Pm-940m-cnc (pre-assembled)

Hi Guys,

I received my mill from Precision Mathews and one thing of note is the controller card has been changed to a different brand. I assume the pendant is also different and will share a picture of it later but for now here is the supplied from factory nMotion CNC controller.

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Cheers,

Jake
 
Em... This is exciting news. I will be VERY interested to see how it works, and if mine comes with one. Mine is supposed to ship tomorrow!

PZ
 
Ok, sorry for the delay. Here are the pendant pictures I promised.

I'm still getting the software configured little by little. A fellow pm-940CNC owner has helped me test the spindle, and also showed me some wiring for things like the coolant pump that were not designated anywhere.

X Y and Z function so far, so the new controller appears to be functioning.

So far I love the rigidity and smooth ground ways. I have yet to check for backlash and such, but the fit feels good so far. I do have a knocking sound in the Z that I need to inspect. I believe it has to do with the slop in the hand crank gear interface with the ball screw...or possibly the screws holding the ball nut are not tight. If it is the hand crank slop I'll probably remove the hand crank assembly entirely, unless it serves to keep the head from creeping down on its own weight ?

Cheers,

Jake

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For those with the latest revision of the PM-940 CNC-VS (2017) that comes standard with the nMotion controller I found the default home and limit switch pins are set "backwards" in Mach 3.
The enclosed picture is of my revised settings that now allow me to home the mill.

Cheers,

Jake

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I wanted the mill to zero out with the table in the NORTH EAST corner so I moved the home backstops to the left side of the X axis, the rear of the Y ( near the column ) and the Z is near the top. ( early 2017 version of the mill with nMotion controller card standard )

I changed the homing setup to what is pictured. Note: Please ignore the soft limits , as they are incomplete and also it depends on where you put the homing backstops on the adjustable sliding brackets.

I like this configuration because it is familiar to a standard X Y graph. Zero is the origin, so as you go from bottom to top or left to right the movement is in the "positive" direction. The relationship between the spindle / cutter to the table is what we are referencing. So when the table moves from the north east to the south west, in effect the spindle is "moving" ( in relation to the table ) in the positive direction. The spindle/cutter being the "plot" point on the graph.

Also a word of caution: My home switch on the Y axis did not push the home button far enough to activate it. Since the Limit switches are de-activated during homing, this could end, "poorly". Best to ensure that the switches are all moving far enough before you home for the first time!

I also changed the cursor keys so when I depress the left arrow key on the keyboard the table moves left. ..... Right arrow, the table moves right, and up arrow table moves closer to the column, and down arrow closer to me / front of the mill. I do this because for me it is far more intuitive and so I'm less likely to crash the table and its payload into something

Cheers,

Jake

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Hey PhazerTwo,

We are lucky ! Yours looks so shiny too....mine is only a a week older than yours and its all dinged up from tearing it completely apart to get it into the basement. Thankfully just about EVERY screw was hand tight, so it was easy to tear down ;-)

Yeah, the ways, dovetails, etc are really impressive. The table glides around so well, and Y travel still makes me smile :)

Now that its back together and I tightened the ball screw end nuts to preload the AC bearings for the X and Y. I checked backlash and it appears to be below .001 on each axis. I need to use a higher quality gauge to be more accurate. The Z was a bit more complicated for me ( see below ) but after all is said and done, the Z is also about .001 backlash.

btw, I found the source of the clunking noise in the Z axis. The solution was to remove the complete hand crank assembly which was not a very easy task but still worth it, imho. There are two nuts on the bottom ("whip") end of the Z axis ball screw that need to be removed to remove the hand crank assembly. ( then you have to lift the ball screw high enough to remove the cast iron carriage that houses the hand crank and captures the ball screw end. ) In my opinion it shouldn't be captured as it is from the factory so I left the nuts off after reassembly. I imagine over time, if the nuts were tight it would wear the main ball screw nut out prematurely and maybe even not allow one to preload the AC bearings on the top. Maybe I'm over thinking it, but thats my take on it.

Jake
 
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Forgot to mention one thing to watch out for. At least on mine , The steel white cover for the X axis stepper motor dragged onto the left side of the way when it over travels !!! Luckily I noticed it right away when i was homing the first time. It needs to over travel to get to the limit and homing stops. For me it was only paint that rubbed off but tolerances being off one way or the other could have resulted in damage to the X way or worse if it halted the movement of the axis. Not sure how to fix it other than weld the holes on that side and redrill a bit lower to ensure it can't be too low.
 
I'll have to check this out on mine. That would be a bummer to smash it up before it ever even makes a part!

PZ
 
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