Official Luthiers Forum!

I’m trying to make a backstrap. I carved a curve in the head-to-neck transition area and now want to put a slight bend in the backstrap veneer to conform to that curve. I’d estimate it’s about a 6” radius curve.

I bought a headplate from Stewmac of pretty nice looking ebony. It’s 3/32” thick and I’ve thinned my headstock appropriately for 1/16” backstrap and 1/16” front plate. I slopped a liberal coating of SS2 on the ebony, wrapped it in foil, and left it overnight. Today I still can’t bend it even a tiny bit. I heated my bending iron until water instantly sizzles and leaned my weight against it and rocked it back and forth for nearly 5 minutes with no effect at all. I tried a damp cloth between wood and iron. Still can’t even begin to feel it soften.

My question is, how thin will I have to make this thing to bend it? Will I have anything left or just a $15 pile of nice ebony dust? Am I doing something stupid or is there some trick to this?

Also, does anyone know how well Rocklite Ebano bends? Maybe that’s a better choice for a black backstrap?

When I've bent gabon ebony for a scoop cutaway I have had to turn my Lmii bending iron up as far as it will go. I've had best success bending it dry. In my experience getting it wet had zero effect. I can't imagine SS2 having any benefit because the ebony is so dense. For the last scoop I did the ebony was about .080" so .0625" should be fine.

That's all I know,

M

Thanks Michael. I’ve just taken it down to .060. I’ll try bending it dry. I’ve got my Stewmac iron cranked up to 11.

For backstraps I find thinning to .040 or less and then just gluing with no heat has worked fine for me.
Sometimes I'll even use a .023ish veneer, making sure I don't have to do much sanding after glue up.
YMMV of course.

I use ebony for my volute as well despite it being a PITA to bend. I used my oscillating spindle sander to sand a bending mold for it to use with my heat blanket. I made the form with a top and bottom so that I can add clamping pressure. I found that SS doesn't do much with Ebony as was mentioned above. .050/.060" is a thickness to bend but not any thicker than that (I had a hell of a time with .075 but did make it work), I also use the bending jig to hold the ebony to the back of the headstock/volute while gluing up.

I too do it as described above, I thin mine to .065" and have never really had a problem.

_________________
"I've been had again"
Tim Benware
Creedmoor, NC

I thickness mine to .050-.060 and simply force it into shape with a flexible caul-never had a problem.....

Great info. I'll try making a pair of inside/outside cauls. I was thinking of also holding a heating blanket and steel slat on the outside while I bend against the pipe if it's still stubborn at .060. I was interrupted by my wife to go out this evening before I had a chance to try bending the thinned piece. Hopefully tomorrow will be a less frustrating day.

Thank you all for the help.

I have found ebony to be funny stuff. You'll buy 20 strips of binding and 15 bend beautifully, a couple won't bend at all, and a couple more just shatter into splinters. I have never found a way to predict what will happen. Sometimes it just won't cooperate...
Do you have another piece?

Good luck,
Mike

_________________
The Biggest Little City, Nevada
www.hammondguitars.com
I love building guitars!

Same experience here but I think that is largely to the fact that ebony is hard to cut and often ends up in the hands of novices or poor quality lumber that ends up being made into things that they shouldn't. For example run-out in ebony is extremely hard to identify (unless you have the whole log) to the point where you'd better rely on a reputable experienced sawyer to sell you workable pieces. The more run-out the harder to bend and eventually the more likely to break. "Deals' on ebony rarely wind up being deals at all at least in my experience. I still have a board that I thought that I could make sides out of that I ended up making binding out of (which did work for a while) that I now use for inlay and random things.

That said, if you buy ebony that won't bend and ends up shattering check out the grain and measure the angle of the run-out. Most reputable sellers will send replacements if the quality (runout) of what you ordered was sub par.

