Prusa i3 extruder body - beyond repair?

I'm halfway through building a Prusa i3 from a kitset from Replikeo.
The extruder body seems to have some severe dimensional issues and it's not coming together at all.

This photo shows how the motor mount holes do not align with the mounting slots:



I couldn't get a good shot of that but there's no way the three screws can be fit as it is.


These photos shows how the extruder idler spring screws do not align with the captive nut holes.






It can be assembled like this (with force..) but there is so much friction the spring does very little - the idler becomes locked in place and can not rotate about it's hinge.
The second image also shows how much slop there is in the bearing mount - the hole ID is ~3 mm greater than the bearing OD!

This photo shows the ovalling of the cold end mounting hole:



This photo shows the effect of the oval hole, it can tilt the same angle in the other direction too, the nozzle making an arc of ~10mm.



I see many (improved) designs have an additional mounting plate for fixing the cold end to the extruder body but from what I can gather mine doesn't.

It's like the part has been printed out of scale. Each problem on it's own can be solved with files/epoxy/drilling etc but overall I think I'd be wasting my time and that I should get a replacement from Replikeo.
Is this a lost cause? This seems like a terribly made part, or am I expecting too much?

Any advice is much appreciated.

Send those pictures to them and request a new part.

You can try to fix it so you can print new parts, but don't think you will be able to print anything decent with that, besides I don't think you will be able to attach it to the carriage.

One more note, those gears will have a lot of backlash, and will be noisy. If you can request herringbone gears.

Indeed forget about these plastic parts, they are simply not usable. I hope the other printed parts are better quality, otherwise I would suggest returning the whole kit and asking for a refund.

Definitely try to get new parts. It seems like they threw together parts laying around. The motor looks like NEMA 14 and the bracket looks like it takes a NEMA 17.

If you don't want to wait for replacement parts:
You can use just 2 bolts temporarily to make new extruder parts. Or drill new holes as a temporary fix.
The Idler bolt spring holes can be drilled with the side of a drill bit to make oval. This will allow play in the movement.
The hot end can be held in place for now with a set screw drilled through the side of the block 90 degrees to the holding screws. Do not drill too deep or tighten the screw too much to deform the opening of the cold end.

I just checked their website and the company is based in China, so sending back the kit and asking for a refund is not an option.

And indeed the extruder stepper motor seems to be a Nema 14 and that just won't work (not enough torque).

Conclusion: yet another bad quality kit hastily put together by a shady company selling on the Internet. If you paid through PayPal I suggest filing a complaint and asking for a partial refund.

Good luck with the rest of the build, you can find proper documentation in the wiki for the Prusa i3.

Edited 1 time(s). Last edit at 03/17/2015 12:31AM by AndrewBCN.

Thanks all.

I will request a replacement part. I think it may be wise to continue the build to see if anything else is faulty and get all replacements at once...

The extruder body is the only printed part, all the rest are moulded and dimensionally very accurate.
I've just measured the motors - they are definitely NEMA 17 not 14, the labels also say 17.
Asides from the terrible quality of this one part the kit appears to be reasonably well put together so far.. We will see.

I'll update as I go - It'll be a slowish build.

Guess that answers my question. I got my kit last week and have the same issues with mine. Just emailed support to see if they'll send me another one.