Bending Wood - Ideas Needed

Jerryc41

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I want to make an oval uke, and I have a mold/form made from layers of plywood about 3½" thick. I made a complete oval the size of the netting on a tennis racket, so that will give you an idea what I'm doing. Then I cut that roughly down the center to make it easier to clamp. I got a wood set from Stew-Mac, and I'm trying to figure out how to clamp the side wood in place.

I figure I'll borrow an idea from YouTube (see picture below) and use a turkey roasting pan on the stove to steam and heat the wood. I also have a heat gun available. I could use clamps, but I would have to cut holes in my mold for the other end of each clamp. That would be a lot of cutting/routing. I could also use two ratcheting straps and wrap them around the form, but I wouldn't be able to use the heat gun. I can't use clamps and straps because each would interfere with the other.

So, if you have any suggestions, I'd be glad to hear them.

Bending Uke Wood 1.jpg
 

Arcy

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Check the Luthier forum. There have been a few threads about steam bending recently. The roasting pan seems tricky since you can’t fit the whole thing at once. A longer enclosed tube may be better: I haven’t used it for instrument type woods, but ages ago I set up a steam bender from a length of black pvc or abs or such pipe from the big orange store and fed it from a wallpaper remover. There are similar setups with details on YouTube. I think the Wood Whisperer has some good videos on steam bending.

To make room for your clamps you could drill some holes for a lot less effort than routing them. A picture of your mold will give the experts more info for specific suggestions.
 

Kenn2018

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I think Mya Moe and Ono ukuleles had some videos about their processes. Usually steaming the wood around a pipe and then fitting it into a form. I think they inner and outer forms that clamped together around the sides. But I could be wrong about that. It's been a while since I saw them.

Some builders use a million thick rubber bands instead of clamps. But I think that was after the top and back were attached.

Good luck Jerry. Sounds like an ambitious, and fun project.
 

BuzzBD

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I honestly think you would be better served to use your heat gun to heat up a section of water pipe and bend it on that. Or bend an electric barbecue starter to fit inside a piece of pipe, or a propane torch. The problem with steam is unless your system is pressurized, you are limited to 212 degrees F max. The minimum temperature I will use to bend at is 250F. Bending on a hot pipe is really very easy, just experiment a bit with a few scraps of wood and you are good to go.
Brad
 

Jerryc41

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Check the Luthier forum. There have been a few threads about steam bending recently. The roasting pan seems tricky since you can’t fit the whole thing at once. A longer enclosed tube may be better: I haven’t used it for instrument type woods, but ages ago I set up a steam bender from a length of black pvc or abs or such pipe from the big orange store and fed it from a wallpaper remover. There are similar setups with details on YouTube. I think the Wood Whisperer has some good videos on steam bending.

To make room for your clamps you could drill some holes for a lot less effort than routing them. A picture of your mold will give the experts more info for specific suggestions.

Thanks. The wood is several inches longer than I need, so if an inch doesn't bend enough, that's okay. The pan is pretty big. Another problem occurred to me last night. I'm making the sides from two separate pieces, and each piece will have to meet the other exactly at the base of the bout. I'll check each one for squareness, and I may have to allow a bit of room for sanding.

I tried drill a hole, but I had to drill two 3/4" holes side-by side. Then I had to drill another hole behind those two to allow for the Irwin clamp. I think I'm going to make a female mold to press up against the form I have now. From what I've seen online, the form doesn't have to be solid. I can use several pieces of thin wood with spacers in between.

It sounds like I'll have to spend more time on YouTube.
 
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Jerryc41

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I honestly think you would be better served to use your heat gun to heat up a section of water pipe and bend it on that. Or bend an electric barbecue starter to fit inside a piece of pipe, or a propane torch. The problem with steam is unless your system is pressurized, you are limited to 212 degrees F max. The minimum temperature I will use to bend at is 250F. Bending on a hot pipe is really very easy, just experiment a bit with a few scraps of wood and you are good to go.
Brad

Thanks. I'm not going to be doing this on a regular basis, so I don't want to invest a lot of money into this. Maybe I'll experiment with some kind of hot pipe.
 

uke51

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Please excuse the debris currently in my shop....

Here are some images of a mold I used for a similarly shaped uke. I used a heat gun & heated the mold thru the holes on the bottom of the mold.
the mold is hollow, and I used sheet metal for the bending surface. I didn't need a hot pipe with this shape.On a uke with a tight waist, I use a hot pipe to ben the waist, then clamp into a mold to bend the upper & lower bouts.

