Mostly Injection .Molded CNC

The cost of 3D printed parts (for those without a 3D printer) is most of the cost of a MPCNC.


Has anyone looked at injection molding some of the plastic parts?


Also, I am just curious: If a big company you have heard of wanted to produce and sell MPCNCs would you be willing to license the design? I am not with such a company, but this looks like the perfect design to bring CNC routing to a mass audience via hardware stores.

Aww come on…less than half.


Yup. I started with this in mind. I had designed it for this reason with as low as possible unique part count, dafts etc. I used to do this in a previous job. Then I quickly realized paying for mould would stifle the evolution and I doubt it would lower the cost much. Print farms now are so cheap and fast and I can start shipping a new part the day I create it…and have. The real kicker comes in when I found out I would need three different sized builds, that just tippled the amount of moulds but does not change anything about the size of the print farm. Heck Prusa and lulzbot print there parts and there daily unit count has just got to be insane. If they aren’t using a mould there is a reason.

Yes. The last “big” company that talked to me about it didn’t see eye to eye with me. I am first and foremost concerned with support, they said yes we already have a call center that can help out…ummm nope, I had some suggestions they only wanted to sub out a call center. They just wanted to move units and didn’t seem interested in the project at all. They just didn’t feel right, there might be someone out there with a better approach. I would love to be able to step back a little bit and focus on development more…but that is a whole new level of business.


I had this idea that milling hdpe block might be quicker than printing. Plus it would recycle all the milk bottles that my two baby boys are getting through. If I ever get round to this ill let you know.

This could be accomplished a lot easier using silicone molds and two part polyurethanes. It would take some skill to make the molds, but once there made, you can make a part in a few hours, and you have a variety of properties to choose from. In both the silicones, and polyurethane.

I have a home made vacuum chamber I use for just this purpose. I haven't tried molding the mpcnc parts, but I'd assume you would use rods set through your molds for the bolt holes, so uou can pull them from the mold before releasing/removing the part.

As far as what to begin with, just cast the 3d printed part. Of course, I’d suggest some post processing such as filler painnt and sanding, or casting the initial part with a hi-res sla printer. The better the first part, the better the rest.

I have a Form 2 SLA Printer. It does make very fine parts and molds.

Have any of you seen this write up where Formlabs used the Form 2 to make some molds for a $3.5K desktop injection Molder? It is worth reading just to say, “Thats cool.”


That would be great if you had parts printed from a form lab. I could walk you through making the molds. They’re not to difficult.

I have a couple form 2’s at work, I can’t run a whole set of MPCNC parts on them sadly but I’ve been thinking about how awesome they would perform. I’ve been using their “rigid” resin recently which is filled with Glas balls and it is, well, rigid. Would love to have a center assembly printed in it.

If you are serious about that…Wait. Don’t print the center pieces yet. SHHHHHH

Ooh, I like the sound of this… I’ve snuck a couple small personal parts through at work, but I don’t know about the whole center assembly… Maybe if I bought my own resin and cleared it with my manager to start parts at the end of the day to make sure the printers aren’t needed by anyone else for work stuff.


I just ran it through the slicer, honestly didn’t even expect it to fit. One XY piece would be 20 hours and $50 in resin, ouch. I’d be really curious to see the performance, the parts I have made with it feel so good.


Any ideas on specific parts to focus on if I were to try stiffening frame parts via material/print methods/etc? I’ve been thinking about carbon filled filament, that would be doable at home & cheaper than resin.

The weakest part on the current build (525) is the XYZ.

Hm, that’s 11.5 hour print and $22 per, not quite as bad. Maybe eventually. I wonder if I could mill an aluminum variant…

What infill percentage are you slicing the parts with? If your casting a mold, you really only need the minimum to keep it dimensionally stable. I’ve never used a form lab, so I can’t be of much help there. You would only need to print one of each different part, since you can use the mold to make multiple parts.

I’m not sure if aluminum would offer many advantages. Im sure it would be a bit more noisy.

I thought this was a cool and simple explanation of the benefits of using a uerethane.

Smooth-on has some really great products as well.

I feel urethane will be a big improvement over pla.

Oh sorry, I was getting off topic just talking about functional one offs, not mold masters.

Formlabs offers a free sample print. I wonder is several people get together and order a different part, eventually you will have a set for masters lol.


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Haga, I like the idea. They will probably just give you a standard sample part (I think often a chess piece) to show off detail/etc.

That would be a worthwhile investment. Giving back and paying it forward too. I like that.