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Z-axis accuracy

crussell

crussell

Member
#1
#1
Having a problem where my z-axis is consistently printing about 2mm short. No idea where to go to fix this. The other 2 axis are fine. I'm using slic3r with the downloaded gmax settings. I did have a warped rod so it had to replace it if that could have anything to do with it. I replaced both (and the nuts) at the same time for consistency using 1/4-16 GP acme from McMaster-Carr. Any thoughts on what to check or where to look are much appreciated.

Thanks,
Chris
 
R

raykholo

Member
#2
#2
Not sure what you mean by short. A picture would help.

In the first layer is the nozzle putting down a substantial enough amount of plastic?
 
crussell

crussell

Member
#3
#3
Hi Ray, thanks for the reply. Won't be able to get a picture up until after the weekend, but by short I mean if I tell it to print a cube that's 10mmx10mmx10mm, length and width are fine and measure at 10mm, but the height is about 2cm short, would only be 8cm tall. I noticed this seems to be exponential when I do taller prints. Got a couple of really nice midget tree frogs...

I've played with first layer height. That seems to be the balancing act of getting a good stick vs getting a good layer. Right now it seems ok- meaning it's not squished out paper think but still a little flat on top and is sticking good. Not sure if my calipers would be accurate enough to tell the thickness, but maybe about that of an index card? Will try to get some pictures up Monday when the wife gets back with the laptop so I can upload.

Thanks,

Chris
 
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raykholo

Member
#4
#4
Thus making the midget of midget tree frog literal.

I understand what you mean now but the picture would still help diagnose the issue.

There are a lot of small tips I have in mind that somewhat pertain to this but none of them nor any combination of them would be directly responsible for this.
 
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raykholo

Member
#6
#6
Just of whatever prints are experiencing this issue.

And if possible, what your first layer looks like. Ideally a print with a slightly larger footprint, let it do the perimeters and kill it once it starts shading in. Or just take the pic and let it keep going :) This isn't the cause of the issue but I do want to rule out any issues related there.

While you're doing that, take a few steps back and give me a nice shot of the bed overall from the front. I'd like to see the aluminum angle and springs.
 
crussell

crussell

Member
#7
#7
No springs one mine, my friend! I completely rebuilt the bed while I was waiting for the rods to get here. I'll try to get a print going and grab a few shots.
 
crussell

crussell

Member
#9
#9
Ok, to test upload, I'll start with these. I couldn't get the darn thing to square up with the included feet, so I improved the joint plates to a 5 bolt style and replaced the leveling feet to larger ones that can be adjusted from the top. These are just MDF, but once I get it printing accurately, I'll replace with printed ones. For now, it's rock solid.
 

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crussell

crussell

Member
#10
#10
Inspired by my router insert plate, my bed design used ridged tube for attachment and leveling screws in the corners for adjustment. The base is 1/4" MDF with some holes drilled out to reduce weight, but keep ridgidity. The angles attached on all 4 sides allow the platter to be easily removed and interchanged with different materials. Want glass? Just drop a piece on. Need to sand the plexi? Just take it outside to avoid the mess.
 

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raykholo

Member
#14
#14
Awesome build and mods. I'm working on a CNC router right now, after putting a dremel on my gMax failed miserably.

Your problem has reminded me of a theory I had a while ago. Can you try flashing the "Dual Extruder Marlin" firmware from the download page http://www.gmaxprinter.com/?page_id=146?

Let me know if you need any guidance on that. I don't think there will be an issue given that you only have 1 extruder, but if you end up with a Mintemp error and the printer won't move or something like that, you can just go back to the single extruder firmware. In which case I will make the hypothesized change myself and send you that firmware for testing.
 
crussell

crussell

Member
#15
#15
Flashing the firmware now. Do you want me to try printing using the dual extruder settings for slicer, or the same standard single extruder settings I was using before?
 
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