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Bobsdad
11-30-2015, 08:53 AM
Thank everyone on this forum for the wealth of information posted here. I have been reading and following in the background for a few months and decided to try a build with a Hana Lima tenor kit. All was going well, back and soundboard thickness down to .069, neck scarf joint cut and glued up, braces and tone bars cut, sanded and shaped. Built a go-bar deck, glued up the enharmonic bars. All was fine until I glued the bridge patch and clamped with go-bars. When I removed the go bars I found that the bridge patch had cocked about 1/4 inch from horizontal. I'm not sure what the impact is and thought about trying to remove and reglue the patch but am not confident enough that I won't damage the soundboard. My thought now is leave it cocked and just notch the tone bars appropriately. Any and all of your thoughts would be appreciated.

Allen
11-30-2015, 09:05 AM
Well, if it was me, I'd replace it.

Beau Hannam Ukuleles
11-30-2015, 09:14 AM
Well, if it was me, I'd replace it.

yer- just plane/chisel/sand it off and glue on a new one.

saltytri
11-30-2015, 09:18 AM
Well, if it was me, I'd replace it.

Me too. Building instruments provides endless opportunities to experience the humbling sensation of having painted oneself into a corner. :)

If I'm correctly envisioning your problem, you ought to be able to remove the patch by shaving it down with a sharp chisel. There's no reason that this should adversely affect your build structurally or tonally.

When you glue down the replacement plate, consider sprinkling a few grains of sand on the glue before you put the piece in place. This will keep it from sliding when you put the go-bars in place to clamp it. It only takes a few grains: think 10 or fewer.

Michael Smith
11-30-2015, 09:48 AM
I agree with others removing a glued up element is an important basic skill. I would shave it off with a hand plane and put on another.

Bobsdad
11-30-2015, 09:53 AM
Unbelievable reposes (and quick). Removing and replacing it is! Thank you all. This is a great experience for me and I'm looking forward to the whole process. I used to be a cruising sailer and totally enjoyed new destinations but the voyage was definitely half the fun.

Cheers

Beau Hannam Ukuleles
11-30-2015, 09:56 AM
When i screw up, i try to trick myself into doing anything other then just re doing it-
After a few hours I realise there is no way out of some things and it has to be redone.
Now, i skip the double guessing myself and just redo it straight away- I know it hurts, but then it feels better. :)

Huvvers
11-30-2015, 12:38 PM
Maybe use salt instead of sand. It won't hurt your plane iron if, by chance , the patch moves again.

Farp
11-30-2015, 01:16 PM
I'm halfway into my first build, also. Last Saturday, I glued the back braces on and the one on the upper bout had enough play to not be at 90 degrees to the center line. I am being taught by a seasoned luthier and I asked him what he thought when I returned today to start in again. He said I could just leave it, as it wasn't too far off; or I could replace it. Well, I decided it would bother me to have it off; so we got out a sharp chisel and started to remove the crooked brace. As I was chiseling away, I asked, "Is this the first time anyone has chiseled off a back brace in this shop?"

His reply was one to remember. He said, "Nothing is a first time in this shop," and he gave a knowing smile. I felt better, lol.

Kekani
11-30-2015, 01:32 PM
Mike Chock once told me early on its not how good you can make an instrument (anybody can do that), its how good you cover up the mistakes.

Moore Bettah Ukuleles
11-30-2015, 01:40 PM
Mike Chock once told me early on its not how good you can make an instrument (anybody can do that), its how good you cover up the mistakes.

Or knowing when to leave things alone!

sequoia
11-30-2015, 04:50 PM
Yes, glue can act as a sort of lubricant that makes things skate away to an alarming and disastrous degree. Been there. My thought though: 1/4 is pretty big slippage, however, taking the patch out isn't going to be an easy thing. It might want to pull tear-out pieces of the top out as you remove and that ain't gonna be good. Definitely, you have to true it up for your bracing, but maybe you could square it up by just cutting it down and chisel out the pieces? The patch would have a smaller foot print and the braces closer (not really a good thing). Another thought: just sand the thing out and start over assuming you have not put in any more braces. An orbital sander will take that thing off in mere seconds. If you are using Titebond, I've found that being patient and letting the tack take hold helps alot (about 2 minutes) with skating.

Yes, recovery from disaster is all part of the fun. The biggest trap is thinking, oh well, it's probably going to be ok. Sometimes it is and sometimes it definitely isn't.

Kekani
11-30-2015, 09:00 PM
Or knowing when to leave things alone!
Or just throwing it away.

A recent one was a dropped neck, no inlay, but fully fretted and bound fretboard and headstock. Dropped it and cracked the heel. Tried to fix it, but I could see the crack line, even if no one else could, until I told them. That was enough confirmation. I was almost done finishing it! Gave it to a friend; he'll use it, but won't sell the instrument (was better than anything he can make right now).

