Thread: Mirror 3D Pantograph with router

Probably. My first thought was to make the connecting links cross each other instead of being parallel. But that would produce a mess.

Google [mirror linkage] was unproductive.

But Google [reverse motion linkage] has possibilities.

A near negative of the shape (not actually a mirror copy) can be made by placing the workpiece above the linkage, with the cutter pointing up. For a more perfect version, I think the linkage would need parallelogram motion in the vertical direction too. And every hinge introduces errors.

Cheers,
Joe

If you can make a plaster cast of the piece, that will give you the required mirror image to use on a pantograph.

Thanks for the replies;

I think maybe my concept of a mirror image is incorrect. Maybe mirror image is the wrong word.

Try this: I have a left hand, palm up, thumb pointing south. I want to copy it so that I create a right hand, palm up, thumb pointing north.

Norm

Yep. What Chris said.

Originally Posted by Frank&Earnest

Yep. What Chris said.

umm...maybe not ....that will give you a mould (a negative of the object)...which when cast will just reproduce the original.
there is a technique using "pointing" and measurements that I can't quite recall at the moment. I'll have a think .
as a matter of interest...what's the project fly?

Yes, the previously mentioned methods would only produce copies (IMHO).

I want a left and a right copy. Like in book ends. If you have a bookend with a figure facing out into the room. An exact copy would have the opposite bookend would be looking at the wall. You'd want to have both book ends facing out into the room.

The best mechanism that I can visualize is control arms arranged in a diamond shape. The "tracer point" is on one of the diamond points and the router on the opposite diamond point. So if the "tracer point" is moved left, the diamond collapses and moves the router right. The up and down movement stays the same as a regular pantograph.

Unfortunately, that's about as far as my mind can visualize... So rather than re-invent the wheel, I'm asking if it has already been invented.

Norm

OK, I'll explain myself. I should have learned by now that quick reading and quick answering make poor responses. I read "the piece" in "make a plaster cast of the piece" as a model of the "other side" you want. My imperfect English could also be to blame, I took "cast" as meaning "model", not copy. I thought Chris was not advocating anything different from underfoot's (and Ian Norbury's ) good advice of always making a plasticine model of what you want, in this case two specular objects. Casting them in a more solid medium like plaster allows you to use them with a normal pantograph.

Sorry for the poor exposure.

Consider a scissors with a diamond frame at the handles. A ball joint at the fixed pivot could accommodate the vertical motion, with the guided pin also free to move up and down. The rest is self-explanatory.

In any pantograph, the hinges must be snug, or have a biasing force to remove backlash. Knife edges and v-grooves are typically used in industrial scales, steelyards, etc.

Cheers,
Joe

......still , what is the original we want to copy? In my work experience , I' ve never seen people complicate their life so much , like when they try to make something "the easy way"
(climbing 4 floors up on narrow stairway with compressor and nail-gun to nail 4 nails is the perfect example - who needs that hammer , so old-fashioned)

-how about just carving the damned thing?

Originally Posted by joe greiner

Sorry for the poor exposure.

Consider a scissors with a diamond frame at the handles. A ball joint at the fixed pivot could accommodate the vertical motion, with the guided pin also free to move up and down. The rest is self-explanatory.

In any pantograph, the hinges must be snug, or have a biasing force to remove backlash. Knife edges and v-grooves are typically used in industrial scales, steelyards, etc.

Cheers,
Joe

Reminds me of the Sketchograph, an old kids toy. Or a variation of it. That's an interesting concept there Joe.

Originally Posted by Artesano

)
-how about just carving the damned thing?

yeah...well...there is that

otherwise, there is a cnc forum.
you may be able to program one of those fandangled things to do your bidding

Upon reflection (no pun intended), a ball joint at the fixed pivot won't work, because the only restraint against lateral wobbling would be provided by the guided pin. It would be better to mount the fixed pivot support and the slot for the guide pin on a board with a transverse piano hinge underneath the fixed support. The board should have a smooth surface, and the free pivots could extend to that surface to provide additional lateral control.

For best control, the diamond should be a lot bigger than the scissors arms.

Of course, you could just carve the damned thing, and of course you could program CNC. But where's the engineering challenge in that?

Cheers,
Joe

Originally Posted by joe greiner

But where's the engineering challenge in that?
Joe

yep.....engineers...really can't help themselves can they

Trust yourself and do it. All the information is in you, and in hands you have the best instruments available on earth to do it with.