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Also what are the dimensions of the carbon fiber tubing you are using

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That sounds too heavy IMO. The UTB can be as thick as you like - I do mine 10mm thick - but you can go down to 6mm on the X without a problem. I would do the soundhole braces 4mm, but keep them tall. Tall thin braces are always better than wide low ones because they have a much higher stiffness to weight ratio.

The picture I posted of the carbon braced guitar wasn't mine. I don't think it's too critical - you're only adding stiffness to an already stiff structure and they don't add a lot of weight. You could go with 6 or 8mm OD tube.

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Made my bending jig pieces today and a work board cut out a lil bigger than I need so I have a good solid flat surface for working and clamping.





What kinds of wood can be used to brace the bridge with. I have some walnut I can shave but I also have plenty of red oak and cherry left from building some puzzle boxes. Which would be preferable.

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All right been taking my time and doing some more research and reading. I decided to bend my sides before doing any more work. I want to make sure I can bend two cut out sides before I cut my sound and back board. The pick below shows my work on my bending machine.


I drilled the dowel holes for two reasons the first is so I could align the two halves and do any filing or sanding to make sure they are flush with each other. The second is so when I install my clamp blocks on either side and fit them over the dowels I'll be able to swivel the arms at the tail and head. The 3/8" all thread I'm using will fit through both the dowel and the clamp blocks.

What I've realized after designing and buying the parts of my machine is that the money is in making tools. It cost me $30 in parts to make and they sell for ridiculous amounts of money. And most I've seen for sale you have to make or buy your form seperately.

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Got my neck out tonight and realized I had it made to fit at the 15th fret and the grellier plans have it jointed at the 14th. No big deal I used my fretboard and measured the new placement of bridge which was only about a half inch. Also realised the first fretboard would have worked, oh well the second has markings like the grellier fretboard on the OM plans so it's cool.

I would like to try bending my sides this weekend. I'm so nervous about bending the cutouts. Would anybody have any tips for cut away bending on a machine. I will be using this method for bending.
http://youtu.be/cqpDQ2z0iO8

I've heard of adding ammonia or windex to the water I soak them in, how do you guys prepare your sides for the bender. I would tell you what species of wood they are but LMII didn't tell me. Here's a pic.

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I have to say, I would worry about using that technique (though it obviously worked for those guys). There's a lot going on there and he's got a helper. I don't know how even the heat will be using a heat gun, but the main thing is how many different things they're paying attention to at once. If you can't buy a silicon heating blanket, consider making a light bulb bending machine. Pretty sure there's a tutorial for it in the Fixtures and Tutorial forum. Especially doing that cutaway, you should be pretty sure of your wood temperatures.
Maybe someone else has used the technique you are referring to and has some tips, but I'd try to make a unit that doesn't require you to be bending and at the same time, heating the wood. Also, John Mayes has a great article on thicknesses and bending temps for various woods. You will obviously know the wood species you're bending for your actual build, so consider referring to that to be sure you're giving yourself the best chance possible to succeed. He's obviously using bending blankets, but the point is the temps and thicknesses he shoots for .

A heat gun is a good source of heat, but remember this: the heat only goes where the air blows. See in the video where they had to readjust the curve in the lower bout? I think that was from the heat not being evenly distributed. So keep it moving to spread the heat further out. otherwise, you can end up with a kink in the wood, which can be hard to get out.

I simply use a brush, dip it in some water, and paint the wood with it. Then wrap it as in the video, I use aluminum foil. doing this, when the heat gun hits the magic temp, the heat will flow through the damp wood very quickly. Of course, the water will soon be gone, which is why in the video he checked then redamped one end.

I would not under any circumstances put anything other that water on the wood, especially ammonia! Ammonia can react with the tannin in the wood, turning it black. It is an excellent natural stain for red oak for example. Also, in ages past, furniture pieces were darkened by "fuming" with ammonia. They would put the piece under a tent, and let ammonia vapors do the work. Any wood with lots of tannin can be susceptible to this.

