Just about to buy

Hello all. I’m David from Spring, TX. I stumbled on to the MPCNC while searching for a CNC solution. I was just going to pull the trigger on ordering and things started going out of stock. I read about a sticky that would show product availability and updates but couldn’t find it.

So while I wait until things become available, I figured I’d introduce myself and ask a couple of questions.

I’ve been woodworking for a few years and have a CO2 laser. I figured a cnc would allow me to diversify my creations. I’m looking to create a cutting area of 20” x 20” this is my first cnc build but I’m pretty technical. Wood will be my primary medium but I’d like to maybe work with some acrylic and aluminum (nothing big though.)

I saw a build on YouTube where a guy used solid bars for the frame to increase rigidity. Has anyone tried this or know the pros and cons?

I was going to use the Dewalt but is there another option that would be better (even if it’s a bit more.)

That’s all I can think of now but I hope to order soon and get started.

It is a common question, but no. The dewalt 660 is a good balance, and it is more than enough power for what we need, it is rigid, and it is built to take some serious abuse.

That seems overkill to me. I haven’t tried a solid bar, but the tubing is very rigid. If you want to pay a little more and get great rigidity, then go for the 25.4" size, and buy some stainless steel tubing.

For your size build, it will be super strong. Just be careful not to make it too deep . Most bits are less than an inch long anyway. If you need to mill thicker material, then build the bottom so it can drop out and fit larger stock.

1 Like

Welcome David, nice to see another Texas resident here. I’m just outside San Antonio and just built my first MPCNC this weekend after WEEKS of going back and forth on what to do/get. I made mine with a cut area of 36" x 24" using the 3/4" EMT recommended and even at 36" side it’s more rigid than you’d expect. I may add some internal supports later if I see the need. I’ve only gone as far as getting mine to draw last night so no real cutting yet.

The folks in the forum are extremely helpful, @jeffeb3 has saved my sanity at least 4 times in the last 3 days or so alone! :sweat_smile:


At 20x20" it would be plenty rigid as built. Having the laser will really help make cool stuff with the engraving capabilities.

1 Like

There are some good threads where people have used a dial gauge to measure what flexes, and the biggest factor is that sideways flex in the moving tubes is magnified by the length of the Z axis.

You could beef up the moving tubes, but then you’re increasing the weight on the frame, and the mass that the stepper motors have to start and stop. Ryan has balanced this design to the point where there are no ‘easy wins’ left. There’s loads of space for customisation, but you’re likely to add cost and complexity for little benefit until you have some experience using the machine.

Building a slightly smaller machine both increases rigidity and reduces weight.


Hello David from Spring. I’m David from Josephine… Originally David from Willis.

Everyone else has pretty much answered your questions, so I’m just a useless commentator this time :slight_smile:


Welcome to the crew! Or should I say krewe, since it’s Mardi Gras? :partying_face:


The use of solid bar is actually detrimental…

The physics of the matter is that (all else being equal) the stiffness increases as the 4th power of the OD. A 10% increase in diameter will equal ~46% increase in stiffness, but the flip side of this is that material INSIDE a tube has a similar DECREASE in benefit.

Basically, you add a lot of weight for a negligible gain in stiffness. The significant added weight is more detrimental than tiny additional stiffness.

@jeffeb3’s recommendation is spot on. If you have options, use the largest diameter option available. Material also plays a part, of course. In theory the 25.4mm tubes would be approximately 35% more rigid than the 23.5mm in the same mild steel, but the stainless will be significantly stiffer still.


Thanks everyone for the responses. This is nothing like the laser community, they can be a bit tight lipped on best practices. I have a buddy that has access to carbon fiber manufacturing. Would a tube of that be stiffer than the stainless? I ask because I always read carbon fiber was stiffer, it would look AMAZING, and the cost wouldn’t be astronomical.

I really like that Ryan worked out the best starting set up, but I’m a tinkerer at heart so I have to tweak or I start to twitch.

Also, I didn’t see where to get info on stock levels

IIRC, CF is not stiffer and/or deforms under load in bad/ugly ways.

Also, go to the contact page for stocking updates.

1 Like

Thanks. If it was a snake it would have slapped me and said “I was right here, dummy!”

I suspect I know the answer toy next question, but here it is anyway. The 3d extruder option…use that or pay more and get a standalone, budget unit?

So now back to the waiting game.

1 Like

Honestly, don’t worry about the extruder for right now. You really can’t get decent Z-Axis for printing, unless you print a lot of large, flat objects. You’re better off learning CNC with the base build, and later building the MP3DP… :slight_smile:

edit: For multi-purpose uses, I’d go with the vinyl cutter and/or laser, since those tend to be large, flat surface operations. If you’re into RC airplanes, board game inserts, or larger-scale modelling (scale railroads, miniature gaming, etc), perhaps a foam cutter (see @dkj4linux for all the info you could ever want on that subject). Or just stick with plotting or even painting. There’s some great examples of art being done by MPCNC machines.


stiffer in some directions. Not in others. Part of the problem is all the bearings are a point load on the outside of the tube. Even the steel tubes start to flatten where the bearings ride on them all the time. The CF would start to crack unless it was really thick with many many layers. And then it would be much more expensivel


Carbon fiber tubes will start to delaminate due to the point loads.


I will go with a standalone unit later. I have a laser already. I was jus thinking of cost. Thanks again for all the info

This thread seems to sum up all the most common questions we get (I think). David P, you are a smart cookie to get them all. Really need to update the FAQ’s and probably from this thread…

David don’t overthink it so much. Build a cheap one (as designed) have fun see if you can improve it later, it is cheap enough to do that. Heck try some CF since you can get it cheap, maybe print some fitted rollers or something could be fun. that just changes you from a guy that wants to use a CNC to a guy that enjoys messing around with one (that is most of us…you fit right in).


Ordered today. Now to clear a spot!


So during the pandemic downtime I decided to start my build. Things were going good but slow and now I’m wiring up. I have a question about the Rambo 1.4 board and connectors. When I plug in the motors none of the connections are snug, they just slip right in & thusly can slip right out. Is this normal?

BTW I went with the stainless steel tube, 24”x24” work area, standard Z-axis length. I’ve tried to flex this thing and it’s stiff. Great design.

The loose connectors are typical. The DuPont connectors on the wires don’t match the plugs they are being inserted into. They will work, but can come loose. I had a bunch of issues with mine coming loose, so I eventually broke down and bought a box of connectors off amazon and made custom cables with the proper locking connectors.

But, get everything working before you do that. If you start having issues with steppers, make sure to check the wires. Once everything is working correctly, then decide if you want to go the route of custom wiring harnesses.


Ok great. Yeah I have it on my dining room table so it was really just for the test. It’s going out to the garage when it’s ready. I’ll look into new connectors once I have it functional. If you don’t mind, could you share a link of what you used?

Thanks for the quick response