East Texas MPCNC Primo - a somewhat basic build

I figured I’d start a build thread for posterity, though I suppose it’s not that unique of a build. Maybe for keeping my own sanity through social interaction is a good enough reason :slight_smile:

I’m a newbie to CNC I suppose. So excited about diving in and working through it. I can probably come up with a dozen projects I’d like to do, but the imminent need is for cutting foam to create male plugs for composite molds. I am building a 2012 BMW 128i with all the basics (big stroker LS, 6 speed, giant tires all the way around). A sort of do-everything set up. I needed to build the flares for the fenders, do not like what is for sale, and so am going down the sadistic path of doing my own. I could just mock up foam on the car and pull from that, but I needed a CNC anyway right? So here we are. Flares are prototyped in Rhino from a 3D scan I made of the fenders. Now on to the CNC part…

Build volume will be 28"x18" X and Y. Z clearance may be set a little higher than ideal while I do the foam project (haven’t decided but likely 5"), then shortened after for future projects. Build volume was a compromise of fitting the thing in a specific place in my garage, knowing I could go smaller later, and figuring what size I wanted to make the foam slabs that will be individually cut and fit together to form the male plug.

3/4 EMT conduit. I’ve received all the hardware from V1 and new Makita router so ready on that front as well.

Finally finished printing the actual MPCNC pieces. Still have to print electronics enclosures and dust collection. Still gotta remove the brim from a few pieces (prints take too long not to include a brim IMO)

Did most with 6 perimeters, 8 layers top and bottom. Bumped it to 8/10 for the feet. Set to .30 layer height on an .40 nozzle.

Coming off the filament comparison post I made, I’ll share my filament choices. (The complete ones are marked, the rest is to be soon and may change my mind before they print :slight_smile: )

QTY Part Name # completed Infill Filament
2 Corner Bottom 2 50% Atomic PLA Metallic Silver
2 Corner Bottom Mirrored 2 50% Atomic PLA Metallic Silver
2 Corner Top 2 50% Atomic PLA Metallic Silver
2 Corner Top Mirrored 2 50% Atomic PLA Metallic Silver
2 Lower Belt 2 50% Sunlu PLA Grey
2 Lower Belt Mirrored 2 50% Sunlu PLA Grey
2 Upper Belt 2 50% Sunlu PLA Grey
2 Upper Belt Mirrored 2 50% Sunlu PLA Grey
2 Wire Darryl 25% Atomic Orange PETG
4 Stop Block (Dual only) 25% Atomic Orange PETG
4 Corner Leg Lock 4 50% Atomic PLA Metallic Silver
4 Feet 4 50% Atomic PLA Metallic Silver
2 Truck 2 50% Atomic PLA Metallic Silver
2 Truck Mirrored 2 50% Atomic PLA Metallic Silver
4 Truck Clamp 4 50% Prusa CF PC Blend
1 Z Motor 1 50% Prusa CF PC Blend
1 Z Coupler 1 50% Prusa CF PC Blend
2 Nut Trap 2 50% Prusa CF PC Blend
1 Upper Tool Plate 1 50% Prusa CF PC Blend
1 Lower Tool Plate 1 50% Prusa CF PC Blend
Dust Collection
1 Dust Boot Inner V2a 25% Atomic Orange PETG
1 Dust Boot Outer V2 Thin 25% Atomic Orange PETG
1 Dust Boot Outer V3 25% Atomic Orange PETG
1 Dust Top V3 25% Atomic Orange PETG
1 Main Body V3 50% Prusa CF PC Blend
Tool Mounts
1 Makita Top 1 40% Prusa CF PC Blend
1 Makita Bottom 1 40% Prusa CF PC Blend
1 Makita Tramming Tool 25% Atomic PLA Metallic Silver
1 Knife Pen Mount 50% Atomic PLA Metallic Silver
1 Pen Holder 50% Atomic PLA Metallic Silver
Center Assembly
2 Core Z Clamp 1 2 50% Prusa CF PC Blend
2 Core Z Clamp 2 2 50% Prusa CF PC Blend
3 Core Clamp 3 50% Prusa CF PC Blend
1 Core ClampY 1 50% Prusa CF PC Blend
1 Core 1 70% Atomic PLA Metallic Silver
Electronics Cases
1 Gnarly Base 25% Atomic Black CF PETG
1 Gnarly Pass Through Lid 25% Atomic Orange PETG
1 Gnarly Plain 25% Atomic Black CF PETG
1 LCD Body 25% Atomic Black CF PETG
1 LCD Clip 25% Atomic Orange PETG
1 LCD Right 25% Atomic Orange PETG
1 LCD Left 25% Atomic Orange PETG

Atomic PLA did very well on the test, and I like the metallic silver (sort of looks like aluminum if you close one eye and look sideways at it). So I chose it for most things. I used the Prusa CF PC Blend for some of the mounting pieces. I may reprint some of the other pieces in this later, but PLA will work great for now.