I hope this helps...

IMG_0965.jpgIMG_0967.jpgIMG_0966.jpg
 

Jerryc41

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Please excuse the debris currently in my shop....

Here are some images of a mold I used for a similarly shaped uke. I used a heat gun & heated the mold thru the holes on the bottom of the mold.
the mold is hollow, and I used sheet metal for the bending surface. I didn't need a hot pipe with this shape.On a uke with a tight waist, I use a hot pipe to ben the waist, then clamp into a mold to bend the upper & lower bouts.

I hope this helps...

View attachment 127073View attachment 127072View attachment 127074

That's quite a setup. For one or two ukes, I want to keep it simple. I'm going to make the other half of the mold today.
 

Jerryc41

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I need some advice/explanation. I made a mold very similar to the one in the video, but the wood for my sides is tapered - wide at the neck and narrower at the bottom. I want to keep the original narrow ends so they will match perfectly at the base of the uke. Like the man in the video, I will have to cut both pieces of the sides, and I'm not sure how to do that. Ideally, I would have the narrow end flush with the end of the mold when I bend it, but I can't imagine being able to get it lined up like that while I'm bending it. If I could do that, I would cut off the excess on the wider end.

In the video linked below, he marks the center of the uke on the mold and then transfers that mark to the side to cut it. This starts around 2:25. Since I bought this wood from Stew-Mac, I'd rather not mess it up. Pictures below.

03.jpg 04.jpg
 

eclipsme

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I have been down this road. I learned a bit about steam bending wood some years back while working on wooden boats, so this seemed like a natural way to get started. It was fun, I learned a few things but really more of a pain and production than is needed or desired.

I recently bought a bending iron from Amazon - $100. I have so much more control than I ever hoped to have using steam and a form. I can immediately bend to a line without even thinking about spring back.

I was told this, but I had to figure it out on my own: there really is a reason so many do not try to steam their sides.

Also, if you insist, there are very easy and cheap ways to make a steambox. I also tried the turkey baster but it really did not work out so well.

Good luck!
 

Jerryc41

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I have been down this road. I learned a bit about steam bending wood some years back while working on wooden boats, so this seemed like a natural way to get started. It was fun, I learned a few things but really more of a pain and production than is needed or desired.

I recently bought a bending iron from Amazon - $100. I have so much more control than I ever hoped to have using steam and a form. I can immediately bend to a line without even thinking about spring back.

I was told this, but I had to figure it out on my own: there really is a reason so many do not try to steam their sides.

Also, if you insist, there are very easy and cheap ways to make a steambox. I also tried the turkey baster but it really did not work out so well.

Good luck!

Thanks. Is this the one you got? If I order one, it won't get here till some time in July. By then, I will have lost interest. :D

https://smile.amazon.com/Yinfente-G...rds=guitar+bending+iron&qid=1589390202&sr=8-1
 

Jerryc41

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I heated a pan of water on the stove and let the side sit in the steaminess for a while. Then I started bending it. I kept pouring hot water over it and hitting it with a heat gun. It put up a good fight, but I won. It's sitting out in the garage, clamped tight.
 

eclipsme

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Thanks. Is this the one you got? If I order one, it won't get here till some time in July. By then, I will have lost interest. :D

https://smile.amazon.com/Yinfente-G...rds=guitar+bending+iron&qid=1589390202&sr=8-1

Looks like it. There are many that look exactly the same but from different vendors, and I believe they all originate in China. Are you in the US? Perhaps you can find a vendor that stocks them closer to home...

Also, this model has thermostatic control, which I wanted. These are also available without for close to half the price.

Be sure to look at EBay also. I am often having better luck finding faster shipping there these days, though YMMV.
 

Jerryc41

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Be sure to look at EBay also. I am often having better luck finding faster shipping there these days, though YMMV.

Considering the price, I've given up on the idea of a bending iron. I doubt I would use it more than once or twice. I'm going to continue with the form I made.

I took the wood out yesterday, and it looked pretty good - just pretty good. I put it inside the tennis racket and clamped it. When I checked it later, one end had started to split just below the racket. I'm not giving up on it, though. I'm going to try bending it again today, and I'll repair the split with a patch on the inner side of the wood. This is all experimentation.

