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Reverse Pantograph?

Posted: Fri Jan 14, 2011 1:27 am
by Covah
Friends,
I recently turned down a phonograph because it was missing a foot. Then it occurred to me another foot could be carved with the existing foot as a model using a pantograph. However, the new foot would have to be a mirror image. Such a machine would be a boon to furniture restoration in general. Any ideas?

Thanks!

Re: Reverse Pantograph?

Posted: Fri Jan 14, 2011 7:41 am
by JohnM
The piece to be copied would have to be mounted on a turntable connected to the carving turntable in such a way that the turntables would rotate in sync with one turning clockwise and the other turning anti-clockwise and vice versa. The pantograph would have to be a diamond shape with either the top or bottom of the diamond being the 'fixed' point so that as the tracing point is extended, so is the carving point; as the tracing point is retracted, so is the carving point. The 'fixed' point would have to be mounted to an adjustable, lockable gimbal (or gimbals) so that the entire pantograph can move relative to the axis being traced/carved upon the model/carving. There would need to be an attendant 'frame' to contain the pantograph arms to ensure that the tracer and router bit maintain the same plane. I suppose the fixed point might be attached to the frame and the frame gimbaled (and counterbalanced).

Perhaps the tracer and router could also be electronically, hydraulically, or pneumatically servo-ed to eliminate the need for the pantographic arms.

No idea how one could mount an entire phonograph or other large carcase upon the tracing turntable. Perhaps a casting could be made of the foot to be copied for tracing purposes. Having said all that, unless one was going for mass-production, I don't think there is any substitute for a good set of carving tools, a couple of pairs of simple calipers, a contour gauge, a favorite way to sharpen, a pair of eyes, a steady hand, and a little self-confidence!

Re: Reverse Pantograph?

Posted: Fri Jan 14, 2011 7:44 am
by Brad
The capability exists via a laser pantograph: http://www.arctron.com/3D_Surveying/3D_ ... /index.php

You scan the original, convert to a vector file, mirror it, then drive a CNC machine. Simple, quick, accurate and out the financial reach of most restorers..... :lol:

I could imagine you could find folks with some or all of the capability. It would probably only be worthwhile for the rarest of machines

Re: Reverse Pantograph?

Posted: Fri Jan 14, 2011 7:51 am
by JohnM
Brad wrote:The capability exists via a laser pantograph: http://www.arctron.com/3D_Surveying/3D_ ... /index.php

You scan the original, convert to a vector file, mirror it, then drive a CNC machine. Simple, quick, accurate and out the financial reach of most restorers..... :lol:

I could imagine you could find folks with some or all of the capability. It would probably only be worthwhile for the rarest of machines
Dang! Buck Rogers stuff!

Only US$29258! Then you'll need the CNC router!

Re: Reverse Pantograph?

Posted: Fri Jan 14, 2011 2:17 pm
by estott
A proper furniture restorer would have no problem carving a new leg.