Pete Howlett
12-01-2015, 01:41 AM
Mistakes are one of the keys to learning. Recovering them unlocks the door to skill and judgment. As a new builder you are not going to make a first perfect piece - in fact, most of us still building are waiting for that Great Day! I never, unless it is absolutely critical, allow my students to correct mistakes. They need to have a reminder that there is world of difference between the work of a master and that of a novice... replacing the patch is a good exercise. Replacing a slightly off brace is an unnecessary but good exercise. I remember my first build... I ended up binning it :) If you want to know the story of my first ukulele builds ask Bob Gleason - he fitted the bridge patches I left out :)

Bobsdad
12-03-2015, 11:11 AM
Thanks all for each of your inputs. I'm glad that I fixed (re-did the bridge patch) it was easier than I thought and gave me a valuable lesson.....fix mistakes and learn. I used a Multimaster vibrating tool and sliced the bridge patch off pretty cleanly without damage to the sound board, sanded a bit, cut a new patch from scrap bloodwood, glued it up and proceeded with sound bars and braces. See the attached. again thanks for the support!!!!86058

chuck in ny
12-03-2015, 02:51 PM
i am a career building tradesman and cabinetmaker. the best thing about the situation is that while most things go well, some inevitably do not. we laugh at the situation, have plenty of expertise, yeah, we effed it up, we would be glad to fix it.
it's an inherently spiritually superior situation to be in than, say, being a doctor and having done the same.

...when gluing fiddly pieces. have the base, substrate, clearly marked out with the correct position. you can put the block on with yellow glue or another choice, rub it around for a minute or two, and wait for another minute or two. practice this on scraps to get the rhythm and feel. you wait for the piece to tighten up a bit before applying the clamp so it doesn't skate.

sequoia
12-03-2015, 07:02 PM
Just one thing: your fan braces look way too thick there in that picture. Probably too late and the top is on, but I think you could severely whittle a lot off there. Like maybe half. Things kinda want to be delicate there. Just saying...

Bobsdad
12-03-2015, 10:11 PM
Hey Sequoia, thanks! It's not too late, I haven't even bent the sides yet (or decided how I'm going to do that). When you say 'too thick' do you mean width or height? I'll spend more time on them. Thanks!

sequoia
12-04-2015, 07:09 AM
It is hard to say width or height by just looking at a small picture. My feeling is that you have made a structurally strong top perhaps at the expense of acoustics? Hard to say without the piece in hand and there are other far more experienced builders in tuning braces than me. Also it looks like you have tied off your fan braces to the transverse brace. While structurally sound, I think the fan braces need to move independent of that transverse brace. ...By the way, your work is extremely neat and tidy and scalloping is first rate.

Bobsdad
12-30-2015, 05:10 AM
So I'm still moving slowly on my first build of a Hana Lima mahogany tenor and with my first attempt at side bending hit a snag. I built a Fox bender and assembled the 10mm spring steel slats (2) and silicon heat blanket. The sides were sanded to .065" thickness. I sprayed the sides with H2O, liked up the waist with the slat / blanket sandwich, brought the temperature up to 240 degrees and let it sit for 5 minutes at 240 degrees, lowered to 212 degrees and slowly bent the sides. I then turned the blanket off and let everything cool for eight hours. When i removed the bent sides from the jig the sides sprung back a considerable amount probably half way to straight. I then tried to force them into a mold and in doing that crack the sides at the waist. So I'm trying to figure out why the sides did not hold the shape of the bending jig. My thoughts tell me that I cooked the wood too long at too high a temperature or eight hours of cooling time was not enough.

So it's back to slicing up some sides and try again...and maybe again and again until I get it right. I had no fantasy that first attempt at bending would go perfectly so while disappointed i'm now more determined.
Any insight will be appreciated.86899

Moore Bettah Ukuleles
12-30-2015, 05:33 AM
It doesn't sound like you got enough heat. I usually bend my sides at around 325 degrees or so. I'm able to pop them out of the form within a half hour with minimal spring back.

RPA_Ukuleles
12-30-2015, 07:45 AM
You can try also to undersize the bending form to compensate for the side thickness and any slats/blankets/whatever. I also exaggerate the waist bend and the ends at the blocks. That way the spring back is somewhat compensated for. But this is of course separate of getting your heat issue "ironed" out.
:biglaugh:

http://i913.photobucket.com/albums/ac331/rpashop/Screen%20Shot%202015-12-30%20at%201.36.04%20PM_zps7vcbh6oe.png

Michael Smith
12-30-2015, 08:04 AM
Wrap your sides in aluminum foil (helps keep moist and evens temperature.

If you are using one blanket have it on the outside of the wood. (wood, wrapped in foil, blanket on top, spring steel above and below this package.

Use higher temp (300 F minimum)

don't wait so long to make the bend (soon as you are close to 300 F slowly and gently start the bend. If you wait too long and dry out your wood you will have problems) The idea is to be both at a high temp and moist at the same time.

as soon as you are done with the bend shut it down and let it cool for 20 minutes. Then run it back up to 290 F. Shut it down right away when it gets there. Allow to cool for an hour or two and you should be good to go.

There are some woods that are incredibly hard to bend even when you are extremely careful. I did a leopard wood set that gave me fits. I resorted to Supersoft 2 a veneer softener. That did the trick.

Bobsdad
12-30-2015, 10:37 AM
Thanks folks for the quick response. Higher heat makes sense. I watched the Mya-Moe video and Char said she bends at 212 degrees, others on this forum said they bend at about 240 so I guess every one has their own way. But higher heat makes sense to me so my next try will hopefully be better. I did offset the bending mold 2mm smaller than the build form. Unfortunately I only had on set of sides that came with the kit...so, ran out this morning to the local exotic wood place and picked up a 6"X5"X24" piece of pricy Brazilian Mahogany, sliced 4 pieces off and sanded them down to .075" . I'll give another go soon.

Again thanks

Paul McCauley (Bobsled)