Now some do use something called Supersoft and swear by it, but I have no experience with it.

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"Those who tilt at windmills are only considered insane by those who can't see the dragon."

Heat gun also works ok up the back of a pipe.

Are those your practice sides, Jeremy? I reckon they're Khaya (African Mahogany to some).

I've had success soaking Khaya in a bath for 15 minutes and then recharging with a spray bottle as it dries. I've done the same with Rosewood twice but both times it took me longer to bend than the Khaya - Yet to perfect to my process for Rosewood.

Been a busy day and didnt accomplish anything new!!!

Yes them my practice sides. I'm gonna have to half each one. I have no way to cut them down to size after I bend them and sanding, filing and planing 3 1/2 inches would just be a waste of wood. Unless someone has a better way to cut them down. Plus ill get four tries. If they break they break, I can buy more (but hopefully it works). I checked out heating blankets and saw the reason I did not consider that option. Mainly price. My machine idea I actually pieced together in my mind after watching a lot of videos and re watching them of people using clamp benders. There are a couple people that use these type of clamp benders on cutouts and they do it rather quickly but they do use blankets. I do have access to sheet metal so I can sandwhich the pieces like in the vid link. And yea I will mos def have someone to help me. If it don't work I can make a pipe bending unit using the gun no problem.

Thanks for all your tips and help.

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An old clothes iron works pretty nicely as a heat source. My bending rig is strictly bargan basement, less than $20.
Scroll down to the bottom of the second page:
viewtopic.php?f=10133&t=37283&start=25

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All right all right all right!!! I had a good hour today to finish my bender. All I have to do now is install my 3/8 all thread and make the three blocks that will clamp down.

I like the iron technique!!! That's pretty cool. I just had an idea pop into my head on the cutout. I could prolly do it by hand on the machine with a pipe and the heat gun blowing through it, then ill finish it with clamp once its already bent closer to the shape I need. Standing behind it like that and pulling it into place should allow me to feel the wood and not over stress the bend all at once like y'all are talking about. Hmmmmmm.

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Not the most pretty thing I've built but also not the ugliest!

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Ok so I decided instead of pulling the pipe from behind while it was heated might be a lil difficult. So instead I drilled holes through my metal pipe and mount it as a clamp. I then took a piece of sheet metal and bent it using the machine so could mark accurate reference points. After that I wrapped my pre soaked side strips in wax paper ( because it holds in moisture better) and sandwiched them between the previously marked sheet metal strips. I then fed the whole thing through the machine checking my reference points. Now the fun began. I did this in five minutes by the way. We started heating the waist and clamping it. After that we did the bottom heating and screwing the nuts arcing it down til we got it too the complete horizontal position and clamped it tight. The cutout was both easy and fun to do thanks to the pipe. We just blew through the pipe with the gun while I used the extra lenght of all thread for handles and arced the pipe clamp down to its horizontal position, then clamped it down. I did both sides in this manner. So easy to do. The pipe clamp was a genius idea!!!

Finished machine.

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Sides in bender cooling.


Close up of pipe system.


Finished side. Ill have to do some adjusting with a pipe but it turned out great.

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Nice job. I really like the use of the pipe as a ram for the cutaway, and leaving the threads long to give you the leverage you need. Do you anticipate any trouble with the actual sides being a couple inches wider than your mold?

I actually precut the sides before hand leaving around 2mm extra on each one.

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I did learn something though which I will have to correct before the next use. I used 3/4" dowels for my levers and as we started to tighten the second side board the dowels started cracking. I drilled through dowels and the block to relieve some of the stress on the dowels but it takes so much pressure! Next time ill use some steel electrical conduit instead of the dowels. Let me tell you this drilling through that galvanized pipe was hard and broke a drill bit. It was best to start small then enlarge the holes and ream out so it slides on the all thread easily. All in all a great machine. It worked exactly how I designed it.

