Spindle Runout Issues on PM-728VT

[netmagi]

I am curious if the test bar you purchased is hollow, does it feel lighter than it should be for that diameter and length?

It's quite heavy. I believe it's solid throughout. One end is threaded to accept the drawbar, the other is a solid ground face

 

[pontiac428]

I may or may not have been helpful by freaking out over the bearings (I'm still a bit freaked), but I did think about it a little bit while I lay awake after midnight. I came to the conclusion that even budget-class bearings should be an order of magnitude tighter than what you're measuring, even on a bad day. Without additional information, like spindle deflection and thrust assessment, and some consideration of your test setup (you never said whether you were using a Hardinge collet or a China drill chuck to hold your rod, and there are many grades of precision rod to consider). I tend to favor the principle of parsimony, where the obvious choice is most often the right one. I think the dealer is now on board to help get to the bottom of things, which is good. I expect the buck to stop there, but if it doesn't, at some point you should probably demo your test setup for us.

Edit: More than one person on this forum has bought a test bar from China or India, and found them to be eccentric. I have one, but I have never used it and am less inclined to try after seeing other people's findings. Maybe I can play with it this evening.

 

[netmagi]

I may or may not have been helpful by freaking out over the bearings (I'm still a bit freaked), but I did think about it a little bit while I lay awake after midnight. I came to the conclusion that even budget-class bearings should be an order of magnitude tighter than what you're measuring, even on a bad day. Without additional information, like spindle deflection and thrust assessment, and some consideration of your test setup (you never said whether you were using a Hardinge collet or a China drill chuck to hold your rod, and there are many grades of precision rod to consider). I tend to favor the principle of parsimony, where the obvious choice is most often the right one. I think the dealer is now on board to help get to the bottom of things, which is good. I expect the buck to stop there, but if it doesn't, at some point you should probably demo your test setup for us.

Edit: More than one person on this forum has bought a test bar from China or India, and found them to be eccentric. I have one, but I have never used it and am less inclined to try after seeing other people's findings. Maybe I can play with it this evening.

It's an actual R8 test bar from Glacern. Fits directly into the spindle:

Glacern Machine Tools - Test Bars

Glacern Machine Tools manufacturers CNC Machine Vises, Precision Tool Holders, and Indexable Milling Cutters for vertical and horizontal cnc milling machines.

www.glacern.com

 

[G-ManBart]

It's an actual R8 test bar from Glacern. Fits directly into the spindle:

I don't have any experience with one, but I would expect that to be a quality test bar.

 

[WobblyHand]

I'd expect it to be good, however, I'd measure it to be sure it was what I thought. Been burned before, so I just measure stuff these days.

 

[ddickey]

Boy those are a pretty penny.

 

[netmagi]

Boy those are a pretty penny.

yeh, they're pretty proud of them, but it's also probably not easy to grind 3 different related faces to such a high precision. According to the spec sheet provided by Glacern, it's within 2 microns (~.00008") on all faces.

 

[pontiac428]

Less than 2 microns on that test bar. Let me guess, you're not using a Harbor Freight indicator, either, am I right? That answers those questions.

 

[netmagi]

Less than 2 microns on that test bar. Let me guess, you're not using a Harbor Freight indicator, either, am I right? That answers those questions.

Mitutoyo 513-473-10E

I REALLY like my grandfather's and uncle's old Starrett stuff, but anything I buy new is Mitutoyo, and it's never disappointing.

 

[pontiac428]

Mitutoyo 513-473-10E

I REALLY like my grandfather's and uncle's old Starrett stuff, but anything I buy new is Mitutoyo, and it's never disappointing.

I dunno man, that ruby tipped tenths indicator might need quarterly calibration due to seasonal variances in the earth's magnetic field and proximities with other planets. And NIST considers a room to be temperature controlled only if it maintains 25 centigrade +/- 1 degree at all times. This casts serious doubt on your reported results, you know. There goes your legal defense.

Welcome to the forum, by the way. I hope you get your mill resolved quickly. I get the feeling that Matt deeply cares about his business, and with his attention you will end up with the machine you were expecting.