O-ring insertion tips

Hello, I’m just starting to put things together but have just broken my first o-ring!
Does anyone have any suggestions on what I might have done wrong? The ring seemed well positioned on the tool and foot but it didn’t seem to want to pop onto the hook. I think one side got on eventually but I didn’t hear a clink but tension came off that side of the tool. I couldn’t think what else I could do other than push harder and the band broke. I thought perhaps it might have been sliced between the tool and hook but I’m not sure why one side seemed to work and the other didn’t.

I’ve now managed to get the bands in with out any more breakages. I tried a few things which may have helped.

  1. I lightly sanded all parts of the tool and feet that I thought the band would be in contact with.
  2. I warmed the band with my breath prior to fitting (the room I’m working in is only 16 degrees C).
  3. Maintaining pressure on the large gear. I had originally applied most force to the motor mounts as the gear felt a bit wobbly, but despite the nut tool being in place the gear was lifting by a small amount.

I’m not sure which of these action helped as I didn’t test them in isolation.

Glad that you got them in. My guess is that 3) is most likely to have helped. Or alternatively 4) practice.
The band is effectively in four sections as you put it in. Getting those pretty even so that one is not stretched too far may also matter.
For interest, what exact bands have you got? We were having a discussion of breaking on another thread.

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Mine are official Openflexure Industries O-rings so user error is the problem here I think. For the one that broke the hook looked like it had some viton left on it so perhaps it had a bit of a rough finish but it’s hard to tell visually.

Thanks for posting about it, and I’m glad you got the bands in successfully! I’m also glad the kit includes a couple of spares :slight_smile:

I think the trick is to use the nut tool to hold the actuator column in place - this is more or less equivalent to applying pressure to the large gear, but a bit more reliable… It used to be specified in the instructions, but it’s possible it got culled at some point.

It’s still in the instructions I was using but there was enough play that the tool was becoming angled once the band was on. I think I lack the dexterity to hold in place, squeeze and not crush the actuator :slight_smile:

haha, yes it is a bit fiddly! I have intended for about 2 years to move the hooks slightly lower down the actuator column, which would eliminate the need to hold it in place. I should really get round to doing that one!

Is the band insertion tool in two parts e.g.

It seems to stabilise the tool but I didn’t see any pictures of it being used like this. It took me a few attempts to print the cup part so I was a bit confused when I finished assembly and hadn’t used it :upside_down_face:

Yes, the band insertion tool is supposed to be those two parts together.

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