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Please recommend a micro adjustable DTI holder

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awemawson:
Pekka,

The bore of the tool pockets is brought into alignment by adjusting the relative positions of the tool disk and it's locating  half of the Curvic Coupling - they are bolted together but have a largish rotational tolerance to allow the adjustment. This rotation sets the correct 'Y' axis (height) alignment (there is no Y on this lathe but that's the direction we are correcting). Having set this rotation and bolted the Curvic up tightly, X will now be out of kilter but then it is a matter of moving X until the tool pocket is in alignment in X, then telling the controller the 'grid shift' on the X axis for ongoing use.

Previously I had set the tool disk rotational position just by tweaking it until a radial lathe tool holder had it's tool mounting surface aligned to X axis movement, which 'should' get the rotational position correct, but it's actually more important to get a tool pocket adjusted to be exactly on centre line.

So the plan is to swing a DTI mounted in the chuck round the inside of an axial VDI 40 tool pocket adjusting the tool disk until I get identical (but opposite) readings on top and bottom of the pocket, lock the disk up, then move the X axis using the controller until the left and right reading are also equal and opposite. Then I can set the X 'grid shift' parameter, which will be half the error value in microns now displayed on the control having moved it from where it thought X=0 was !.

PekkaNF:
OK. Starting to "get" it...I thought that it would be possible to put identical diameter pins to WDI mounting pocket and chuck - and to compare their position difference with a DTI moving in Z-direction (rotation axis). Easy on manual lathe....but this has bed slanted and not that easy to use sling mount for DTI

A challenge.

awemawson:
Pekka,

I already started down that track : The other day I turned a precise 10 mm spigot in the lathe leaving it in the chuck and mounted a 10 mm dowel pin in a 10 mm VDI 40 end mill holder. I bored and reamed a 10 mm hole in a bit of hexagonal brass that slid on the pin, and if in alignment should slide from the dowel to the spigot.

This was to check alignment when I suspected that it was 'out', and it is !

PekkaNF:
If you fit similar pin into chuck, there is no way to mount DTI to compare this chukked pin H/V positions to VDI mounted pin position?

Pekka

awemawson:
Sadly not Pekka. Also I don't have a collet Chuck on this lathe, and the current hard jaws are showing 8 thou run out, so it's a case of either turning a spigot as I did before and leaving it undisturbed or buying some soft jaws and boring them to suit.

Unlike a manual lathe you don't have exposed ways to slide a DTI holder along as all is covered by robust Swarf guards, which is why I made the sliding sleeve.

Once I've found time to sort out a rigid Chuck mounting for the DTI it should all work out ok I think

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