Cause of "The Lean"

cope413 · Post by **cope413** » Thu Jul 18, 2013 5:33 pm

Ok, I got the arms installed and the printer back assembled.

I had 2 fans on the Rambo, but I added a 3rd after hearing about the overheating possibility.

What should I change the motor current to?

ApacheXMD · Post by **ApacheXMD** » Thu Jul 18, 2013 5:43 pm

When I was trying to solve the layer shifting issue, i tried motor current settings from 100 to 255. With higher currents thenmotor drivers will run hotter but you seem to have adequate cooling there.

I'd look again at the noise issue. Do you have the shielding on the cables connected to ground?

cope413 · Post by **cope413** » Thu Jul 18, 2013 8:06 pm

So far, so good!

I upped the motor current to 185 from 155 and just printed a 50mm cal cube and it printed flawlessly with no lean. It was printed at 40mm/s. I have 2 40mm fans and 1 10mm fan in the Rambo compartment, so I think it should stay cool enough.

I'm going to try the original part I was struggling with and see what happens, but it appears that motor current was the issue.

The TL arms are 50x better than the stock arms - at least as far as ease of installation, weight, and precision. We'll see how they perform.

Thanks for your help.

I'll update with a picture of the finished part

bvandiepenbos · Post by **bvandiepenbos** » Fri Jul 19, 2013 11:32 am

cope413 wrote:So far, so good!

I upped the motor current to 185 from 155 and just printed a 50mm cal cube and it printed flawlessly with no lean. It was printed at 40mm/s. I have 2 40mm fans and 1 10mm fan in the Rambo compartment, so I think it should stay cool enough.

I'm going to try the original part I was struggling with and see what happens, but it appears that motor current was the issue.

The TL arms are 50x better than the stock arms - at least as far as ease of installation, weight, and precision. We'll see how they perform.

Thanks for your help.

I'll update with a picture of the finished part

GREAT! glad to hear you found something that helps.
Is that 185 for X,Y,Z Motors?
My XYZ is at 195
What is your extruder motor set at? I use 240 on it, but the motor does get pretty warm... probably should back it off to around 220-235

Printing from SD seems to work better than USB, as far as printer pausing every few minutes making a blob in print.

Thank you for your feedback about our CF arms!

Post by **geneb** » Fri Jul 19, 2013 1:04 pm

That's interesting - on Orange Menace, I'm running all three axes at 128 with zero issues. Sounds to me like you've got something adding friction to the system.

g.

Polygonhell · Post by **Polygonhell** » Fri Jul 19, 2013 1:20 pm

I think a lot of people run the belts too tight, and the lateral forces on the stepper shaft cause the bearings in it to bind. I noticed this after chasing some backlash on mine that ended up being a damaged belt.
I also think it's easy to over tighten the cheap state bearings, when one end of a connection is AL tighter is not always better. If you use too much force on the eccentric bearings, you literally deform the extrusion, and until the bearing has deformed the entire length of travel, you can have pretty uneven resistance to movement.

Post by **geneb** » Fri Jul 19, 2013 7:59 pm

I'll revise the adjustment procedure a bit to reinforce that the cheapskate should grip the extrusion only enough to keep it from any off-axis motion. An ideally adjusted Cheapskate should fall easily and quickly when raised to the top of the tower and released.

g.

cope413 · Post by **cope413** » Sat Jul 20, 2013 3:35 pm

Ok, so now the machine is printing great - excellent alignment and uniformity, but the print has stopped twice in about the same spot. The buffer got down to 0 and it seemed to freeze the machine

The first time was via usb. After checking the forum for a solution, I printed the 2nd time off the SD card. Same issue.

What causes this and how do I resolve it? Also, is there a faster way to upload a file to the SD? It won't recognize standard gcode, and sending it through rephost took like 3 hours for a 7mb gcode file.

Polygonhell · Post by **Polygonhell** » Sat Jul 20, 2013 3:41 pm

cope413 wrote: Also, is there a faster way to upload a file to the SD? It won't recognize standard gcode, and sending it through rephost took like 3 hours for a 7mb gcode file.

Plug the card into a card reader on the PC and copy the file to it, it will take seconds.
The arduino to SDCard interface is over SPI and hideously slow, it's compounded by the fact the host software sends 1 line at a time over the USB connection, where the latency kills you.

As to the stopping, is it just one model or all of them?

The first thing to do is see if it fails in dry run mode, and track down the GCode it's trying to execute when it fails. And determine if it's actually always the same line, or just around the same time into the print.

cope413 · Post by **cope413** » Sat Jul 20, 2013 3:50 pm

When I add a file through my pc, it isn't recognized when i mount it through rephost.

And it's not the same line, it's just around the same time

Through USB it was line 278,893 - through SD it was line 311,803

I haven't tried anything this big since getting it up and running again. I can try another print that will take 2+ hours, but I'd like to figure out the issue so I'm not wasting filament.

cope413 · Post by **cope413** » Sat Jul 20, 2013 3:58 pm

the gcode is good too... just went through it at both those positions and it's correct

Polygonhell · Post by **Polygonhell** » Sat Jul 20, 2013 4:06 pm

Turn on all the logging in repetier host and see what it says when it stops.

There was an issue where a comms error would cause the host to continually send the same line, but that shouldn't happen off SD Card. And it was addresses in one of the early 0.8 releases.

Errors like this you can check by copying the file to SDCard using repetier host, it effectively runs all of the coms code and none of the movement code.

You might also want to try forcing ASCII commands, it's in the printer settings, instead of letting it select Binary ones.

It could also be an electrical noise issue, it's relatively common for people to turn on a fan or something else with a lot of back EMF on the same circuit and have it cause the printer to disconnect.

When copying in a PC the SDCard file names have to be 8.3 formatted and all capitals.

cope413 · Post by **cope413** » Sat Jul 20, 2013 4:09 pm

Ok, I'll try that.

Does it change anything to tell you that the printer stayed on - extruder and bed both stayed heated - it was just stuck in its place

Polygonhell · Post by **Polygonhell** » Sat Jul 20, 2013 6:26 pm

cope413 wrote:Ok, I'll try that.

Does it change anything to tell you that the printer stayed on - extruder and bed both stayed heated - it was just stuck in its place

No that implies it might be comms error.
Could you control the printer from the host?

cope413 · Post by **cope413** » Sat Jul 20, 2013 8:16 pm

No, had to hit emergency stop. Everything was locked up.

cope413 · Post by **cope413** » Mon Jul 22, 2013 1:59 pm

No idea what was going on, but tried the same file from the same SD card trying to replicate the problem - didn't change anything - and it printed perfectly.

Printed all day yesterday with no issues.

Random glitches? I thought maybe the Rambo overheated, but I've got a 40, 50, and 20mm fan on it - one on the back, one across the front, and one blowing at it - so it doesn't seem like that would do it.

Not gonna mess with anything because it's printing beautifully, but it's still kinda weird...

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