate a recommendation so as not to potentially waste gorgeous figured stock.

I'm not making a mould for this one, despite being hugely tempted to do so. It will be a hand-form glued to a 1cm thick maple core, so there is some leeway in terms of how accurate the bend has to end up...perhaps...

Thanks all.

Edited April 5, 2008 by Prostheta

[fryovanni]

There is a big difference in the grain of curly vs quilt vs birdsey.

Curly- Best figure is displayed when quartersawn. The grain rises and falls in small waves. Creating a rolling runnout. This is from what I have found to be the most likely to "crack" in a tight bend. It is managable, but you need to be extra careful to get an even heating well ahead and behind the bend, if you don't it will focus the tension and that is when it will crack. Thin the wood around tight bends, do not try to bend thick.

Quilt- Best figure is displayed in a flatsawn orientation(generally closest to the outer part of the log,FWIW). The grain rises and falls in wider patterns and generally has a bit more twist and mixing going on. This is not as prone to cracking, because the grains runnout is broader(generally speaking) and not at as sharp an angle in relation to the face. The flaw that is more likely with this figure would be seperation in a tight bend(more akin to shake). Be careful with how much moisture you use because it will create other issue with distortion. Again do not try to bend thick in a tight radius.

Birdsey- Flatsawn shows this figure, and the density of eyes increase closer to the center of the tree, often times birdsey develops a mild quilting figure. If anything, the quilt will pose the biggest distortion issues. The eyes of course create spots of high density and low density that can create issues(especially surfacing issues with blades).

Take it easy on the moisture, these are not woods you want to soak heavily. The mix of exposed endgrain and sidegrain make them suck up and release water irregularly. Be sure to get the wood up to temp ahead and behind the bend (don't create spots of focused stress), support the wood very well (back and face) while bending. These woods are absolutely best bent with heat blankets and a good solid form. If you use pipe, be sure you have several extra sides, there is a very good chance you will break a set or two.

Best of luck!

Rich

[Prostheta]

Thanks Rich - that's exactly the info I was hunting for. I was hoping flame might be more forgiving than quilted (or at least more manageable than as not) due to the shallow depth of the sides on the instrument build. 1-1/2" of depth seems more suited to flame as opposed to quilt.

I'm definitely going to invest in a steel bending form, but a blanket and mould seem a little excessive for a one-off use - until I go through several sets of sides of course ;-D

I've decided to design out the radii around the top and bottom horns and to sharpen them up like a florentine cutaway has (to extend the acoustic/solid cross here) so the major radii are the waist and body and seperate pieces for the cutaways. I'll bind the outer corners of the horns.

The build is going to be a semi-hollow brethren of my wife's acoustic:

Back

Front

Multi-lam binding with a super-Strat style design.

Hell - i'm going to buy both sets. If the flame breaks, I'll go quilt.

Edited April 7, 2008 by Prostheta

[jammy]

What a concise, useful, well worded reply Rich!

[Setch]

As others have pointed out in other threads, a heat blanket will pay for itself the first time you avoid snapping a side and having to buy a replacement. Given that this is your first go at bending, and you're using a wood which is eye-catching precisely for the reason it has lots of runout, I'd buy a blanket without hesitation.

[Prostheta]

Thanks Setch. Does anyone in the UK manufacture/sell heat blankets or is LMII pretty much the only source? That's probably my major hesitation, buying/shipping/chancing import.

[Setch]

Omega have a UK site, and carry the correct size of blanket for use with a fox-type bender. I expect some one here knows the model number - Rich, Mattia?

[fryovanni]

Here is the Omega UK site-link

I picked up 6"x36" blankets. It has been handy having a bit of extra width. I can use them side by side for other flattening and bending tasks. If you have trouble figuring out the part or don't see it listed, just give them a call. I know they make both 5" x 36" and 6"x 36".

