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View Full Version : Catastrophic failure first time trying to bend sides.



Ukemakinmecrazy
10-24-2016, 03:41 PM
Any tips? Bought a heating blanket, sandwiched it between two pieces of aluminum roofing flashing soaked the wood for a bit in water, wrapped it in water soaked paper, then wrapped it in aluminum foil and placed it in the aluminum flashing sandwich. put it over my mold and clipped it at one end with the sandwich standing up vertically. waited till it started to wilt and slowly tried to bend the sides down. all went well until I reached the waist. Then I had a hard time getting it to give at all (it was planed to 2mm and sanded a good bit after that. kept letting it get good and hot and then applied some pressure (not a lot) and heard a crack. The board broke in two. Took it out of the sandwich and it was scorched on both sides.

Man this is a lot harder than it looks.

Yankulele
10-24-2016, 04:32 PM
what kind of wood?

Nelson

BlackBearUkes
10-24-2016, 04:47 PM
Here is how I do it. Get a piece of thin stainless steel about the same thickness as the flashing you used. Forget about all the paper and other stuff. Soak the wood in a tub or tray of water for about 15 minutes. While the wood is soaking, set the stainless on the bending form then lay the heating blanket on top of that. When the wood is ready lay it on top of the blanket, attach the middle or waste bending block on top of the wood without bending it. Plug the blanket in, as it gets hot slowly bend the wood into the waste almost all the way in to the form. Bend the top bout section of the wood into place and secure it once it is done. Do the same for the lower bout section and secure. Once all the steam has escaped from the wood, unplug the blanket and let the whole thing cool down. Once cool, remove the wood and place into your building form. Do the other side the same way.

Different woods, especially curly or figured woods could use a stainless piece on both sides of the wood. I've been bending with this method for 20 years and have rarely broke a piece of wood, but sometimes wood just breaks, forget about it and move on. The more wood you bend, the easier it gets and one day its just another part of the process. Good luck.

Dan Gleibitz
10-24-2016, 06:04 PM
Took it out of the sandwich and it was scorched on both sides.

I think this might be a clue.

By the time you scorched both sides, I reckon the wood was dried out, brittle through, and set into its existing shape.

Based on my limited experience, too much heat is not a good thing.

saltytri
10-24-2016, 06:16 PM
It happens to all of us from time to time. Take heed of the good advice offered by others in this thread, keep trying, and you'll get to a way of doing it that works for you. Also, at the outset it helps to use wood that tends to bend without a lot of drama, like cherry or myrtle.

Michael Smith
10-24-2016, 07:20 PM
Your problems I can see from here

1 Aluminum Flashing is too flimsy. You want blued spring steel I have used stainless but it isn't as good as blued sring steel

2 If you scorched you probably dried out your packet

3 Bring the waaist down first but leave it up about 1/4 " to 3/8" then do the lower bout then the upper then bring down the waist the final 3]8"

4 You didn't say the wood but most wood does not benefit from soaking. Just a spritz on each side is usually plenty

5 When you get up to temperature don't dally. I't much more destrutive to the process to dry out completely than move too quickly once you are up to temp.

6 What is your wood thicknessed to and what is the species? If you have difficult expensive wood using supersoft and pre steaming can work wonders.

Rrgramps
10-25-2016, 04:20 AM
Any tips? The board broke in two. Took it out of the sandwich and it was scorched on both sides.

Man this is a lot harder than it looks.
I did the same thing, then used a hot-air gun into a pipe and the next pair bent perfectly. I'll have my SM bending iron in a couple of days.

Flame me if you want, but bending sides on a bending iron seems to take out the mystery; for me. Firstly, the moisture can be monitored directly, because it can be seen. All the activities of bending are right in front of the operator, and not hidden in a package of fabrics, foils, slats, plywood, and cauls.

Starting with a hot iron:
Monitoring moisture content is easy, (bubbles and steam) and starts by spritzing both sides lightly (maybe more depending on the action/reaction of the particular wood). The water will bubble on the outside surface as it's held against the iron. With patience, wait a few seconds for the wood to relax. If the water is no longer bubbling, spritz again, and resume contact with the iron. Don't let it dry out for more than a moment; let the wood relax and turn plastic. It will.

Maybe I'm wrong, but I had a better experience with the bending iron than with my fancy Fox bender and temperature monitoring black boxes. Although I still use thermocouples and digital displays to track temperatures; not sure they're totally necessary if tactile experience is gained. I still use the timer to shut things off at 30 minutes or so, in case I forget.

Beau Hannam Ukuleles
10-25-2016, 05:13 AM
I think this might be a clue.

By the time you scorched both sides, I reckon the wood was dried out, brittle through, and set into its existing shape.

Based on my limited experience, too much heat is not a good thing.

This happened to me the first few times i used a heat blanket. I was used to light bulbs which take ages to heat up. THe blankets just baked the wood in 2 mins on high and everything cracked.

