My new z-axis (self constructed)

I am currently planning a major upgrade for my xcarve. My overall goal is a more rigid machine.
My xcarve is mostly a hobby I wanted to pick up the challenge and plan things for myself. That said, I am no machinist / toolmaker, so I decided to build the z axis first, to have a proof of concept, that my underlying design overall would work. I am well aware of the aftermarket z-axes available, which to be honest will be better designed, but that wasn’t my main concern. Challenge and poc it is.
Most parts I used are openbuilds, except for the aluminium plates. In the end I will keep from my xcarve the wiring, the controller, the anti-dust system.

One remark: I am not a native speaker, so I hope I got the english technical terms right.
Intro done, now to the fun part, pictures!

Planning was done in Fusion360, for the whole new cnc machine, here a picture of the planned z axis:

At first I needed to cut the c-beam to length and tap the holes:

After that I mounted the first linear bearing and made true it’s parallel to the c-beam (on both, top and side):

Then I mounted the second linear bearing and made sure it’s parallel to the other one. I had a difference of max 0.02mm, I guess that’s alright, at least I hope so :wink: :

Finally my 10mm thick alumium plates arrived, which I had cut from a german online shop, based on my cad file:

Then I installed the flanged bearings in the end parts and mounted the first one:

After that the carriages were installed and the second end plate:

Then the front plate was installed (on the inside having a anti backlash nut block):

After that I installed the leadscrew and fixed it using lock collars:

Final picture:

As you can see holes for 2 spindle mounts are already in place. I don’t have a picture of that right now, but will edit my post later.

[Update]
Here’s the picture with spindle mounts installed:

Improvement suggestions are highly welcome, especially if I can implement them in the current design without redoing everything.
My first impression is good. It seems pretty rigid, it moves when the lead screw is turned, everything seems alright. Unfortunately I don’t think the xcarve can handle the weight right now, so I don’t have installed it yet.

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Are these 20mm rails and blocks? Do you have another 8 of them for X and Y?

20mm rails might be overkill (*) on a 20-base profile with 8mm leadscrew, but if you do have enough of these for X and Y, don’t worry about it. It looks great.

If you don’t, you could save them for X or Y (with Y carrying most of the weight in a gantry style machine) and swap them with something lighter (and cheaper) for the Z.

(*) People have been using MG series, size 12mm (rated for ~3kN) on desktop machines. Yours look similar to HG series size 20mm (rated for ~30kN). Each. A machine light as an X-Carve cannot handle a fraction of that load. On the other hand, if I drove a Fiat and someone gave me a Ferrari engine, would I use it? Hell, yeah!

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Thanks for your input, highly appreciated.
Yes indeed they are 20mm. I don’t have them yet, I wanted to do the z axis first as a proof of concept.
As I said I’m no machinist / toolmaker, so I didn’t have an exact look into load sizes. The shop I’m buying these has 15mm, 20mm and upwards. The difference for 8 rails will be about 250 €, so it’s a really useful information. Switching isn’t possible, since I have a 100x1000 machine, so my z-axis will remain with 20mm :slight_smile: .
My current state of planning is more or less this (I have done several iterations since I rendered this pic, but it shows my intentions):

planning

Everything will be 10mm aluminium plates from the same manufactures as the ones of my z-axis. I can’t really judge whether 15mm will be sufficient, reading your comment my gut feeling would be “should be sufficient”, what do you think?

While my CNC isnt an Xcarve I think it still applies, whenever I did an upgrade the next weak link appeared :wink:

Looks like a very solid Z-design you got there, quite similar to my own I rolled out some time ago. The “weak” link in mine is the narrow width of the whole assembly but that was a compromise done to allow maximum X-travel as my machine have a small work space :slight_smile:

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Totally agree on the “next weak link” thing :smiley:

Quite interesting design. I see you have your bearing “lying on the side”, I was planning to have the linear bearing on top and bottom of my x axis. Any reason you did it that way, maybe z axis height clearance or something similar?

The main reason was that my gantry (X) already had SBR16 rails installed so it was to make it fit the existing structure.

Should a redesign of my gantry happen all I need to change is the main back plate :slight_smile: I have wanted to build a new upgraded machine but it is working so well…!

I ended up using MGN12 rails/blocks for the Z-axis BTW plus 16mm ball screw. (SFU1605)

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Okay, that makes sense, makes upgrading really easy.
I am currently looking into which rails I should use for x and y. Unfortunately vendors in Germany are rare. Having read @EliasPolitis comment and having seen the 20mm rails live and on my z-axis I think they would be overkill. The next question for me is should I get 15mm or 12mm or anything else and where to buy :smiley:
Currently the 15mm from the vencor I already bought the 20mm is the favourite which will be around 500 €

Here in Norway we dont have any outlets beside industrial / commercial vendors => way to pricey for hobby machines…
I have purchased most of my stuff from various sellers on ebay and have had no issues with what I have received.

If I go with square rails/blocks for v2 I am undecided between 15 or 20mm. On ebay the cost difference is neglible.
If all I would want to do is wood 15mm will be more than enough I am sure, but for extensive metal work bigger is definitely better.

Same here. I even know people working for manufacturers of linear bearings and have no chance of getting them.
I didn’t have a close look into ebay yet. Everything I have found until now from foreign countries is cheaper than the german vendors, but customs and shipping will render the cheaper price useless often.
I am quite happy having found an openbuilds vendor in Belgium which has the whole openbuild selection. Even that is a problem in Germany…

My main material is wood, but in the future I definitely want to be able to cut aluminium in an appropriate manner. Since my cnc is a hobby and not a business I don’t care whether my piece is cut in 45min or 1h. But I don’t want to wait 3h :wink:

There are one or two outlets for hobby related CNC-components (personal side business more or less) but they mainly evolve around chinese import parts…and they seem to import per order…so I order my own…

Check out ebay for HGR15mm rails or similar.
We do have import duty (VAT+a fixed fee) applicable for purchases above approx €36 (incl. shipping) so I try to purchase below that amount to avoid 25% VAT and the €20 fee.

One example, but VAT applicable:

My very first iteration of my CNC could only do (and unreliably so) 0.2mm DoC in aluminium with a 3mm tool. That ment very looong carve times indeed… There is a part I mill on occation that did take 5hrs, I can now do it in 20min :slight_smile:

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Great, thank you, I will have a closer look to ebay then :slight_smile:
This are the ones I currently bought (only shorter and the 20mm version)