Problem with 3D Print of Roller

Hi Everyone
I’ve just started printing parts for my 525 J (25.4mm) machine and would appreciate some help please. I am using a borrowed Wanhao Duplicator I3 (Version 1), PLA filament and Slic3r. I have about a month of 3D printing experience but have spent that time 1) getting the printer working, 2) printing test pieces (cubes, yoda, 3D Benchy) with good results and 3) modding it to work better (Z tower brace was the biggest improvement). I am not an expert by any stretch.

Print settings are 3 layers & perimeters, 55% infill, 0.26mm layer height, 30mm/s print speed for most and 15mm/s for external perimeters and top solid infill and 60mm/s bridging and overhangs.

On to my MPCNC build. Apologies for the novel that follows:

I started with the Pineapple Coupler - no problem. Then I printed a Roller. It has some potential issues (see attached images):

  • gaps on one the side only of the part that appear to only be 1 perimeter deep (image 1)
  • some filament drooping in the gantry cross bar curve, where the curve softens upwards instead of staying in the pipe diameter (image 2)
    The part was orientated on the build plate with the bearing wings to the left (standard when the part is added in Slic3r), Slic3r seam position setting of “Nearest”.

I have noticed from my testing that orientation of the part on the build plate makes some difference, possibly due to better/worse cooling from the cooling fan (just noticed Slic3r setting “Detect Bridging Perimeters” is “ON” so it uses 60mm/s bridging speed and 100% fan for overhangs).

I then printed a Roller-M. I sliced it with the part orientated with the bearing wings to the front and also changed the Slic3r Seam Position setting to “Aligned” (been playing with that too). I printed it with these settings, same filament. Near perfect, no gaps on the side of the part but slightly worse drooping (image 3). This could be due to the cooling and speed as noted above.

I have also printed a Roller Mount with no problems.

So my questions are:

  1. Is my first roller with the gaps usable? Will they weaken the part too much?
  2. Is the drooping a problem to worry about?
  3. To fix the drooping, can I carefully heat that area up to re-melt the PLA and smooth it out?

I would appreciate your guidance.

Hamilton, New Zealand

Those are mostly cosmetic issues, really. The semicircular area clamps onto whatever you’re using as rails, so if there’s a little bit of sagging or drooping it’s no big deal. The layer gaps, they only go a single perimeter deep and they don’t go around the whole object, so the chances of them compromising the strength is minimal.

I wouldn’t worry about it, to be honest.

Those are mostly cosmetic issues, really...I wouldn’t worry about it, to be honest.

Thanks Nate, I appreciate your advice.

I actually weighed them both today and was a little surprised to find that the first Roller (with the gaps) weighs 75g and the second RollerM weighs 87g. Ryan lists these parts as weighing 90g each so the one I’m worried about is 12g lighter (~17%). Side by side they are the same height and the features line up so it hasn’t skipped entire layers.

I’ll print the other Roller and RollerM I need and compare the weights before deciding on if I bin it or not. Worst case is I use it as a spare.

If Ryan reads this, have you noticed any variation in weights over the parts you’ve printed or seen this before?

Filament will weigh differently between colors, manufacturers, and even spools of the same stuff.

I agree with both of them. That drooping is the only reason I mirrored the rollers, make sure you put the droop on the same side on both ends of your rails and you should be okay.

But if you are trying to get better prints I think that is mostly a extrusion temp and cooling fan issue. little less temp, more fan. I am a bit obsessive about calibration pieces. I like the bridge pieces and the overhang torture test for this one.

I’m not saying your setting are wrong but mine are different. I have used the same ones forever so mine could be more wrong but seem to work for me. using your numbers, 30 print, 25-28 external, 32-34 bridging. I think that drastic change in bridging speed might have caused the missed lines, unless you are using volumetric extrusion than you might be okay.

So many printing subtleties

Thanks Barry and Ryan, much appreciated.

I’ll do a little more calibration with slower print speeds and lower extruder temp (was 210 degrees C). More cooling is trickier without getting a bigger fan and printing one of the cooler duct mods that are around. I’ll try the Slic3r cooling settings to see if I can get the fan to kick in earlier first.

I love this MPCNC idea and had been hanging out waiting for the 25.4mm version so thanks for that Ryan. A lot of guys at my work are really keen to see this in action - as am I.

Calibration is tedious and a bummer…but once you get it, man, are things easier. This is why I think most people tend to stick with one brand of filament, setting for one brand of PLA will be different for another.

Yea, getting everything dialed in takes time. Usually once you get one filament working, you can adjust into another with the first settings, then save it out as your new settings. I have different settings for different colors, and materials. Also have settings for different speeds and layer heights.

Thanks Guys.

I’ve just bought a couple of new rolls of filament so am calibrating things up now for that. Barry - that list is impressive! I’ve been working towards the same thing; as I make changes to my settings I save them so I have something to go back to.

Anyone know what the overhang angle is on the Roller for the cross beam radius (where I was getting the droop)? I was thinking I could whip up a quick test piece in CAD with the 25.4mm radius softening out to the angle overhang. That way I could test my settings without doing a 6 hour print.

Otherwise, what is the worst overhang angle in the MPCNC?

There is a nice overhang test piece on thingiverse.

My parts I try to keep all overhangs at no more that 2 sides at 50 degrees, a few are 45 though. That particular one is 45, from the tube tangent unfortunately.

Thanks viscous. I’ll make up a test print.

I just enabled supports and it did create a mid bridge point there. It’s easy enough to remove and clean up a bridge and they use so little plastic with SLic3r that I usually just leave supports on all the time and let the slicer decide if I need them.

I just finished printing my 4 Roller parts. However, I noticed I did not print the RollerM piece and all 4 are the Roller (not mirrored).

Will this be a problem? It looks like the center spacing of material (inside where the bearings are housed) is the only difference between the two.

Should I print the RollerM pieces or should I move forward with the 4 Roller pieces?

If your prints came out well you will be fine. The mirror is mostly for people who can’t seem to get the print right causing them to have alignment issues.