Cracked Rollers

Hi guys,

I’ve recently purchased (from here) the parts for an MPCNC. While mounting in the rollers, I noticed that one of them had a little crack (see pictures). I thought that’s not a big deal and moved forward. A few days later I took a look at the rollers again and saw that all of them have a crack in the same place.

The parts I’ve bought are for 25mm pipes and I use 25x3 mm pipes.

Do you guys know if they are still usable, should I replace them or should I just throw in some glue? Also, what might have caused this? I did not tighten the bolts a lot…but perhaps I overdid it?



Yeah looks like you might have over tightened them. They should be okay but I suggest you back them all of 1/4 turn.

Would some glue be of any help? And if so, what type?

CA Glue kindof melts PLA, so you have to be careful. It will make a good bond at the end though. Otherwise, something like epoxy or hot glue or construction adhesive are all options, but they will make a mess. If you poke around it and nothing’s moving, I wouldn’t worry about it. Don’t break it worse with your hulk like strength though.

Alrigt, thanks a lot! I’ll give it a try and cime back with the results.

Usually, what I do when I have that kind of issue (which did not happen to me with the MPCNC parts so far, lucky me) is to put the part under the printer extruder, then use it to extrude hot plastic to seal the part.

The result is not visually great, but the bond is pretty strong.

You may want to crank a bit the temperature at which you print in order to get a better bond between layers. Here again, the result will not be as pretty, but for this kind of parts what you are looking for is strength, not look.

Also, you may want to redrill all your holes to the correct sizes with a drill bit, it will avoid useless constraints and forces within the part from when you installed the screws.

if you have some filament, you can put it in an electric drill and “seal” the crack with some PLA.

*but it would just seal the surface, not the whole crack.

Might be better off with some construction glue - but as said above, be careful with that.

Two of mine have cracks just like that, which I attribute to over tightening the bolts. Had been using it that way for months with no worsening of the crack or noticeable negative effect to the quality of cuts. What I ended up doing instead of re-printing (will do eventually) is taking a drop or two of Goof-Off Superglue Remover (works great when you glue your fingers together, as I seem to often do) and put it into the crack, using something thin to ensure it coats the inside surfaces. One of the solvents in the compound works almost like acetone on ABS. Apply some clamping force and let the solvent evaporate. Creates a very strong bond.

All 4 of my feets have also cracked like that, but I printed my own in PLA.

I got…
Tamiya model cement (butyl acetate/acetone if I read the label correctly)
methylene chloride cement.

Which of these are going to work best?


In the absence of solvent welding, good old superglue is awesome for PLA.