Weird flat spots on round objects w/ infill/interior feature

[Gr8Scott]

I have a kind of weird problem on my Rostock Max prints. I have zero retraction on the settings. Seems like I get weird flat spots on one side of all of my round prints. The printer seems to be programmatically following this same out line in some respects because my printer has started to consistently follow this pattern when there is either infill or an interior feature to print. When it's nothing but round stuff to print, it seems to immediately start printing round circles again. I did get a kind of weird bulge along one spot going up the circle, but it printed that circle correctly otherwise. the hollow inner side of the tube doesn't show the bulge that was there because I used a grinder to remove it.

[img]http://i152.photobucket.com/albums/s179 ... 010375.jpg[/img]
[img]http://i152.photobucket.com/albums/s179 ... 010377.jpg[/img]
[img]http://i152.photobucket.com/albums/s179 ... 010378.jpg[/img]

The fact that it doesn't mess up when not printing interior features or infill indicates to me that this isn't necessarily a mechanical issue. The outsides are blobby due to lack of retraction, but otherwise the prints look more or less OK.

[Polygonhell]

I'd say you are printing to hot but the that's probably not the issue with the flatspot.
My first guess would be mechanical.

[Gr8Scott]

I probably need to add a little more information here. This flattening artifact is facing away from the Z axis (or facing between the X and Y axis). Odds of the X and Y axis having difficulty moving up at exactly the same time in the same place over and over again like this are kind of low IMHO, so that leaves the Z axis. The problem is, the Z axis doesn't want to move downward with gravity? That also doesn't make sense to me. I tried loosening up the X axis in case it was too tight, but that only seemed to made the flattening more consistent than before (which could also be a function of time as well...)

[Gr8Scott]

Found the problem I think. Moved my various axis around with the machine off and notice that the Z axis had a slight give and then thunk that indicated that the pulley was slipping and then catching after a bit of movement. I had previously checked this and found no perceptible slippage, but that changed during my last two prints as it worked itself loose. Learning as I go...

Thanks for listening to me patiently.

[Eaglezsoar]

Thank you for letting us know what the problem was. We all learn when a problem happens and the fix is posted.

[Tinyhead]

Any chance you could provide more info on this? As Polygonhell mentioned, it looks like you're running pretty hot. It's good that you got the flat spot figured out, but the print itself looks like you're running PLA without a fan at a higher than normal temperature.

[Gr8Scott]

I didn't get around to dialing in temp really before I lost both thermistor ports at the same time. Not sure what happened, but it sure didn't make me happy. I am going to have the change the pin references in Config-H for the thermistors and give it another shot and see if I can't get some solid prints out of this thing.

That isn't PLA BTW. That is ABS. I don't own any PLA. My goal is to work my way up to printing Nylon for tougher parts. That and T-Glass (glaze or whatever it's called). I think I was printing at 235 all the way. Should I drop it a bit for ABS?

[Eaglezsoar]

I didn't get around to dialing in temp really before I lost both thermistor ports at the same time. Not sure what happened, but it sure didn't make me happy. I am going to have the change the pin references in Config-H for the thermistors and give it another shot and see if I can't get some solid prints out of this thing.

That isn't PLA BTW. That is ABS. I don't own any PLA. My goal is to work my way up to printing Nylon for tougher parts. That and T-Glass (glaze or whatever it's called). I think I was printing at 235 all the way. Should I drop it a bit for ABS?

Yes, 235c is a little hot for ABS. Most ABS prints in the area of 205c - 230c. You should try for the lowest temperature that extrudes well, sticks well,
and works best for you. I think a lot of 3D printing is experimenting. Once you dial it in for a specific filament you throw a different one on and have to
go with the what works best all over again. I recommend a spreadsheet where you keep track of your filaments by color and manufacturer so that after
awhile, you will know what settings work the best.

[gajtguy]

Aw man I love that suggestion.

[Gr8Scott]

Agreed. When I dropped temp a bit, I noticed more separated layers. 235 might seem hot and boogery, but it did seem to help layer adhesion overall. While I do want to put out nice looking prints, I'm more concerned with function and solid layers than looks for now. Once I get to where I can refine things and make them look better and "gild the lily" a bit, I'll take care of that. For now, I just want to see if I can print a functional part even if it is gappy and sloppy.