PDA

View Full Version : Side bending help?



funaddict
12-04-2009, 02:27 AM
Hello All!
I'm on my first build and am having trouble with my bent sides. I bent them on a hot pipe (BBQ starter for heat) and am happy with their shape. My problem is they now have ripples in them. I'm wondering if they are too thin, or maybe I shouldn't have soaked them. Here's what I did:

Thickness sanded to 1/16" (.062) with 80 grit on sanding drum.

Removed sanding scratches with RO sander with 100, then 150 grit. Now thickness is between .045 and .055.

Soaked in warm water for 1/2 hour (the wood sides, not me!) While pipe heated up.

Bent sides. This seemed to be suprisingly easy, maybe because they were so thin? At this point the sides looked pretty dry, as the hot pipe steamed most of the water out of them. I believe they didn't have any ripples in them at this point.

Clamped in form overnight. The forms are fairly smooth and I don't think they imparted the ripples into the bent sides. When I took them out of the forms, I was disappointed to see the rather pronounced ripples running through the length of the sides.

Wood is quilted Western Big Leaf Maple, salvaged a dozen years ago from a tree that had washed up on a deserted peach in Puget Sound, near Tacoma.

Anyone have any ideas? I bent another pair of sides, same wood, same thickness, without soaking first, (just spritzing the area I was bending as I went) and without clamping in the forms afterward. This second set was definitely flatter but still had enough of a ripple in it that I wouldn't want to use it on a uke. I also realize that I should probably switch to 100 or 120 grit on my sanding drum, as I did quite a bit of sanding with my RO sander to get rid of the course scratches. Maybe this over-sanding contributed to the ripples, as the softer areas of wood grain probably got sanded thinner than any harder areas of grain, and the ripples seem to loosely follow the grain lines of the wood.

Any comments or insight or advice would be much appreciated. Thanks for all the informative and entertaining info on this board.

Alan

dave g
12-04-2009, 02:32 AM
You might have them a bit too thin...

Moore Bettah Ukuleles
12-04-2009, 05:25 AM
Yikes, that's might thin! I don't work with maple too much but from what I recall it bends very easily. I'd start with a thickness closer to .080". And you may want to hit the inside of the sides with your RO, but there's no need to do any finish sanding until after you're glued up.
As a point of reference, before bending I sand my sides to .075" with 120 grit.

PaulGeo
12-04-2009, 06:43 AM
Drum sanding on a lathe... brilliant!

Kekani
12-04-2009, 07:01 AM
I've used WBL Maple, a lot. I prefer working with and the resultant sound of Curly Maple (QS), but the Quilted (FS) is just too much eye candy to ignore.

You already know that your sides are throw away thin (as in, throw them away). The maple that you have doesn't look too quilted to the point where you'll run into other issues, but if it is, then that would explain where your rippled occured, especially due to the flatsawn cut.

Here's the thing, Quilted WBL is probably one of the easiest woods to bend, and soaking them for 1/2 hour at .045 probably warped it before you even started. I do mine at .090 with a quick spray of water prior to bending on the bender - takes about 2 minutes (if that).

The problem that you'll run into with really nice quilt is that you'll have what looks like an uneven surface (when its finished), actually be an uneven surface (when its being built), especially on the sides. I work the quilted maple about .010 thicker than other woods, simply to be able to sand down flat. And we're not even talking about grain raising prior to finishing (that's another story in itself).

Here's an example that I really needed to pay attention to:
http://i291.photobucket.com/albums/ll290/kekani427/Ukulele/IMG_1359.jpg

Be sure to show us the next set - Aaron

Moore Bettah Ukuleles
12-04-2009, 07:12 AM
oooooh....... from the picture it looks like hammered metal. Nice!

zog
12-04-2009, 07:31 AM
I have some maple coming that is supposed to look like that.

