1220 × 2440 build

[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]

Malcolm is this all made from the aluminium profile stuff? I would love to hear a run down on the processes you went through to get to this stage.

[malcolm01]

Malcolm is this all made from the aluminium profile stuff? I would love to hear a run down on the processes you went through to get to this stage.

l


Like you I was trying to build this cheaply and myself, made the mistake of building a torsion box as a base. It still sagged no matter how sturdy I thought it was. Then I just followed my instincts and built it. I used aluminium where I could, I’ve stuck in a few pictures, the gable ends of the gantry I had made from a local engineering firm, they cost a fortune.



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