Need advice re rails/tubes - I'm purchasing on Monday


I am going to order my stainless steel tubes on Monday. 25mm OD x 2mm WT. Lowrider 2.

I’m using the calculator in mm for the Lowrider2 CNC.

I am going with a X-Usable Width of 1100mm (I read a comment on the V1 site that 1200mm is really the max you would want to go). And I am planning a Y-Usable Length of 1700mm. (Please let me know if you think 1100 is going to problematic)

I have some questions that I really need your help with before I go to order on Monday morning….

  1. When you guys buy your tubes, do you round up the number a bit or do you cut to the exact dimension the JSCalc Output value gives you?

  2. How do you decide on the correct Z-Usable Height value? When you first visit the JSCalc page, it already has an input value of 89mm. I really have no clue what height value to choose.

  3. Again, do you round up on the Z Height tubes length when ordering?

  4. At the moment, the supplier has told me that the welded tubes have the seam on the inside - which is great so as not to interfere with the bearings going back and forth. But I asked him about the finish, and he said they had ‘scale’ to them - not satin and not polished. I am not familiar with this term. Is it a standard term that shouldn’t be a worry for my project, or do I need to have them polished??

Problem is I am ordering from abroad and cant see first hand. I am hoping the vendor will be able to send me a quick picture - just hope the tubes are suitable because I have been finding it very difficult to find reasonably valued 25mm OD x 2mm WT tubing in Europe.

Your help is very much appreciated!!! Thank you!! :slight_smile:

Edit: Reading back over your question I just noticed you are building the Lowrider. If I noticed earlier, I would not have answered this question since my machine is an MPCNC. I think the answer is largely accurate, but you will need someone who has built a Lowrider for better info.

How do you decide on the correct Z-Usable Height value? When you first visit the JSCalc page, it already has an input value of 89mm. I really have no clue what height value to choose.

This measurement is the distance from the top of the spoilboard to the bottom of the nut on your router. In this space must fit 1) your material, 2) any clearance you want for clamps, and 3) the amount the longest router bit you will use on that material sticks below the nut. Note the greater you make the working space, the more leverage on the Z axis when cutting. So making the Z axis taller either decreases the accuracy of of your cuts or requires you to slow down your cuts or both. So others may argue for other calculations, but for a starting point I would do the following:

Max_Material_Thickness * 2 + 10mm + 15mm

The “* 2” is because you probably want enough bit length to do a contour cut completely through the material. The “10mm” is for clamp clearance. The “15mm” is because sometimes you may want to go below the material such as drilling holes for pegs for two-sided milling. Or you may not be able to get a bit that exactly has the amount sticking out you need and end up with a longer bit.

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If you have a way of cutting the lengths yourself I would get them longer than you needed and trim them down once it’s all in place and mocked up. For a few extra mm’s the cost difference should be minimal. Depending on the vendor they may give you full meter/half meter lengths or full foot lengths anyways. I’d be sure of that if I didn’t have a way of cutting it myself.

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My printer is working away on the home-straight for the printed parts, my V1 engineering box with all the goodies and Rambo board are waiting on my desk.
It is just the rails/tubes and the table that are missing. I know I want an as large work footprint as is possible so I can keep my options open to projects. Unfortunately after stacking the storage boxes in my single-car garage, I am left with just under half the floorspace, meaning I cant get the full length of Y-axis I wanted. I could get the surface area I wanted if I put one of the Y-axis against the wall but is this practical?
As I want to be able to work on wood, metal, plastic, etc etc, I am wondering if there is a ‘general go to height’ for the Z-axis that I can aim towards.
I am a 3d printer kit assembler, and this is my first project such as this.
Thanks, Bel


I found out, that the cheapest choice is to buy 6000mm tubes and let the metal workshop around the corner cut them. So you have some spare Millimeters in length, no matter if you built an MPCNC or an lowrider.

Give them a little extra space is not too bad, as you find out soon that the machine could be a little bigger on the one or the other direction.

Z Size is the most important thing to me. Simply because you can move the massive bit away and have larger Z dimensions to work on. I have a net height of 60mm in Z-Axis. Once I am starting to enhance the machine, adapting Z-Axis to 120mm is one of the first things. And if it is just for my own convenience.


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Can your storage boxes live under the table to get you the y axis space you need?

