Mandola Build


John Page

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A few months ago I resolved to build a mandola/guitar hybrid, and I just finished up the frame for it. Still a lot of progress (all of it…) to go, but I thought I would share the process here. The entire thing will take twice as long as it should because my only shop is the foot of my bed. That means my work space is about 10 sq. ft. and I am limited to hand tools. Although, I do not see that as much a limitation as I do another means of enjoyment from the project. I have no experience whatsoever with building instruments, so this will be a trial by fire so to speak. If anyone here knows what they are doing, feel free to chime in! Any advice would be appreciated :)

Here’s a link to the first part- building the frame.

Because of file size limitation, I’ll only post a few photos here. A more detailed look at the progress is in the link to my blog.

Cheers!

John

27 Frame finished_smaller.jpg

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because my only shop is the foot of my bed. That means my work space is about 10 sq. ft. and I am limited to hand tools.

Wow, someone with a smaller shop than me!

I have no experience building an instrument - but It should be fun watching someone else take on the challenge.

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Thanks everyone!  

How do you hold lumber to make cuts? Clamp it to the footboard of the bed? That's dedication, my friend!

It's a precarious affair! I have had to lay longer boards across my bed with the free end balanced on the waste bin, cutting between the two while I kneel on the board. Smaller stuff is easier, as I can clamp it in my little machinist's vice and cut from there. If I am lucky, midsized lumber balances on the waste bin itself and I can cut directly inside it, making cleaning up the dust all the easier. 

Cheers!

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  • 2 weeks later...

Alright folks, I need some help. I've been struggling with steam bending the sides for this project for the better part of a month now with minimal results. The tight curves are the worst, and (although on the inside where it will not be seen) the grain is lifting and cracking more than a little. I have tried everything I can think of to get it to bend easier and more cleanly, but to no avail! I've used the steam box, soaking for long periods of time in hot water, using a hot mandrel to bend around, clamping and pressing and every combination of the lot. Finally, I tried reducing the thickness of the wood by about 30%, which I thought would help but did virtually nothing. At this point I am considering changing the shape from an A style mandola to something like a teardrop that you see in lutes. <_<

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Was the wood you are trying to bend kiln dried? If so, you may find it all but impossible to steam bend, especially if it was dried too quickly, or at too high a temperature. Have you considered a cold lamination? I suppose that would be impractical with the limited space and tool set at your disposal.

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Thanks for the video, that was quite helpful. I think I am still a bit on the thick side, so I will go back and bring the sides down some more. I wish I had a form like that!! Makes mine look all the more sketchy :mellow:

Just tried to bend another one of the smaller, tighter pieces (on the neck side with the opposing curves) and there was some major cracking, but it was on the inside still so hopefully I can glue it back together and sand it back. 

I'm not sure if the wood was kiln dried, but I would assume that it was not. I ordered the sides from a luthier supply, so hopefully they know what they are doing! I thought about a lamination, but honestly I don't know where I would be able to get enough veneer that wide and that thin in a nice wood. Honestly, that sounds like the best option now anyway... Maybe I'll struggle through trying to thickness plane another set of sides by hand? Would rather not have to do that, but worst might come to worst <_<

Thanks for the advice!

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I bent guitar sides, the best way to go about it is to thin where the bends are. I soaked my material in distilled water, and used a bending jig. You need to apply small pressure as the wood gets hotter and the water starts to steam, the bend can take more and the fibers will allow bending without breaking. It's all about feeling what's right as it's happening. 

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Thanks for the advice! Do you happen to have any recommendations for keeping the wood hot after it is out of the steam box? I don't have any means to use a heated bending jig that I can think of. 

On another note, I had to build another bending press/jig (see it here) that worked better than the first, but obviously I still had problems with it.

 

16 first position_smaller.jpg

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Unfortunately I do not. I tried to make an improvised one with a length of pipe and a torch, which sort of worked, but not quite as well as I had hoped. If I could get my hands on some properly heat treated spring sheets, I would absolutely do that, but for the limited scope of the project it seems a bit overkill to track down a pair just for this. If there was a luthier nearby, though, then it'd be another story!

