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My new Jig
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=16504		 Page 1 of 1
Author:  Mike OMelia [ Thu Mar 20, 2008 10:01 pm ]
Post subject:  My new Jig
Maybe I will post pics of it tomorrow. On my first attempt to attach the back to the rim, I had endless problems. But not this time. I am actually affraid to show it because it will look "over engineered" (I am an engineer).

I burried six nuts on one side of the mold so I could attach a sized piece of 5/8 plywood. On the other side, I burried 12 nuts on each side of the mold about 5/8" from the inside edge. In each of those nuts, I screwed in a 4" threaded rod. Starting to get the picture? After fitting the back, cutting the kerfing for the spars, etc, I laid the back on the rim (in the mold, back piece of plywood attached. I cut four lengthwise strips of 1/8" poplar (about1.5 inches wide). Got them at Lowes. Then, I cut 8 pieces for the crosswise direction. Using wingnuts and large washers, I strapped the top down with this contraption. Worked like a charm!

BTW, those nuts that I burried were those things with a hex socket in the top and these auger like blades on the side. Drill an oversize hole, and crank it in. I had considered tie down straps, but on reflection, the forces they exert on any edge hanging over the rim is so high as to possibley cause a fracture. My little web of poplar straps creates even pressure over the entire back.

Hope I'm right about this! Beginning to think the hardest part of building guitars is building the jigs.

Mike
Author:  KenH [ Thu Mar 20, 2008 10:08 pm ]
Post subject:  Re: My new Jig
slackkey_mike wrote:
Hope I'm right about this! Beginning to think the hardest part of building guitars is building the jigs.

Mike


The first few guitars I built, I spent twice as much time building the jigs as I did the guitar. Since then, I find myself either making new and better jigs or modifying the old ones to better do their job. Good jigs are how I am able to build as many guitars at once as I do. It is also a good part of making repeatable guitars with the same tones and sounds as the last ones. It is never wasted time to make a jig to do a job properly!

I am having a hard time picturing what it is that you have built, but I'm always interested in a good jig :) Please post the pictures when you get the chance?
Author:  ChuckH [ Thu Mar 20, 2008 10:09 pm ]
Post subject:  Re: My new Jig
Post some pictures, I just don't get it.
Author:  Hesh [ Thu Mar 20, 2008 10:14 pm ]
Post subject:  Re: My new Jig
It sounds like you need a go-bar deck.
Author:  Jeremy Knight [ Thu Mar 20, 2008 10:28 pm ]
Post subject:  Re: My new Jig
I love jigs! Joining the top and back to the sides seems to be a challenging set of parameters for a jig. Here is one version of a jig that I have come up with.

I drilled about 24 holes around my solid mold and made a big sandwich with two concave dishes for the top and back with the body in the middle. I then squeeze it all together with threaded rods and wing nuts. It works pretty good and I can clamp it down quickly before the glue sets. I also disperse a few extra clamps on the blocks and body for good measure.

It's not perfect, but I thought it was a creative solution.
Author:  Mike OMelia [ Fri Mar 21, 2008 12:51 am ]
Post subject:  Re: My new Jig
Jeremy is close!! laughing6-hehe I even had pressure point problems at the ends like you did. OK, I'll post a pic tomorrow... but NO laughing!!! Ok?? pfft

Mike
Author:  Mike OMelia [ Fri Mar 21, 2008 12:52 am ]
Post subject:  Re: My new Jig
Hesh wrote:
It sounds like you need a go-bar deck.


Naah. That would be too easy.

Mike
Author:  Billy T [ Fri Mar 21, 2008 2:51 am ]
Post subject:  Re: My new Jig
slackkey_mike wrote:
Hesh wrote:
It sounds like you need a go-bar deck.

Naah. That would be too easy.
Mike


I like the way you think Mike! laughing6-hehe laughing6-hehe laughing6-hehe
Author:  Mike OMelia [ Fri Mar 21, 2008 10:09 pm ]
Post subject:  Re: My new Jig
Here are some pics
Author:  Mike OMelia [ Fri Mar 21, 2008 10:12 pm ]
Post subject:  Re: My new Jig
Some more:
Author:  Mike OMelia [ Fri Mar 21, 2008 10:15 pm ]
Post subject:  Re: My new Jig
I also need some advice on the side spars (keep rims from splitting). I have enough kit material for two on each side. Thought I might need more... can make some out of back stock. How many, and placement??

Mike
Author:  Jeremy Knight [ Sun Mar 23, 2008 6:17 pm ]
Post subject:  Re: My new Jig
That's quite a serious spreader you have inside your mold. I like it.

I place thin mahogany side braces about every 4 inches along the sides. I think it would be fine to use about any material. A lot of people even use cloth tape. See the thread on rim braces ( viewtopic.php?f=10101&t=16526 ) if you haven't already. There's all kinds of ideas and philosophies out there.
Author:  Hesh [ Sun Mar 23, 2008 6:37 pm ]
Post subject:  Re: My new Jig
laughing6-hehe laughing6-hehe laughing6-hehe laughing6-hehe gaah :D

Forgive me please Mike - that was not me laughing my dog used my Mac's mouse and hit those emoticons.........

Regarding your jig...... If you are using HHG, and you were not I hope, could you position and tighten all clamps, wing nuts, bank vault steel rods, in 15 seconds? It looks like it would be tough to get all the clamping pressure in place in time before Titebond would gel too.

But it does look cool....... :D

As for side supports this has been coming up a lot today and you will find two other active threads right now on the subject. Just glue around 5 side supports per side in place. They can be 1/4 - 3/8" wide and just butt them against the kerfed linings. You will be fine. In the future consider using side tapes and/or inletting your wooden side supports into the kerfed linings.
Author:  Hesh [ Sun Mar 23, 2008 6:39 pm ]
Post subject:  Re: My new Jig
Oh and I just noticed something else if I may please. You need to be able to pull your spreader components out of the guitar through the sound hole after the top is installed. It appears to me that this might be problematic with the size of your spreaders.
Author:  Mike OMelia [ Mon Mar 24, 2008 9:15 am ]
Post subject:  Re: My new Jig
Hesh, Thanks for the spreader tip! I had not thought about that!! :oops: Maybe I can "hollow" out the shape a bit (so it can go through the sound hole).

Actually, its the 4 (axial ) straps that do most of the work. So, I have time, but I can see where go-bars and a radius dish would be faster.

But, yes, I will most likely invest in a go-bar deck. Mine needs to be collapsible, I have no room to store it. But the designs I have reviewed make my design realizable.

Thanks all!

Mike
Author:  Kirt Myers [ Mon Mar 24, 2008 1:29 pm ]
Post subject:  Re: My new Jig
Here's what I came up with when I switched to hide glue. 3/4" insulation for a little cushion, reinforced with fiberglass drywall tape. Then the little wooden pads glued on for the go bars to bear against and to help distribute the pressure. The whole thing is basically one piece and somewhat flexible to conform to the radius. I lay it on top and put one gobar on the center large piece of wood, then add bars to the critical areas first around the rim. Took maybe 40 seconds to get them all in place. I like it.

Image

Image

Just another way...food for thought.

Cheers.
Author:  Mike OMelia [ Thu Mar 27, 2008 3:35 pm ]
Post subject:  Re: My new Jig
Picture please?

3/4" insulation... do you mean foam board?

Mike
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