Repair ABS part

So after 5 weeks of building (and waiting for deliveries from China), my Prusa i3 boxframe was finally ready to print this week. Bed levelled, all axis moving smoothly and calibrated, print bed and J-Head heaters tested, so I tried to load the filament ready to calibrate the extruder... and I broke the extruder!

Probably a typical beginners mistake, I didn't realise the filament had come out of the guide hole and it got forced under the idler bearing, which cracked the ABS bearing mount. I have to say here, kudos to the seller on eMaker who provided my printed parts, he's going to ship a replacement without charge, even though I offered to pay.

In the mean time though I have the weekend free, and a nearly working printer to stare at, so does anybody know a reliable way to repair ABS (strongly enough to take the forces on the idler mount on a Greg's wades extruder)? I'm considering superglue, or maybe a 2 part epoxy like araldite, or JB Weld. I think the 2 parts may be stronger, but may be hard to clean off if they fail so I probably only get one shot at this (also I don't want to add bulk into the crack and change the dimensions).

Anyone had any experience with this?

Superglue is how I fix stuff I break. Seems to work just fine.

Give ABS cement a shot, like for sewer pipes. That, or Acetone will melt both parts back together.

If it's ABS then the proper method is Acetone. It melts the surface and acts like welding the parts together and is stronger than any glue would be.

Or MEK based solvent cement that is used for welding plastic pipes. It is thicker and more aggressive than acetone.

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Thanks for the suggestions, in the end I decided to try what I had (acetone, and 2 part epoxy)... with no success, but maybe this will help someone else.

The acetone was painted into the split with a small artists paintbrush, the repair looked and felt solid within 15 minutes but I couldn't guess if it cured at the same rate internally. After 2.5 hours I got impatient and tried re-installing the idler, but the split opened up again once I put pressure on with the springs, so unfortunately I don't know whether the failure was due to my impatience, or the method (as this is my first RepRap I also have no idea whether the springs I'm using are applying too much force).

Two part epoxy (JB Weld) is worse than acetone, I gave it 24 hours to cure this time, but it failed with even less pressure than the acetone weld.

My conclusion is that acetone would probably work on any other part, it just wasn't up to the forces on the idler caused by the springs (but with the caveat that a longer curing time may have helped), it is certainly vastly superior as a repair method for ABS than 2 part epoxy. I'll probably also stock up with a MEK based solvent to try next time, as nophead suggested.

Yes it can take 24 hours or more for the acetone to evaporate completely and make the bond strong. It's also import to use enough, if it was a crack I would pry it open as far as is safe then drip acetone on it so that it goes deep inside. If it were 2 separate parts then I would paint both parts then push together and clamp as tight as possible. If there are gaps from missing material then you can put some filament and acetone in an acetone safe jar together for a day or two then use that as a gap filling paste.

you could melt the part with a soldering iron for a quick job, probably deform some of it. but iv done it b4 and its a quick messy fix

you could melt the part with a soldering iron for a quick job, probably deform some of it. but iv done it b4 and its a quick messy fix

Still would advice trying aceton. Sometimes it takes a few applications of it to make the ABS good and soft enough to stick to each other. I have a few batches of ABS that just don't want to glue with aceton though.

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