Dan Cameron's slot mortiser
Dan Cameron sent me some pictures of his slot mortiser, inspired by my design, but with a few interesting changes to it.
I have constructed a slot mortiser inspired by your design, and I thought you might be interested in some of the details....
... the x/y motion is implemented by the use of a single pair of drawer slides and four UHMW sliders riding on a 1/2 inch thick granite tile.
The slides were (I think) 24" and I cut them to 18" and 14" Actually, they were both both part of a double extension slide that I drilled out the welds to separate.
The theory here is that the tile is polished essentially dead-flat, and the sliders pull upwards on the drawer slides to eliminate virtually all of the free play in their motion. The drawer slides, in turn, hold the sliders down flat on the granite (along with gravity).
Vertical motion uses a wooden dovetail mechanism. The sliding surfaces are lined with a single layer of UHMW tape. One side of the dovetail saddle is adjustable for sliding tension. The body of the router is a very strange shape, so I hung it from the plunge base with an acrylic sub-base and a tight fitting circular hole in a piece of plywood.
A note on the threaded rod vertical control. I did not use a t-nut. Rather, I threaded a block of UHMW (or may be it was HDPE) using an undersized pilot hole. The plastic stretches as you tap it, resulting in a friction inducing, low backlash thread. The crank is not all that hard to turn and it stays put. I learned this when I built my screw advance box joint jig.
For the single handle control arm I used a pair of rod end (Heim joint) fittings and a long 3/8 inch bolt with the head removed.
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