Molding techniques for making extruder parts

Good day,

I was thinking about reprinting some parts of my extruder. Also, it is always useful to have some parts in reservoir so if something breaks, it can be replaced immediately.

However, what do you think about printing the things once and create a molding negative from it. This way, gears and stuff could be copied faster in the future. Well, I am not familiar with molding at all - thus my question about your thoughts on suitability of this for extruder parts.

Greetz :-)

I think it would work if you could be sure the molding or casting material wouldn't shrink. OTOH, in the time it takes to mess around and do all that your printer could probably spit out a lifetime supply of the parts for a few cents each. If you want to learn about casting, I think it's a great project. If you just want to build up a supply of spare parts, just print them.

If you want parts that are going to last and won't require keeping spares, look into machining them out of metal.

Smooth On is a company that sells silicone, and resins and they did a page and video on doing just what you are asking about [www.smooth-on.com]

A few parts are too complex to mold them, but the idea of recycling the scrap PLA that piles up under my printer is pretty tempting.
And we could do some surface smoothing/edging etc. as well to make better parts.

To overcome shrinking issues, you could print the part larger ( ie. scale it with Cura ), depending on the shrinkrate stated by the supplier of the silicone/whatever stuff.

Imagine printing parts from PLA, build a negative mold and then use any high-temp plastic you didn´t dare to use on your printer....( even aluminum or bronce is possible )
-Olaf

Edited 1 time(s). Last edit at 05/24/2015 04:34AM by o_lampe.

Some of the new 2 part poly-urethanes are very impressive in terms of strength and machinability of the cured material. I've used Smooth-On Smooth-cast 300 and been very impressed. Making dimensionally accurate molds is pretty challenging though. A lot depends on the shape of the parts you want to make. Still, in terms of the potential quality of the finished parts, it's definitely a technique worth exploring.

We could even use water solible filament to mold more complex parts. Like AquaSolve Water Dissolving PVA from MakerGeeks.

We can surely smooth the printed part with a sponge and water?
-Olaf

Very interesting! So the resin is shrinking as you're saying. I'll try something about that the next times, I assume :-)

You also mentioned an all metal extruder: Do you have any experiences regarding this topic? Two obvious approaches are: (1) Machining an extruder from metal which was designed to be printed from plastic (e.g. Wade's extruder or such); (2) Buying an extruder kit (e.g. MK8 Extruders available on Ebay, Banggood or Gearbest). Option (2) seems more reasonable to me at first glance but I am not sure about the extruders' quality.

I am highly appreciating your thoughts!

I´ve once made an aluminum cast twin carburettor manifold for an old Mini cooper. It was pretty messy and took lots of grinding afterwards. But it worked.

For simpler parts, I´d ask a machining shop to do it.
A Wade´s extruder in metal would need a complete new construction ( e.g. reducing wall thickness ).
I´m using a MK8 Extruder and it works fine so far. Only had one clogged nozzle, because I tried to print a part, that was sliced for a 0.4 nozzle with a 0.2 nozzle.

If you were able to cast perfectly shaped nylon herringbone gears for Wade´s, you´re my man!
-Olaf

For me, a metal extruder would be the best solution. No worries about breaking plastic gears and stuff.

I am assuming that designing and giving the extruder design to a machining shop takes more time and money than getting one from china. :-P However, it's interesting that the Wade's extruder uses transition gears but the MK8 ones mostly don't.

Sounds like a MK8 Extruder is worth the (actually relatively little) money :-) If you have recommendations regarding a specific MK8 extruder, please let me know.

Edited 1 time(s). Last edit at 05/26/2015 08:01AM by mardy3d.

If you're looking for a reliable, mostly (all?) metal extruder, check out the BullDog XL. I've been printing 1.75 mm ABS with it for about 5 months with an E3D v6 hot-end and haven't had to clear a single jam out of either.

@mardy
Did you start this molding thread only to discuss different all_metall_extruders?

If you want to bring reprap development further, please keep this thread focussed on the molding theme...
-Olaf

I started it to explore new terrain. From your feedback I understand this technique is not ready to use and since I don't have the time to develop it, it is not of interest for me anymore - at least for productive use. Different for the extruders.

This side discussion is less productive than the extruder one. However thanks for your advice: I'll ask a new question about the extruder.