Broken extruder

So this happened



Stupid me didn't bother to print extra parts as one of the very first things I did. I think I can patch it back together long enough to print a new extruder, but i'm kinda skeptical at this point. Not sure how it happened but the bowden tube looks like it got pushed right out the side, nut and all. I'm guessing due to the thin walls near the nut cavity for each screw hole.

Edited 1 time(s). Last edit at 12/28/2013 04:39AM by maik.

Wow. That is a first. I am stilling running the very first one of those ever printed. My guess would be it has to do with the print quality of the original part. I would just epoxy it back together and print a spare. I would not bother to change it until the repair breaks again though. Also be sure to print that with 50%+ octagonal infill.

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Ah good idea with the epoxy, any recommendations for the type? I'm unfamiliar with what might work best. And thanks for the tip about infill, I wasn't planning on changing the model at all, figured it was just the wardtech parts.

Edited 1 time(s). Last edit at 12/28/2013 07:07PM by maik.

I have had a few things stress crack on me and come apart like that. Usually it is because I am pushing the mechanical properties of the part or the part was not printed so well.

The best way I have found to repair is using solvent welding. Put the parts back together the way they are suppose to be and using a syringe with a fine needle (blunt dispensing needles are way safer than sharp ones aliexpress or ebay should have them) and put a drop of solvent in the crack. The solvent melts the plastic and then evaporates off and you have a good joint.

For ABS I use 100% MEK, which I found at a local engineering store.

For PLA I use 100% MEC (methylene chloride) which I obtained a small glass bottle of it from a local sign maker which works a lot with Acrylic (PMMA) sheet. It was about $10 from memory. They had Weld-on 16 as well but this is very viscous as it has fillers in it. So it is not as good as pure MEC for wicking into cracks/close fitting lap joints. Good for joint acrylic sheet though.

However both MEK/MEC are nasty chemicals so if you do use them, wear good/suitable gloves, safety glasses and avoid inhaling the fumes.

Another good PLA glue is locitite 480. I have used it a lot for close fitting lap joints with good success. However for large cracks good old 5-20min epoxy has saved me many a time, only trick is to let it fully cure which depends on your abient temp, but usually I find 24-48hrs is good enough to get a joint which can be fully stressed.

I would just use some five minute epoxy because I always have some around. But if you are going to buy a small amount in one of those two cylinder syringes you may want to go with a metal reinforced one. They are usually black or grey when mixed and the name usually refers to being metal like (here is the one from lepage [lepageproducts.com] ).

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Quote
maik
Ah good idea with the epoxy, any recommendations for the type?

I have used loctites poxy pac many a time for work and for home. Stuff's expensive though, works really well.

If you are in the US I have heard good things about JB weld but I have never used them myself.

I find the cheap two syringe type epoxies are alright but you really have to leave them for a few days to cure before loading the joint(my definition of loading is putting a lot of hand force on things). They say they are 20min to 1hr cure but they really take time, if your ambient temp is around 30oC though you might find it is quicker.

If I am in doubt I just try and glue two pieces of scrap together and then try to rip them apart before I attack the real thing.