MPCNC Primo project status – 11/24/2020

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 recap of what has been completed and worked on since 11/10/2020 update;

  1. Created Open Items list to help manage what I have to complete. – I got lost in the weeds.
  2. Designing and printing custom parts; fan covers, wire management, button mounting brackets, etc
  3. Broken Anet A8 printer – This could have not been the worst time.
  4. Working on the electronics enclosure – Actually redoing it.
  5. Built a Hat for the Pi4 for cooling and power connection.
  6. Learning to crimp Dupont connectors. – This is actually painful!

I have been having a heck of a time dealing on what to do next. After 30+ years of IT work, you would think I would know better. I created the Open Items list so I would not get distracted. I would start working on something that would lead me to something else and I would never get back to the original item I was working on. At this rate I will never finish. I was amazed at all of the items. I will get the machine working before everything is done. I started working on the full parts list and costing, this is coming soon.

Printing parts – I have been working on the drag chain cable mounts, as well as motor covers for the electrical connections. For the drag chains, I am going with 15mm x 30mm. This will hold the electrical cable for the Dewalt DW660 as well as the shielded cable for the steppers and limit switches. Many thanks to Nick Ellson and Alfred Vink, for the contributions that they have made to the drag chain design that I have been working on. The initial parts look good, print well and should work out well when complete. I will make everything available on Thingiverse and my Github account. I decided that I would redraw the parts and will provide contribution links when I am done. The part pictured on the left has been totally redraw and the plate on the right needs modification to handle the offset from the truck better. Everything will be designed around the 1″ (25.4mm) version of the Primo.

The parts for the electronics enclosure has been a priority over the past week or so. I talked about this in the 11/10/2020 status. I have been designing and printing mounts for the Pi4, GRBL ESP32 MPCNC board, wire management, fan and filter covers for the case, buck converters, etc. I have also had all sorts of small parts on the Primo that broke or are showing some stress fractures. One of the end stop clamps just broke off. It was not even being used yet. As a side note, I do not like the Z axis tubes and have a much better way of cutting the stainless steel tubing. This is on the list of things to change.

Broken 3D Printer – During the process of this project my trusty 3+ year old Anet A8, heavily modified I might add, started throwing all sorts of thermal faults. Turns out that the heater cartridge needed replacing. I hate cheap Chinese parts. Could I get the cartridge out of the heater block, not so much. I guess that there was a small amount a filament leaked out between the heater block and the nozzle and coated the bottom of the block to the point that there was no longer any way to get the grub screw out. Fortunately I had/have all the parts. As a side note, the printer is still using the original Anet board running Marlin 1.1.9. For about the past year, the printer has been having all sorts of issues with controlling anything heat related. No matter how much I PID tune the nozzle, it still fluctuates 5 to 8 degrees. I have an SKR 1.4 turbo, and new display to replace the electronics. Things are going to stop so that I can take care of this upgrade. Octoprint is also on the docket to be upgraded as well.

Redoing the electronics enclosure – Two issues and a few small things; How do I restart the Pi4 independently from all the other electronics; and the metal back plate was a pain to work with. I also had all sorts of issues with cable management. I went looking for the cable management raceways, and I forgot how expensive they are. I designed some standoffs with hooks to manage the cable. The back plate was a piece of sheet metal that I scavenged from an old Dell case that I had laying around. What a pain to be able to screw things to. I had originally looked at a NEMA 1 case for this but they are very expensive. So I went with an old computer case. Like I stated in previous updates, I gutted and created a back mounting plate to hold everything. The mounting plate is now a 1/2″ piece of plywood. Not the best, but I will earth ground the surrounding metal case. The back is now solid and easily manageable. I see all sorts of setups similar to this, so they must be on to something. As for managing the Pi4, I added a 12v relay and a illuminated switch to be able to independently turn the 5v power on and off to the Pi. I have designed some custom plates for the front of the case to house all of the connectors and whatnot. The back has the aviation connectors for each of the motors and limit switches. In an effort to make custom cables, I started working through how to crimp Dupont connectors. This is hard to get right consistently. By the fourth tail cable, I was getting the hang of it.


Messing with the USB-C connector from the Pi4 to the 5v 3 Amp buck converter was not something that I wanted to do. So I created a custom hat that extends all of the Pi4 GPIO pins to make them accessible as well as using the Pi4’s pins 2 and 4 for positive and negative connections. When you build a few hats for ATX supplies, you get used to doing things like this. I also, added a 5v fan for cooling of the Pi4’s processor. This is all integrated together using a JST connector. This was all made from parts that I had on hand and was actually fun.

With the holidays and the upgrades to my Anet, this project will slow down over the next few weeks, More to come and thanks for visiting!


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