file Question Reference Positions Shifting during operation

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12 Jun 2015 20:52 #22166 by carbon
I have been working with a SC600 for about a month now and am having recurring problems with the refernce positions shifting in the x and/or y axis during 3D printing and CNC machining. I will be in the middle of a job and the entire x or y axis will shift either positive or negative in either the x or the y direction. It is a step shift in the entire coordinate system as the job will continue on with the new refernce points. After shutting down and looking at the x and y locations I find that the reference positions have jumped. I checked pulleys and belt tightness and see no problems.
I put a dedicated fresh laptop on the system and this reduced the problems with the CNC operations as long as I slowed down the feed rate to 90% in the Win NC PC controllers pop up window. I then started operated the 3D printer and am finding the same problems in the middle of the print. Again the only solution seems to be slowing down the feed rate after starting operations.
I believe all of this points to a communication issue between the SC600 controller and the laptop. I am thining that shifting away form the USB interface and using the parallel port module and or adapting the USB I have to a parallel port might help the problem. Is this a common issue with Win NCPC and the USB control. I have seen it with two sparate laptops and the SC 600. Would MACH 3 help eliniate this proble? Or is there a problem with my SC600 "brainboard"?
Any help would be appreciated.

Thanks,
Gary

SC 600. WinPCNC Pro/UNC, 3D Printhead, Aluminum Bed, Foam Cutter, Engraver

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12 Jun 2015 21:02 #22167 by frankjoke
Replied by frankjoke on topic 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).

Frank
Steppcraft 600/2 + HF500 + SwitchBox + Laser + Schleppmesser
Absaugung und Vakuumtisch
an Mach3 oder UCCNC mit Taster für Z-Null und Werkzeuglänge

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12 Jun 2015 21:41 - 12 Jun 2015 21:43 #22168 by tikka
What feedrates, I mean what values are we talking about? If slowing down helps, a mechanical issue seems probable IMHO.

Stepcraft 600SF (version 1) parallel port
Proxxon IBS/E
Mach3
devCad Cam Pro; devWing Cam; devFus Cam; Profili Pro 2
Last edit: 12 Jun 2015 21:43 by tikka.

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12 Jun 2015 22:10 #22171 by carbon
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

SC 600. WinPCNC Pro/UNC, 3D Printhead, Aluminum Bed, Foam Cutter, Engraver

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13 Jun 2015 08:08 #22175 by tikka
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).

Stepcraft 600SF (version 1) parallel port
Proxxon IBS/E
Mach3
devCad Cam Pro; devWing Cam; devFus Cam; Profili Pro 2

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21 Oct 2019 15:05 #57510 by BLACKBETON
Replied by BLACKBETON on topic Reference Positions Shifting during operation
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

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02 Nov 2019 20:33 #57595 by Fillingham
Replied by Fillingham on topic Reference Positions Shifting during operation
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.

Stepcraft S420
UCCNC
VCarve Desktop v10

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02 Nov 2019 23:41 #57596 by Fillingham
Replied by Fillingham on topic Reference Positions Shifting during operation
Maxime,

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

Regards
David

Stepcraft S420
UCCNC
VCarve Desktop v10

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04 Nov 2019 11:14 #57608 by peterg1000
Replied by peterg1000 on topic Reference Positions Shifting during operation
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!!

SC 420/2, Industrial VFD spindle from StoneyCNC
UC100 + UCCNC
Cut2D, Autosketch10, Draftsight, Eagle 9.5.1


There is no problem, however simple, that cannot be made more complicated by thinking about it.

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04 Nov 2019 15:11 #57610 by Fillingham
Replied by Fillingham on topic Reference Positions Shifting during operation
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.

Stepcraft S420
UCCNC
VCarve Desktop v10

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05 Nov 2019 21:40 #57614 by goranc
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

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06 Nov 2019 11:05 #57617 by Fillingham
Replied by Fillingham on topic Reference Positions Shifting during operation
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?

Stepcraft S420
UCCNC
VCarve Desktop v10
The following user(s) said Thank You: goranc

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