Building the MPCNC Primo

Please refer to the Projects Section for all of the entire MPCNC Primo Build information.

Updated 8/23/2020 – I am building a torsion box to support the Primo. After purchasing the material 3/4″ (19.3 mm) MDF and birch plywood, I placed the initial Primo legs on the table to see what the dimensions “would feel like”. I am going with 44″x 44″ (about 1.1 meters square) torsion box. This will also provide about 4 1/2 inches around the machine for cables, power, air, and vacuum. I am hoping to put a cover on it as well. The top and grid of the torsion box is made from MDF and the bottom is going to be made from the 3/4″ birch plywood. This is going to provide something strong to connect to the legs. I am still working my way through Fusion 360, and used it to work out the math/dimensions for this table. I am still trying to figure out how to have Fusion 360 act like boards instead of merging the surfaces. If anyone know, drop me a note via Contact Us. The top if going to be 5 1/2″ thick, that is a 4″ interior grid. The casters are ordered, and I have all of the lumber to make the legs and bottom shelf. I am going with the 2″ x 4″ thing, but I am going to plane them down and try to do a nice job. I am still debating how tall to make the table. One major requirement is to be able to disassemble the table to be able to move it out of the basement where my shop is. I do not have a lot space in the shop and this will most likely live in the garage. That is another project <evil grin>.

I am going with a 3/4″ spoil board. I am still on the fence about grooves for T bolts to hold material down. We will have to see. There is a lot of material; so it should be ok. All of the wire has arrived as well as the aviation connectors. I am still figuring out what todo with the limit switch cables and connectors.

I have been busy with a few other projects, including having a day job. Please look at the screen project for what I have been up to.

Updated 8/8/2020 – Assembly has started. I have the trucks, feet, and part of the gantry built. I ran into a few problems with the tolerances on the bolt/screw holes, some being to small and others, such as the holes for the end-stop switches, are to large. Getting the the main bearings in core module took a bit more force than I would have liked. Per the instructions, they still move freely enough. Another issue is the tubing in the feet and getting them aligned and flat on the bottom. I put this off until I get the mounting/spoil board in place.

I did have a problem with the Z axis tubes. They came in the wrong length. I ordered 11.5″, see below, and they came in at 22.5″. I appreciate the extra tube, but….

I have been sitting on the box for a while and really cannot send it back to get the right ones. Have you ever tried to cut polished 304 stainless steel? Not easy, fortunately an angle grinder, deburring tool and a file did the trick. I cannot wait until I have to drill the holes in the Z-axis tubes. I am going to have to make a jig to help with this.

I am also going to add plastic grommet inserts for the end of the tubes. Even with cleaning up the ends, there is no way that the wires will not get nicked on the ends of the tubes. I found something on Thingiverse, however I am not finding anything specific for 1″/25.5 mm with .870″ ID size. If I cannot find an existing design, I will just model something specific for this application. Because of licensing, I have been forced to switch from Solidworks to Fusion 360. This has been a real learning.

I have also been working on the design for the torsion box/table. I think I am going to start with just some 3/4″ MDF on the floor and continue with the construction. There is so much to do that I have time.

Updated 8/2/2020 – All of the “Ordered” parts have been delivered. I have also been following Nick Ellson post regarding cable chain management. I have downloaded his STL’s and will take a look soon. I have also reviewed all of the documentation on the Grbl_ESP32 MPCNC controller. Wow, a lot there. I am also looking at the closed loop stepper controllers from BigTreeTech. I am thinking I want to use them. If all goes well, assembly will start today. I have to pick up a few sheets of 4’x4’x3/4″ MDF to mount this on. The torson table will come later.

Update 7/24/2020 – All of the printed parts are finished. I have also received most of the ordered parts. I am still waiting on the electronics and the belts. Depending on the weekend activities, I am going to go pick up the MDF to mount this on. I am not going to build the table until I have this thing working. I have also been looking at the GCode sender and I think I am going with CNC.js on a Raspberry Pi 4. I want to build a cabinet, using DIN rails and power supply for the equipment. One other item has been how bad the end cuts are on the stainless steel tubing I bought. I used a Dewalt conduit reamer to clean up the edges. It does not work well with stainless. Ripped the one inch round right off the tool. I am going to use a file and see about putting a cap on each end. The ones that I found on Thingiverse, are not for this OD/ID tube. I will design and print something when I get the machine put together.

