Acetyl u joints

[Holy1]

Hi Everyone. So I installed some dampers a few weeks ago when SEEme had them on sale and picked up some of the new u joints too. After installing everything I have been struggling to get great prints again. I noticed the hotend platform was really sloppy, side to side and up and down. I had a look at the the new ujoints and measured the pins where they attach to the arms and they were only at 3.80 mm to 3.90 mm. They should be 4.00 mm. Doesn't sound like much but a huge difference after I put the old metal ones back on. They measured a perfect 4.00 mm.

Anyone having iffy prints after installing these should check theirs.

[bot]

Good observation. I think I got lucky and all my parts are very consistent, as I've been getting excellent prints myself, but I've been daydreaming of what a truly industrial delta printer would be made of.

Could be fun to build one... would cost a lot though, but imagine how nice it would be if the entire setup was as rigid and precise as possible. I don't think the quality of the prints would go up so much, but the machine could be built to exacting tolerances and thus calibration might be minimal.

Okay sorry for the off topic rant. Thinking of these tiny imprecisions led my mind to wandering.

As for a solution to your problem, I would print some shims if you can print layers thin enough.

[Generic Default]

The backlash in those U joint pieces is a huge problem for print quality. You will notice a slight waviness to all prints because of resonance and vibration caused by them.

Acetal or PTFE or really any type of low friction plastic would be better than aluminum. And the rods should be as close as possible inside the U joint holes.

The industrial delta printer is actually easier than you think to make. Thicker aluminum extrusions, metal frame connections, ultra-rigid arms, heated chamber, ect. Easy. I hope to build one by mid January once I have some free time.

[Jimustanguitar]

I've been daydreaming of what a truly industrial delta printer would be made of.

Like the Nemesis I and II?

I got a set of the plastic ujoints before they started shipping with kits, but haven't installed them yet...
I like the idea a lot, but I'm not sure if they work as well as I'd really want them to.

[Earthbound]

I bought a set of the acetal joints. Solve one problem by trading it for a different problem. They don't bind/wear like the aluminum joints, but they aren't made to the same tolerances so the backlash hurts print quality as others have stated.

Acetal is a superior material in many ways, but molding the parts doesn't achieve the required tolerances. A machined acetal joint (either from a solid block or molded rough) might be ideal.

I'm living with the backlash for now, since everything else is dialed in and print quality is acceptable for current project.

[bot]

I think with the Acetal (I think that's the right chemical) u joints you basically HAVE to add tension to the arms to remove the slop.

[JFettig]

I think with the Acetal (I think that's the right chemical) u joints you basically HAVE to add tension to the arms to remove the slop.

I have rubber bands on mine and it stiffened it up some but I can still push the end effector around a lot more than I'd like to be able to!

[bot]

Try cable ties (zip ties, zap straps, whatever you wanna call em.) I have mine quite tight and I basically can not move the effector at all. Trying to make the effector wiggle moves the whole machine if the steppers are on.