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Some interesting crack / pillar clamps Started by apartmentluthier, Sep 13 2006 03:34 PM




"I posted this design years ago, so some may have missed it. It's a variation of my 'calamari' clamp.

This clamp can be made for less than a dollar. The plastic pipe material can be had for free from plumber's cut offs.

If you republish this design please give proper attribution." - Oded Kishony

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If I understand what I am seeing, Oded.... You are gluing the (semi-disposable) bars of the clamp directly to the work... and you will cut them away when the repair is dry?  That's fiendishly clever.




Yes, that's what he is doing.  Maybe someone more adept with searching this site (than I)can provide a link to the thread where he states the source and thread size for the brass screws (and of course, his special wood for this :P ).  Very clever indeed.   jeff

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Tower clamps is not an original idea of mine. I believe that the person responsible for it originally was Peter Moes. One of the most creative and innovative violinmakers around. Search for "tower clamps"


Nor am I the only one to adopt this clamp design, IIRC Bruce Carlson uses a very similar tool. 


I bought the hardware from MSC Industrial supply, I used 8/32 X 1 " Knurled brass thumb screws and 8/32 knurled nuts and 1" 8/32 brass studs and I also bought an 8/32 tap. This together with some scrap maple resulted in about 20 clamps at a cost of about $1.50/clamp + about an hour of my time.


The thumb screw is at the top of the clamp, drilled and tapped on one side and is used to spread the towers apart

The bottom is composed of the stud screwed into the tower, an oversized hole drilled into the opposite tower, with the nut used to bring (clamp) the towers together.


In addition a wedge ( which should be placed corner to corner and not as shown) can be used to help level the crack. I should also add that there is paper between the tower and the plate to facilitate later removal.


You can do it for even less money if you choose to use plastic hardware which is cheaper and also has the advantage of being lighter in weight but somewhat less durable and attractive (IMHO)




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The wedge, which should be 'catty cornered' ie diagonally placed over the part that's raised (on the inside which, of course, will be the lower side on the ouside of the plate) This will help push it downward to correct for a raised 'step' in a crack repair.


BTW this method is used on all sized instruments, not just large ones. But is usually reserved for more problematic cracks.



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