Rrgramps
10-25-2016, 06:44 AM
This happened to me the first few times i used a heat blanket. I was used to light bulbs which take ages to heat up. THe blankets just baked the wood in 2 mins on high and everything cracked.
Thanks, Beau. Seeing your work and knowing you are a voice of experience, helps those of us who are plodding through by the school of hard knocks. Not glad you fried and broke wood in the side bender, but to hear that old timers had this happen too, may just keep us from giving up at the loss of a few supplies; struggle thoughest we may.

Ukemakinmecrazy
10-25-2016, 06:50 AM
DOOOH, it was Cherry. I think I need to control the heat better.


It happens to all of us from time to time. Take heed of the good advice offered by others in this thread, keep trying, and you'll get to a way of doing it that works for you. Also, at the outset it helps to use wood that tends to bend without a lot of drama, like cherry or myrtle.

cml
10-25-2016, 06:59 AM
Why all the blankets? I bent my sides around a hot pipe as shown by Rob O'brien, worked great. I get that you want a more automated jig when building for a living, but for us hobbyists?

Pegasus Guitars
10-25-2016, 07:57 AM
There are plenty of takes on bending. On my website pegasusguitars.com I have a tutorial on my bending procedure. It is in the "More" dropdown list at the top of the page. Titled "How I bend guitar and ukulele sides". I've bent a lot of sides with my set-up and have not found any species that are particularly difficult. There is no "one way" to do it, but this works for me. Control of the temp and a fast, efficient process is very important.

Pete Howlett
10-25-2016, 10:19 AM
Those blue steel shims are too springy, they will spring straight and crack a fragile set of figured koa before you could say heat bender! I have no sympathy with hose who look for sheericans in tort cuts to luthiery. Doing a 'basic' apprenticeship in hand skills is what I learned (apart from a whole host of other stuff~) on my research travels this Fall. Although I admire much the 'can do' confidence of many of the Americans I met, an old fashioned European craft apprenticeship as followed by my more than capable assistant is nothing to be sneered at. Emulating the careful step by step approach, even in an amateur context will minimise the disappointments and failures aired here.

Ukemakinmecrazy
10-25-2016, 03:46 PM
Those blue steel shims are too springy, they will spring straight and crack a fragile set of figured koa before you could say heat bender! I have no sympathy with hose who look for sheericans in tort cuts to luthiery. Doing a 'basic' apprenticeship in hand skills is what I learned (apart from a whole host of other stuff~) on my research travels this Fall. Although I admire much the 'can do' confidence of many of the Americans I met, an old fashioned European craft apprenticeship as followed by my more than capable assistant is nothing to be sneered at. Emulating the careful step by step approach, even in an amateur context will minimise the disappointments and failures aired here.

For those who wish to quit their day jobs that is good advice, it's is a hobby for me. But I would still like to do it well.

Rrgramps
10-26-2016, 03:22 AM
For those who wish to quit their day jobs that is good advice, it's is a hobby for me. But I would still like to do it well.

Gotcha on that this is not a day job for many of us. Sticking with your original plan and dialing in the major variables will eventually get your recipe for bending sides. You know what those variables are already, so this can be weeded out by your own R&D. Dialing in the major variables of heat, moisture, and timing will take a little experimentation. Ballparks are all we can offer, since we have different equipment.

If we pitched all of our thermometers into a circle, they'd probably measure 15 degrees F or more differences. Our heating blankets and controllers also give variance. The timing and feeling plasticity in the wood are also going to vary amongst us to some degree.

Most of all, don't be discouraged and keep your confidence level turned up high.

Dan Gleibitz
10-26-2016, 03:46 AM
Most of all, don't be discouraged and keep your confidence level turned up high.

Excellent advice!

Keep trying Ukemakinmecrazy, the payoff is totally worth it.

cml
10-26-2016, 06:27 AM
Excellent advice!

Keep trying Ukemakinmecrazy, the payoff is totally worth it.

Dan, your uke is coming along great!

dustartist
10-26-2016, 09:59 PM
What was the thickness of the sides you were attempting to bend?

dustartist
10-26-2016, 10:08 PM
I am a big fan of Pete Howlett, and I think his methods are sound, but I am also a big fan of spring steel. I think its really all in the application, I am the first to admit it can be unruly unless properly controlled, but its properties are useful to me. It provides better support at the waist bend for me, since it provides some resistance on the back of the bend. I find it easier if there is support under the waist. I also monitor the temperature and use a router speed control to keep it from getting too hot. Koa bends fine around 240F, so once I get there on the temperature probe, I start bending and try to get it done fast. I don't usually let the temperature get above 300F.

Ukemakinmecrazy
10-27-2016, 03:41 AM
Thank you for the info and advice.

Pete Howlett
10-27-2016, 08:13 AM
I use 0.25mm shim stock. That blue steel stuff is far too thick and will rust if you use water.

resoman
10-27-2016, 08:30 AM
The blue stuff will also stain the wood black even if you only spritz the wood to be bent. I know about this first hand

Ukemakinmecrazy
10-27-2016, 09:42 AM
What was the thickness of the sides you were attempting to bend?

