Official Luthiers Forum!

They do seem so get pretty snippy over there about the least little things. Lots of good information there too and lots of good people, but lots of rules and regs. Cool jig. Thank you.

So I guess you saw the post then. Thanks Todd for linking there. It starts to get a bit confusing when I have two post going that are the same. But I like to get the views of all that I can.

ANother newbie question can you explain the sled to me please

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Formerly JJH

I learn more from my mistakes than my successes

there is some great info there but i dont post anymore becouse of some of the other people that post and moderate the place.

Thats a great way of doing radius dishes though it took me a while to figure how it worked

A suggestion my friends please. Let's confine our remarks to the merits of Chris's jig and not compare the OLF to the MIMF out of respect to both very fine forums. I have no authority to make this request here but I do have a sense of fair play and as such I have personally always viewed the MIMF and the OLF as complimentary organizations both benefiting many, many builders for many years. We are fortunate to have them both available to us.

Thanks for posting this Todd and Chris!

You spin the dish and after one revolution you then advance the sled towardes the center of the dish by an 1/8"- 1/4" and spin the dish again. At the end you have a radius dish for sanding and glue in up the top and back of a acoustic guitar. You also use it the sand the radius into the braces. Well it's one method. This one uses streight rails instead of radiused curved rails. If you check back at the link you will see the math for the rails and a couple of extras I just put on the sled to make things a bit easier too. It involves a $5 harbor freight clamp but I think a neat addition.

That's a pretty cool jig, but it looks to me like they'd have spent more on parts and certainly labour than what just buying a set costs. It'd make sense if it were something that you needed many of but seeing as these are the sort of thing most builders will just have one set of for years, if not life, it doesn't make a whole lot lot of sense to me.

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Richard
http://www.guitarmaker.com

I had the box from when I made a tapered back body form for building my tricone and the wood for the sled was left over wood that was 14" X 8' X 3/4". I've used the rest of that board for my work bench drawer fronts. All that it cost me was $5 for the HF clamp and a new 1/2" router bit that I'll use many more times and the price of some screws. Two dish without sand paper I think are something like $180. and then double that for sanding dishes. I'm not saying that's unreasonable for someones time to make them but I have the know how and time and tools, just a little short on cash. But if I wanted to save money then I'd just buy a guitar instead of building one. Where's the fun and joy in that? Seems to me alot of us make our own jigs and tooling. I just wanted to show someone what I did at really no cost to me and maybe they are wanting to see how it's done so they can make their own dishes. That's what these forums are about. The sharing of ideas and the expantion of others ideas, don't you think. And I got a new camera and I actually like making these essays. It's easier for me to do a photo essay then try to explain it in writing. And besides my spelling and typing really sucks.

Todd, thanks for clearing up any misconceptions about the MIMF policy. But, I notice your signature, what does it mean?

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Mark Swanson
Swanson Guitars
http://www.MarkSwansonMusic.com

The radius cutting jig is based on what's called the "long compass". Here's a
url that describes the technique. There used to be a good description of
exactly how to make a jig specifically for making radius dishes, but I've lost
track of it. Think of having your router bit at the center point of the V-shaped
part of the jig instead of the pencil shown.

http://gicl.cs.drexel.edu/people/sevy/luthierie/compass/Long_compass.html

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Gene

Politicians and diapers must be changed often, and for the same reason- Mark Twain

http://www.youtube.com/watch?v=tvGemvizrz4
Here's my YouTube demo if you want to see it in action.
Todd, I had a Chris video it too.

Thanks, Chris. The youtube vid is useful. There was a link somewhere on the math to calculate a short segment of a large radius arc. I'm sure I have it on my computer but I can't locate it. Anybody remember? Thanks.

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Greg
http://garibaldiinstruments.com/

Greg, Try this and there's more info above.
http://www.liutaiomottola.com/formulae/sag.htm