Observations on mangling a DRO scale

I had a redundant old hardened stainless steel DRO scale which I wanted to repurpose as a register strip on my small CNC mill. It needed a bit chopping of both ends and a slot machining at both ends for 6mm hold down screws.

To hard for a drill I used a 6mm solid carbide 3 flute milling cutter to drill a couple of holes at the first end. Using dripped soluble oil the cutter did a good job drilling through but objected violently when I tried to machine what was left between the holes to form a slot.

Screw holes abandoned and on to the shortening. I used an angle grinder mounted in one of those pivoted holders ( Aldi or Lidl ?) with a thin (1mm?) abrasive disc. First end cut of relatively easy but half way through the second end the disk stopped producing sparks and stopped cutting. Following some aggressive pushing and bouncing the wheel suddenly bit and started cutting again and then the second end was chopped of.

It was now I discovered that the thin inlaid printed strip was glued on and the heat had melted the glue so the end of the strip came away slightly from the scale. I fixed this by warming up the backside of the scale with a flame and lightly clamping in the vice. Job done apart from making small hold down clamps, one for each end.

I have posted this in case anyone is contemplating similar scale cruelty – it might save someone from a degree of experimentation.

Rik

They are made of super tough stainless, even the cheapo ones

Cut with an angle grinder

Drill with a carbide tip, high pressure, high torque, low speed

I must have been lucky (but I dont think so) when I modified three different 'Hardened' (cheap) calipers.

I used a hacksaw to cut off the jaws and ordinary HSS drills and taps for the mounting holes.

Key thing when drilling this stuff is slow speed and high pressure. I tapped M4 in a 3.5mm hole and dont recall any problems.

Ian P

I'm fairly sure I managed to drill a couple of these with a cobalt drill.

I made a tailstock DRO from a set of Aldi digi calipers. The holes drilled easy. Guess they must have been soft metal.

Steve.