Does this mean I have to reprint?

I am having challenges assembling the actuators. There seem to be many challenges. The specific one I want to understand is at the foot of the actuator.

  • in this image the “foot” is not attached to the “leg”.
  • in this image… the “foot” (bone) is connected to the “leg” (bone)…

Does it matter if the foot is not attached to the leg? I was thinking if those dastardly O-Rings are put on, all will work as planned? (If not it was sadly way too easy to break. It happens when I screw in the gear too tight.

Thank you very much.

I am not sure that I understand. Neither of those images has a foot?

Have you looked at the Version 7 instructions, with the cut-away diagram of the actuator assembly?


The foot is needed so that the O-ring pulls the actuator column towards something fixed in relation to the main body. Without the foot the O-Ring would just hold the actuator column together.
As the instructions say, this is the trickiest part of the assembly. The vital part is to have the nut tool inserted to lock the actuator position. This keeps the hooks that receive the O-ring clear of the top of the housing so that there is space to get the O-ring in. The band tool cover is mentioned in the instructions, but not shown in the render. It will help you to keep the two sides of the band tool pushing evenly.

By the way, you can paste images inline into a post, which makes it easier to read than using external links.

Actually I see the break now in your images at the base of the actuator column. Unfortunately it will not work in that state. You will need to reprint :cry:

If this happened when you screwed in the gear too far, are your bolts the correct length? The actuator should be able to have the bolt all the way in without pushing the base off the column.

(If no-one is looking you might be able to use glue to get it back together, but it is an internal part and you will not necessarily notice when it breaks again)

Thank you @WilliamW …I’m laughing because not only have I looked at the assembly instructions multiple times, I’ve enjoyed several helpful videos (two live stream thingies from Richard…where I noted he also had to reprint…and the difficulty with getting the o-ring attached…so of course, I made this part MORE DIFFICULT by making O-rings with TPU…I got it working once (I think…)…This other person (Tech vinnie or something) had a noble effort and helped too.

You bring up a good point, I do not understand the terminology well enough and I am sure it has been documented. I’ll go back and find it. Thank you.

my bolts are m3x25mm … which was stated in the instructions. I wonder at this length if applying too many turns to tighten the gear (to make sure the nut is in it’s spot…) will inevitably caused this. I just wish the main body part had printable sub assembly in the <= 4 hours print time so it doesn’t harken back to a time where computers used punch cards. One mistake on a card…and well… tough luck. Get to the end of the line. See you in a few days…hmmm…

It should not break with the bolts screwed right in, that will not have been the cause if you have 25mm bolts. Unfortunately the position yours has broken is narrow with quite a lot of stress. The design has been strengthened in that area, and it is a big pain having to print a whole new body.

@Williamw Thank you very much for your help. When you note:

The design has been strengthened in that area.

is there an updated stl? Or is that design in the stl file I got through clicking on the main body within the assembly instructions.

I am very grateful for your advice and insights.

@WilliamW - what are your thought if I go to m3x20mm instead of m3x25mm. I know you said even tightening doesn’t cause this breakage. My thoughts are I distinctly heard a crack as I was tightening. (Thank you).

The strengthening was many versions ago, it will be in the STL that you downloaded. Using shorter bolts I think will mean that the nut will come to the end of the thread. If you want to bed the nut you could use a shorter bolt first, but all of this should not be necessary. I have a couple of bodies printed recently, I shall have a play myself. Which axis was it?

It is interesting that you heard a crack, I am clutching at straws for an explanation - did you have the big gear on?

The flexure where you are looking is the weakest point. But I have normally seen it break overtime and normally within the flexure. We did find that there was night and day difference in the reliability of this area between very new good quality filament, and cheaper/older filament.

Old filament can absorb water which when heated in the printer can work its way into the plastic causing more brittle prints. It might be worth trying a different new spool for the main body if you have one.