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Spookydad
01-01-2013, 11:06 PM
Santa brought me a Pro-Tram tool for Christmas. :)

I tried it out last night and I am puzzled by the readings I am getting.

I calibrated the tool using the supplied magnet and the included instructions. I thought the mill was pretty good in the x direction, and according to the tool, it was off by 0.0002". Just as a check, I decided to turn the tool 180 degrees and now it is reading 0.0024" out. Nothing else had changed. (The spindle is retracted and locked. The head was locked for the readings. The same readings were given over 3 separate tests.)

I knew the head has a nod in the y axis. The tool reads 0.0134" out. This is the mini-Tram so this is over 3" so it is time to break out the shims. When I reverse the tool, I get the same 0.0022" discrepancy.

So does this mean my spindle is bent?

Neil

uncle pete
01-01-2013, 11:34 PM
Neil,
Something doesn't make sense. If your spindle was bent then it's bent the same amount all the way around for the full 360 degrees of rotation. That wouldn't give you the variable readings. You have 3" between the indicator plungers? .0134 on your Y axis is way too much for standard work. That's over .053 in 12" Yeah it's time to shim that out. But I get the idea you have more problems than that. Something is moving for sure going by your non repeatable results. What make / size of mill? I'm almost sure I'm wrong, but without seeing it in person it's possibly loose spindle bearings? I'd double check your results and tram with just a single indicator just to see what that shows.

Pete

Spookydad
01-02-2013, 12:06 AM
There is something odd with the mill, I was just making sure there wasn't something that I was missing on the tramming tool.

I have a Grizzly 0619 Mill. A few weeks ago I began to notice a clattering noise in the spindle. I called Grizzly and they had me remove the top ring where we examined the spindle bearing. The tech had me put the ring in the vise and spin the bearing. The noise was there so we thought that the clattering was coming from a loose bearing. I didn't realize it until later but the noise was coming from the ring rocking on the vise jaws. When I put the ring back on to the mill, the noise was gone but it was because the ring was installed 180 degrees from where it was originally. So there is some misalignment, I am just not sure if it is affecting the tram.

The numbers I gave were from memory so I will double check them tomorrow.

Neil

oldtiffie
01-02-2013, 12:13 AM
Santa brought me a Pro-Tram tool for Christmas. :)

I tried it out last night and I am puzzled by the readings I am getting.

I calibrated the tool using the supplied magnet and the included instructions. I thought the mill was pretty good in the x direction, and according to the tool, it was off by 0.0002". Just as a check, I decided to turn the tool 180 degrees and now it is reading 0.0024" out. Nothing else had changed. (The spindle is retracted and locked. The head was locked for the readings. The same readings were given over 3 separate tests.)

I knew the head has a nod in the y axis. The tool reads 0.0134" out. This is the mini-Tram so this is over 3" so it is time to break out the shims. When I reverse the tool, I get the same 0.0022" discrepancy.

So does this mean my spindle is bent?

Neil

For the OP:

your mill is OK.

X error = (0.0002 + 0.0024)/2 = 0.0026/2 = 0.0013"

Y error = (0.0134 + 0.0022)/2 = 0.0156/2 = 0.0078"

Spookydad
02-02-2013, 10:51 AM
I have been meaning to update this thread for a while but you know how it goes...
I figured out that the column was canted diagonally and that was giving the pro-tram problems. Once I fixed the column tilt, the pro-tram worked great. Checking the tram by reversing the pro-tram gave a difference of less than 2 tenths. I suspect that is more from sloppy bearings than a fault with the pro-tram.

I am happy with the pro-tram and now I am not afraid to tilt the head because I know I can get it back quickly. For you old-timers, yes I know I should invest the time to learn to do it manually.

Neil