Making a jig to hold the EMT and I’ll probably cut it on my SWAG band saw. I’ve shimmed it to be almost perfectly square but if I’m not happy, I’ll try my metal chop saw.

Hoping to start on the bench this weekend. I mocked it up in Fusion360. (there are casters on the toolbox…sorry for the omission)

Top is semi-torsion box I guess. 1x4 frame with 1/2 plywood on top and bottom, 3/4 MDF on top of the “box” for the base. Then the MDF strips and T-track on top of that. 2x4 legs, 1/2 plywood sides and back. 1x6 wrap around the top perimeter.

Anyway, I’ll post as it goes along. Big thank you to Ryan for making this a possibility for us all.


Hey, welcome to building an MPCNC. :slight_smile: Those threads are a lot of fun, also a dump for you to remember how far you’ve come. I like to go back through mine and enjoy the memories.
As for the dust collection: After roughly two years I added this one: Printables. It’s absolutely great because you only lose ~5mm. It does not work too well with too much fine dust from MDF though. Not sure about foam, might clog it.


Thank you! That’s the one I had planned to print at some point. I will probably add it later though. I’m anxious to get this thing going :slight_smile:


Made some progress.

  • Dust collection parts and electronic boxes printed so parts box complete
  • Table complete
  • Feet mounted
  • Outside rails cut
  • Trucks assembled

I had surgery on one eye a couple of weeks ago and still pretty much blind on that side. So not super proud of all my cuts on the table. It’s one of those “well considering I did it with one eye tied behind my back…it’s good enough”

Decided to go with a 4.5" Z height. Not a big deal to shorten later but that will let me work on 2" foam pretty easy (I lose a few mm with the dust collection)

I am very happy how well it’s gone together so far. I made some templates for the feet to lay them out as square as possible using straight edges to layout the box where they go. It’s a perfect as I can measure with a tape measure (so < 1/32") parallel and square with the corner bottoms on. Heights on the corners are dead on as well. Very happy with that!

I am going to add mid span braces and still have to print those. Decided to go ahead and buy double ended studs with right hand / left hand threads to allow fine tuning. Some of the EMT isn’t perfectly straight so the plan is to determine which is the high side of the bend, put that upward, then use the mid span supports to bring them down to straight. That’ll put a slight compression on the legs and should make everything even more stable, certainly straight. The gantry rails will still sag a little I suspect, but the rails won’t compound the deflection.

Studs for the mid span won’t be here until next week but hoping to be able to get a few other things complete and maybe have it all assembled by end of next week.


Sigh…just realized i swapped the x and y rails. It became apparent when i went to put the core on the gantries.

Just spent an hour getting the trucks square…

I’m going to bed.

All good now.

Tomorrow is wiring day


Great colour choice :wink:


I agree, it looks amazing!


Got it wired up and everything looks to work great!

Still gotta loom, tape, organize the wiring and mount the board but it’s fully functional at least.

Hope to tidy it up tomorrow and start testing and calibrating.

Have to say, this went a lot smoother than expected up to this point. I realize all the real work of getting stuff made is still to come, but very happy how well thought out the build of the mpcnc is. Impressive job Ryan!

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Obligatory crown shots :slight_smile: Very happy!

Top left was best.

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They are missing the circle, but they are all pretty dope. :slight_smile: Now bust out that wood! :stuck_out_tongue:

If you want to do some more things with a drag knife or pen there is a pretty great holder for the Primo that you can just place in the normal holders so you don‘t have to take the bottom one off all the time.

So I guess that wraps up my basic build thread. I’m not happy with my wiring so I’ll change that up over time. But it works, and that is a huge milestone.

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Ha! I forgot to select that in Estlcam. Didn’t even notice it. :slight_smile:

Thanks for the tip on the holder. I have a drag knife I bought too and may try that out.

I will look up the alternative holders. I wasn’t excited about taking the lower off so a better option would be nice.

This one. I printed it but never used it. I was always too lazy to take out the router… :smiley:

Thanks! I’ll check it out.

With circle…


It really is spot on.


Nice build, well done!

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I set the endstops and drew some squares and checked for squareness and accuracy. Drew one 1" smaller than the build volume.

Squareness looks spot on. Maybe 1/64" of an inch off in one direction, but it’s hard to tell as I think the pen mount lets the pen flex just a slight bit. I’m going to draw some X’s on each corner and check again. I may not change anything until I set up the router though and double check. It’s really really close.

I think I’m perfect on the X dimension. Y looks to be 1/16" small, but it’s consistent across the full length. I’ll tighten the belts slightly and recheck but it’s also very very close.

Super happy about this. I took a lot of care in measuring and re-measuring everything. I think that’s key so you end up really close when done and don’t have to get into the loop of calibrating from way off.


I skip drawing lines altogether when checking squareness. I move the pen above the surface to each corner, drop the pen/marker down until it hits the workpiece, then move the pen/marker back up. This leaves dots in the corners which gets rid of all flexing of the tool holder.