Wednesday, November 10, 2021

Watchmaking Machinery 2 DRO Cross slide


I ordered a digital caliper DRO (digital read out) for the cross slide of the Taig lathe off of eBay.

Well: it was stuck on its bracket with tape; the tape pulled the back caliper sticker off and the anchor point tape came off too; the bracket was some purple transparent 3D print stuff that was less rigid tha PLA; also the anchor bracket had a twist which caused the slide to bind.

The calipers had the measuring jaws cut off. That was the only good thing-other than the whole thing was a sort of inspiration template for me.


So I cut an aluminum block into a "C" shape with a drill press, hacksaw and jeweler's saw to connect the drilled holes.


Then i remembered I got my bandsaw running straight (by twisting the table and adding more tension). So I popped a bi-metal blade with tiny teeth on it to help with the rest.

I made the anchor point with a drill hole that was also counter sunk most of the way down. I didn't go all the way down so the part of the hole that narrows down would grab the head of the screw and keep it from pulling through when i tightened the t-nut (which is just a screw and tiny nut).

The Allen key wrench is on the screw in the photo. Then I bandsawed the top quarter of the tiny anchor off. I then drilled two screw holes in a bracket and the anchor pieces, paying careful attention not to go down the center so I wouldn't interfere with the Allen key wrench path.

When tightened, the two halves trap the end of the calipers. As the cross slide moves toward or away from the operator it pushes or pulls the caliper slide which measures the movement to .01 of a millimeter. You can also hit a button and it displays inches.

Anchor point is solid. The plate over the caliper slide end is raised, because it's acting as a clamp. Standing normally it isn't apparent to the operator, and looks pretty cool.

The big C-block is super sturdy. A screw feeds up from the bottom to a nut that is in that T channel.



A single screw holds it to the block. This allows it to pivot counterclockwise for installation and removal. It also allows me to make sure the slide is perfectly parallel to the carriage and slidebefore tightening the anchor point at the other end.

The C-block is most of a 1" x 2" x 4" bl9ck of aluminum. Much, much stiffer than the 1/4" thick 3D printed plastic bracket which visibly flexed.

My C-block doesn't move. Sliding out and returning to starting point gives me a repeatable readout of "0.00mm". You don't get much better than zero-hundredths of a millimeter.

Watchmaking deals with 0.3-0.8mm (tenths), which is much larger than 0.01mm (hundredths).

Meow²