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araugh
09-07-2012, 01:30 PM
So it's a brand new day, and again I am learning. Today working on some 0.190 6061 aluminum and everything is going SWIMMINGLY! Feed rates are right, air for cooling and vacuum for chip collection are working together nicely, bits are running shallow and cool, the finish I'm getting on my edges is just beautiful, all that good stuff. It's not until I'm done that I realize all my interior profiles are messed up slightly. Here are a few pics to illustrate.

https://lh5.googleusercontent.com/-GKxiZ2aAK98/UEoq0F6oFwI/AAAAAAAAC08/LlzYIUWJUqI/s774/2012-09-07_13-01-51_706.jpg
https://lh3.googleusercontent.com/-9O1MzmLvPQs/UEoq17HTgZI/AAAAAAAAC1I/mekL3zfaZZo/s774/2012-09-07_13-02-01_850.jpg
https://lh4.googleusercontent.com/-xrB_TKPAags/UEoq4yowNoI/AAAAAAAAC1U/8fMWOXWBiYE/s774/2012-09-07_13-02-16_967.jpg
https://lh3.googleusercontent.com/-xdCxsAPeNXw/UEortMAnZmI/AAAAAAAAC18/FmjFjMTvfrY/s1372/2012-09-07_13-15-33_551.jpg

Does this mean the bottom wheels on the YZ carriage need to be loosened slightly? Is there another way I should be compensating for this? The PRS Alpha is supposed to have closed loop steppers, should it be correcting for this or do the closed loop steppers merely help it regain position after the unsuccessful cut? Or is this all user error in the programming? I'm pretty sure it's not bit deflection, my cuts are shallow and this is happening even on cleanup passes. I'm using a bit with only a 1/2" CEL and less than an inch total OAL out of the collet. The holes all measure in the correct dimension on the X axis, but on the Y axis they're only slightly larger than bit diameter.

Any guidance you folks would be willing to offer?

Brady Watson
09-07-2012, 02:54 PM
Pull the Y motor and check that the pinion is tight...then pull the lower wheel covers on the YZ and make sure they are snug.

-B

araugh
09-10-2012, 09:23 AM
Man brady, you're good. One of the wheels on the y axis was completely loose. I tightened it up and will keep a close watch on it vibrating loose again. Warming up the spindle now so I can do a test cut.

araugh
09-10-2012, 04:56 PM
No luck there unfortunately, which is really surprising to me that it was working at all with one of the wheels so loose. Thanks anyway!