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 If I could get my hands on some properly heat treated spring sheets, I would absolutely do that,

Is this the sort of stuff you need - you know that once you've finished the mandola you're going to want a guitar and a fiddle - might as well invest in the tools.

https://www.onlinemetals.com/merchant.cfm?id=1187&step=2&top_cat=1175

 

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Thanks for the suggestions! Both of those sound very enticing. I'm not sure how wide of a rule I can get, but that sounds like a fantastic and cheap option. Henry, I totally agree! I was of half a mind to make a fiddle to start with, but decided on the mandola first. There might be one of them in my future too! That shim stock looks perfect, but I might try and find it somewhere that sells less than 50ft coils!

Any chance anyone out there knows a ballpark thickness? I assume that the thinner the better, but you never know!

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Good to know! I think I might have also found a place online that has what I am looking for, but it turns out I might be able to get away with leather spacers. After planing, scraping, sanding and filing the sides down another mm or so for most of Saturday, I was able to do some tests yesterday with promising results. At first I thought all hope was lost and was about a minute from scrapping any effort to get the steam bending working. It's been almost 8 weeks since I started bending <_<

Anyway, yesterday I went for it and used a piece of 5-6oz leather on either side of the wood, and it did wonders! The first piece still cracked into oblivion, but I was being too impatient. After realizing that the leather can both act as a pressure surface, but more importantly a reservoir to hold in heat and moisture, all the problems magically disappeared! The wood was drying out and cooling off too quickly, and as a result becoming embrittled before it was fully deformed in the press. 

I did a slight modification to the steaming setup where I can take the pipe that goes into the box and use it like a steam gun. After the wood is steamed, I set it in the press between the two pieces of hot, wet leather and clamp it just enough that it does not move around when I pick it up. From there, it's straight back to being blasted with steam, all the while slowly clamping down until the press is fully closed. (pictures of all this to come...)

Now, the dilemma is the amount of set that remains after unclamping. By virtue of the nature of my shoddy press, the two pieces do not align perfectly when the 2mm board is between the halves. That means I cannot get perfectly even surface coverage when clamping. Extrapolating one step further, the pressure is not even so the amount of  bend coerced into the wood is not even. For the tighter curves, I have found a way to do them alone, but for the broad arc of the sides it is proving difficult. in the best of the bends so far, I have only been able to retain about 85~90% of the curve. This might seem good, but that is only for the tight bends, which are the only ones that cannot be clamped/glued into place for the final construction. 

For now, that's where I sit. There's a piece clamped in the press right now, and there were no sounds of cracks. A long way to go, but getting there...

And finally, here's a picture of the full scale drawing I did before doing any of the building. 

Cheers!

Pattern smaller.jpg

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Another thing I just happened across, although well beyond the scope of this project-

https://www.youtube.com/watch?v=9Z0SsAyHKzc

Apparently you can use pressurized anhydrous ammonia to do some radical bending in hardwoods. Who would have thought! (Except that guy, of course!)

Edited by John Page
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Right-o! It's been a crazy and stressful week trying to get these 6 side pieces bent, and I think I'm finally calling it here. At last I have something wood related to show for the weeks and weeks of brain melting framing. 

The upper left corner piece that joins to the neck and brace has the worst of the cracking, but fortunately it is all on the inside and half of it will be cut off. The rest will be glued and sanded and hopefully no one will be any the wiser. Those two pieces that have the most curve were the sensibly the most difficult. Instead of trying to make the S shape, I decided to just use the neck block brace as the topmost bit of the body instead of trying to bend it back the other direction (tried and failed many times, cracked it a bit on the last). Maybe I'll thin down the ends and just cold laminate it to the block? Either way, I'm happy with how the sides have taken the bends. There is a small bit that will tighten the curves during assembly, but only a few millimetres at most, and only in the large sweeping curves. 

Now the real fun begins...
 

Steam Bent smaller.jpg

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