Getting ready for my first cnc router build project… need help

I am ready to order and build my first cnc router. But as i enter into the unknown, i have some questions.

I’m looking to build a workable routing area of 18” x 36” dedicated CNC router primarily for cutting vacuum forming bucks (molds) out of mdf and maybe use it for trimming parts out of formed plastic. I do not know programming or even basic electronics… barely can make 2D cad drawings with light burn but Im having a blast. And I can assemble anything. Just built a laser cutter/engraver (diode of course) and have been having loads of fun cutting stuff I’ve drawn in light burn.

I’d like to be able to order a complete Primo kit. The conduit here is 3/4” typical homedepot stuff. I do have access to elect supply for 1” if that is better (or whatever conduit is the right size/thickness)

The questions are when ordering the MPCNC Primo kit,

  1. which control board is best, Rambo or SKR? What would i need to know to determine which is best for me. I am hoping that it is as easy as my laser engraver all said. Plan do draw bucks (or have them drawn) on the computer than send to machine to carve out of mdf.
  2. Which tool , i.e. dewalt, makita or 52mm, 55mm etc is the best way to go for my intended use
    3 . are limit switches required and which should go where if so

I know I can build the machine… deciding on the parts where variables exist are where I get stumped because I do not know why one choice is better or more suitable than the other. That is where I will stare at the order form hoping the answer jumps out and says. “””here i am””””. Lol

So, if y’all could design the perfect CNC router for carving vacuum forming bucks out of MDF, what exactly would you order form V1 (and anywhere else that is necessary) to assemble a complete setup.

Thanks in advance

Given your 36" working axis for the long side (which is on the higher end for an MPCNC), your machine would benefit from larger tubing, but 1" electrical conduit will not work. You need 1" stainless steel or DOM tubing, and 0.065" wall thickness is pretty common. Conduit is measured from the inside, tubing is measured from the outside.

which control board is best, Rambo or SKR?

Given you are wanting to use a laser on this rig, I’d go with the SKR Pro, though I’ve been doing a lot of laser work on my MPCNC and have a Rambo board. Note there are a number of problems on this forum concerning issues with the firmware on the screen that V1 ships with the SKR Pro. People are getting around the issues by running the screen in Marlin mode, so everything works, but you lose touch capabilities and menus.

3 . are limit switches required

Limit switches are not required, but for your task, you will likely benefit from them. Primarily, endstops are used to square the machine…to make sure when you cut a square it ends up square and not a parallelogram. A secondary purpose is to be able to return to the same place on the spoilboard. It sounds like you might be doing repeated operations on things held in a fixture, so retuning to the same place is beneficial. For the SKR board, you will need to purchase endstops and extension wires separately. They come with the Rambo board.

Which tool , i.e. dewalt, makita or 52mm, 55mm etc is the best way to go for my intended use

Given the variety of materials you want to cut, you will benefit from a router what has variable speed control. I suggest the Makita trim router or the quality clones of this router. The Makita ships with a 1/4" collet. You will likely want an 1/8" collet as well. Some of the clones come with both collets, and some of them (at a price premium), support E11 collets, which allow a much greater variation in the bit shank sizes.


Thank you Robert for the reply and explanations. That has already saved me a lot of trouble in the future starting with ordering the right sized printed parts based on the rods I’ll be better off getting.

I would like to point out that I DO NOT plan on using a laser, this will be a dedicated ROUTER only machine. Given that, would the SKR Pro still be a better choice or would the Rambo board be better? Or is there a third party 32bit board that would be even better, easier, etc.

To complicate things more, somebody asked if i knew if the stepper motors were 12v or 24 and they said i needed 24V steppers for a machine that size… LOL. Man, i just want to build it, plug it in and start carving. :slight_smile:

Hey Peter, welcome come to the forum.
The SKR can take 12V to 24V, for the Nema17 Stepper motor, the voltage and amperage will be controled by the board and Stepper Drivers TMC2209 (recomended) or whatever driver you decide to use. In most cases the Nema 17 stepper motor can handle 2.5AMPs, we run it much lower.
If you decide to buy the board from V1 Shop, the board will be flashed with the right firmware and you wont need to worry about voltage and AMP.
You will be good either way.

1 Like

The Rambo board is the long-time workhorse for the MPCNC. They have a low failure rate, can take a lot of abuse, and are well tested by V1 and the numerous MPCNC users. There are a number of examples on this forum where builders have shorted out pins on the Rambo board with zero impact on the board. On a lot of microcontroller boards, shorting out pins will kill the pin or even the board. I would lean a bit towards the SKR Pro if you are planning on doing any operation that pushes the max feedrate of the machine…laser engraving, rapid foam carving, etc. If you are not going to be pushing, then the Rambo is a safer choice.

is there a third party 32bit board that would be even better, easier, etc.

