[chris505]

Ive been building some sleeves on the tormach 15L, and my zero is constantly changing. To keep the part consistent i have been taking the Z axis to 0 and moving my work piece to the tool. i understand im off probably a few thousandths but not .250 or better as the parts show. the included picture shows three parts all zeroed the same way and all ran on the same program, but with vastly differing lengths. ANY IDEAS? Once again ive called tormach and never get a response from "tech support"

[tmarks11]

I suspect you have a problem with your tool offsets being set incorrectly. Are you touching them ALL off to establish the total offset before you begin?

For example:
1. Start with a turning tool (3/4" wide) touching right against the part with Z=0 indicated.
2. Switch to a parting tool. This tool is only 0.100" wide, and with the width of the tool holder taken into count, the left hand side of this tool is probably at least 0.250" to the right of the edge of the first tool.

So if the second tool didn't have the right offset, when you push it into the material, you are cutting 0.250" to the right of where tool #1 edge would have been.

Also, when you set the parting tool z-xis offset, you have to manually add the width of the parting tool (0.100" of whatever) after you touch it off. This ensures that the command z-axis movement will move it to a position where the piece to the right of it is the right length (see page 28 of the manual).

You didn't really tell us how much experience you have with lathes, so this might be patently obviously, if so, my apologies.

Another possibility is the part is slipping in the chuck during turning. That can give you inconstant lengths. You can mark the part with a black sharpie after you tighten the chuck, and watch to see if it moves. What kind of chuck are you using?

[LeeWay]

Are you setting G30 or do you home the machine between parts? I have made several thousand identical parts on mine, so something is certainly not going right for you.

Oh and regarding support, I called once and the guy had the answer I needed. Call lasted about 5 minutes.
I have emailed with a couple of issues and I always received at least one and sometimes multiple answers within about a day. Sometimes sooner. They do have that kind of reputation for support.

[tmarks11]

If none of the above helps, than I would take check to make sure the setscrews onto pulleys for the z-axis are tight (parts 28 and 35 in the diagram on page 139). Loose coupler or pulleys are the usual culprit for lost motion on an axis.

btw, Tormach generally has awesome troubleshooting guidance in their manuals. If you look on page 132, there is a number of steps to follow for troubleshooting lost motion on an axis. step #1: improper application of tool offsets. step #2: loose pulley. step #3: chuck not tight enough....

How are you cutting the hole through this parts? Are you drilling or boring? If drilling, what size drill bit are you using? I ask because step#5 warns that using too large of a drill can result in lost steps due to high loading...