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It took me a long time to finally get my bending machine(Fox LMI) done. Did it according to the vid from LMI. I'm building a square neck reso. Now, after reading in archive here, I find that my bending form and my mold may be off.
I built both from a plan. Traced the exact form and cut the bending form and mold the same. Plan on using a blanket instead of bulbs, with 2 spring steel slats. I never compensated for the blanket, slats, & side. Not having a heat blanket yet, I estimated the width of my bending form 6 1/2 wide to fit the width of the blanket's 6 in(didn't want it to be too tight). So should I have made the bending form smaller to compensate for the thickness of the sandwitch? And is the width 1/2 too wide? Man I hate to start over again! If I stay with what I've got, can I make the sides fit inside the mold using my turnbuckle spreaders to keep it in place? It seems to me someone started a post on this and I can't find it. All your comments would be appreciated
Dave

An extra 1/2 inch is not going to cause any problems. You aren't going to have a side 6 inches wide are you? As long as the heading blanket is covering the wood, you should be fine.
As for the mold, I built my first one the exact size as the outside of my guitar. There was enough flex in the sides once I bent them to fit into my outside mold and it wasn't really a problem either. I now make my bending mold 1/8" smaller than the guitar to accommodate the thickness of the sides. I put my heating blanket on top of the wood so the only extra thickness is the thin metal slat that goes between the wood and the mold.

If you are planning on using two heating blankets, than you'll have to make your mold a bit smaller but I have never had to use two blankets. I've heard that two blankets make bending a bit easier but, frankly, it isn't very difficult with one.

If you do feel you need to change the size of your bending mold, you don't have to start over. You only have to make the mold part. You'll want to have practice doing that part because that is what will change as you build different body styles.

Mike,
I was hoping I could get a way with leaving it. I'm in the shop now evaluating everything. When I first started w/the mold and bending profile, the two guys that I spoke to said just build a mold w/a plan or a guitar you want to copy. So first I traced my custom built reso I have now that I love, and one from a plan. I decided to go with the plan guitar as the body was a tad bit smaller. It more resembles an old guitar(square neck) I like.
I wonder if making the bending form smaller really makes that much of a difference. Aren't we making them (sides) fit anyway, once they go into the mold after drying? Of course, I don't want to have sides that are going to have to be trashed after trying to fit em"!

Thanks
Dave

You don't need to make a new form, you'll be just fine. The sides will fit to the outside mold without any issue, don't worry.

_________________
Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Dave buddy I think that you are OK too. I agree with Mike on all counts.

I'll add that my blanket does not have heating elements that go all the way to the side of the blanket. There is a 1/2" area on the edges of the blanket that has no elements. So I line things up with the closest edge of the bending form to me and then using a ruler position the wood/side about 3/4" in from the edge of the blanket. I check this several times in the middle and at both ends. Since you have extra width it would be a good idea for you too to be sure that the side is aligned properly prior to bending it into submission.

I also use one blanket and on top of the wood but with a slat over the wood and under the wood and the blanket on top of the upper slat. Then I add a 3rd slat over the blanket to help concentrate the heat downward.

And my forms and molds are the same size.

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Ann Arbor Guitars

Ok, Sounds like we'll go for it w/what we got!
Thanks everyone.

Dave