2'2 MPCNC or 2x4 LowRider 2

Hello everyone,

I posted this over at the MPCNC side, but was hoping to get some more input.

I was looking to get some advice on making a decision between a 2’x2’x3"(work area) MPCNC Primo and a 2’x4’(work area) Lowrider v2. The main material I will be working with is 3/4" MDF and some soft/hard woods for sign making. I would like to use the CNC to cut bartop arcades with the largest piece(side piece) being 22"x16" so I could cut one side on the MPCNC, but two sides on the low rider which will be nice. I have some experience working with the Shapeoko xxl, but I’m still very much a beginner.

Obviously there are pros and cons with both machines, but my main concerns are the following. I already have a 611 and 660 router as well as a 3d printer so those are not a factor.

-Ease of use and repeatability; From reading around the forums the MPCNC is a little easier to use and start jobs.
-Rigidity; With the release of the more rigid primo is 2x2 work area machine pushing it? I’m pretty sure a 2x4 lowrider will be plenty rigid,
-Speeds, Feeds and Performance; I know this is tough to answer with everyones machine being different, but best case scenario which machine will perform better in regards to accuracy and speed if they were both cutting a 22"x16" bartop side on mdf for example.
-Sawdust; Since I will be mainly using MDF that dust is pretty bad for you and gets everywhere so I like the idea of being able to build an enclosure for the MPCNC. I have a 5hp shop vac that I can use for the lowrider so Im hoping that could control like 90% of the dust. Clearing chips in general is just a huge plus.

-Maintenance; Is the up keep on either machine easier than the other?

Any tips or experience from owners with both machines with similar sizes will be greatly appreciated. I know Ryan has a 2x4 machine which seems to be plenty capable, so I guess Im more curious about the primo and its capabilities at a 2x2 work area. Thank you all in advance.

I have a Primo with the exact work area you are looking for and I have had good results. It is pretty much at the high end of the recommended size for Primo though before moving to a Lowrider. The largest piece I have cut is 17"x17" 3/4 inch pine board and everything came out square. I don’t have any experience with a lowrider so I can’t speak to that. Hope this helps.

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Thats good to hear! Pine board is something I will be cutting as well so its good to hear that you have good results. What are you using for tubing?

I used THIS .083" walled DOM from Summit Racing.

HERE is my build thread if you’re interested.

HERE are the largest pieces to come off the machine so far.

The spoil board is 24"x24"

Edit: sorry, spoil board in the Primo pictures is 21"x21", my old Burley board was 24"x24". I just haven’t gotten around to making a new one for this rig.

Those engraving came out pretty nice, good work! So is Steel the consensus for tubing for the primo in regards to price/strength? Kind of feels like Stainless Steel>Mild Steel>EMT right?

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I guess its a lot about the tubing wall thickness. I think I read in another thread there might be a pretty close comparison between DOM and stainless. But yeah, EMT is at the bottom. I went with the DOM based on price and since I could pick it up locally. Plus I was chomping at the bit and didn’t want to wait for the “C” version to be released. I’m actually glad I didn’t wait. The rigidity of the new machine compared to my old EMT Burly was very apparent. Especially at the size I built it.

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My current conundrum is very similar to this, but logic had me working from a different angle:

  1. I need to have a fully enclosure and the lowrider is a bit more complicated for that - so unless I can be convinced otherwise am heavily leaning towards the Primo.

  2. maximum space I have for a total footprint is 4’ x 3’ and at within that space I can build a Primo @ 820 x 520mm (about 32" X 20") Lowrider a bit longer on the x and similar y

  3. Why would the Primo be less accurate at this dimension and would a mid span support fix that probem?

  4. Or should I just say to heck with the enclosure challenge and bite the bullet on the LR?

  5. I have deliberately ignored the “what are you going to use it for” question - because I just don’t know, but I do know that no matter how big I make it, I will wish it was an inch longer/wider.

A 32" long working side means those long pipes are going to be… 44" or so? When the router is in the middle, they will be 22" away. It will be hard to keep the router from sagging. The mid span supports will help with that. The router is also going to try to move laterally, and that one pipe in the gantry is going to be trying to keep that from happening. At 22", it will move “more”.

