MPCNC Primo Project status – 11/3/2020

Hello all, been a few months since I posted an update. Going forward, please review the Projects Section to find all of the older posts about this as well as other projects I am working on.

I have completed a lot of work and here is a quick recap;

  1. Torsion table has been completed
  2. All of the parts printing is complete – Well not really, keep reading!
  3. Electronics have been purchases and the enclosure is being constructed – More to come on this
  4. Main rails and trucks have been installed – Twice, Keep reading!
  5. Core ands Z axis has been installed – Well not really, again keep reading!
  6. Repurchased and reinstalled all of the bearings and one of the rails.

The full project history is located in the Projects section of the site. I am working through a list of all components, cost, etc and will get this posted as soon as I can get it done.

Torsion box table update

Below is the Torsion box table, 44″ x 44″ x 35″. The top is 5″ and made of 3/4″ MDF. Since MDF can be pulled apart easily, the corners of the top are reinforced for the Primo feet to connect to. The bottom of the torsion box, is 3/4″ birch plywood for stability and strength on the legs. It is using casters with feet that can handle 2000 lbs. This is stable, flat and can be easily leveled. First time I used Fusion 360 do design anything like this, multiple components and cut sheets. Worked ok, I have a lot more to learn. I finally gave in and purchased a personal license.

Work that is currently going on;

Frame installation – This was relatively simple. However, I think that this can be improved. The holes on the feet are not large enough to allow for tiny adjustments. At one point I was off about 1/16″ on the square and no real way to adjust the feet to finish squaring the frame. I had to fill the old holes with wood and glue and then redrill them. Painful. I came across a few folks that ran into the same issue.

The forums also reported that with the bottom open on the feet, it is possible overtime to have the tubing push down into the MDF and mess with the height of the rails. To solve this, I cut a piece of thin sheet metal and made a cap for the bottom of the foot.

Reprinted and reinstalled all four trucks – Upon the initial installation, these never fit properly around the stainless steel tubes. I am using 25.4mm polished stainless tube and have checked the dimensions several times to make sure that they are correct. I had to really torqued the bolts to snug up the fit around the steel tube. I could never get them to stop wobbling around. A day or so after I installed the trucks I found that all of the bolt holes had cracked. Over torquing them is the reason that the plastic failed.

Thinking it had to be some sort of printing issue, I reprinted one of the trucks. Prior to this, I verified that my printer was running properly and that a test cube was dialed in properly. I used the exact same S3D profile on the same 3D printer. After reprinting, and to my horror, I figured out what changed. The files from Thingiverse. Both STL’s are marked with a “J”, so I know that I have the “same” parts. However, when I compare the files from June to October; they are not the same. Here is two visual differences;

There are more differences. The June 2020 trucks are taller, wider, and the holes for the bolts are much smaller than the October ones. I compared the files from June against the ones that I downloaded in October. Not only are the file names different between the ZIP files, but they are not the same. I check on Github and I cannot find the older version. This is frustrating, here is the files and differences between June 2020 and October 2020.

Here is what is worse, I installed the core and had the exact same problems. It wobbled all over the place. Reprinted the Z clamps and what do you know, fits perfectly. I put together the Z axis and it does not slide into the core. The core is to small and does not have the clearance to allow the Z axis to slide into it. I have reprinted the core, 33 hours; and guess what it turned out to be the Z coupler, motor mount and tool plates. I should have reprinted the easy parts first. I get the dumbass award. They are reprinting now. Another spool of filament gone. How frustrating. The part size problem is not the printer or the slicer. You cannot get larger parts from the same amount of plastic like that. I weighed them, the June 2020 parts are heavier.

Here is the thing, I posted a message on Facebook and the V1 forums and neither posts got feedback from Ryan. Nothing. I got some information about another tube size that had some issues, but nothing about the change in the files. As far as I can tell, something must have happened and Ryan posted the corrected ones sometime after June 23rd.

Update 11/5/2020 – I finally talked with Ryan; I guess he is a busy guy and had not had a chance to get to this post. I originally posted the issue I was seeing on the October 24. 2020. Jeff poked him on the 26th and Ryan then contacted me. I guess that I must have gotten a hold of the Beta files.

Here is Ryan’s remarks; “All the files get marked with a revision number if anything changes, eg “V1”. If it does not have that it is an original part. The 25mm version of the machine was released as a beta since I can not source the tubes to test it. When you downloaded the first parts you had there should have been “beta” on the file links, and the main page posts, FB, and the forums all had info links as we discovered and tested the fixes. When everything was resolved the beta tag was removed.”

Reordered and reinstalled new/different bearings – This project started for me over a year ago and I ordered the right size bearings for the Burly, however I did not take the recommendations that Ryan provided at Amazon. I purchased about 100 bearing at about $20, that are “low noise”. They are also technically the right size, actually no they are not. This is on me. I went back and spent the $45 on the right bearings. Totally different fit and are smooth as butter (with the right part tolerances). I still had to reprint the trucks. No matter what they would never fit.

Reordered one of the polished stainless steel tubes. – For whatever reason, I think this is on me; one of the tubes is short by about 1″. That mistake is now costing about $30 to get the correct tube cut and reshipped.

Electronics – I have most of the wiring, electronics, etc. I am using an old ATX case that I had laying around to house everything. I modified the back side to cover all of the holes, so that they can be drilled to what is needed. The inside has been stripped of all the bays, and the back plate has been flattened to ready the back panel. I have been able to update the GRBL_ESP32 MPCNC board and interact with it. Shout out to Bart Dring for help with this. His Slack channel is very helpful. I am going with GRBL, Universal GCODE sender, and a Raspberry Pi4. Two Mean Well power supplies, 24 and 12 volt. The 24 volt is for the ESP32 board, and the 12 volt is for the internal fans, and buck converter for the PI. I am using DIN rails to hang everything. The designs for mounting the cables and whatnot inside the computer case is ongoing. The DW660 is going to be turned on/off with the use of GRBL. The ESP32 controller has a relay in it that can switch this. I am putting the E-Stop on the power to the ESP32 and that should take care of stopping everything.

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