If the wood isn't hot enough when you bend it it gets that faceted
look. You need to make it thicker like Chuck said if you make the sides .080 you will have a little fudge factor to get them ripple free. I have used mostly maple sides (plain, birdseye and flamed) on the 23 ukes I have made this year and it is easy to bend. I usually only soak it a minute then bend it with a blanket setup.
I have made one with a very thin sides, .045, but later reinforced the thinnest parts (upper bout) with carbon fiber. Top and back also were in the .045 range
concert size all flamed maple. Came out loud and light.

I think thicker sides are better, some guitar builders are doing double sides.
the thickness and bracing of the top are the most critical for good sound.
(my opinion)

nohandles
12-04-2009, 09:17 AM
Wood can be a bugger to bend. Next time try a bigger radius pipe and it should help the problem.
I got a multiple curvature bending iron early on and it really helped. Doug

E-Lo Roberts
12-04-2009, 11:09 AM
Yikes, that's might thin! I don't work with maple too much but from what I recall it bends very easily. I'd start with a thickness closer to .080". And you may want to hit the inside of the sides with your RO, but there's no need to do any finish sanding until after you're glued up.
As a point of reference, before bending I sand my sides to .075" with 120 grit.

I agree with Chuck's specs. .080" with no pre-sanding needed at this point. I believe the .045" is your problem. It's too thin and the soaking just warped it..e.lo...

funaddict
12-04-2009, 04:45 PM
Thanks All, for your replies. I'll have to try again this weekend. I'll make another drum, and wrap it with 120 grit, and keep the first drum with 80 grit on it. Making the drums on the lathe is fast and easy, and should be easy to switch between drums for different grits. I'll go for .090ish and no long soak.

Thanks Aaron for the pic. That's the look I'm going for, although my quilted WBL has some blue streaks in it from sitting on the beach for some period of time.(see attached pics) I thought about trying to bleach it all blonde, but I think I like the streaking to remind me of the beach, both in Puget Sound and the North Shore of Oahu, where I grew up. I posted on another thread that I'm trying to build a uke using free, salvaged, and/or scavenged materials, other than the fret wire, tuners and strings. The back and sides are Quilted WBL maple. The neck is curly maple from a tree I cut down while building tennis courts in Seattle. The top is some beautiful old growth redwood that came from some 2 x 8 balcony rails from an old house I remodeled. Curly koa binding left over from a huge batch of pen and pencil sets I made for some AT&T Haw'n promotion years ago. Curly koa fingerboard and bridge from a 90 year old man here in Yakima who lived in Kealakekua back in the 60's, who's wife won't let him woodwork anymore. Spruce bracing from dunnage from lumber deliveries at work. African Blackwood scraps for nut and saddle from a friend who turns peppermills. I think that covers it except for neck and tail blocks. I'll have to scrounge around the woodpile.

Anyway, thanks again. I'll post progress pics as I go along. Any and all advice always welcome.

Alan

Moore Bettah Ukuleles
12-04-2009, 04:48 PM
You asked for advice. I advise you to send that maple to me. ;)

funaddict
12-04-2009, 04:57 PM
Chuck,
If I'm over in Seattle and Bill Gates rear ends me and offers me a quick $1,000,000 settlement, I'll send you the rest of that stash of maple and have you build me a uke like Spooners. I guess it would have to be a Fun-ulele! That was a seriously beautiful instrument!

Alan

Kekani
12-04-2009, 06:27 PM
That is some nice quilt that we couldn't see in the pic. Definitely start thicker. You'll see what I mean about leveling.

Lots of builders keep aware when bending figured wood, but mostly from a "let's not crack it" point of view. Maple, no matter how figured, bends easily without cracking, but doesn't necessarily bend easily and end up "flat".

Aaron

koalohapaul
12-04-2009, 07:18 PM
.090" might be a little difficult to bend. The difference between .080" and .090" might not be much visually, but you'll definitely feel it. Our production ukes have sides that are .080" thick, but I usually take the customs down to .070"-.075". Figured woods aren't fun to bend. Especially since everyone wants AAAAAAAAAAAAA curly koa sides.

Flyfish57
12-05-2009, 07:07 AM
Aaron and Allen Wow that's some nice quilted maple--I get seasick looking at it--Sweet!