Slipping motor ??
April 14, 2014 07:18AM
A frustrating problem keeps haunting me.

I am trying to print Matts (iamburny) Extruder and Z gears. I have tried about 8 times now and each time I have a failure. See photos attached.

I thought at first I had an obstruction because it seemed to happen mostly at near enough the same height (6.5mm'ish) - but no obstruction.
I then thought belt slippage - I tightened the belt using Matts belt clamps and spacers - a pinging belt but still the problem.
I then thought slipping/overheating motor - I swapped the Y motor with the extruder motor - same problem.
I have tried slicing several times and changing the fill - same problem.
I have tried printing just the large extruder gear on its own, the other three smaller ones together - Still the same problem.
I did have - M906 X1000 Y1000 Z1000 E1000 - but my last try I tried resetting back to 800. Less clatter but still the same problem (the three smaller gears)
Although the slip seems to occur at roughly the same height it can vary.

I still have:
M203 X15000 Y15000 Z300 E3600; tweaks to speed
M201 X1000 Y1000 Z15 E1000; tweaks to acceleration
Set

Could it be these settings ??
I am about to try without these two tweaks but thought I would ask for advice as well.

Everything else I print seems to work really well. I printed a thin wall test up to 20mm high and it looked the business. A similar 50mm high box worked well too.

Any help on this gratefully received.

Tim
Attachments:
open | download - photo 1.JPG (143.9 KB)
open | download - photo 2.JPG (160.5 KB)
open | download - photo 3.JPG (138 KB)
open | download - photo 5.JPG (132.9 KB)
open | download - Gears_GCode.txt (1010 bytes)
Re: Slipping motor ??
April 14, 2014 07:36AM
Hi, not sure what the answer is yet. Your gcode doesn't seem complete... You can check it with this website to see for any obvious errors: [gcode.ws]
But i imagine it's a mechanical/motor problem. I've occasionally had something similar, but never regularly or twice on the same print
Re: Slipping motor ??
April 14, 2014 08:57AM
Hi Squags

I just included the first bit of the gcode file for info.

Tim
Re: Slipping motor ??
April 14, 2014 11:23AM
OK, I think I am going to cry

Reset Config back to the original as provided, ie without:
M906 X1000 Y1000 Z1000 E1000
M203 X15000 Y15000 Z300 E3600
M201 X1000 Y1000 Z15 E1000

and printed the large gear again. Same result !!
A slip in the Y at about 3/4 of the way up the Z.

A selection of heights it fails at are:
7.8, 7.6, 7.2, 3.5, 3.8, 5.7, 7.9mm
and on printing the other three gears together
9.75, 7.95, 8.0mm

Presumably everyone else can print Matts gears off without a hitch?
Re: Slipping motor ??
April 14, 2014 12:13PM
Quote
Fiddler
Presumably everyone else can print Matts gears off without a hitch?

I have printed them 4 times now without the sorts of errors you are getting, in fact the last set were great.(the first 3 weren't that bad, but had the odd blob and were a tad rough)

Did you try Matt's gcode?

Regards,

Les
Re: Slipping motor ??
April 14, 2014 02:35PM
Quote
Fiddler
OK, I think I am going to cry

Reset Config back to the original as provided, ie without:
M906 X1000 Y1000 Z1000 E1000
M203 X15000 Y15000 Z300 E3600
M201 X1000 Y1000 Z15 E1000

and printed the large gear again. Same result !!
A slip in the Y at about 3/4 of the way up the Z.

A selection of heights it fails at are:
7.8, 7.6, 7.2, 3.5, 3.8, 5.7, 7.9mm
and on printing the other three gears together
9.75, 7.95, 8.0mm

Presumably everyone else can print Matts gears off without a hitch?

I've printed the extruder gears and the z-axis gears, both ok, but I also have not tweaked speed, current etc.


Another RS Ormerod Mk1 meets the world smiling smiley

Retired now but I used to make....
CNC Machined Mk1 aluminium bed support plates for the Ormerod
CNC machined X-plates and ribs for Mk1 & Mk2 Ormerods
CNC machined bed support arms for the Mk2 Ormerod.
Dual Hot-End heatsink blocks.
Re: Slipping motor ??
April 14, 2014 03:57PM
Try watching your Y belt, as it might be to tight....
I had something similar with Matts gears, cos they are quite demanding for being right.
With your Y belt, you want it tight enough not to slip and not to tight else it will bind and stall the motor on a step or two....
The best way to discribe it is slacken the belt and watch it as a -Y happends.... If the belt arches up a fraction, then it's a touch slack...
So tighten it untill you can't see the belt lifting on a -y movement... Matts belt tensioners are good, but they are fiddley to fettle. His Version 7 are the best....
I had to pack mine out to get the tension right, but you can use a bit of cornflake packet, for that.....


Please send me a PM if you have suggestions, or problems with Big Blue 360.
I won't see comments in threads, as I move around to much.
Working Link to Big Blue 360 Complete
Re: Slipping motor ??
April 14, 2014 05:47PM
Just for info:
All my prints so far have been printed thru USB so I thought, just to see, let me see if printing direct from SD card would make any difference. It did not. Still the same problem.

The last print I just did from SD got 6.22mm thru before it started to look as if it was skipping. It looked as if it "skipped a tooth" every layer, gradually moving to the left and creating an overhang with each layer.

Earlier I did a print of the single small gear without a glitch.

That kind of suggests to me that all else being equal the motor must be gradually heating up and slowly seizing and not being able to pull the bed towards the motor. The intensity of the large gear seems to bring this on.

Kim - thanks for your suggestion, tomorrow morning I will add a couple more of Matts packers and reduce the Y belt tension a bit.

I m determined to print out Matts gears and then move onto your Big blue.

Tim
Re: Slipping motor ??
April 15, 2014 07:55AM
Quote
Fiddler
Just for info:
All my prints so far have been printed thru USB so I thought, just to see, let me see if printing direct from SD card would make any difference. It did not. Still the same problem.
The last print I just did from SD got 6.22mm thru before it started to look as if it was skipping. It looked as if it "skipped a tooth" every layer, gradually moving to the left and creating an overhang with each layer.
Earlier I did a print of the single small gear without a glitch.
Tim

Are you using DC42's later firmware? If not you will get frequent problems with the steppers skipping on corners because the acceleration algorithm has a bug in the RepRap firmware and causes too high accelerations in some circumstances.

Dave
(#106)
Re: Slipping motor ??
April 16, 2014 10:35AM
Hi all

Problem solved. I followed Kims advice to slacken off the Y belt a little. No real audible twang now but still just tight enough not to sag at any point. All good.

It must just have been Matts large extruder gear put just enough strain on my Y motor for a crack to appear.

Currently printing an 8 hour box for my son! then off to start a 5 hour print of the Blig Blue.

Tim
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