What might be causing slip errors?

[canadaduane 0]

Here are some example pictures of the problem I'm seeing:

http://dl.dropbox.com/u/118766/Ultimaker/slip1.jpg

http://dl.dropbox.com/u/118766/Ultimaker/slip2.jpg

http://dl.dropbox.com/u/118766/Ultimaker/slip3.jpg

From another google group post (I can't seem to find it at the moment) I remember hearing that this can be caused by:

a) electrical interference in the stepper motors, or

b) loose belts

If these are the only two things, then I wish there were something else to blame, because I'm not sure how to go about fixing those. But maybe someone here knows a way to the solution.

In the case of (a), how does one eliminate interference if the wires are already twisted nicely? How can one measure interference? I suppose I could remove them from the sheathes and dangle them all around the machine and see if things improve.

In the case of (b), I can feel that the belts are possibly a little bit loose, but I can't see how to tighten them any more. The adjustment screws are already as tight as they will go.

Am I missing anything?

Thanks!

Duane

[ddurant 0]

Which firmware are you using?

Also, are you using skeinforge or netfabb? If skeinforge, which verion and what sorta feed rate?

[canadaduane 0]

Which firmware are you using?

Also, are you using skeinforge or netfabb? If skeinforge, which verion and what sorta feed rate?

I'm using Sprinter firmware, and Skeinforge 0035. I have the feed rate set at 120 mm/s, but I've also seen this at lower feed rates (80-100).

[ddurant 0]

Have you disabled the Fillet module and set ExportGCode Small? What's SpeedTravel Feed Rate set to?

Do you hear any sounds when this happens?

 

a) electrical interference in the stepper motors, or

b) loose belts

Probably not interference if all your wires are still twisted and I wouldn't guess loose belts would cause this unless they were really loose..

Another thing that can cause skips is the nozzle smacking a blob at high speed - in general, you don't want the nozzle touching the print at all. There's sortofan exception on overhangs that curl up but those usually aren't too much of a problem.

Also, very sudden & rapid changes in direction can cause skips, though I think that's become a lot less common with sprinter/marlin.

[greenarrow 0]

My machine slipped just like yours when I first got it. There where three things I changed:

1) I found one of the end caps on the rods was too tight preventing the rod from rotating as freely as it could.

2) I Greased up the outside rods really well.

3) I turned up the power a tiny bit using the adjusters on the stepper driver boards.

[canadaduane 0]

Another thing that can cause skips is the nozzle smacking a blob at high speed - in general, you don't want the nozzle touching the print at all. There's sortofan exception on overhangs that curl up but those usually aren't too much of a problem.

 

Ah! I recently changed the thickness from 0.3 to 0.285, and I've noted an occasional bumping of the nozzle here or there. What's the best way to reduce the flow rate in SF 35? Tell it that the diameter of the incoming plastic is larger than it really is?

[canadaduane 0]

My machine slipped just like yours when I first got it. There where three things I changed:

1) I found one of the end caps on the rods was too tight preventing the rod from rotating as freely as it could.

2) I Greased up the outside rods really well.

3) I turned up the power a tiny bit using the adjusters on the stepper driver boards.

Thanks, greenarrow. I might try number 3. Was this adjustment a hardware or software adjustment? I know how to modify the Arduino code and upload that. The hardware is more of a weak point for me

[mr_seeker 0]

My machine slipped just like yours when I first got it. There where three things I changed:

1) I found one of the end caps on the rods was too tight preventing the rod from rotating as freely as it could.

2) I Greased up the outside rods really well.

3) I turned up the power a tiny bit using the adjusters on the stepper driver boards.

Thanks, greenarrow. I might try number 3. Was this adjustment a hardware or software adjustment? I know how to modify the Arduino code and upload that. The hardware is more of a weak point for me

http://wiki.ultimaker.com/Electronics_build_guide

Link for number 3

[ddurant 0]

Another thing that can cause skips is the nozzle smacking a blob at high speed - in general, you don't want the nozzle touching the print at all. There's sortofan exception on overhangs that curl up but those usually aren't too much of a problem.

 

Ah! I recently changed the thickness from 0.3 to 0.285, and I've noted an occasional bumping of the nozzle here or there. What's the best way to reduce the flow rate in SF 35? Tell it that the diameter of the incoming plastic is larger than it really is?

