Laser / CNC 3D printed CNC: MPCNC, Root2, PrintNC

[jpatton]

I am currently working on printing out the MPCNC Primo after it came up in a different thread and was curious who all had experience with them or any of the other 3D printed CNC's. What were your favorite boards to run the machines off of? Favorite spindles? Especially with the MPCNC are there any favorite accessories that you have found to use with the machine? This one will typically be used for wood, but I am also keeping the size down and using 1" DOM tubing to hopefully keep the rigidity up so that I can mill some aluminum etc from time to time.

 

[Charles_McG]

I’m also working on an MPCNC. I upgraded my CR10S-S5 with the TH3D board a while back, so I’m planning on repurposing the original board. I had to buy a replacement OEM screen - the one V1 sells wouldn’t work with the Creality board, even though you use the same #defines with the OEM. I went through the various articles and got VS Code and Platform.IO up and running and got a firmware built that seems to be running.
I’ve got a Harbor Freight / Chicago Tools spindle I plan on putting on it.
I’ve got a bunch of 1” extrusion handy, and thought real hard about trying to modify the design to use them. I built modified trucks in Tinkercad starting with the Burly parts - but abandoned the idea looking at the Core. Still printing parts.

 

[jpatton]

I have just about finished printing everything off. The center core is a beast. I am still debating on electronics but I am leaning towards the SKR Pro 1.2 with TMC2209 drivers. I have read a bit about using a spindle vs router and am still debating which way I would like to go with that one. I have ordered 1" stainless tubing since I don't have anything else handy and that should ensure its pretty solid. Depending on how this one mills I may use it to mill that parts for the PrintNC and then move up to it but we will see once I get this one built.

 

[Charles_McG]

If you find a way to square the trucks without taking off the steppers, I want to know. I had to back up to that step when I couldn’t get the core anywhere near square.
One side still likes to drift, but it’s much closer than it was.

 

[jpatton]

Yea I will let you know if I figure it out, I am probably going to be using dual endstops on the machine which may help since it supposedly allows it to square automatically. We will see how it works and I am sure good old Mr. Murphy will rear his ugly head somewhere along the way. I have parts being shipped USPS that have been in transit for about 3 weeks going from NY to PA so whenever these things show up I will start putting it together.

 

[Charles_McG]

Last night’s build pic. I’ll be trying pen plotting next.

 

[Charles_McG]

 

[Tobor]

Question: Regarding round tubing vs. 80/20 tubing, is the cost benefit of round tubing worth the perceived/actual reduction in accuracy?

 

[Charles_McG]

Question: Regarding round tubing vs. 80/20 tubing, is the cost benefit of round tubing worth the perceived/actual reduction in accuracy?

I’m sure the stiffness question can be answered- but the cost was the same to me. It’s all scrap, so I thought using the extrusion was worth exploring.

 

[Charles_McG]

By the way, I drew a crown!

The first try faltered because of bad connections to the control board.

 

[Charles_McG]

Calibration: I whipped up a simple square in Illustrator to do the equivalent of how I calibrated my printers.

It took a couple tries, but did adjust exactly how you think it should. I did find that one axis had drifted off square- maybe when I had the bad stepper connection earlier in the day. When the diagonals weren’t equal, I checked, and it was about 3/4” off. I disabled the steppers and put it back in place by hand with a tape measure, then re-engaged and repeated the drawing. It’s as close to square as I can measure.

 

[jpatton]

Question: Regarding round tubing vs. 80/20 tubing, is the cost benefit of round tubing worth the perceived/actual reduction in accuracy?

To the best of my understanding the steel tubing is actually stiffer in that size range the the 80/20 as far as accuracy I am not sure how much it actually affects it. You can find plenty of CNC built with the 80/20. The Root2 is one that uses extrusion, and there are a number on openbuilds.

Slowly everything is coming together. Hopefully actually get it put together in the next couple of days. Still need to clean up the ends of alot of the tubing as well before I start bolting it together.

 

[jpatton]

By the way, I drew a crown!
View attachment 445745
The first try faltered because of bad connections to the control board.

Hopefully I can get mine to this point before too long. Nice Job!

 

[Charles_McG]

First cut. The foam test went so well that I pushed ahead to 3mm plywood. The board was clamped to the foam, on top of the piece of foamcore that I was pen plotting on - not the most level. It cleaned up nicely with a needle file run over it.

 

[jpatton]

I may be missing this but what software are you using? I haven't decided yet and there are a few options between LinuxCNC, mach3(4 is out i guess), or estlcam.

 

[Charles_McG]

EstlCAM. To be precise...
payloadbay -> PDF -> Illustrator -> select paths -> export as SVG -> Estlecam -> resize, set origin, pick tool, set part and hole paths, save CNC program -> save gcode to sdcard -> put SDcard in CNC (old Creality CR10S controller) -> setup board and tool starting point, turn on dremel (1/8" double fluted routing bit) -> print from card.

I set the tool starting point just like I do with the 3D printer - barely drags paper slid underneath. With the steppers off, I manually drag it into position and turn the Z coupler with my fingers.

 

[Charles_McG]

Video.

 

[Charles_McG]

@jpatton , fyi: I'm finding the connectors on the ends of the cable harness supplied by V1 to be completely inadequate for connecting to the controller board. The pin spacing is the same, so it works, but it pulls out too easily, and if it's loose at all, the steppers skip.

 

[jpatton]

@jpatton , fyi: I'm finding the connectors on the ends of the cable harness supplied by V1 to be completely inadequate for connecting to the controller board. The pin spacing is the same, so it works, but it pulls out too easily, and if it's loose at all, the steppers skip.

Thanks for the information. I am actually building my own harness instead of using one of theirs. I finally have it all together and am really impressed on how well everything fits and bolts together. I did have to redesign the endstop mounts to fit the limit switches I am using, so I am printing the last two of these out right now. I did go ahead with the 500W spindle so we will see how everything bolts up and works.

 

[Charles_McG]

I built mine for 300x600x100mm working volume. The 100mm is what went into the calculator- in reality it depends on how the tool mounts.
Anyway, I’m finding that the long gantry is really easily bumped out of square when the stepper motors are off. It’s also really easy to bump back during setup, so I’m not worrying about it. But I am checking before each session.

 

[jpatton]

Making some decent progress. Have some wiring to clean up and going to print some cable chains, enclosures for boards, etc. I did get the crown drawn at least, so that is definitely a start. I have to extend the wiring for the end stops and I will tell you how it works out auto squaring with the dual endstops as soon as I get that sorted out.

 

[Charles_McG]

I'm interested in hearing about how the dual endstops work out.
I'd have to review how they work - if my board can be set up for them - as I recall, they aren't using the endstop inputs that3d printers use.

How big did you make your work volume?

 

[jpatton]

My work area is 24x18x3.25in. I did keep the recommended depth for rigidity. The dual end stops seem to get the job done just fine, although it did take me a minute to figure out they had to be normally wired closed not open to function correctly. Once that was taken care of everything seemed to work just fine. Based on drawing squares and measuring with calipers I am as close to square as I am going to get.