It is very easy to be all doom and gloom. But the truth is, there’s no gate you go through at a specific length that will ruin your machine. It is more like, a smaller envelope of working parameters. If you build it really tight, you can throw a lot of bad parameters at it, and it will just plow through the pain. If you build it bigger, you might have more failed cuts, or you might just need to go slower or do more cleanup after the build. But my first mpcnc was 24"x36", and I had a bunch of fun, learned a ton, and finished some excellent projects. I had trouble drilling holes with it, and I had some chatter. But it got me hooked.

You’d be surprised how little this will be true. There aren’t many hobby cncs this large out there. So a lot of projects you will find are smaller. Bigger projects also mean more materials and $$. If you’re creating the project yourself, it is easier to cut off an inch than build a bigger cnc, so it is easy to manage.

Really though, that question is designed for some specific tasks. If you are cutting through parts (like signs) out of sheet goods, then bigger is ok (same with flat pack furniture). If you are trying to make 3D carves out of solid wood, that is easier with a smaller machine. If you are doing aluminum, that 32" axis is going to make that nearly impossible.


That lateral pulling against the long axis…
Here is what a 4 ft DOM 0.1 wall looks like…

And in slow-mo because why not…

Now, the difference between 3ft and 4ft is a lot bigger than the difference between 2ft and 3ft, i think.

Yeah, so that’s ok if you know how to CAM. You can accept that in a roughing pass, and a finishing pass will have almost no load, so there will be nearly zero deflection. It can also be cleared up pretty easily with some sand paper.


I’d be really sad if that were my first cnc, but I’m pretty stoked actually. I think it’s not a huge amount of deflection as is, and in case it’s not super clear from my last couple of sentences above, I think it would be acceptable at 3ft, or at least not disappointing.

I just wanted to bring a visual to your description of that type of deflection since I had one handy. I don’t always have something good to contribute, lol.

I might also point out that I do have mid span sports on the outer rails. They don’t contribute anything to this flexing, but it may be helping keep some of the flex from transferring to the Z direction.


Thank- you for your detailed reply Jeff, I have had another light bulb moment! :grinning: I greatly appreciate the time you take to answer here - I truly understand the frustration that answering the same question over and over can provide.

I am keen to keep a minimum of 1/3 sheet as a footprint (say 36" x 16") if I have an end use in mind it’s mostly to allow me to build templates for larger scale (sheet) projects which can be built in parts if necessary. I am realistic enough to know that a 2.5 hp router run around a template will cut a “fair bit” more efficiently!

I don’t think I am misinterpreting your comment - it seems that even at that sort of footprint, I would be best to go back to plan A and run with the LR - I am pretty sure I won’t be building watch parts, but it would be nice to have at least the same level of accuracy I can achieve by hand.

Solving the dust enclosure for the LR will be just part of the fun.

Hi Tony,

The video of the chatter is that on a 4’ footprint? Also if you don’t mine me asking where did you get your DOM from?

Yeah, 2x4 cut area and the wobbly tube is the longer direction. I got mine from a local store.

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I planned on a 24" by 30" area, and then cut tube for 25" by 37" to give me some wiggle room.

Ill be using 1" structural steel. Not stainless.

I think that I’ll be okay, learn to go slow to get things done faster. It takes less time to do it once slowly than to do it twice quickly, and then still need to do it slowly to get what you want.

I grappled with the same quandry. What I want is large for MPCNC, more comfortable for a LowRider. Perhaps when I get more shelving for the garage, and more stuff ON shelves in the garage, therefore more floorspace, then I’ll build a LowRider. I have not ruled out building something a little more traditional. There are plenty of DIY CNC plans out there, but most seem to involve needing something better than I have already got in the workshop. The MPCNC is probably good enough to build several of them if I need something bigger.

If I do build something bigger, then the plan will be to cut down what I’ve got to make it smaller. Say 25" by 19" to be capable of milling aluminum. Maybe even smaller. 12" square is probably enough to do almost anything that I might want in aluminum.

There’s never a question that hasn’t been answered before if we look hard enough. Unless something has changed in the last three years?

Thank you. I’ve been struggling with the same quandary lately and this just secured my decision on an LR.
Having limited room, time and finances at the moment, the plan is to start with 2x3 (possibly 3x4) and expand later when space is available.
Main use will be cutting small sheets of up to 5mm ply and MDF and hopefully upgrade to full sheets with CO2 laser down the track.

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