That sounds like you're using the print-o-matic stuff built into repg. I know it's there but I've never used it.

My preference would be to scrap SF35 and all the stuff that's integrated into repg - use repg just as something that preheats & sends gcode to the bot and download/use SF by itself. Any version past 40 (44 is the latest, dated 2011-10-08) will behave a lot better than SF35 does.

[somerwil 0]

I had some problems with the same results when printing on Marlin Build 1 which I tried to connect to Netfabb. The connection worked but this problem showed up on the first prints... I decided to go back to Marlin Build 2 (which is unable to connect to Netfabb) and the problem disappeared.

What's wrong with going to the Marlin Build 2 firmware. I'm not quiet experienced yet but so far I'm really happy with this version of the firmware.

[canadaduane 0]

That sounds like you're using the print-o-matic stuff built into repg. I know it's there but I've never used it.

My preference would be to scrap SF35 and all the stuff that's integrated into repg - use repg just as something that preheats & sends gcode to the bot and download/use SF by itself. Any version past 40 (44 is the latest, dated 2011-10-08) will behave a lot better than SF35 does.

I'm giving this a try (SF44) and I'm finding it to be a little disorienting, although I think I can push through to the end. Little things are really big when getting started I guess. For example, where does start.gcode go? I see one in ~/.skeinforge/alterations/start.gcode, and I see one in skeinforge_application/alterations/start.gcode... and yet neither of them is being read when I produce test_export.g! Also, why is the suffix .g now, rather than .gcode? I wonder if I'm doing something wrong.

Anyway, I think this path will be worthwhile in the end, it's just hard slogging at first, especially without beautiful 3D objects to show for the effort so far

[ddurant 0]

I'm giving this a try (SF44) and I'm finding it to be a little disorienting, although I think I can push through to the end. Little things are really big when getting started I guess. For example, where does start.gcode go? I see one in ~/.skeinforge/alterations/start.gcode, and I see one in skeinforge_application/alterations/start.gcode... and yet neither of them is being read when I produce test_export.g! Also, why is the suffix .g now, rather than .gcode? I wonder if I'm doing something wrong.

I always use (the windows version of) ~/.skeinforge/alterations/start.gcode. Check the Bookend module to make sure it's active and that the file names are correct. Does that help??

Never seen the .g thing before.. Er.. It's probably something in Export. I've got Activate Export, Analyze Gcode, Gcode Small set and File Extension set to gcode. Is that what yours looks like?

[brictone 0]

I'm getting random shifts with something I'm trying to print. I was using build 2 of marlin and all seemed well then I upgraded to a newer version and it started shifting all over the place. At first I thought it was marlin but I'm trying different versions and nothing seems to work. I haven't gone back to the one that worked yet. that's next.

I took the printer out of cold garage. checked the belts, tuned the pots, oiled the rods, slowed down the print. next I'll try printing at 25mm/sec and travel at 100mm/sec I don't know maybe I just need to rebuild this printer from scratch.

[ddurant 0]

I'm getting random shifts with something I'm trying to print. I was using build 2 of marlin and all seemed well then I upgraded to a newer version and it started shifting all over the place. At first I thought it was marlin but I'm trying different versions and nothing seems to work. I haven't gone back to the one that worked yet. that's next.

I took the printer out of cold garage. checked the belts, tuned the pots, oiled the rods, slowed down the print. next I'll try printing at 25mm/sec and travel at 100mm/sec I don't know maybe I just need to rebuild this printer from scratch.

I think there may be settings in the firmware that need tweaking for it to behave just right - like changing source code type stuff. I don't know what those changes are, though.

To be honest, the talk of acceleration math and jerk settings and such sorta just goes right over my head. It's awesome that people are really engaged and tackling this complicated (to me) stuff but a version with things preset to what will work for most people without tweaking would be great for those that don't really want to know all the details.

[brictone 0]

Well I went back and slowed everything way down. 25mm/sec 100mm/sec travel. Changed the layer height to .2 with skin on. (compensate for speed) It did not shift on the same print I was running. So I guess my printer has a speed limit with this firmware. :/