Just under 2mm

Ukemakinmecrazy
11-14-2016, 05:03 AM
Controlling the temp made all the difference. 95645

sequoia
11-14-2016, 05:32 PM
Congrats on your success... My only thoughts are that the heel and neck blocks look a bit over sized. Easy enough to trim down. Then again, might not make that much difference.

Ukemakinmecrazy
11-15-2016, 05:05 AM
Thanks, this has been a great learning experience. The sides curled a bit at the bends, but I figured out that wetting them and clamping blocks on them for a while straightened them out. I may just Dremel sand the blocks down a bit. I hope I don't screw this up, the figured Cherry in this set is beautiful and I am trying to make this for my granddaughter.
Congrats on your success... My only thoughts are that the heel and neck blocks look a bit over sized. Easy enough to trim down. Then again, might not make that much difference.

Ukemakinmecrazy
11-18-2016, 09:57 AM
Coming along nicely

95752

95753

Dan Gleibitz
11-18-2016, 10:28 AM
It sure is! Have you decided how you're going to attach the neck?

Ukemakinmecrazy
11-18-2016, 12:11 PM
Kind of at a stand still on that. This is my first Uke build, so a bolt on may be the easiest thing. I bought a couple of cheap Mahogany Chinese necks off Ebay I could use. I like the idea of a dove tailed neck, but I'm not sure they made these long enough to allow for a dove tail joint, and I don't have a jig so I am nervous about it. Any advice or tips will be greatly appreciated!

Ukemakinmecrazy
11-18-2016, 12:17 PM
My neck options

95765

95766

sequoia
11-18-2016, 08:21 PM
My thought here is that you might be putting the cart before the horse when you glued on your bridge. That position is determined by the the length of the neck after it is attached. It is easier to move the bridge up or back to get your scale length absolutely perfect than it is to adjust the neck or fretboard. Still, as long as you are reasonably close and you can finagle the fretboard in there to perfect length you are going to be alright. But maybe next time you might want to attach the neck and freboard first and let the bridge land where it wants to be later.

Ukemakinmecrazy
11-19-2016, 10:04 AM
Oh it wasn't glued on, just sitting there for effect.

95773

Ukemakinmecrazy
11-21-2016, 07:05 AM
Any advice on attaching a bolt
on neck?

Yankulele
11-21-2016, 08:30 AM
You might take a look at this: http://www.theamateurluthier.com/projects/htmlpages/marfinishneck.html She's got a lot of well-documented good ideas.

Nelson

mikeyb2
11-21-2016, 10:19 AM
Any advice on attaching a bolt
on neck?
this is how I did it, with a threaded insert.
95817

Dan Gleibitz
11-21-2016, 11:17 AM
Any advice on attaching a bolt on neck?

I used an M6 bolt with a 10mm diameter metal cross joining dowel. Like these:
http://www.strictlybedsandbunks.co.uk/prodimages/barrelboltsandnut-1.jpg

Made a simple jig modeled after something I found on the forum similar to this but simpler:
http://forum.ukuleleunderground.com/showthread.php?78090-Bolt-on-necks&p=1211409#post1211409
Then flipped it around and drilled the matching hole in the body.

Drilled the 10mm hole for the dowel and knocked it in with a hammer and rod. Slotted side up in case it needed turning.

The pros will roll their eyes and shake heads, but if the holes don't align perfectly to set the top of the neck at the exact height of the top of the body, you can widen/file the bolt hole in the neck to get some play for perfect alignment. Once it's tightened up there will be no movement.

It would be easier to drill before carving the neck, but that's not an option for you.
You'll need to spend some time sanding the end of the neck to match the body no matter which method you choose.

Ukemakinmecrazy
11-21-2016, 11:48 AM
Anybody used hanger bolts? I saw a web page where a guy used those and it seemed like a good way to go.

Ukemakinmecrazy
12-06-2016, 08:39 AM
The latest progress.

96132

96133

DPO
12-06-2016, 09:28 AM
Anybody used hanger bolts? I saw a web page where a guy used those and it seemed like a good way to go.

Hanger bolts are great, very easy to install. All my banjo ukes use them.

Rrgramps
12-06-2016, 03:12 PM
The latest progress.


Good looking axe, indeed.

Looks like your ukulele neck is attached with (a hanger bolt?).

pahu
12-06-2016, 05:26 PM
The latest progress.

96132

96133

That cherry is stunning. I cant wait to see it with some finish on it.

Ukemakinmecrazy
12-07-2016, 04:29 PM
I actually used two, one larger one near the top and a smaller one near the bottom. Hope it holds up.


Good looking axe, indeed.

Looks like your ukulele neck is attached with (a hanger bolt?).

Ukemakinmecrazy
12-17-2016, 07:11 AM
Progress

96376

96377