If you can.... Get ahold of a dealer who sells acoustic sets(an acoustic side is wide enough to make a end matched set). Ask them if they have any offcut single sides (in flamed maple if that is your preference). Often when cutting sides you get extra pieces, and these can be purchased inexpensively. If you want you can ask if they have a loose side set(this would yeild two bookmatched sets for your guitar). Flamed Maple sides are not expensive generally, if you can buy a nice board and resaw that would be best (also should be very inexpensive, as the width you are after is small, and easy to come by).

Peace,Rich

[Prostheta]

Many thanks Setch, Rich! I've got a pair of quilted and flamed sets in the post which are 2-3 times as wide as I need them. They're 1/8", which is probably twice as thick as they need to be but I can thin them no problems.

I presume that these products do the same job:

http://www.omega.co.uk/ppt/pptsc.asp?ref=S...&Nav=heam01

Here is a 6x36" blanket which looks like it's just the ticket Setch:

SRMU020636 which is a 2.5W/in², 6" x 36" blanket at £52.

[fryovanni]

Many thanks Setch, Rich! I've got a pair of quilted and flamed sets in the post which are 2-3 times as wide as I need them. They're 1/8", which is probably twice as thick as they need to be but I can thin them no problems.

I presume that these products do the same job:

http://www.omega.co.uk/ppt/pptsc.asp?ref=S...&Nav=heam01

Here is a 6x36" blanket which looks like it's just the ticket Setch:

SRMU020636 which is a 2.5W/in², 6" x 36" blanket at £52.

That blanket should do fine. The 2.5W density will be more forgiving than higher wattage blankets (less likely to burn, although they heat up a tad slower *but that is not long).

Now if you go back through some of the side bending topics in the acoustic section you will find info on bending forms, how to use metal slats to make up a "sandwich" that will give you the best results. A couple key items, Use craft paper to control staining between slats and the wood. I like to seal the slats with a bit of masking tape, this will keep moisture and steam in the slat better for more even heating. Be sure the form is evenly supported. Use flexable slats, especially for tight bends(stiff metal slats can actually break the wood as it is pulled from the form and returns to flat). Use a thermometer to gauge temp. Do not try to bend until the wood has become flexable, you should be able to feel a significant change in flexability(almost feels like plastic), thin slats will help you gauge this. Use a controller to limit the temp of the blankets, even 2.5W density will eventually overheat the wood(although it is much more forgiving). If you are bending a wide radius, you can leave wood .090" with no trouble (I can do this on a non cutoway with no issues), if you do a very sharp radius (say an upper horn on a cutoway) it is better to be in the .06-.065" range(this will pose no structural issues, because the area of a tight bend becomes very strong due to the bend itself).

peace,Rich

[Prostheta]

Major radii are in the order of 3-6" on the outside, with one 2" radius on the lower cutaway. I bit of thinning required there methinks. I'll pick up the accessories mentioned for sure. Anybody would think I was going to make a habit of guitar building ;-D

[Dave Higham]

I've also been thinking of investing in a heating blanket so I gave them a call. Spoke to a guy called Robin (Ext 2201) who was very helpful and knows his stuff. They also have controllers, thermocouples, etc and he said they could supply the wiring diagrams if needed.

However, all the blankets are for 110v supply. He suggested buying two blankets (either 3"x36" or 6"x18") and wiring them in series for 220v. which sounds very cumbersome to me. He said they can supply 220v blankets but it would be a special order. Not necessarily more expensive, but longer delivery time.

If you buy the blanket with controller and themocouples it brings the total up to about £115.

[Prostheta]

I would go for longer delivery time. Patience is something I learnt through guitar building :-D

I'll give Robin a bell I reckon. Great info Dave!

[lizdarocker]

Thanks all, helped me out alot really!!

Liz

[Mattia]

...or get a power transformer. It's what I do, also because I like American routers/power tools and had them anyway (ie, fixed base, and even with shipping and taxes they're STILL cheaper over there than they are here for the professional quality stuff; compare the 1617EVS by Bosch, which you can now find here for around the 430 euro mark. That's 670 dollars vs around 200 dollars)

Re: controllers - there's an article in one of the 2006 issues of GuitarMaker that describes 'rolling your own' controller, complete with list of parts. Will likely be doing that.