The path of least effort is to buy a board, driver, and display combination that V1 sells…even if you don’t buy it directly from V1. V1 has well tested firmware for these combinations. For other boards, either the firmware has little testing, or V1 doesn’t maintain firmware for the board. We see “other” boards come across the forum, and the builders do get these boards running, but it can be significantly more work.

if the stepper motors were 12v or 24 and they said i needed 24V steppers for a machine that size

Stepper motors themselves can run at higher voltages. They don’t require a specific voltage. Both the Rambo board and the SKR Pro can run on any voltage between 12V and 24V. The benefit for higher voltage is more torque at higher speeds. For most common MPCNC cutting, the machine does not approach speeds where 24V provides a benefit. Based on what I see on the forum, 95% of all MPCNC machines run on 12V.


There is a lot of bad information out there.


ha… no kidding. I am SO GLAD Ryan directed me to this forum…thank you all for answering my initial and for my future newbie (aka. stupid) questions. I can learn pretty much anything quickly however, that which I don’t know that I don’t know will always puzzle me… thanks to all who have and will keep it all straight.

1 Like

it seems to me that if I first build a usable routing area of 18 x 36, and later decide I want 36 x 36 (or whatever), that I would only need to increase the lengths of the y axis rods and reassemble ??? or am I missing something ‘huge’ ?

Wiring, too, but 3x3 is kinda pushing it. I’m sure you can cut mdf and plastic, but you’ll have to be careful to get good parts.

Order longer belts and roll the excess up and tuck in the end of the tube. Then you only need longer tubes to increase your area. 36" is getting towards the long end of practical Primo length (as I understand things).

Oh yeah, and wiring as @turbomacncheese metions above. I already have ridiculously long wires as I wasn’t sure where my control box was going to end up relative to the rest of the machine.

1 Like

ok… decided to scale it back a bit in size for now (can always make a bigger one later).
looking at workable area of 16 x 26
I cannot find locally any 1" DOM or even Stainless Steel. I do show some 1 in. x 10 ft. Electrical Metallic Tubing (EMT) Conduit at home depot… OD is actually 1.163 and with the ID of 1.0409 in my feeble mind says wall thickness should be about 0.114. will this work?

No. The parts are either 1 in OD, 25mm OD, or 21mm OD (that’s the 3/4 conduit).

See roberts explanation above.

you are correct… Robert already answered that above… now I’m starting to overthink stuff so that I miss the obvious.

guess in need to spend the 225.00 and get the stainless steel 1" O.D. tubes and be done with it rather than spending so much time on tubes… lol

1 Like

Better to ask a question twice than miss something and overspend. I’d even support the idea of posting your final shopping list before you order. No good having a low cost of entry if you end up buying multiple times for stuff you don’t actually need.

Any chance you have a metal store near you? Mine has a room full of remnants, and i can usually get what I need for really cheap. Have to go in and look, though, because they don’t keep inventory.

Just to put it out there…

I work for a company that sells structural tubing. We don’t advertise for retail, and our website lists a $500 minimum order, but that’s for delivery, even if it doesn’t say so.

We have farmers and some local fabrication ships that come in and pick up steel for one-of projects and are happy to just sell it at a “cash sale” price. For 1" DOM 0.065" wall, that comes to about $40 CAD for a 20’ length (last I checked). The downside is you need to buy in whole lengths, but the price is much lower than most places you order from on the net.

Look for a wholesale steel tube place. Ask at a welding fabricator shop.

There might not be a lot of variety. For example, we don’t sell stainless steel, and the only wall size we have ready to go is 0.065" and for other sizes, we won’t deal with it unless you’re ordering enough to get a bundle from the mill, because we don’t want to stock the leftovers. But the price on what we do usually stock is way better than retail. It’s worth a phone call to someplace local!


did some looking, found local shop that has 1" OD EWT with .065/ .095 & .125 wall, he assured me it is a true 1" diameter (not like the 1" conduit) additionally, they did have only 1"OD DOM at .125 wall which is quite pricey given it’s thickness.

I’m hoping to hear from you experts that the EWT at 1" OD will work. :slight_smile: because it’s 5x less expensive than the DOM…

After thinking on this all evening, I have settled on building a 28x20 usable area with 3.25 Z axis MPCNC router. In the cart i have the following:

Primo bundle for 25.4mm rods (1” dom)
SKR pro and TFT controller
SD card
Tool mount selected for 700 series Makita RT70x
Wiring for limit switches

End stops limit switches, two were listed options… no idea which will serve my purposes better, end stop or roller end stop?

Am i missing anything?
Thanks in advance

I will need it later

well folks, I placed my order !!!

  • Primo bundle for 25.4mm rods (1” dom)
  • SKR pro and TFT controller
  • SD card
  • Tool mount selected for 700 series Makita RT70x

I know I’ve been overthinking this… I appreciate all the help and look forward to the build and sharing.


Found 1” DOM locally at welding shop in next town over… but they only have .120 wall. For $120 including tax for 22’, its a bargain. Unless y’all say its too heavy. LOL :stuck_out_tongue_closed_eyes: