1220 × 2440 build

[JAZZCNC]

5k sounds reasonable to me, thanks for the break down Jazz, that's helpful and exactly what I needed, a ballpark figure ... have you seen CKJCNC on eBay? They seem to be doing a lot of business selling CNC machines, sub 10k plus VAT for the 1325 model (1300 x 2500 x 200 working area). Certainly looks the part, at least to my untrained eye! About 11.5k inc VAT.

They are just Chinese imports. If you notice they say Orders being Taken. You could import one of these your self for lot less money. Shit loads on Ali express.
https://www.aliexpress.com/af/1325-c...ewCP=y&catId=0

[malcolm01]

5k sounds reasonable to me, thanks for the break down Jazz, that's helpful and exactly what I needed, a ballpark figure ... have you seen CKJCNC on eBay? They seem to be doing a lot of business selling CNC machines, sub 10k plus VAT for the 1325 model (1300 x 2500 x 200 working area). Certainly looks the part, at least to my untrained eye! About 11.5k inc VAT.

Hi Mark
I’ve just finished building an 8x4 CNC. It works ok,
I fitted it with 25mm ball screws on x and y axis and fitted a ready made z axis. The guys above were correct about ball screws whipping or wobbling while running, the y axis is fine, but the x axis has vibration issues. I’m planning on changing the x axis drive to rack and pinion which I’ll be buying from America ready made, I would recommend if your building a machine to avoid ball screws over 1500mm like one of the other guys said.
It will cost around £5k, it did for me, but when you see that thing cutting out your parts you’ll be glad you did it. I love my machine, I hardly cut anything buy hand if I can help it.
Best of luck.
Malcolm, from Ayrshire, Scotland


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[JAZZCNC]

Hi Mark
I’ve just finished building an 8x4 CNC. It works ok,
I fitted it with 25mm ball screws on x and y axis and fitted a ready made z axis. The guys above were correct about ball screws whipping or wobbling while running, the y axis is fine, but the x axis has vibration issues. I’m planning on changing the x axis drive to rack and pinion which I’ll be buying from America ready made, I would recommend if your building a machine to avoid ball screws over 1500mm like one of the other guys said.

Hi Malcolm,

I wouldn't do that to be honest because R&P comes with it's own issues and I'm guessing you mean CNCrouter parts R&P which isn't the best thing in world. Ballscrews can work fine if done correctly.
The trick is to get the screw speed down. So to do this you use pitch that is higher than you need and apply a ratio. I'll guess you used 10mm pitch.?
If you had used 25mm pitch then applied 2:1 ratio you would half your screw speed. The ratio makes it the same as if having 12.5mm pitch so you have little more travel speed still with decent resolution. The ratio also increases your torque so little more grunt.

If you use Fixed end bearings both ends of screw and put under slight tension then you won't have any issues. If you watch the video of the Vertical machine it's using 2525 screws done this way and traveling at 15Mtr/min. In testing I had it upto 25mtr/min and still with little left.

[HullMark]

So it definitely sounds like building my own will be best option as I'll know exactly what I'm getting/ putting into the machine, so long as everything's accurate and I take into account all the issues learnt so far by everyone else. Oh and spend a little more too!

Jazz, that makes perfect sense. I was wondering how slowing down the speed of the screws would effect the whip that's been mentioned. Hopefully that'll be a cheaper fix for Malcolm! Thank you for sharing your progress malcom, ill be sure to keep in touch and up date with any developments ... Is the vertically mounted CNC one of yours jazz?

[Clive S]

Is the vertically mounted CNC one of yours jazz?

Yes it is I have personally seen it. Why not ask him for a quote? He is not to far from you.

[malcolm01]

So it definitely sounds like building my own will be best option as I'll know exactly what I'm getting/ putting into the machine, so long as everything's accurate and I take into account all the issues learnt so far by everyone else. Oh and spend a little more too!

Jazz, that makes perfect sense. I was wondering how slowing down the speed of the screws would effect the whip that's been mentioned. Hopefully that'll be a cheaper fix for Malcolm! Thank you for sharing your progress malcom, ill be sure to keep in touch and up date with any developments ... Is the vertically mounted CNC one of yours jazz?

I wonder how I’d go about fixing the other end. It has a floating bearing, it’s only held on by a sirclip, other end is designed to be fixed 🧐


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[HullMark]

Without seeing something Malcolm, with my inexperience, I'd find it difficult to offer any kind of solution. I've seen parts available on a uk website CNC4YOU ... seems to be a lot cheaper than I've been advised here for screws and bearings. Anyone used these guys before? There's fixed and floating bearing supports for sale on there Malcom if that's of any use.

[routercnc]

I wonder how I’d go about fixing the other end. It has a floating bearing, it’s only held on by a sirclip, other end is designed to be fixed ��


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I'm in the process of doing just that on my new Mk4 machine on the long X axis. Because of the arrangement in the design I will not use off the shelf parts - instead I will be re-machining the floating end to have a lock nut and thread, and then use a thrust bearing between the lock nut and radial bearing to vary the axial pre-load. I'm likely to need a spacer in there to ensure force lines pass through the right part of the bearings. Hopefully when I get the video out (could be a few weeks yet) it will be clearer, and in my case it should make a neat job of it.

Alternatively, and easier if it can be done on your machine, you can use the same fixed end bearing set (that you have at the drive end) with angular contact bearings in to apply the axial pre-load, but you would need access to a lathe to machine the floating end of the ballscrew to suit. Then to apply preload to the ballscrew depends on how it is bolted to the machine. If the bolts run through the vertical holes then you just need to pull the ballscrew tight and torque up the fasteners. If the bolts run through the horizontal holes you need some way of shimming it away from the mounting face to get the axial load applied.

edit: apologies, realised I've replied to a poster, not the OP. Malcolm, create a new thread if you want more.

[malcolm01]

Without seeing something Malcolm, with my inexperience, I'd find it difficult to offer any kind of solution. I've seen parts available on a uk website CNC4YOU ... seems to be a lot cheaper than I've been advised here for screws and bearings. Anyone used these guys before? There's fixed and floating bearing supports for sale on there Malcom if that's of any use.

That’s where I bought the lot from. Fixed at one end and floating at the other.


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[malcolm01]

I'm in the process of doing just that on my new Mk4 machine on the long X axis. Because of the arrangement in the design I will not use off the shelf parts - instead I will be re-machining the floating end to have a lock nut and thread, and then use a thrust bearing between the lock nut and radial bearing to vary the axial pre-load. I'm likely to need a spacer in there to ensure force lines pass through the right part of the bearings. Hopefully when I get the video out (could be a few weeks yet) it will be clearer, and in my case it should make a neat job of it.

Alternatively, and easier if it can be done on your machine, you can use the same fixed end bearing set (that you have at the drive end) with angular contact bearings in to apply the axial pre-load, but you would need access to a lathe to machine the floating end of the ballscrew to suit. Then to apply preload to the ballscrew depends on how it is bolted to the machine. If the bolts run through the vertical holes then you just need to pull the ballscrew tight and torque up the fasteners. If the bolts run through the horizontal holes you need some way of shimming it away from the mounting face to get the axial load applied.

edit: apologies, realised I've replied to a poster, not the OP. Malcolm, create a new thread if you want more.

Yes I understand now. Ooft they’re 2.6m long, I have little engineering knowledge I’m a joiner.


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