Hi Uwe,
Sounds like a good plan. Will do that.
It is the Z-Axis that is worrying me still though. To keep my options open, what would you feel is a good length of Z-Rail to order?
Thanks again for your help! :slight_smile:

Hi Robert,
No worries about the edit regarding MPCNC and Lowrider2 - you definitely helped with things to keep in mind.
Thank you! :slight_smile:

Hi Brent,
Yes, I think you are right.
I guess it wouldn’t really matter if there was a bit of excess tube material poking out the outboard sides of the setup would it?
Thanks :slight_smile:

Hi Tom,
Have tracked down a great table solution, and will indeed be stuffing as many boxes as I can under it to get that Y axis space!!! :joy:

Hi everyone,

As you can probably tell, the Z-Axis height choice is making me nervous. I want to build my LR2 to be as adaptable to various sized projects as possible.

So what is your vote on the best Z-Axis height to go for?

In my still somewhat limited use I’ve mostly cut flat stock, plywoods, and other boards. I’ve never needed much z-height and keep in mind the functional depth of cut will be limited by the bits. Most 1/8" bits will just have enough cutting edge for 3/4" (~20mm) plywoods for cutting through . If you wanted to cut deeper you’re looking at 1/4" bits to gain another 25mm or so. Cutting deeper than that you’ll run into limits of clearance to the router base etc.

I don’t know what you are planning on cutting but I’ve not heard many people having issues with not enough z heights. If you imagine you’ll be carving into big thick stock or the tops of assembled pieces there wouldnbe other considerations. The other part too is I think rigidity starts to figure in with really high z-heights.

All that is a long way of saying, (a) know what you want to or imagine you’ll be cutting and use that to guide you, or (b) stick to the designs recommended heights, start using the machine and see.

If you find you want or need more height, swapping out some longer tubes is pretty easy, especially if you order a little extra to cover this possibility with your tube purchase.

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I made my tubes longer on both X and Z. the longer Z won’t hurt this gives you more Z height. the extra on the X, I wouldn’t make it more than 1" or about 26mm. I’ve done this and it’s working great. My Z is about 4" .

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It’s me again.
Got the table sorted out and very pleased! It is the base of an English pool table that was going to be chucked out - when painted up will look excellent! :slight_smile:
About to go ahead with ordering finally the rails.
And back to my original concern about the Z height dimension. I am ordering from abroad so want to get it right. I also, as you guys suggested, want to have them a bit longer than needed. I have a dewalt D26200 (the EU version of the 611) with a 1/4" bit - my intention is to use a collet adaptor when necessary to change to 1/8" bits. (I know, I know, I sound such a newbie!)
So does ie 365mm Z height rails sound sufficient lengths? Or should I order longer?
I really appreciate your help.

Sufficient is only for you to decide but I think it’s lots unless you imagine doing a lot engraving or sculpting on big thick pieces of wood.

Here’s mine to help visualize if it is helpful.

My tubes are about 320mm:

With an 1/8" bit in and my 611 bottomed out in the mount I have a bit more than 100mm of z height to work with before the tube would get past the lower bearings:

I’m not a prolific user but I’ve never needed more than 80mm of total z height for cutting. I’d also say that 95% of what I’ve cut so far has been sheet goods, less than 26mm total depth of cut.

With your 365mm tubes you’ll have closer to 150mm of z height to work with. Some of your dimensions may be a bit different for spoil boards and table setup but hopefully it helps with the decision. If not order longer :grin:

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Thank you very much for taking the time to take images to explain, much appreciated!. :slight_smile:

Have now ordered my rails/tubes with a bit extra, and off to the local hardware store at the weekend to pick up the table surface material.

Can I ask what software/s you use for going from design to cut?

Thanks :slight_smile:

Pretty standard stuff here for me, I design in fusion and cam in estlcam.

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I am running on Macs. I do have a very basic Windows 10 pc somewhere in the house, but it is very low spec, and not really sure if it would stand up to the ESTLcam. I have a Pi3 but cant yet rap my head around how to get all that going.
Seems as though most Mac users go for the Fusion360 way with regards to design and CAM…I think I have a steep learning curve ahead of me! :stuck_out_tongue:

I run estcam with a win 10 RCA tablet it also runs V-carve Pro fine

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That is interesting! Will have a look at it! Thanks :slight_smile:

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