Is it possible to home just one or to axis every level?

Hi fellow reprappers

I'm beginning to see some problems with my x axis slipping and I was wondering if it was possible to home it after every level? As my current setup isn't exactly *ahem* presice and slipping about 10mm to the side after about it's 20th level.

I'm using a ramps 1.2 shield configured with Marlin and Pronterface and I'm generally using slic3r for the majority of my prints atm.

Cheers,

Ollie

Easiest way I could think of to do that would be editing the G-Code semi-manually (with find/replace) to add the code to home the X axis just after each upward move of the Z axis. Look through the G-Code, after the initial set-up moves, lines that start with G1 Z (with a number following the Z - that number is how high the head should be to print the new layer) are moving the Z axis to rise up to the next level. I believe the code you'll need to add to home the X axis is G53 X0.

For the long term though - addressing the hardware issue would be the way to go, and print faster, too.

Have you identified what is slipping? First places I'd look are:
- Pulley is not secured to the X-axis motor and is slipping
- Belt is loose and slipping - this should be easy to identify because the slip should happen in increments of the belt's tooth width
- Too much friction on X-Carriage movement / too little power to the X-axis motor, resulting on steps occasionally being missed.

Ah, yeah, the repstrap it's slipping on has string as a belt... Yeah, I kno, it's only temporary while I print off another printer, but it works mostly, except for the slipping...

I'll get editing then, cheers Billmi.

Ollie

P.S. for my machine it seems to be g28 to home, just thought I'd let you know just incase

Edited 1 time(s). Last edit at 04/08/2012 12:10PM by Ollie.

note that homing is probably not that accurate, and going to be a tiny bit different each time.

se5a Wrote:
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> note that homing is probably not that accurate,
> and going to be a tiny bit different each time.

True, bit it's so much more accurate than what I was getting before,

maybe wrap the string around the pulley 2 or 3 times instead of just half a turn? may help. also try to clean and oil the x axis surfaces and if that doesn't work, turn up the current on the stepper motor.

lastly, turning down acceleration in the firmware (marlin) helped the most. my acceleration on x and y is 750mm/s squared just for reference. the original values are far too high in my opinion.

Yeah, the string has about 3 turns on it, although in one direction the string seems to get slightly stuck and causing a small amount of jitter as it prints, not not alot.

I wasnt too sure what to use for the acceleration numbers in the firmware, I'll try turning them down to around 600 and see what happens.

Cheers,

Ollie

You can 'Home' every layer in Skeinforge, but Slic3r doesn't have this feature. I did this almost exactly a year ago, when I built a repstrap, which had the same problem as it used smooth belts. I was able to print a low-quality pulley, then change to toothed-belts, and incrementally print better pulleys.

That sounds a pretty good idea, although I think before I get there I'd better recalibrate my wade's extruder, it's not printing lines after the first couple of levels. Only what can be described as evenly spaced globules of modern art... I need to turn up the steps per mm in the firmware I think.