[Joscerb55]

CNC Help! Milltronics Partner III- Encoder Issues

Hey all,
Hoping you can all help us at the shop.
We purchased our first CNC machine to make simple 2D parts ( through holes, counter bores, pocketing, exc ) a couple months ago and things seemed to be going great. We have our own separate programmer ( who is quite rusty; using M4 instead of M3, a lot of air time when it should be rapid, and breaking bit after bit after bit.. frustrating to say the least )
But now we are experiencing a lot of problems over the past 2 weeks. Every morning when we start up the machine ( if we are working on the same project (60 or so parts )) we have to re-zero the part because the Y axis is always off .040” to .060”. and sometimes when we load a program, it automatically shuts down with a black screen saying shut down the machine and boot up ( which doesn’t seem like an encoder issue?)
The past two days have been very bad. In between tool changes, even at 100% feed, the XYZ axis’s would crawl almost like it was at 10% feed. This does not happen every time; usually “works” if we restart the machine, which is ludicrous.
So it has been a mixture of incorrect programming, and (possibly) encoder issues
The X axis always seems to be spot on

Our main concern is the z axis right now, because re-zeroing X and Y every time the machine is started up is not a huge problem.
So yesterday we started to LIGHTLY disassemble the machine ( just the top cover that exposes the belts ) and two side small panels that also exposes the Z motor and some wiring

What is the easiest solution here? We called Milltronics and the service person said to inspect the coupling in-between the motor and the encoder, but I personally cannot locate what the encoder is
I took a handful of pictures to make this easier for both of us :-P

1 http://i47.tinypic.com/33tqx6f.jpg

2 http://i48.tinypic.com/11mdts3.jpg

3 http://i46.tinypic.com/o0a3kn.jpg

4 http://i46.tinypic.com/nfnnfo.jpg

5 http://i48.tinypic.com/67mb6b.jpg

[ZZZZ]

Usually, the axis encoders are mounted to the motors at the opposite end from the pulleys. Your Z axis encoder is located at the other end of the armature shaft from the small pulley in your first photo.

If you Home and set a zero, then your axis positioning moves repeat but you don't always Home at the same place, you want to look at the Homing process. Check the switches and the ramps, they can get sticky from dried coolant and dirt/swarf/etc. Make sure to check the timing - the encoder should make 1/2 turn on the last move when you Home, slip the belt until you get it.


If your positioning problems happen after you Home, look at the belt and pulleys. Check the thrust bearings, make sure the nut is tight.
Then check the couplers, the encoders, and the wiring. Something is loose or the encoder is bad.