When we do an ebony back strap for a so-called 'smiley' volute, it is worked over a hot pipe with stock that is 18-20 inches in length, no more than 0.075"-0.080" in thickness (0.055" seems close to ideal), and the bend made close to the middle of that length. This allows far more leverage and control than working with the usual head plate-sized blank, and usually produces two articles for consideration if the bend is of correct radius (very slightly larger than nominal radius) and sufficient length.

_________________
For the times they are a changin'

- Bob Dylan

Unfortunately, no. I originally bought 2 headplates @3.5x7 before I realized (duh!) that I needed a piece 7-3/4" long for the backstrap. Also, when the first 2 arrived I found one was only 6-3/8" long and the other had a deep divot across the middle that looks like it came from stalling in the drum sander. Stewmac graciously replaced both parts and I bought one more extra-long piece for the backstrap.

Do you resaw that yourself? I've found only small pieces (at daunting prices), apparently cut for headplates (too short), fretboards (too narrow, unless you bookmatch), or too expensive to make me enthusiastic about resawing it myself (archtop tailpiece blanks). Well, come to think of it, I did find some online exotic wood dealers selling larger boards but as a hobbyist making a one-off guitar I find it hard to part with $200-ish or more for a single board to make my backstrap, even though it would make a bunch of them.

Unless you are determined to use ebony, other woods bend readily to work well for a back strap, such as, rosewood or walnut...

_________________
Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

Good point. I do have some walnut if this doesn't work out. I could dye it black. I'm pretty set on black for this.

Is that rosewood in your first picture, with the open-back tuners? Both of those look fantastic.

Those both look great

For me using ebony is not just an aesthetic decision. I am one that is determined to use ebony for the very reason that it's a PITA to bend- it's stiffness. Of course it's only a small part of the whole picture but I do want the headstock (front and back) as stiff as they can possibly be as the stiffer that area is- the more efficient the energy transfer to the bridge/soundboard becomes. It's probably a very minor factor but the little things add up and I am pretty much stuck in my ways at this point. The Malaysian Ebony that I've worked with (3 sets) I've found to be even more stiff than Gabon Ebony. I may be wrong about that but the only side I've ever broken while bending was Malaysian. I love that stuff.

Thanks, yes, rosewood in the first and walnut in the second. Both bend readily. I really like the look of figured walnut and I have used it several times for back straps, heel caps, and head plates.

_________________
Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

Well, for what it’s worth, I finally got it to bend a tiny bit at .060”. I bent it dry at the hottest setting on my electric iron, as suggested. The bend is slight but it’s just enough.

Thank you all for the timely advice.

I've bent ebony backstraps before--did it on a pipe along with a fair amount of cussing. Nowadays, I use 3 layers or so of ebony veneer and laminate it in a vacuum bag. when its done, you can't tell that its not one solid piece, and it is very easy to get good results.

Dave

That's really nice! Good idea to use veneers!

_________________
Steve Sollod (pronounced sorta like "Solid")
www.swiftcreekguitars.com

Nice! I'm going to have to try that.

I do the same as Woodie using a piece that is longer than needed with at least 5" overhang on the pipe and just lean into it. Once it sets, it pretty much holds.
With the binding shattering in the bending process, I've found that selecting your wood for runout to be the best cure for that. If you are buying pre made strips that's a bit harder to do I would imagine, but runout increases the chance of it falling apart and SS exacerbates that problem.

Nice strap on the banjo Dave

Our ebony is purchased in 3"-5" wide 4/4 stock...we usually resaw for 2-3 fretboards or 5-6 headplates. Any waste is sanded to thickness and used as thicker veneers. Exotic in Frederick, MD or sometimes a hole-in-the-wall hardwoods and flooring place over by Tyson's Corner will have some nice, well-seasoned stock.

_________________
For the times they are a changin'

- Bob Dylan

Thanks for the info. I’ll check the local hardwood dealers here. I don’t recall ever seeing ebony locally tho. Most likely I’ll look for alternatives for the future.