My MPCNC Primo

MPCNC Primo project status – 11/10/2020 – It’s Alive!

Please make sure that you review the Projects Section to find all of the older post about this as well as other projects I am working on.

Here is a quick recap on what was completed since the 11/3/2020 update;

  1. It is moving! Really….It is. No crown yet.
  2. All printed parts for the MPCNC are complete!
  3. Problems with McMaster-Carr 5mm Stainless lock nuts, really… – Not going to believe this.
  4. Electronics are installed in the custom house, and are running. – Kinda
  5. All of the repurchased items are in and installed.
  6. Searching for dust shoe, cable chains, etc.
  7. Custom designing all of the mounting plates for the electronics.

Printing problems fixed – All of the hardware issues are resolved. Like I said in the last update, somehow I got a hold of some Beta STL’s and they were the wrong size. Ryan was kind enough to help me out with this. The addition of the better bearings and the new polished stainless steel tube on the X axis has made everything move smoothly. The X and Y axis has very little deflection in the Z direction. I cannot feel anything in the X and Y direction. I will be putting a indicator on that shortly to see what I am working with. The X axis is currently out of square by about 1/32″. The Y axis is spot on. I believe that the endstops for squaring should take care of this. If not I will work to get it better squared up.

Problems with 5mm nuts? – I do not know if I would call this a problem, however I was really surprised by this. I really do appreciate the Primo design for its use of standardized hardware. This is much better than the Burly that had a lot of different screws and whatnot. The 5mm screw/nut combination is a good size and everything fits well. I got the 5mm pan head screws and locking nuts from McMaster-Carr. During the construction; I kept having nuts getting jammed on the screws, breaking free of the nut traps and in a few cases the nylon ring came right out of the nut. In some cases I had to cut the screw to get them apart. I verified with a tap that the nuts and screws matched. It turns out that there is some sort of sizing problem with the nylon ring in the nut. I figured this out by trying a different set of nuts 5mm nuts that I had laying around. Everything was smooth and tight, went together easily and the new nylon grommet held everything like it should. Really strange. I order more of the nuts from Amazon and the screws from McMaster-Carr. I am going to go back and replace a few of these that were too hard to move around.

Electronics work/setup is underway – I am a big fan of James’ YouTube channel Clough42. After the Electronic Lead screw series of videos, I wanted to utilize some of the techniques that James employed to house all of the electronics. He did a great job. However, spending several hundred dollars for the Nema 1 cabinet was totally outside of the budget. Yes, I actually have a budget for this project. More on that in later articles. I did have several old computer cases, that with some modifications, it I could house all of the electronics. I removed the guts of one case, closed and taped up any holes, used the steel from some side panels from another case to seal up the back and created a back plate, some paint, and I have a new case. Turned out better than I expected.

The system needs 24v, 12v and 5v to power everything. I also want a general power switch for everything as well as an E-Stop on the controller that handles the motion system. Using DIN rails in conjunction with ferrules and terminal blocks, makes the setup modular and reconfigurable. I want to start with GRBL, but eventually use MACH3 or MACH4. The most interesting part was the DIN rail Mean Well power supplies. Turns out that the DIN rail variations are actually pretty competitively priced and are a lot smaller that the “real” versions. The 24v is being used exclusively for the Grbl_ESP32 MPCNC controller board. Per Bart, the controller require 5 Amps and the 10 amp version of the 24v power supply was EXPENSIVE. I was going to run everything from the 24v supply, hence the need for the greater amperage. The 12v is being used for fans, and with a buck converter the Raspberry Pi4. Any other future power will come from the 12v supply.

As you can tell by the picture, the case was stripped of its drive bays, and other protrusions. The back plate is a side panel that I cut down from a Dell side panel and is screwed down to some standoffs inside the case. The chassis is earth grounded as well.

Another pending item is controlling the spindle, DW660, and Z height probe. The ESP32 controller has a built in relay for turning the spindle on and off as well as pins for the probes, start and stop. All of this will utilized eventually. I am also looking at a 1.5kw air cooled spindle with VFD support.

When I am complete, I will put together a wiring diagram. I am still working on it.

It is alive! – Over this past weekend and with some of the preliminary electronics working , I was able to move all of the axis’s via GRBL and Universal GCODE sender. It was great to see all of this hard work come together. I was originally going with CNC.js, however I gather that the UGS team has worked with the GRBL development team directly, and the GRBL site recommends this one. We will have to see. I like the idea of using the Pi4 headless, however I have all of the cables and whatnot to add a monitor and keyboard. It was great. I have been working on this on and off for about 5 months and it was great to see something working.

Looking for and designing ancillary parts – In an effort to make modifications easier, I tend to want to own the designs for the parts that I use. Using STL’s directly to make modifications is messy. I recently made the switch to Fusion 360, and am starting to get the hang of it.

I am working on;

  • Mounting DIN rail/blocks for ESP32, Buck converter, and Raspberry Pi4 – I have designed a modular DIN rail connector that can be used as a universal mount for all of the brackets. I have the Pi4 one complete, and the preliminary brackets for the buck converter and ESP32 controller.
  • Case fan covers – In an effort to keep dust and debris out of the case, I am using some vent filters cut to fit the three 12v input fans. The exhaust will vent out of the bottom of the case. There is a 5v fan that will be specifically on top of the ESP32 controller to cool the drivers. I found something that I like on Thingiverse, however it is not thick enough. I am still searching.
  • Nema 17 stepper motor covers to house the GTX-16 connectors – I have found some on Thingiverse, however they are just not right. I am using them as an example for some of my own.
  • Cable chains – There are several on Thingiverse that will do the job. Just need to look in more detail and pick one.
  • Dust collection collar – I am using the Dewalt DW660 and there are several good dust shields available and I just need to pick one. I also want to put a small air compressor on this to help remove the chips from the cuts. This will most likely be an upgrade to whatever I decide to use.

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