Help: X axis skip/jumps

Okay so got my Darwin built and every thing seem to be working fine. After I get the extruder running I start printing. Now it seem like it is printing fine except randomly the x axis seems to stall or jump forward 1-2 mm. An example is that printing the 10mm cube when it is printing the boarder it misses and never get back to its starting point. Other times it can print the board fine and makes a nice square. Then when it start the in fill it skips /jumps /stall i am not sure what to call it and then start printing out side of the boarder. sometimes making a parallelogram rather than a square.

Things i have tried.
-Tighten belt
-losening belt
-slowing down the xy speed
-tightening the drive pully

I have tried to watch where the problem is coming from but. Because it happens randomly i can never pinpoint the problem.If you have any ideas I am open to suggestions.

Well I think I may have fixed it....I adjusted the trimpot on the stepper board and it appears to be operating as it should. Just printed out the first layer of widebar.stl and so far no jumps or weird shapes. I can't think of any reason why it would have been tweaked out of position in the first place. I mean up until to day the x axis function normal. IF things change I will mention it.

Well I spoke to soon. The problem is back. dang it.

Are you sure it's the x-axis that's stalling /skipping ?
If so, loose the belt (to not turn the motor for now) and check if the bushings run smoothly over the rods, use as little force as possible to move the carriage by hand (use your little finger of the "bad" hand) just push where the belt is fixed.
You may feel if there's something wrong.
The rods may be bend a little or not perfectly round, or they simply need some lubrification.

It may be the y-Axis that's causing the error.
Check the y-drive pulleys first.
Maybe they are not glued properly and slip on the rod.
Else repeat moving the y-Axis manually (without the motor attached).
grease if necessary.

If no mechanical error is found,
reduce the motoropwer via trimpot to the minimum and increase the power on all all motors synchronously until desired result.

I cannot imagine anything else, but I may be wrong

'sid

Edited 1 time(s). Last edit at 08/23/2008 04:46AM by sid.

Well I am begining to think it is not mechanical error. mainly because I have gone ofer everything almost twice. Filed down platic to make sure the belt had enough clearnce and or grip. I have just noticed that in the terminal window i get this text and it seems to happen every time there is a shift.

zmax: 1.0
zmax: 20.0
sendMessage error - retrying
sendMessage error - retrying
zmax: 1.0
zmax: 20.0
sendMessage error - retrying
sendMessage error - retrying
sendMessage error - retrying
sendMessage error - retrying

except sometimes there is more or less sendmessage lines.

This would also explain why I could never see a mechanical problem and why it is so random.

Well, try and quit each and every other application running on your pc other than the reprap host,
(disable automated system idle after xx minutes)

If you're still getting errors, ask Forrest to help with caching the printed object in the reprap electronics, so that there is no need for reprap-pc communication whilst printing

'sid

Well I kind of realized something stupid last night just befor going to sleep. I did most of that. Unplugged my flashdrive, restarted the host software a dozen closer other programs....but never restarted the computer. I dont think i have turned it off in like a 2 days now....just close the lid. So i feel really stupid for not even trying to restart the computer which.... is usaly the first second and third thing you do when a computer is not working. I will try that later to day when I go to back to the campus.

Quote

...caching the printed object in the reprap electronics, so that there is no need for reprap-pc communication

But not actually fixing the source of the problem

Comms errors coinciding with motion problems seems like a bit of a smoking gun to me. You'd be best off waiting for someone who actually knows a little more about electronics (or the host software) to take an interest, but I wouldn't be surprised if you were getting interference on a comms line somewhere

Well I think my problem is over heating related. After I leave the Darwin alone for several hours I can come back and print out a nice relatively cube like cube. As i start more prints it starts getting worse. If i wait a few minutes it can print the first layers with out problem but then go wacky. Also I never really paid attention to it before but if I leave the darwin powered for a while the motors start to "click". I can look on the Stepper boards and see one of the leds go off and on. Almost like its is attempting to idle at a quarter step. If I cycle off the power supply, the problem goes away. Also this does not happen on all the boards all the time. Usally the x and y. The Z axis does it but rarely. When I blow on the the heatsinks on the stepper boards the stop clicking for a bit.

I am going to go to frys and pic up som thermal paste and see if i can get/make some larger heatsinks. That or get some small fans to attach to each board. If you have any other ideas why the board are overheating do tell.

Had the same problem. Others are having the same problem. I don't know what it is about the hardware that causes this but it is annoying. I'm doing the same thing you are. Setting up to cool things down even more. Fans, larger heat sinks, thermal pastes, etc...

Demented

Well here is a video of the problem in action for those of you that have had my have had trouble understanding. [www.vimeo.com].

Edit: I also just got some temp reading from a IR Thermometer. It topped out somewhere around 130C - 135C. Which is pretty high. I got curious so i looked up the specs on mouser for the chip. "Maximum Operating Temperature: 130C" So definatly found a problem.

Edited 1 time(s). Last edit at 08/25/2008 11:07PM by ronanwarrior.