Hi everyone, I’m planning out a first build of an MPCNC. My main goal is to have a machine capable of cutting a 2D contour out of some aluminum (MIC-6) for a 3D printer bed, as well as wood. I am in the US so everything is going to be in inches for me. The cutting area isn’t going to be too large, around 12-15" or so. I’ve taken a look at the calculator and I think a ~14"x14"XY area puts each rail length in the range of ~24 to ~27 inches.
What Z height is recommended if I want to cut 3/4" MDF or 1/4" aluminum? I am new to CNC routers but I understand that the tool length will come into play here. I plan on using the Makita trim router as my spindle.
Another question is the tube/round bar of choice for the rails. I’ve seen a couple of videos on YT where their MPCNC’s have used round bar steel for the outer rails and kept the conduit for the cross members. I’ve also seen others using steel tube rather than conduit, maybe for higher wall thickness or something. I want to make my MPCNC as rigid as possible to cut aluminum, so is it worth paying a little bit extra to put more material in the rails?
Other than that, I plan on using Inland PLA+ for the parts, for the controller I will use an SKR Mini E3 running Marlin, and for CAM I will use Fusion 360. I do have to build a table which will probably be made out of 2x4, 4x4, and some MDF panels. It might have wheels on it (I’ll get the locking kind) since I don’t have too much space in my garage.
I also had a question about power requirements. I’m going to use a Meanwell LRS-350-24 power supply for the motors, the Makita router which is 1.25HP 6.5A, and a small shop vac which is 2.5 gal and 2HP. I don’t have a lot of outlets in the garage but I’m wondering if using all three at the same time might cause issues with the breaker.
The minimum should be able to handle all this fine.
I’ve never seen a mixed size machine. Conduit is measured by what it can hold (so it is 3/4", but the outside is 23.5mm). Tubing is measured by the outside diameter. 1" is 25.4mm. 1" conduit is 1" on the inside, which is far too large.
The 25.4mm is more important for rigidity than anything. Stainless steel or DOM steel tubing work. Make sure you get the right sized stls. They are not interchangeable.
We don’t have precompiled firmware for that board. Take a look at the MarlinBuilder releases to see what we have. If you already have the board, look for something similar to adapt from.
You definitely could. The machine motors don’t take much current. But the router and the vac both need large amounts of current at startup. You might squeeze by just by starting them at different times. Worst case, you will need an extension cord for the vac to put it on another circuit.
I’ve seen a couple of machines using solid rods for the outer rails including the one in this YouTube video. Note that the rod and the tubing have the same outside diameter. Given the $$$ he probably paid for the rod, and the flex tests published by Ryan, and the ability to add a mid-span support if necessary, solid rod seemed like overkill to me.
I’m wondering if using all three at the same time might cause issues with the breaker.
Check the breaker for its ratings. I’ve found in the US that breakers are usually 15A or 20A. Your setup would be tight on a 15A breaker, but okay on a 20A breaker. I run my MPCNC setup (including the small VAC and the Makita router) plus some other things like lighting on a 20A breaker, and I’ve never triggered it.
I plan on using Inland PLA+
There is no standard for what makes a “PLA+,” but they tend to be more rugged, but less rigid than “regular” PLA. You are looking for rigidity, so compare data if you can, or maybe default to a regular PLA. For wood, I doubt it maters, but for metal…
The conduit version of the MPCNC uses 3/4" electrical conduit which is 23.5 mm on the outside. Conduit is sized by the ID not the OD, and electrical conduit has a galvanized coating that varies in smoothness. My first V1 CNC (Burly) used conduit. I replaced conduit with 1" (25.4") tubing when I upgraded to the Primo. The slightly larger and harder tubing with its smooth surface gives a feeling of being notably more rigid and has smoother movements. If you were just cutting wood, I’d just say “whatever,” but with a target of cutting aluminum, I’d suggest the larger tubing if you can afford it.
SKR E3 Mini since I saw a TeachingTech YT video where he configured Marlin firmware for a 3018 CNC
This board appears to be a 4 driver board. The two Z plugs are wired together in parallel to a single driver. This board will not support dual endstops. Supporting dual endstops may or may not be important for you.
As Jeff mentions, the path of least resistance is to pick one of the boards that V1 maintains firmware for. I’ve seen a couple of instances on this forum where someone started with the Marlin firmware from TeachingTech, and they struggled. The issue is that the TeachingTech’s files are dated and use an older version of Marlin, so it can be difficult to merge things together.
buy more if it is better.
I don’t mill aluminum, but I’ve read a number of topics on the forum concerning cutting aluminum. People do succeed in cutting aluminum, but it seems to take a smaller, ridgid machine, well tuned with the right bit to make it work. If you struggle cutting aluminum, you are not going to know if the less rigid PLA+ is playing any role in your struggle. It will probably work fine, but if I was targeting cutting aluminum, I’d be doing everything I could to make the machine as rigid as possible. Of course you can always reprint the parts if aluminum is a struggle.