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Eric Pavey
CG, art, projects, chocolate
CG, art, projects, chocolate
Eric's posts

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Z-wobble saga continues. Man, everything about my bot is locked in but this.

Once again, z-wobble seems to be coming back, even though I've purchased new leadscrews. I was about to re-straighten my whole machine, which I wasn't looking forward to, when I figured I'd try something easier first: I was running my stepper drivers at 1/32 microstepping, but since I have a RADDS board, I can push them up to 1/128: Why not, never tried before.

The good: Overall, just better quality all around in all departments. And at first I thought the z-wobble was gone entirely.

The bad: But under inspection, I realized z-wobble is still there. It's much less then before, at 1/32: At distance to the naked eye you don't really notice it. But if you take a flat plane and hold it up to the light, you can easily make it out via the PLA's specular.

Before the stepper driver change it was more of a wobble in the print and generally poor vertical Z quality (XY has always been good). Now, it's a square-tooth pattern, exactly 2mm apart, the same pitch as the leadscrew. So it's got to be leadscrew related, right? I printed the below tower in vase mode... so I'm having a hard time figuring out how a constant rotational turn of the leadscrew would result in a square-stepped pattern.

I had to really try to get the artifacts to show up in the below pic by getting the light to shine on it just right. But it's driving me bonkers. Any thoughts appreciated.

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Couldn't figure out why my print was under extruding. During the debugging process I noticed what you see in the pic...
I had printed it with "normal" pla, and it finally have up, but after many hundreds of hours of use. New version is in Makergeeks Raptor PLA, so I'm hoping it'll last a bit longer ;)

So, it's back again : Crazy z-wobble. I've done nothing to my machine since I purchased a new leadscrew to fix the problem (which it did), but once again I have crazy z-wobble showing up again in my prints. No point posting pics, you can clearly see the pitch of the leadscrews in the z-height . I'm mainly just venting, but also genuinely confused as to what would make this show up with a vengeance again. Other than me smashing into a leadscrew, which I have no memory doing.

Any offhand thoughts on what to poke at with a stick?

Printing PLA on PEI : Any secret sauce? I recently picked up a sheet .8mm thick, but I can't get PLA to stick to it. Heated\unheated bed. Wiped down with rubbing alcohol. I can tram it from close to far, but it later just pops off. Calibration cubes do work, but they're just barely sticking there. Anything bigger though at some point just ejects itself.

I've done a ton of reading online and all sorts of people are swearing by it. My first attempt has been lackluster. Any thoughts appreciated!

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First time printing with petg on the cbot: Took a number of prints to dial it in, but I wanted to show a comparison. The only difference between the two is the one in the back had the cooling fan on, one in the front, off (actually I turned it on right at the top, and you can see the quality improve).
This is with Makergeeks "HD Blue Glass" PETG, 245c nozzle, 70c build plate, 45/mm sec, .6mm volcano, 300 micron. I couldn't get it to stick to gluestick on aluminum at all, but gluestick on blue painters tape worked well. 

PSA: I've been reading for some time to use the purple gluestick, but no real reason why. I've had a bunch of white gluesticks around the house, and have been using them thinking, "what's the difference?". They seem to work ok. Or so I thought:

Picked up some purple Elmer's the other day, and man, what a difference. PLA sticks so much stronger, and the glue is so much less 'gooey' after it heats up. I just swipe it directly on my aluminum build plate, and the purple just vanishes once heated up.

If you've been using white glue-stick do yourself a favor an go get a purple one.

Has anyone made a modular mount for a LJ12A3 proximity sensor? Since I have the direct-drive build plate, I want to use the pair of holes on the back that's opposite the belt clamp, to mount one of these in. I can model one up myself, but if one already exists.

Noob question: when people refer to an OX cnc, what does the OX stand for? Been searching all over and never found a definition. I've got some theories in my head, but figured it was time to ask ;)

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Little show and tell from the cbot's weekend printing ;) just about exactly 1kg of pla.

Followup question to an issue I had a while back: I'm doing a cut of some terrain (on my xcarve), and have the rough and finish passes as two separate files. Rough cut works fine, it's about 800k. The finish cut, 4.8megs, is giving me grief: something is causing chilipeppr to 'pause' the cut every few seconds. This is the behavior I'm seeing ('c' for cut, and 'p' for pause, numbers are seconds):
c8 p3 c5 p4 c3 p2 c7 p5 etc...
When the pause happens, everything in chilipeppr locks up: the gcode widget showing the commands flying by, the grbl widget showing the SPJS Queue #, and the virtual toolhead.
What could be causing this? Chilipepper, grbl/Arduino, spjs, chrome?
Luckily it always comes back from the pause, but it looks to nearly double the time of the cut.
Any thoughts appreciated.

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