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Author Topic: Table Squaring Compensation....  (Read 14093 times)

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Re: Table Squaring Compensation....
« Reply #20 on: January 01, 2010, 01:55:30 PM »
Rich ol' buddy, :)
 With all due respect, I think you are out there a bit with this one. ::)
IF that is a quill, (and I will assume the spindle is true to it, otherwise I'm outta here)
    indicate it true to the column ways...then
True the column to the table, (or V-V) by trammeling,
and DONE ! No squares, light gaps, feeler gauges or whatever.
Let the indicator do the work.....it can see better than the eye.
Respectfully,
Russ :)

Offline RICH

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Re: Table Squaring Compensation....
« Reply #21 on: January 01, 2010, 03:13:02 PM »
Russ,
Quit being nice to me  ;D  as I may be "goofy" on this one.   ;)

I have seen where a sharp corner as shown in the pic will cause the head assembly to skew  the Z axis  / quill out of allignment with the column. As you tighten the gibbs the head will start lifting away and rotate by riding up the radius. Just knock off the sharp corner and all is well. So you thought the column wasn't right / perpendicular to the X and Y and the Z is scewed when actualy all is ok. I have seen this also on joiner tables where you couldn't get the two tables alligned ( hey , Rockwell actualy gave me $500 bucks for that one and a nice thank you letter ). So that was step #1 since if that was happening you could be there alll day and would never get the Z right.
RICH

Re: Table Squaring Compensation....
« Reply #22 on: January 12, 2014, 05:15:46 PM »
Hello All,

I also have a TownLabs TL521ACH-3-ER16 purchased in late 2012.  Works pretty well for cutting shapes so long as you do not have to move the z axis very far to pick up a xy location.  If you try to do precision work with this mill, parts that will be assembled, you will run into problems.

After analyzing the problem I came to the conclusion the the XY stage assembly would need to be re-machined since the surfaces are out of parallel, and as a result there is no way to shim anything to correct this problem.  The top surface is out of parallel with one or more of the XY plane surfaces in the stack up.  I was surprised to find this problem since so much of this design is pretty good (this is a quality problem, not a design problem, and the error is large).

The machine is pretty rigid compared to many of the other mills in this class, and is cast iron, far superior to the aluminum machines people try to sell on the internet.

The only mechanical weakness I found is the spindle column cantilever assembly, it is pretty flimsy and as a result vibrations do not get damped out, even though this is a sturdy cast iron design, it is difficult to get the kind of finish a design like this should provide (the vibrations get transmitted into the surface finish).

I have not contacted TownLabs about this problem but intend to soon.

Best Regards,
Karl