Ordering 1" Steel tubing but have a question on type and thickness of material

So I am ordering my rails today but need some input. I am ordering the 1" OD steel from SpeedyMetals

They have both Steel and Stainless Steel tubing. The two options I am looking at are.

1" OD DOM Steel tube. .049 Wall

1" OD Stainless Steel tube .065 Wall

I know most people have been going towards the stainless but the .049 Wall stainless is considerably more costly than the DOM .049. The Stainless .065 on the other hand is the same price and the DOM .049. So my big question is which is better, the stainless tubing at a sightly higher thickness and thus heavier or the DOM due to is lighter weight? I know the thicker/heavier is not always better when it comes to rigidity as this would also be increasing moving mass.

I’m also not sure if the annealing process on the stainless steel has any impact. I know it creates a softer metal so it can be worked easier. The DOM metal is not annealed. I’m no mechanical engineer so I’m not sure of the differences in the mechanical properties of the 2 metals and their impact on our implementation in the CNC machine.

Thanks in advance for any input.


Stainless steel usually has a much better finish, but I have not seen or used either of their materials. If you don’t want to pay for stainless, just use EMT. The other stuff might be very soft, or have a poor surface finish, could easily rust and cause issues on your surface, who knows.

I did a quick and dirty flex test and based my recommendations off of that.

I can’t speak to the dom steel tubing other than to say for my application (in the basement) I’d be concerned about rust.

I did go with the speedy metals 1" 065 wall tubing. My machine is 24"x36" usable (about 36"x48" tubes), and the tubing is sort of ridiculously overspec.
The finish is perfect and all bearings ride smoothly.
I think I could stand on the rails (don’t trust the printed parts to hold me though), and if I ever expand the system, I’ll use more of this tube.
The only concession was that the printed parts assume 049 wall tubing, so the nut traps that get inserted into the z-tubing needed some ‘adjustment’ to fit. Worked great and took all of 10 minutes to sand down.

Oh, and the tubing is pretty tough… Like I had to use a grinder and files to get the ends smooth and deburred.

Awesome thanks for both of your feedbacks. My stainless is on its way!

What did you use to cut the tubing?

I used a holder for my angle grinder Klutch Angle Grinder Holder.
It lets me cut pretty darn square and is a little faster than a hacksaw and miter box, which would also work fine.

William which steel did you end up getting?

You said "I did go with the speedy metals 1″ 065 wall tubing. " was that the Stainless steel link one?

I just ordered the stainless steel from speedy metals

Is this the one you used and were happy with?

Thanks for your time!

That is the one I purchased. It is buttery smooth and the travel of the carriage is smooth and solid by hand. I’m down to the belts and wiring. I have 4 belt tensioners left to print and a pen holder so I can get it finished and wired. I feel like I’m close to the finish line finally

Awesome to hear!.. ordered the same tubing… hopefully it works out lol.

I have all the parts printed… have everything needed except the tubing… hopefully will have it by end of next week.

I’ve also been looking for anyone that has added a water cooled spindle and VFD drive in the range of 1.5kw to 2.5kw to see what kind of luck they have had

Seems some people are trying to build a 24*36" MPCNC and even discussing using big VFD based spindles. Is this really realistic? What kind of accuracy can you expect from such a setup? I am impressed by the design but there are limits.

That is a tough one. I don’t really know the limits and they are a bit different with every build.

I can say Lack of power has never even been close to an issue with the dewalt 660 for me. Most of us dial it down and run it at half speed with a speed controller which I am pretty sure is less than half power if I understand DC motors at all.

You are right though there are limits. Smaller spindle equal faster accelerations and higher accuracy. It’s like strapping a rocket booster on to a car driving in a neighborhood, tons of power for no good reason. The limit of this machine is rigidity Meaning if you want to strap on a giant spindle you should be making a tiny machine, not the other way around. You are right though there are limits. Smaller spindle equal faster accelerations and higher accuracy.

I know the information is pretty scattered in the forums now but If the goal is to mill full sheets of wood a different router would be nice, but that also usually means less accuracy from more runnout(runnout isn’t a big deal on large routers because of the way they are typically used). Most people milling full sheets can accept a lot less precision because it is wood. Wood tolerances are very loose, due to the nature of expansion and contraction. Lots of requests for half and full sheet solutions but I don’t want to make one unless I can come up with something that doesn’t require a 5’x9’ table to be permanently set up. There are other machines that achieve this very well, but are expensive. I could easily make a really inexpensive knock off but that’s not really what I would like to be known for. If I come up with something unique I will make it ASAP.

Sorry lots of coffee and lots of ideas…

Hey Guys,

I am not really concerned with accuracy all that much… I’m looking to make my first build of this machine to be able to mill hdpe multi layer material for creating 2 color plastic signs essentially.

The larger format will ultimately be needed in my applications but i’m building this first one as a test.

My issue with the dewalt router is that it uses brushes on the motor and brushed motors do not last relatively long.

I’d rather spend some extra money up front for a long term spindle solution.

the design of this cnc is fantastic… I understand there are limitations… i’m curious to see what the limitations are and see if they can then be improved upon easily.

a full sheet machine 4x8’ would be absolutely perfect my needs… hopefully we get there down the road and vicious 1 i’m sure your design would be incredible for this large format machine if you decide to do one… I would absolutely build one.

I’m building a 3’x4’ (~25" x ~37" working area) MPCNC using a Makita RT0701C router. I doubt I do much metal work at all if ever to be honest. My main focuses are woodworking and laser work for signs/clocks/cuttingboards/ and furniture inlays. I wanted to make sure I could do what I could to make it rigid since I was going beyond the recommended starting size so I decided to go for the stainless tube. As I mentioned I haven’t finished building yet but I hope it will be rigid enough to give me some accurate work at my size. I guess time will tell.

Josh, Mike,

Were you happy with Speedy Metals? Was the steel tubing straight and work out well? Thank you.


Frederick, I was very pleased with the stainless steel tubing from speedy metals.

They had quick turn around time and I had the materials in about a week.

so far so good with it.

I’ve also been very happy with the metal from Speedy. It was easy to cut and file and the result is a super smooth rail that is amazingly strong.


I’m also happy with my service from Speedy Metals.

I built a 24" x 24" cutting area MPCNC using 1″ OD Stainless Steel tube .065 Wall:

It costs me $85 with shipping to New York, ordered on a Friday and received the following Tuesday.

So one thing I would say about the 0.065" wall is to consider a different material for the Z assembly. I know there’s a lot that goes into it already, but I just finished my Z assembly and with the DW660 attached it weighs almost 9 lbs! Without the DW660 it was almost 6 lbs… I’m guessing you could drop it by 1-2 lbs by ordering thinner steel, aluminum, or even carbon fiber tubes… I don’t know how big of a deal it will really be, but even wit the 0.065" wall it’s pretty easy to bend a 4’ long rail.

Thank you for the endorsements of Speedy Metals. I had previously found a marine supply store on the web, but they were almost twice as expensive. And the suggestion of using lighter tubes for the Z assembly is awesome. I have been hacking my way through the 250+ post topics under Getting Started before I ask my questions, but since this topic had people with experience with the vendor, it was definitely the place to ask. Based on other posts by the Keymaster, I have already placed the order for the DW660.

My remaining question is whether the Extra Tool Mount (DW660) is included in the Bundle PRINTED PARTS - 25.4MM -1". It does not look like it. I am trying to avoid failing to order a part necessary to complete the CNC, although I do have a small Monoprice MP Select Mini 3D Printer. Regardless, thank you for your answers!

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You choose the mount you want included in the parts drop down.