A pantograph for a plasma cutter

A CNC plasma cutter would be a handy thing to have for cutting intricate shapes. I often use a pantograph with my router to do things that would normally require a CNC router, so I figured, if it works for a router, why not for a plasma cutter?

I started with some boards of silver maple that I milled on my own sawmill a few years ago, and it's been drying in my basement since. I'm confident that it's stable. I jointed, ripped, and planed it it to get the pieces of the appropriate size.

Building the pantograph

Making sure I have all the parts cut out by stacking them how they will be in the pantograph.

The large piece of wood in the long link in the back needs to be just wider than the links that fit with it, so I measure the stack then trim the part of the link half a millimeter wider.

The holes need to be precisely drilled. I used my callipers to score lines from the end, setting it to half the width of the parts and scoring from both sides. Then punching a divot at the intersection with an awl.

The point of a brad point drill naturally aligns itself with the divot, even if the drill bit wobbles a little.

I trimmed a 45 degree angle on the ends of all the links. There was enough of these that it was worth setting up the table saw (normally, I'd just mark them and cut them on the bandsaw)

The torch part of the plasma cutter needs to mount in the middle of this link. I made it wider so I could drill a hole large enough without drilling it apart.

But I want the ends of the link only as wide as the rest of the pantograph...

... so I set up the table saw to cut away parts towards the ends, then finished the cut on the bandsaw.

Finally, adding a slight chamfer to the sides of the links using a small palm plane, and the ends using a carving knife

I glued the links together, starting with the middle part with one side. That way, I don't have to worry about aligning all the pieces at once.

Hinge pins and alignment

I used some 3/16" (4.5 mm) stainless steel rod for the pivots. Here, cutting the length that I need. Stainless steel rod can be bought at places like The Home Depot, Lowe's, or other hardware stores.

The holes I drilled were a very tight fit, so I cut a notch in the end of the remaining stainless steel rod and used it as a reamer to expand the holes to get a better fit.

I then added the other sides of the links, using pieces of stainless steel rod to help align it. I checked that the rod is square to the link.

When I glued the long link, the clamps pulled it out of square slightly, so I used a longer clamp at an angle to pull it back into square.

The ends of the link with the plasma torch need to fit around parts of the other links. This fit was too tight.

So I shaved a fraction of a millimeter off the ends of the pieces on the inside on the table saw, then cleaned up the burr with a carving knife.

Then clamping the links on.

While the glue dried on the link, I assembled and glued together the pivot mount. This is the thing that holds the links on the back of the pantograph, opposite to where the follower mounts.

Continue to part 2