Tailstock DRO

[PeterT]

I can offer some potential reasons:

- the threads in a typical TS may not be of same quality as say a leadscrew. Its not really considered the precision end of the lathe. Especially if it seen heavy drilling use (wear) which may be showing up as backlash. Now that you have an DRO on it, put the dial on a number so it stays put. (Don't lock the quill). Pull & push the quill & observe - do you see any displacement on the digital display?

- my dial can be nulled or set by rotating into a position. its a friction thing, not a thumbscrew lock. But it had this irritating habit of scuffing just a tiny bit so was 'losing time' every rotation. I thought some debris got in the crack but it was actually not turned with parallel thickness. QC issue that can probably be fixed.

- you might have something goofy although I thought most of those metric/inch bastard hybrid lathes were behind us. I have seen some dials with a truncated graduated scale. Like 0.100" increment on the IMP side of dial & a 'stubby ruler' scale on the metric side. Works dandy as long as you only turn it < rev. And sometimes they got the dials mixed up, IMP bastard on IMP pitch lathe when it was supposed to be MET bastard. Hope this makes sense. Yes DRO takes away some of this bygone fun & games.

 

[Susquatch]

I will post a pic later, but basically when you set the tailstock dial to zero then turn it one full inch on the Mit scale the dial is like 3 or 4 thou (can't remember) past the zero.

I think @PeterT covered most of what I would have said.

I had a mill that was like that. But it was caused by a screwed up lead screw. I plan to sell it, but if I was keeping it, I'd add a DRO sort of like you did and be done with it.

 

[1018Machine]

I can offer some potential reasons:

- the threads in a typical TS may not be of same quality as say a leadscrew. Its not really considered the precision end of the lathe.

- you might have something goofy although I thought most of those metric/inch bastard hybrid lathes were behind us.

Ya I pretty much figured it was a pitch issue in the screw where they got as close as they could in metric. There's no end play in the quill, everything is tight as the machine was bought new by me and I use the machine moderately. Despite the fact that tailstocks aren't really meant for precision work I'm glad I decided to add the scale as now there's no doubt. For some of the operations I use it for it will be beneficial.

 

[Susquatch]

Despite the fact that tailstocks aren't really meant for precision work I'm glad I decided to add the scale as now there's no doubt.

I don't think that's true. There are many applications where tailstocks are meant for precision work. You might not have encountered one yet, but there is a reason why they have a good scale and I'm of the view that your add on scale for your situation is more than just simply "beneficial".

Yes, the most obvious reason for the discrepancy is a metric imperial mismatch.

 

[1018Machine]

I don't think that's true. There are many applications where tailstocks are meant for precision work.

For the most part they are meant to drill or bore a hole but myself (as perhaps a few others) use them for precision boring for things like spindle pockets or bearing journal shoulders. I'm just happy to know that what I did was beneficial.