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Top Thickness?
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=5194		 Page 1 of 1
Author:  RichB [ Mon Feb 20, 2006 6:21 am ]
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I'm getting ready to glue-up the bracing for the top (Englemann Spruce). I'd like to thickness sand it to a final thickness of .110" before bracing it . All I have now is a digital Vernier Caliper, which only will allow me to measure around the perimeter & soundhole area. Is there a way to acheive this w/o that special thickness gauge?
Author:  Mattia Valente [ Mon Feb 20, 2006 7:07 am ]
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In a word...no. You can get digital and/or analog (what I have) dial guages for pretty cheap, and build yourself a stand for them. Works great.
Author:  Bruce Dickey [ Mon Feb 20, 2006 7:08 am ]
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Link to Read about this caliper at Stew-Mac

Rich, that is what most do, myself included. The large thickness calipers are really needed more for arched tops and backs. You measure all around and in the soundhole, and you are close enough to be consistent.

most get close before joining, say .125 to .135 (others like full thickness for joining, then start thinning) (I prefer to thin to get the plates equal, because they usually vary quite a bit between slices) That leaves room to level the rosette and do the final sanding from the rear of the bookmatch to reach your .110 inch measurement. Good luck, post pics.Bruce Dickey38768.6418518519
Author:  old man [ Mon Feb 20, 2006 9:06 am ]
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If you have the perimeter where you want it, lay a straight edge across the top and it will give you an idea of the high spots.

Ron
Author:  crich [ Mon Feb 20, 2006 11:53 am ]
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You can pick up a dial indicator for $7 @ Harbor Freight. I buildt a stand for it so I can thickness anything up to 13" wide. I'm thicknessing now,glad I took the time to build one! Clinton
Author:  MSpencer [ Mon Feb 20, 2006 12:06 pm ]
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I don't know if all the Harbor Freight sales are the same, but they were running both the dial and digital on sale, dial was $5.95 and Digital was $15.95.
Author:  RichB [ Mon Feb 20, 2006 12:40 pm ]
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Well...being the usual impatient, can't wait for anything person that I am, I used my digital caliper, and maintained a constant thickness all the way the edges of 2.75mm. And the soundhole edge is 2.82mm. The top has a nice ring to it, so I went ahead a started gluing-up the braces. I can always sand on it later, if needed...right?
Meanwhile, I can think about getting the thickness indicator that's usually used for measuring. All of a sudden, there's load of tools I'm finding that I need!

Bruce Dickey...On your Site, where you explain how you sharpen your chisels...what size is that curved dog-legged one that you are showing? I gotta get me one of those. Nice...A lot of good info there! Thanks...
Author:  Bruce Dickey [ Mon Feb 20, 2006 2:48 pm ]
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That is a Hirsh Cranked Chisel



Rich, the purpose for that chisel is to shave brace ends, helps with clearing the fingers. Others buy the long bladed chisels to accomplish the same thing. This one looks a bit like a glue clearing chisel, but it's not. I really enjoy using it.
Author:  Mattia Valente [ Tue Feb 21, 2006 12:52 am ]
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Bruce: if you're hand planing your tops, a perimeter and soundhole measurement will in no way tell you how thick they actually are. At least, that's how it was with me. I like to take measurements it about 20 different places on any given top, just to make sure I'm thinning evenly, etc.
Author:  Bruce Dickey [ Tue Feb 21, 2006 2:42 am ]
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Mattia, yeah if you are hand planing, you should most likely be able to measure every inch of that top. In that case you need this:



Affordable precision

Thickness Caliper
To carve an archtop instrument you need fast, precise measurements of critical top and back thicknesses. Our new thickness caliper does the job with just a flick of your thumb.



http://www.stewmac.com/shop/Tools/Calipers/1/Thickness_Calip er/Pictures.html#details

or something like it. It even specifies the archtop. I guess it never occurred to me that there were builders planing tops or backs. Spoiled rotten here, I use the drum sander, which of course gets this puppy level all the way across each plate. An edge measurement suffices in that case. Good point.Bruce Dickey38769.4568865741
Author:  Mattia Valente [ Tue Feb 21, 2006 4:05 am ]
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Yep, precisely. I quite like the 'feel' of spruce being planed away evenly, but I wouldn't say no to the thickness sander if I had the space. Right now, I save up stuff, and I'll be heading to a local shop that'll let me rent time on their sander for backs/side, possibly for tops. Harbor Freight (and Axminster if you're in the UK and/or Europe) has just the dial bit for a nice cheap price. A wood/ply frame will work, although since Shane posted his welded contraption, I'm looking to upgrade mine to something with a little less inherent flex.
Author:  rlabbe [ Tue Feb 21, 2006 8:00 am ]
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If you are truly cash starved, cut a 'U' out of plywood, and drill a hole in one end to accept a pencil. Set the pencil to a specific depth, and it'll hit the top anywhere it exceeds that measurement and draw a line for you.

Those dial indicators are cheap, and what I'd recomend, but the pencil is the old-school way.
Author:  Rob Girdis [ Tue Feb 21, 2006 3:32 pm ]
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This is a simple thickness gauge. It cost me $20 used for the dial indicator, the wood was from the scrap box. Accurate and cheap and simple to make.


Author:  Bruce Dickey [ Wed Feb 22, 2006 3:04 am ]
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[QUOTE=rlabbe] If you are truly cash starved, cut a 'U' out of plywood, and drill a hole in one end to accept a pencil. Set the pencil to a specific depth, and it'll hit the top anywhere it exceeds that measurement and draw a line for you.

Those dial indicators are cheap, and what I'd recomend, but the pencil is the old-school way.[/QUOTE]

rlabbe, hey that is cool, anyone with a set of feeler guages can do this. You may have accidently reinvented the wheel here. Cool idea. Very similar to folks setting the stop on a drill press and drilling a million holes to a certain depth before beginning to carve an arched plate. Thanks for sharing this, I truly like it.
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