San Diego - MPCNC

I am about two weeks into by MPCNC build, and I am somewhat obsessed. Between family and work I have been struggling to find time to learn and design my build, but it is coming along. I have been reading as much as I can in these forums and have been resisting to go overboard. I would like to build a solid machine with as much accuracy as possible and have opted to upgrade to 1” stainless steel tubing. I purchased a 20’ length of stainless tubing which has blown my budget for upgrades or any additional tubing right now. This is limiting my usable dimensions to 22x22x5, but I am hoping it will give me good tolerances and I figure I can always upgrade in the future if I want a larger build area.

I am about to purchase some parts from amazon and I am a little apprehensive when looking for acceptable bearings. I feel pricing and quality are all over the place. I purchased some bearings a few months back to make a fidget spinner for my son and was disappointed with the quality and how poorly they spun. How concerned should I be with bearing quality? Will this have a big impact on machine performance?

The printing is coming along, with almost half the parts printed. I had an odd failure printing the Roller pieces last night where after a few layers in it appears the printer went haywire … I assume(hope) it was some glitch in the gcode. I resliced the part and kicked of the printing. I am new to 3d printing so I am unaware if this is common or a sign of other issues. So far so good with the new print.

Failed print:

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Here is the accent color along with the standard black, it was this or the grey that came with my PRUSA.

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Nice printer.

That failed print is strange. It printed the first cm or so fine, then messed up (ok), but then it recovered and finished the part(?). Wow. It looks almost like it skipped up or something. Weird. Hope the next print works. Did you save the bad gcode? You can preview it in slic3r.

There have been some folks here getting really bad bearings. From eBay, IIRC. The bearings aren’t super critical though. Not as critical as fidget spinners. Ryan designs these machines and he runs the vicious1 shop. He makes sure to get good bearings. He won’t guilt you into buying from him, but I will :slight_smile: . His shop pays for the forums and for his designs. I buy something from him whenever I print a new machine. /Guilt trip

Welcome. You’re going to have a lot of fun.

That looks like you had a partial nozzle clog that cleared itself after a few layers and then the print recovered, though not in a usable form! I’ve had this happen several times over the years. Sometimes it is amazing to watch a print recover from an issue, particularly when a portion of support structure falls over or gets knocked loose and then over the course of the next few dozen layers it re-materializes out of the spaghetti just in time to do its job. If you keep experiencing that, you can try a cold pull on the nozzle to clear any debris or burned/degraded filament.

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That poor fellow with the nasty bearings was me… :frowning: I bought some on ebay that in the picture looked like your average 608RS bearing, but I got these crummy ones. I was able to revive them a little by soaking them in citrus cleaner to get rid of any grease, or mainly dirt. Keep in mind this was for my application, not an MPCNC. Keep the grease in your bearings, no reason to take it out. The bearings on the MPCNC play a little ROLE, get it? The size of the bearings are way overspecced for the load that we put on them. The only reason they are the size they are is availability and ease of use. They spin slow and barely have any sort of wear overtime.

Sounds like you want a lot of performance out of the machine. I hope I don’t sound negative but it is unlikely you will have success from the very beginning. To be successful with the MPCNC, it takes some time in your setup. I would argue the most important part to get performance out of your MPCNC is your setup. It is all about your CAM and ability to tune your machines geometry for your work. Don’t worry on the little details like tolerances so much though or you might end up disappointed. It is a great tool if you have the time and design your parts accordingly.


Jeffe you are making me feel bad about buying from Ebay and not Ryan. All ebay has gotten me are flipped LCD plugs and low quality bearings, maybe it is time to buy from the shop. A little donation too :slight_smile:

I already feel I owe Ryan for such a fun project and I am thankful for all that I already learned… I am new to the whole 3D printing / CNC space and I am hoping this project can push me to learn the mechanics, trouble shooting to a deeper level. I had a load of fun building the Original Prusa, but it was more an exercise in following instructions and I am looking to move to the next level of detail and understanding.

Jeff - I will check out the gcode again and see if I see any issues. I looked at it in Slic3er and didn’t see any issues. I am thinking Vincent’s theory about a clog that cleared is most probable.

Kevin - I would consider myself mostly clueless as to what I want out of the machine. I was really excited to start the build, but I not sure what I will be using it for. I am looking forward to learning how to square the machine and get the geometry, and I plan on google’n CAM next so I can figure out what that is.

Thanks for the feedback, I do appreciate it.

My build is progressing, but very slowly. Kids, work, wife and training for a charity bike ride take the majority of my time. I get a few minutes a day to start a print or read up on electronics and assembly. Still having a blast and learning a ton…

My 3D printing skill have been put to the test, the bottom_corners print failed three times with the print coming unstuck at various stages in the print. I am not sure if my printer is misaligned or something is off but figured my issues had to do with the speed the infill was running at. I just happened to be in the room when one print run failed and it was during the infill process, which was running pretty quick. I ended up adding a skirt to the print and slowing the infill down to the same speed as the perimeter speed. That seemed to work for the bottom_corners. I also had issues with the lock_nut where it popped off half way through the print… I was in the other room and heard the part drop off the printer and onto the table. Jumped up and found this.

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Here are the various failed bottom_corners.

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I am new the to 3D printing world, but I am very impressed and amazed with the parts for the MPCNC. Every part is a work of art and the larger components are just amazing.