Update 7/22/2020 – The printer finished the core module and I have a few small pieces to print. I have reviewed the parts list and have ordered the parts that I am missing. I have received the Polished Stainless Steel tube as well. Turns out that the belt is one of the more difficult items to get a hold of outside of ordering it from Ryan. Amazon did not have a lot of options in the 10mm width that was fiberglass reinforced. In checking on the electronics that I had from the original purchase, it turns out that Ryan is no longer providing a RAMPs implementation of Marlin for MPCNC. That is what I had in mind for this all along. I am going with the GRBL_ESP32 from Bart Dring. I was thinking about going the GRBL path, but this sealed the deal. I am not in love with buying a board that comes from Ultimaker. A bit more than I wanted to spend, but I think it will be solid in the end. I am starting to work on the final cost of all of the parts and whatnot. I am not sure that the machine is going to cost less than <$500. I think it might be just a bit more. The machine might not cost this much, but everything involved will be a lot more.

Update 7/9/2020 – As of this post, the core module is about complete, please oh please finish. Just love how accurate S3D and Octoprint are. I am being sarcastic here. 4 shots to get this done.

I have one more batch of printing to do and I will hopefully get to that tomorrow 7/10. I will update the list below as I go. There was a lot of discussion in the V1 forum regarding the % of the core module. I did split the printing process in S3D at 24mm and 116mm and made the middle 30% and the top and bottom at 70% as Ryan recommended.

I have started to go through the parts that I have that I have never used and ordering what I need. I decided that initially I am just going to mount the whole thing to a 3/4″x4’x4′ board on the floor in my basement. I need to get all of the bits put together and get the electronics working. I will worry about the final square and whatnot when I build the torsion table. Like I said in the initial entries below, I am starting with Marlin, and am going to use RAMPS hardware initially. I am really interested in the Grbl_ESP32 MPCNC controller. That is down the line.

The beginning (7/8/2020) – Building an MPCNC has been on the plate for a long time. Like a year and a half. I am interested in understanding how to do CNC work. This will be the start. When I go into 3D printing, that was the purpose; just learning. Eventually, I would like to get a small Grizzly and do a CNC conversion.

I had completed printing all of the “burly” parts and they just sat in the box. I even had all off the motors, router, electronics, etc. When the Primo came out, I tossed out the plastic parts that I had already printed and started again. My poor printer. I have gone through two spools of filament and working on the third. The core module, which is printing now, has started and failed 4 times. 2 power failures, 1 nozzle that literally died under the stress of the amount of filament being pushed through it (70% infill), and a burned out heater cartridge. I have most of the parts, outside of the plastic, that is printing now. Below is the status as as of today. I have ordered the 1″ (25.4mm) 304 polished stainless steel from Metals Depot. The over all dimensions are going to be a working space of 24″ x 24″ x 4″. I am going to lift the spoil board to get closer to 3.5″ high. I am going to start with Marlin, but I want to go with GRBL and then on to Mach3/4.

Printed parts list with status

CountPart NameStatus
2Corner BottomPrinted
2Corner Bottom MirroredPrinted
2Corner TopPrinted
2Corner Top MirroredPrinted
2Lower BeltPrinted
2Lower Belt MirroredPrinted
2Upper BeltPrinted
2Upper Belt MirroredPrinted
4Corner Leg LockPrinted
2Wire DarrylPrinted
4Stop Block (Dual only)Printed
2Truck MirroredPrinted
4Truck ClampPrinted
1Z MotorPrinted
1Z CouplerPrinted
2Nut TrapPrinted
1Upper Tool PlatePrinted
1Lower Tool PlatePrinted
2Core Z Clamp 1Printed
2Core Z Clamp 2Printed
3Core ClampPrinted
1Core ClampYPrinted
1660 Top ClampPrinted
1660 Top MountPrinted
1660 Bottom ClampPrinted
1660 Bottom MountPrinted

Purchased Parts

Nema 17 50OZ/in+5Had
* Belt GT2 10mm4Received
Pulley 16t gt2 10mm4Received
Idler 20t gt2 10mm8Received
Power Supply1Not sure
Wiring kit1Had
5mm to 8mm Coupler1Had
5/16 locknut46Had
M5x30mm Phillips Pan Head Screws65Received
M5 locknut65Received
M2.5x12mm Phillips Pan Head Screws10Received
Grbl_ESP32 MPCNC CNC Controller Ver 1.2.21Received
Raspberry Pi 4B1

Also, I am working on a design for a torsion box cabinet for it. This will live in my garage, and be enclosed with a vacuum system.

I want to be able to cut wood, aluminum, and plexiglass. All lightweight items. I know that Ryan has been able to cut steel with the new design, however that is a bit more than I want to do.

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