[dalianharley]

So I finally settled for sticking to G20 to use my probe,( thanks step. )
I went on cutting a piece of alum using carbide 1/2 2 FL end mill, 4000 rpm, .118 depth and .15 step over. Feed was 22 and after three turns I found the tool has gone nearly half inch deep. I had to reset and then used a 3/8 4 fl hss end mill fed at 15 doing the same roughing mad it worked fine.

The z axis sloping down - was it caused by the pulling force from the tool? I used the number from g wizard and wasn't even being aggressive. Anyone had similar experience?

[SCzEngrgGroup]

Very unlikely the head actually moved down, especially on what was a fairly easy cut. FAR more likely either the tool pulled out of its holder, or the holder pulled out of the spindle. Do you have a power drawbar?

Regards,
Ray L.

[pickled]

I can tell you that neither one of my tormachs like aggressive feeds or DOC's with high helix EM's. Were you using an ER collet? If so are you tightening the sh$t out of it? Once I figured out the proper way to torque ER's in a fixture a lot of my tool height repeatability issues went away. I'm a big fan of the ER20 now and own a ton of them. There have been a number of threads written here on draw bar tightening and also checking for any high spots on the R8 collet itself. I also found that Tormach's white paper on tool pull out forces was a great read. Good luck!

[dalianharley]

yes I do have a PDB, and i forgot to check on that when it happened (my head was swelling after all the fuss...)
the tool was definitely not pulled out, i'll check on my pdb tomorrow - is there some kind of standard test for the PDB holding power?

thanks Ray

Daz

Very unlikely the head actually moved down, especially on what was a fairly easy cut. FAR more likely either the tool pulled out of its holder, or the holder pulled out of the spindle. Do you have a power drawbar?

Regards,
Ray L.

[dalianharley]

I was using an ER collect and yes sir I did tighten the piss out of it :P.
I also use ER20 sets. is 22 feed rate considered "aggressive"? I'm totally new to this so i've been relying on g-wizard but i've always stayed in the "finish" side of the slider...
i'll check the PDB articles, man, so much to watch out for!
thanks for the advice.

I can tell you that neither one of my tormachs like aggressive feeds or DOC's with high helix EM's. Were you using an ER collet? If so are you tightening the sh$t out of it? Once I figured out the proper way to torque ER's in a fixture a lot of my tool height repeatability issues went away. I'm a big fan of the ER20 now and own a ton of them. There have been a number of threads written here on draw bar tightening and also checking for any high spots on the R8 collet itself. I also found that Tormach's white paper on tool pull out forces was a great read. Good luck!

[SCzEngrgGroup]

yes I do have a PDB, and i forgot to check on that when it happened (my head was swelling after all the fuss...)
the tool was definitely not pulled out, i'll check on my pdb tomorrow - is there some kind of standard test for the PDB holding power?

thanks Ray

Daz

Several people have reported pull-out on not-very-aggressive cuts with the Tormach PDB. In most cases, I believe it can be "cured" by properly adjusting the spring washer tension, and by cleaning and lubricating the drawbar and collet taper as detailed in the Tormach documentation. It also helps to lubricate the spring washers with anti-sieze.

The machine should certainly be very easily able to handle that cut without pullout if the PDB is working correctly.

Regards,
Ray L.

[mioduz]

I agree with everyone else. Tool holder coming out of the collet. Or tool out of holder

Sent from my VS980 4G using Tapatalk

[GJeff]

Make sure your collet is well lubed with the exception of the very center where the tool makes contact with the collet. That you should get very clean with rubbing alcohol, provided you're not prone to rust. If the collet isn't lubed right your tool will definitely creep out. Tormach has a detailed guide on it, but that's the quick and dirty.

[mountaindew]

I did a very detailed part the other day and on the very last operation for chamfer the tool went to deep into the part!
I looked at what happened and hit estop because I run tools .05 from fixtures and was afraid it would hit one and damage 25$ carbide chamfer.
Part was spoiled already so no big deal other then this happened at the end and not the start.
First thing I did was think!
OK what would cause this and how can I check it!
Looked at dro and z height was exactly where it was programed. "not a code problem"
Looked at part and fixture to see if it had moved or lifted "nope everything is tight and down"
Then pull tool and tool holder out and measure with tool height setter to see if tool height had changed. "thinking but before I do this maybe check to see if I got tool all the way in before I released pdb"
Held tool and pressed firmly up and hit the pdb button! oops it went up!!!
Well that was dumb! I released pdb button before getting tool firmly seated in collet! lol
Could be very easy to blame this on tool or tool holder pull out, but easy to eliminate because it happened on a .02 chamfer.

Wanted to add this experience to help others first think about results and think about ways to check or test before continuing.
Thus taking much of mystery or guessing out of what caused the problem by listing and checking off potential errors points.
I read posts on so many threads about machine tool problems and wonder what % are they the machine and what % are user errors.
In my experience on my tormach has shown this to so far to be 100% user
I learn fast and I always figured this is one reason why! I try not to blame or say it could be, but look for questions or methods to check for more accurate answers!
Also not afraid to admit I was wrong or when I error, otherwise I fool myself into chasing my tail and not learning.

Simple honest comments and ideas to think about from a tormach user.
md
btw I see a building with a half dozen types of vmc's in my future so its all about learning and experience.

[mountaindew]

cool