EDIT: I found this on eBay - $66, delivered from CA. I'm going to try the pan of hot water on the stove again. I hate to spend $66 to bend wood for two ukes. Wow! That is one long link!

https://www.ebay.com/itm/Violin-Rib...=133381257806efc4ee8d8e30453994dba2891629bb1d
 
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eclipsme

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Considering the price, I've given up on the idea of a bending iron. I doubt I would use it more than once or twice. I'm going to continue with the form I made.

It is certainly possible to have success with this method, with persistence and practice. I built a side bender, which worked well, but ended up using cauls instead. It was tricky making sure the sides were positioned well in the cauls, though.

Also, I found it *much* easier to bend the wood without splitting if you used a thin sheet of metal behind the wood to support it - like aluminum flashing, for instance.
Form and Caul.jpg.

Also, you may want to look at building a simple steam box, though you will also need to figure a way to make steam. They are very simple to make out of scrap wood. This will help in getting the wood pliable enough to bend without breaking. Here was my setup. I used a tea pot as my steam generator.
IMG_20190307_111554.jpg

Here is one of the ukes I made this way.
Uke 2.jpg Uke 2 back.jpg

Good luck!
 

Jerryc41

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It is certainly possible to have success with this method, with persistence and practice. I built a side bender, which worked well, but ended up using cauls instead. It was tricky making sure the sides were positioned well in the cauls, though.

Also, I found it *much* easier to bend the wood without splitting if you used a thin sheet of metal behind the wood to support it - like aluminum flashing, for instance.


Also, you may want to look at building a simple steam box, though you will also need to figure a way to make steam. They are very simple to make out of scrap wood. This will help in getting the wood pliable enough to bend without breaking. Here was my setup. I used a tea pot as my steam generator.

Good luck!

I'm going to try making a bender with some pipe. I have an old fence rail that should be good. I'll probably use a heat gun (or maybe a propane torch) to heat it. With the end of the pipe open, I can try both methods, and I have an IR thermometer to check the temperature. I realize that bending the wood before putting it into the form is the way to go. I found out about using sheet metal as a backing for bending this morning. I think I have a roll of flashing, too. I don't know why people throw things away. :D

What's a good temperature for a bending pipe?

EDIT: It looks like 350 - 400° is good.
https://www.stewmac.com/Luthier_Tools/Tools_by_Job/Tools_for_Bending_Sides/Bending_Iron.html
 
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Kenn2018

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Just out of curiosity, would a steam vaporizer produce enough 212° steam? Or do you need a higher pressure, hotter steam to work?
 

Arcy

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You don’t need high pressure or super-steam. I’m not sure a steam vaporizer would provide enough volume. I’ve used a wall-paper steamer and plugged it’s hose into a hole in a pvc pipe. Works great for long skinny boards.

For side bending I put together a pipe based on Highline Guitar’s video. I haven’t used it enough to run into problems as warned by the most recent comment. Original plan was to use a BBQ starter, but the element was too big for my baseball bat and cracked a bit when I tried to narrow it.
 

eclipsme

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I'm going to try making a bender with some pipe. I have an old fence rail that should be good. I'll probably use a heat gun (or maybe a propane torch) to heat it. With the end of the pipe open, I can try both methods, and I have an IR thermometer to check the temperature. I realize that bending the wood before putting it into the form is the way to go. I found out about using sheet metal as a backing for bending this morning. I think I have a roll of flashing, too. I don't know why people throw things away. :D

What's a good temperature for a bending pipe?

EDIT: It looks like 350 - 400° is good.
https://www.stewmac.com/Luthier_Tools/Tools_by_Job/Tools_for_Bending_Sides/Bending_Iron.html

My bender, and my *only* data point on this, came preset to 150 Celsius (about300F - Google). I have not had to touch it.
 

Jerryc41

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I’ve used a wall-paper steamer and plugged it’s hose into a hole in a pvc pipe. Works great for long skinny boards.

For side bending I put together a pipe based on Highline Guitar’s video. I haven’t used it enough to run into problems as warned by the most recent comment. Original plan was to use a BBQ starter, but the element was too big for my baseball bat and cracked a bit when I tried to narrow it.

I wonder how much heat PVC could take. I bet Google has the answer.

I had never heard of a cartridge heater, but I see they are very small, like 5 - 10 mm. I wonder how that would heat a galvanized fence pipe. I thought I might support the pipe horizontally at both ends. I have some old angle iron I could use.