The build officially started Friday night. I promised my son he could help if he finished his homework all week and didn’t forget his stuff at school ( big problem and very difficult for him). We sat down Friday night and start the middle assembly as I thought that would be most interesting to my son. We got the first few steps done and then were blocked by the lock_nut that needed to be printed.

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I have been using my office/guest room for the 3D printing and figure I need to move into the garage. It’s been on my list since I moved here to build a workbench and figured it was time. I have only been here 8 years and have been using a folding table as my primary work area. I opted to go with the same table as Jeffeb3 as it looked like a simple build. After my 30 mile training ride on Saturday I made a quick stop at homedepot and picked up the necessary supplies. I opted for a full 36x80 bench where I plan on having the CNC on just one side, with the 3D printer on the other. I figure if I need more space I can move the CNC… It just occurred to me that moving the CNC, even if it is mounted on 3/4" plywood may throw it out of alignment, if so this may be a permanent installation.

The workbench was also a learning process as my wood working skill are not the best. I was hoping to have a rock solid bench, but it still has some movement. I planning on adding some braces to the legs for maximum stability. Overall I am happy with the bench and thankful Jeffeb3 posted his bench and link to the plans / youtube build. ( I guess I should also post the link, will need to find it … ).

Here is the end result
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Duplicate post…

Duplicate post…

Yeah, it’s a little floppy side-to-side. For a workbench, I would definitely add some corner braces. For my MPCNC and LowRider, it wasn’t bad enough to make a difference. It would wobble a little, but the work would move with the machine, so it wasn’t a big deal. Here is another video from him that shows a stiffer version:

The build has moved from my office to the garage… The workbench I build that is a standing height has worked out great. I haven’t gotten to bracing the legs yet, and will wait to see how wobbly it is when it gets moved up against some sturdy shelving.

I have the majority of the machine assembled and I am waiting on some wire to connect up the stepper motors. I have a few questions …

So when it comes to squaring up the MPCNC and you are measuring width/length and diagonal, how precise should you be measuring? A few days ago when I first finished assembly I was seeing that some measurements were off by up to a 1/16. After pushing the X/Y around for a few days seem to have improved things. I just measured and they look spot on when measuring with a tape measure, maybe off by a quarter 16th. I know it is important to get things square, so the engineer in me want to know to what precision?

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I have assembled the middle Z stage and have checked the square and tension of the rails and bearings. Everything looks good, but I have not tightened any of the Tension bolts. Am I missing something or do I not understand what tensioning is? Or should I just consider myself luck that no adjustments are needed?
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I ordered the 12v power supply from the parts list. I assume this is only to power the stepper motors. Will I need to get another power supply for the Arduino? I assume I can use the USB connected to my computer, but would like to find a way to have a single power cord. Can I pull some power from the 12v power supply?

Again thanks for your feedback and comments.


1/16" difference in the diagonals is square enough. 1/64" is definitely good enough. The size of the x on all three pipes and the size of the y on all three pipes can have a bigger effect, but 1/64" is still good enough.

Anywhere three bearings are trying to capture the tubing, the three bearings should all be touching. If they aren’t, you can tighten the bolt on the “back” to make then tighter. If all your bearings are touching and there’s no rocking, then you’re good.

The 12V feeds into the Arduino’s Vcc, and it has a 5V regulator on the Arduino. As long as you don’t fry that regulator, you don’t need us power too.

My advice is don’t stop building! I bought the hardware 2 years ago and got half of it built last year. I have the electronics together and have tested them but have yet to put it all together. Family, work, school, house, other projects ect… all take their toll on what we really want to do…

Jeff - Thanks… I spent a lot of time on getting the pipe cut to the correct length. Afterwards I assumed ( incorrectly ) that the length was not that critical. I figured if the pipes were slightly off the longer of the pipes could just hang under/over the edge.

I am glad to hear that I can use just one power supply for the RAMPS & Arduino, I like things clean and simple. I have not done much with the Arduino besides some simple tutorials but have a basic understanding of it. I will need to read up on the RAMPS as it is total new to me. The pair seem pretty powerful in combination with a few stepper motors… I am trying to think what I can build next with the same basic setup.

ZRHERBERT I hope you find some time to finish your build. Looks like you are going down the 3D printing route. I have been making steady progress, but yea it is taking longer than expected. If I hit any large blocks I was planning on taking a day off work and cranking it out.

I was able to find time this week to finish up the Belts, Ramps and Steppers. I have learned my soldering skills have much to be desired… I found a short in my z axis stepper that took a few minutes to sort out. I prematurely taped up all the wiring and ended up stripping it all off while trying to debug. That lesson has been learned.

I am beyond stoked that my MPCNC is up and running or at least moving. I have not hooked it up to the computer yet but was able to do the basic movements with the LCD controls. I was very happy with the small square I was able to sketch out. It was almost perfect and I attribute any anomalies to the pen and not the CNC.

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Ryan… This machine you created is Awesome! I just built an Original Prusa a few months ago, which was a great experience, but nowhere as educational or fun as this build. I am looking forward to the next phase of learning and plan on jumping into EstlCam next…





Thanks! I learn stuff because of it every single day. The bad part is it makes me feel as if I know even less.

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Yea, that realization is called Wisdom

Booooooo, so much more fun to think you know it all. Went fishing with an 8 year old, that kid was pretty sure he had it all figured out. I was so jealous.