Inaccuracy of Cuts all of the Sudden?

[compositecases]

CNC M3, DWP611

Hope everyone is doing well, 

Ran into the issue after being away from my machine for a week. I got my new 1/4" collet from Carbide 3d .com, and am running a Harvey Tool 1/16" PCD Composite End Mill cutting thin 1mm thick Carbon Fiber. 

The first day of using the m3 I cut my file, everything was spot on and my piece turned out perfect. After a few more cuts and figuring out CAM settings and G code sender settings etc. my cuts are coming out wrong. They are off by just the slightest bit in the corners. And just today I had two pieces come out with roughed up edges, and nothing close to the actual file which I have tested on a different CNC which accurate results. 

My question is: 

What might be causing the rough cuts - End mill? Uneven spoil board? Maybe a belt is messed up or a wheel causing the machine to move weird? Overheating of the motors? 

What might be causing the file's to not cut perfectly like they are in CAD? They are simple contour outlines, nothing too fancy. I have tolerance in Fusion set to .001, no additional stock, etc. 

I appreciate any feedback, I am wasting tons of material and can't seem to get these simple cuts accurately done. 

Thanks! 

[Derek the Admin]

I’d check the usual suspects like set screws on pulleys, belt tension, etc. I’d also suggest running things again in a softer material to see if there’re are any changes.

[compositecases]

I checked everything over, and it all seems well. Belts are tight, pulley screws are functioning normal, no slipping or anything like that.

I went ahead and did some more test pieces, and some turned out good and others had really bad precision. The thin material was worse than the thicker material.

I noticed when it was moving along the x axis that it jumped a a couple spots almost as if it was getting caught in something. This was .5mm thick carbon. Maybe slow down my feedrate? I am running 300 mm/s.

Something is causing it to move roughly and not make precise cuts. I might have to take the rails apart and clean them up, and replace my spoil board. Maybe something got caught in the rail causing it to jump/move roughly. Or possibly I am cutting too deep into the spoil board causing bad precision. I guess it is also possible my bit went bad somehow, but i've barely used it. Also looking into maybe things hindering movement like the power cable for the router maybe doesn't have enough travel room, etc.

I moved all the axises by hand and everything seemed smooth to me.

I'll keep tinkering with it and see what I find out.

[maury]

I have an M3 with the 400w DC spindle and of late been having Y axis issues. It seems to, on occassion, slowly add additional pulses so I end up 5%ish too long. I believe its electrical noise comimg from the spindle. Dry runs without actual touching the material and without spindle spinning appear fine. Dry run with spindle on, excess distance.

I have my low voltage controller and wiring on the right side and the spindle stuff on the left.. Funny I've done several dozen 5X7 relief carvings (4-6 hours each) without a hitch, then earlier this week, wham!

I believe my running a "ground" wire from the z asis plate to the AC main ground on the 48VDC power supply has "eliminated" my problem. Dry tests so far seem promising and will continue more tests tomorrow.

Like you, I checked a lot of stuff, definitely isn't mehanical for everything moves freely. I realize you are using a different spindle but maybe my issue and "fix" may assist.. I'd try running the spindle AC cord straight up and away from everything and plugging it in somewhere different from control electronics.

[Bruce]

If you can't run the cable away from the control electronics you could use something like this 1/2" Stainless Steel Braided Sleeving on the power cord of the router.
www.amazon.com/dp/B007KA7FZG/ref=psdc_6577542011_t1_B01MEG9V2R..

Make sure you check the grounding at your power plug. The steel braided sleeving needs to be tied to ground also.

[compositecases]

This is interesting and definitely something to think about. I have my router plugged into the same power bank as my electronics and vacuum etc. Maybe running it separately will eliminate the issue, definitely worth the try.

Will get back when I try it!

[stever]

Sept 23, 2018 16:55:23 GMT compositecases said:

This is interesting and definitely something to think about. I have my router plugged into the same power bank as my electronics and vacuum etc. Maybe running it separately will eliminate the issue, definitely worth the try.

Will get back when I try it!

Also, isolate your usb cable from all of your 120v power cords. Even though it is a shielded cable, I had mine bunched together with power cords and it was causing all kinds of movement issues

Steve