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Tabbed top and back
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=53650		 Page 1 of 1
Author:  bcombs510 [ Thu Nov 05, 2020 9:21 am ]
Post subject:  Tabbed top and back
Hello,

Have any of you gone through the trouble of setting up to use a tabbed top / back with your molds? I’m thinking like the Martin tops:

Image

I have access to a CNC and was thinking about making new molds with the necessary alignment pins and cutting out the profile for my tops / backs to align with the pins. I’m not really trying to solve a problem per se, just wanting to play with the CNC. :)

For those that use this type of locating setup is it worth the effort? Could you share any pics of your setup?

Thanks!
Brad


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Author:  Jim Watts [ Thu Nov 05, 2020 11:36 am ]
Post subject:  Re: Tabbed top and back
Hi Brad,
I do a variation of this, no cnc. I'll try to post a pic this evening.
Author:  SteveSmith [ Thu Nov 05, 2020 12:10 pm ]
Post subject:  Re: Tabbed top and back
No CNC here either but the tabs are still useful. What I do has nothing to do with the mold though. Tops get tabs at the waist and one near the tail block . Backs get tabs near the neck and tail blocks. I use the tabs at the waist and small flat head screws to lock the top to my work board when I do rosettes. I CA a scrap block on the sides near the tail block tab so I can use a 1/8" pin to index the top, at the neck I just drill a hole into the neck block. I do the same on the back, two tabs and two blocks CA'd to the sides. Takes longer to explain than to do it and it lets me make sure the top and back are glued on exactly where I want them.
Author:  bluescreek [ Thu Nov 05, 2020 12:38 pm ]
Post subject:  Re: Tabbed top and back
I use halos that way I can set the notches in the rim as well as setting braces .
Author:  SteveSmith [ Thu Nov 05, 2020 1:12 pm ]
Post subject:  Re: Tabbed top and back
John, my method allows me to mark the brace notches very accurately too (I'm using 1/8" x 1 1/2" stainless pins).

I have to admit I'm not sure what you mean by halos, can you explain a bit?
Author:  Clay S. [ Thu Nov 05, 2020 1:18 pm ]
Post subject:  Re: Tabbed top and back
A number of violin plates show small alignment pegs that go into the top and bottom blocks. Somehow that never caught on with guitars.
Author:  rlrhett [ Thu Nov 05, 2020 2:16 pm ]
Post subject:  Re: Tabbed top and back
bluescreek wrote:
I use halos that way I can set the notches in the rim as well as setting braces .


I'm not sure I know what "halos" are in this context. I lost mine years ago. Can you show a pic of what you mean.
Author:  SteveSmith [ Thu Nov 05, 2020 3:52 pm ]
Post subject:  Re: Tabbed top and back
Clay S. wrote:
A number of violin plates show small alignment pegs that go into the top and bottom blocks. Somehow that never caught on with guitars.


I should of known, every time I think I thought of something cool I find out it's been done by someone else for two hundred years - ha!
Author:  bluescreek [ Thu Nov 05, 2020 6:14 pm ]
Post subject:  Re: Tabbed top and back
https://www.youtube.com/watch?v=i9ubMJXhjq0&t=5s
Martin uses this technique in the top bracing department
I use these same halos to then mark the notch locations in the kerfed lining.
makes for more accurate placement
Author:  James Orr [ Thu Nov 05, 2020 9:11 pm ]
Post subject:  Re: Tabbed top and back
bluescreek wrote:
I use halos that way I can set the notches in the rim as well as setting braces .

This is where I think they’d be useful, too.


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Author:  bluescreek [ Fri Nov 06, 2020 8:11 am ]
Post subject:  Re: Tabbed top and back
it sure helps with fit and finish for sure.
Author:  SteveSmith [ Fri Nov 06, 2020 9:18 am ]
Post subject:  Re: Tabbed top and back
That makes sense John, thanks for explaining that.
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