PC-MAX Problems

Help with printing with specific plastic filaments.
myeager
Posts: 84
Joined: Sun Aug 21, 2016 11:13 am
Location: Boston

PC-MAX Problems

Postby myeager » Tue Jan 17, 2017 7:52 am

I have been printing with PC-MAX. Love the strength of this material.

After several successful prints using Cura, I am suddenly having problems getting through. Seems to be messing up on the infill and support in particular. I tried with this print to slow the print speed for the infill down to the same as the shell. But it didn't get very far at all.

Does this look like a nozzle issue or a filament tension issue? Any thoughts on what to check?
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WP_20170117_08_42_20_Pro.jpg

idiot
Posts: 119
Joined: Thu Jul 02, 2015 7:53 am

Re: PC-MAX Problems

Postby idiot » Tue Jan 17, 2017 7:57 am

It could be a retraction issue. Too much retraction can make the hobbed bolt grind into the filament.

myeager
Posts: 84
Joined: Sun Aug 21, 2016 11:13 am
Location: Boston

Re: PC-MAX Problems

Postby myeager » Tue Jan 17, 2017 9:01 am

I think it was just the tensioners on the filament. I tightened them up a bit, and now it seems to be working fine. Not exactly sure how tight they should be, seems like guesswork. Should they be tightened to like half the width of the uncompressed springs? More? Less?

idiot
Posts: 119
Joined: Thu Jul 02, 2015 7:53 am

Re: PC-MAX Problems

Postby idiot » Tue Jan 17, 2017 9:28 am

I have about 7 or 8mm between the washers on mine, never had a problem with them. I've had filament get chewed into by the hobbed bolt but it was primarily caused by other factors such as true 3mm (not 2.85mm) filament which doesn't travel through the extruder well, too many retractions in a small area, trying to print too fast at too low a temperature etc.

mikronano
Posts: 53
Joined: Wed May 13, 2015 2:42 pm
Location: Chicago, IL

Re: PC-MAX Problems

Postby mikronano » Tue Jan 17, 2017 1:32 pm

From the looks of it, I also get the impression, judging from the perimeter and the skirt, that you need to check your bed level and the flatness of the PEI sheet.
The perimeters have squeezed and loose runs all around. The skirt the same. It is like the nozzle on its path, runs over hills and valleys.
The infill, being right in the middle, seems to be suffering mainly from the bed level. It is like the nozzle is running on top of a bowl in that area.
That all said, I believe your PEI sheet has suffered a lot and now you should probably be looking to replace it.
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myeager
Posts: 84
Joined: Sun Aug 21, 2016 11:13 am
Location: Boston

Re: PC-MAX Problems

Postby myeager » Wed Jan 18, 2017 9:57 am

Thanks Mikronano. The PEI is actually only a couple of weeks old. I think what you are seeing there is that I did not clean off the PVA very well. Although, I admit I did not do a very good job of mounting the new PEI. Even though I followed the instructions to the T, and I put a lot of elbow into working the bubbles out, and it looked good when I was done, a number of bubbles between the PEI and the glass subsequently developed which is making it uneven. My first try at replacing the PEI.

Not sure if I can throw it back in the freezer, pull it off, and try remounting it again. Would that work?

At any rate the subsequent print after tightening the idler retainer thumb screws worked perfectly, so I think that was the primary issue.

mikronano
Posts: 53
Joined: Wed May 13, 2015 2:42 pm
Location: Chicago, IL

Re: PC-MAX Problems

Postby mikronano » Thu Jan 19, 2017 4:55 am

You're welcome. I'm glad it did work after all for you.
Just out of curiosity: how well the PVA is working for you with the PC-MAX? I never had much of success with that glue and that is why I switched to Wolfbite Mega and it's really good. And, yes, it works on the PEI.
As for you question about removing and re-attaching the PEI sheet, I don't think it would work, no matter the method. The 468MP double-sided tape is quite strong and temperature resistant. However, even the slightest attempt to detach the objects, render the tape practically unusable. And that is one of the main reasons why we can never put the bubbles back down! Once they form, they only get bigger!
I don't know the thickness of the PEI sheet you just used but, one way, to address the bubble issue, is to use thicker than the stock sheet. PC-MAX is really strong and when you are able to make it stick very well on the PEI, then the "warping" stress is transfer between the PEI and the borosilicate, attempting to pull the PEI off the glass. The only thing keeping it together is the 468MP. When the bed temp is close to 100-110C the 468MP is still good but is also softened. A strong pull from the PC-MAX, a softened 468MP and a thin (=very flexible) PEI sheet results in bubbles.

Hope I didn't wear you out with all the above :)
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myeager
Posts: 84
Joined: Sun Aug 21, 2016 11:13 am
Location: Boston

Re: PC-MAX Problems

Postby myeager » Mon Mar 20, 2017 3:20 pm

No, didn't wear me out at all, this is great info, and totally relevant. I have been buying the stock PEI sheet from the Lulzbot store. Where would I get thicker sheets of PEI?

mikronano
Posts: 53
Joined: Wed May 13, 2015 2:42 pm
Location: Chicago, IL

Re: PC-MAX Problems

Postby mikronano » Tue Mar 21, 2017 11:23 am

myeager wrote:No, didn't wear me out at all, this is great info, and totally relevant. I have been buying the stock PEI sheet from the Lulzbot store. Where would I get thicker sheets of PEI?
:) I'm glad I could help you.
Well, depending on where it'd be easier for you, you can find it on both Amazon and McMaster-Carr. A couple sizes you could look into are the 0.04" and the (thicker) 1/16" (0.0625" or ~1.6mm). With the latter, you might need to give just a little bit more time for the bed temperature to reach its set point on top of the thicker PEI. It's not a big deal and it's totally worth it in the long run.
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myeager
Posts: 84
Joined: Sun Aug 21, 2016 11:13 am
Location: Boston

Re: PC-MAX Problems

Postby myeager » Thu Mar 23, 2017 6:02 am

OK. Ordered some .0625 PEI. Do you mount the 468MP to the PEI first, and then to the borosilicate? Or the other way around? Any tips on how to get it all together without any bubbles?


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