After truing up my dial gauge and oiling everything I can't measure any backlash in X or Y anymore, Z looks like it could be 5-7 tenths. Think it was just sticking a bit after sitting unused for 9 months.
If your Z axis has backlash the gibes are too tight! The head and motor provide about 300 pounds of constant down force.
Could the machine have been compensated for backlash? Without software compensation, there will always be quite a bit of "backlash"--or more accurately, lost motion--with the dovetail ways design of the Tormach.
When the gibs are set loose, there won't be any backlash if there isn't any wear to the ball screw and ball nut. Tighten the gibs properly and there will be lost motion introduced, even if it's really tiny (0.01mm / 0.0004" or more).
It sounded like the gibs could be loose, but I hope it's not that.
What a steal. Nice job
Yes you need it tight, but not too tight. My comment is merely saying the same, you need the gibs as tight as possible while allowing "free movement". But that free movement is not with zero backlash. Tormach's recommendation is to check the lost motion while tightening the gibs and stop when the lost motion suddenly become excessive. However it does not start with zero lost motion.
If you have done enough tuning on the machine, you'll find that even on a brand new machine with carefully cleaned, flushed and lubricated ways, by the time you tighten the gibs a little bit, there will be very slight lost motion introduced (0.01mm/0.0004"). That's not even with the gibs anywhere near tight.
It will normally increase to about (0.02mm/0.0008") by the time the gibs are about right. If the leveling is done right so the base is not twisted, the gibs are not squeezed too tight, and all the careful prep work are done, you can reduce it to ~0.01mm/0.0004" with some luck. However the more commonly achievable lost motion is about ~0.03mm/0.0012" given how most of these machines are setup by new owners without extensive experience with machine tools installation.
On linear ways, there would be almost no lost motion, but it will not be as rigid as the dovetail ways. Dovetail ways will always have a bit of lost motion. So this is one big reason why Tormach gets some bad rep.
I personally like the dovetail ways.
Looks like a great deal, don't forget the spindle door latch upgrade.
RAD. Yes those are my initials. Idea, design, build, use. It never ends.
PCNC1100 Series II, w/S3 upgrade, PDB, ATC & 4th's, PCNC1100 Series II, 4th
Yeah it was, thanks! Just finished VFD and stepper upgrades and they're quite the improvement. Funny thing is work is asking if I can cut them parts now, on the machine they just sold to me... Could pay for itself with the first job if it comes through haha.