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I've seen kerfing installed in two ways: by gluing it to the sides first and by gluing it to the back and sound board first. Is this one of those things where it's up to the person assembling the guitar? Because I was matching up my bent side to to my stenciled soundboard and it looks like it would be easier to glue the kerf to the soundboard first then clamp the sides to the kerf so get the exact shape. Can someone clarify this procedure a lil for me?

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Well done, great job! Quite a lot of springback but you can touch it up.

As always, I need to state that I'm not really qualified to say, but there are certainly at least three ways to do it (horrifically simplified descriptions):

1, Solera (guitar shaped workboard): Glue headblock and tailblock to top, install kerfing to sides, and glue the sides down on to the top. Then prepare for gluing the back.

2, Radius dish & Go-bar deck: Connect sides into complete rim with headblock and tailblock. Rough shape, glue kerfing, final shape, glue top or back to sides with go-bar deck in radius dish.

3, Clamp a side in place and then affix it with individual dentalones [blocks the same sorta size as kerfing].

I don't think I've seen anyone glue kerfing to the soundboard first. Or dentalones. But as always, someone else can answer much better than I!

Yes. Don't do it. If you're trying to make the sides conform to the outline, the linings will just rip right off and potentially leave the top/back unusable. There are reasons beyond this. The linings need to be profiled in the radius dish to match the arch to the top or back, being a significant one.

Get those sides touched up. Enjoy the process I appreciate your ingenuity.

Got ya! And I am definitely enjoying the process.

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I was referring to width rather than thickness. It looks like your practice sides and the machine itself is maybe 2 or 3" wide. Most acoustic guitar sides are bent about 4" wide. Maybe yours is a really thin body.

Yea I wanted to keep the thinline design for this build. The machine is exactly 2 1/4" wide and I cut my sides at that thickness with an extra mm added.

What I learned from day two of bending sides. MORE HEAT!!!!!! And more moisture. I ended up leaving my other two precut practice sides in the pigloo over night, not in the water but lifted up on a couple 2x4 blocks so they would stay moist. I was worried it would warp the wood but they looked good. When I woke up this morning I removed the blocks they were sitting on and let them soak again for another half hour. When I took them out of the water I flexed them to check the overall ease of the bend and let me tell you they were really soft. We then wrapped them in the wax paper and sheet metal and put the side in the machine. I noticed in yesterday's wood that there weren't any scorch marks so that made me think maybe I wasn't using enough heat because of all the spring-back. So today we decided to go a lil slower in the waist to get everything hot enough and then we baked the $#!! out of bottom bend. The cutout we did the same since it worked so well. After allowing the whole thing to rest and cool for a half hour we then released the waist the bottom and lastly the cut out. The side we pulled out was in a lot better shape and had very lil spring back. The end product was a lot nicer and still no scorching. I'm thinking it sill needs more heat to get it right. They still need adjusting but after today I'm quite confidant I can fix'em.

My next machine I think I'll use pipe on all the clamps instead of the wood blocks, that will allow better heating, I also think I will utilize a couple light bulbs in the bottom of the machine to help get everything hot enough.

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Do you have a cheap digital thermometer you can use to check the temp? Wedge it between the upper slat and the wood. You can probably start bending around 250, but I imagine higher heat, up to 300 or so, would be better.

The heat gun we used had two settings 500 degrees and 1000 degrees. We actually used the 1000 degree setting. The problem we were having was heating the bend at the waist where the block was, you can't really get the heat to the metal because the block threatens to catch fire. The bottom bout and neck didn't have the same problem because there was plenty of metal to heat up the wood and set it. Next time I'll add a pipe at the waist and I should get a better bend.

I don't have a digy thermometer but I do have a couple oven thermometers with thin flat bottoms I could alter to fit in between the slats. I don't know why I didn't think about it, I guess I though 1000 degrees would heat it enough.

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