CNC Lathe Tool Offsets, just a few questions...

[JWB_Machining]

Hey,

I'm using a Haas TL-1 with an import 3 jaw chuck. Should I reset my tool offsets for Diam. every time I use the machine and after I change tool inserts? Also I recently got a threading tool. When I set the offests for the threading tool so I use the part of the tool closest to the chuck to set the offset or should I try and use the tip as what I set my offset for? Just looking for general good practice on setting lathe offsets when you're using a 3 jaw chuck and you know you're not gonna perfectly cenetered everytime you chuck up a new part. Also if I have to re-chuck a part is there any tips on getting it to be recentered or are you kind of just stuck with what you get?

[ulrarrun27]

Practically we wont get the same center repeatability... if it is normal 3 jaw chuck..

Resetting Tool offset after insert change is must. Because every insert has it won manufacturing tolerance.

We normally do 0.2 mm Correction in safer side. then measure and give the necessary value..

Now a days we use auto Q Setter.. On which we run the AUTO TOOL OFFSET MEASUREMENT Program for auto measure. Life become simple.

Arun

[Geof]

The reliability of the chuck has nothing to do with the tool offset setting and it is not necessary to reset every time you use the machine.

If leave the tools in the turret you can leave the X offsets unchanged unless you change an insert in which case it is a good idea to re-check. As ulrarrun27 suggests you can do this most easily by adding a small amount to make the parts oversize then go back down after measuring them.

For the Z offsets if tools are left in the toolchanger (if you have one) but will not be used I think it is a good practice to set them back several inches away from the chuck so you are less likely to index the turret and crash them.

[g-codeguy]

For the threading tool, set to the side nearest the chuck not the nose radius. Now you know exactly how close you can get to a shoulder without hitting it. Plus it is way easier to touch off on the side of the insert.

Even if I am laying out a tapered thread using the point to know what the correct X dimension should be, I will look in the insert catalog, and add the dimension from side of insert to radius center to my Z dimension in the program. Hope that makes sense.