Reference Positions Shifting during operation

In german forum somebody mentioned that this could be caused by a problem not to have the machine grounded and connections having different electrical potentials or having statical overloads especially if you mill plastic.

I had no such problems in WinPCNC or Mach3 so far (connected via USB).

What feedrates, I mean what values are we talking about? If slowing down helps, a mechanical issue seems probable IMHO.

Thanks for the feedback. I thought at first that it might be a mechanical problem but it shifts the reference position in both the x or y or z direction (it varies) and shifts it positively or negatively and affects only that point. Once it shifts there is no other effect except that now the second half of the part is now being machined or D printed either to the left,right, above or below of where the first half was. Creates some real interesting looking parts. Slowing down the feed rates to 90% of the default in WIN NCPC definitely helps. Will have to check what mm/s this value is.

The grounding idea may be something to look at. I have no idea why it would just reset the reference positions but may have something to do with locating the stepping motors. Anyway, that is easy do and a quick fix if it works. Mechanically I have gone though the SC600 and it works fine otherwise with the random shift occurring (usually when I have just left the room). It did do it once while I was watching it with no apparent outside cause, i.e. hung up cable, jammed axis, tight filament, etc.

I'll force a ground on the chassis and gantry and see if it helps. Thanks for the suggestions,

Regards,

Gary

Maybe it is a resonance issue, something like described here. 3D printing shouldn`t create much load on the machine, maybe this contributes to the problem. Maybe acceleration value together with the used feedrate make the motors work at an unfafourable speed region or something. I have noticed missing steps on my machine at high load or going at 700-1000mm/min (too little testing to make any assumptions about this feedrate region, could also be due to high load).

Hi everyone,

I relaunch this topic as i just encountered the same shifting issue.

i was milling brass, as shown on those 2 attached pics, and the job was to saw cut brass plaque (5 cuts, down to 2mm, not the full plaque depth),
the cut is Y axe oriented.

The two last cuts have shifted about -12 mm on Y axe.

and the shifting started between two passes of one cut, where Y cut coordinates were already reached

I checked the NC file but it seems correct, Y coordinates are the same for every cut

IS there any solution ? i'll try though to lower feed on UCCNC while the machin is running, but still, some permanent solution would be relieving.

thanks in advance .

Maxime.

(Paris, France)

SC 600 /UCCNC / HF spindle

I have just started having a problem with y axis shifting during cutting. Part way through the job the y axis shifts by several inches. It just seems to redatum, there are no issues with belt slippage, the axis just smoothly shifts. I tried a couple of different tool paths and the same thing happens. This happens even if cutting in fresh air.

I just recently re aligned the y-axis and lubricated the machine. It jogs along without any problem.

Help appreciated.

Maxime,

Did you manage to resolve this problem? I have just started to have the same issue.

Regards
David

If your Y-axis movement loses datum when running at normal programme speeds but not when jogging, then almost certainly it is over tight adjustment of rollers or poor alignment of the Y axis leadscrews. It should be relatively easy to move in Y by pulling on the drive belt over the full range of movement of the gantry.

You may have to "retune" the Y axis to achieve the necessary freedom of movement. It is all too easy to overtighten the rollers - from personal experience!!

I resolved this problem. This was nothing to do with sticking or loosing steps, the UC100 device was this issue . I had this near power cables and it must have been experiencing some interference.

Hi Fillingham
What is the safe distance between the UC100 and the cables?
I have been experiencing the same problem and my UC100 is very close to the extension cord power sockets.
Thnx
Goran

Hi Goran,
I just made sure that The UC100 was as far away from the power cables for my router and Stepcraft as the cables allowed, probably 3 ft. That got rid of my problem.

I wonder if there is a way of sheilding the UC100?

I have a similar issue and I am sure it is down to electrical interference, i know this as i switched on my workshop vacuum cleaner (which was connected through the same extension cable as the CNC) and the machine zero'd there and then. I still have the issue but i have a question, would a cPL (internet power connectors) cause this issue. I use them in my property and I have a feeling they too may cause interference with the power supply. Anyone got knowledge on this?