Creaking u-joints

[dtgriscom]

I'm now calibrating my branny new MAX v2, but there's one significant issue: the joints creak. Any time I do a motion that isn't straight up or down I'll hear a "tick-tick-tick" as the delta arms swivel against the u-joints. The faster the joints are changing angle, the faster the ticking. Anything that loud is surely shaking the effector platform, which would at least mess with the smoothness of my results. I even used white lithium grease on all of the joints, to no effect.

When putting the arms on the u-joints, I found that some of the u-joint pins were a really tight fit into the arm holes, and needed significant pressure to get them to go in. I'm sure that this is where the creaking is occurring, and am thinking about disassembling the whole shebang and using a rat-tail file to gently enlarge the tightest holes.

In addition, although the u-joints spun smoothly on their axles when tested, after I put on the spring clips the u-joint-to-axle rotation got a lot stiffer. The weight of the arms could still pull them down, but not by much.

So, I have some questions for the assembled experts:

• Have any v2 owners had this trouble when assembling?
• Any opinions on whether lithium grease is good, bad, or indifferent for the various arm joints?
• Any opinions on just how smooth this all needs to be?

Thanks,
Dan

[geneb]

If you actually had to apply force to get the arms to sit properly on the u-joints, you should contact support and discuss it with them directly.

g.

[dgriff]

• Have any v2 owners had this trouble when assembling?
• Any opinions on whether lithium grease is good, bad, or indifferent for the various arm joints?
• Any opinions on just how smooth this all needs to be?

Hi Dan:

Expert I'm not, however my arms were also a tight fit on the swivels - when I moved them manually before connecting to the hot end, I found they were pretty tight in a few places (vertical was fine, but horizontal was stiff). I tried filing them open a bit more, but I was wary of overdoing it, so I put a very tiny amount of lithium grease on the center post on the top and bottom of the swivels and it helped them to move much more smoothly. I think it helped the accuracy of my prints and I don't see any downside to it.

The stepper motors are powerful enough to overcome a bit of friction - but you don't want it so tight that they need to force things, and perhaps cause damage to the belts.

Since doing this a few days ago, there is much less creaking when printing, to the point of being almost none.

[dtgriscom]

The stepper motors are powerful enough to overcome a bit of friction - but you don't want it so tight that they need to force things, and perhaps cause damage to the belts.

I'm not worried about that; I'm worried about the effect on the effector platform. Imagine flicking the platform with your fingernail while printing; the steppers won't mind at all, but I'm sure you'd see a squiggly in the line being drawn.

Since doing this a few days ago, there is much less creaking when printing, to the point of being almost none.

Well, I've now printed exactly one object: a goopy calibration pyramid. The creaking didn't abate, but I didn't see any squigglies in the pyramid, although it had other problems. (Boy, was it cool to hold the results, though!)

[flexman]

Hi guys,

With me it started to make some chirping noise so a added some silicone grease to the u joints and it works great. I guess the lithium grease will also do. Some googling (http://rc.runryder.com/helicopter/t407542p1/) says it does not harm the plastic so it should be fine.