[NIC 77]

I was expecting question about why not linuxcnc, as my nickname suggest Im more of a linux user I started using mach for my first build and I found cheap and reliable USB motion control card for it. About ballscrews, you are corrrect. If I had unlimited budget, I would go with 10mm pitch ground ballscrews. I actually already have some rexroth brand new 40mm diameter C3 ground ballscrews with 40mm pitch, but they are for another build, and only ballscrews cost more than this whole machine. But as this motors are "only" 400W" I think 5mm pitch is OK, it is small machine, so I dont need rapids of more than 12M/min, and I also think 17M/min is too fast - 3400rpm. I will run them at max 2400rpm. When you go with Chinese ballscrews, I think it is better to go with 5mm pitch, at least in my case as I dont need very fast rapids, due to force of the ball on screw. 10mm pitch screws will produce twice as much force on the wall of screw, and I wouldnt be surprised to see backlash even faster on 10mm pitch screws.

The nut on a 10mm pitch Chinese ballscrew is much longer than it is on a 5mm. Not sure how this effects the force on the wall of the screw. Regardless, you are using servos that are capable of higher speeds compared to steppers, and whip doesn't seem to be an issue for you, so I have nothing but praise for you and your design decisions on this build. Truly an awesome build sir. I come back every now and then to look at how you've done some things. Certainly one of the best builds as far as quality and performance go.

I just have one question for you. Where did you buy your ballscrews? I've been reading some horror stories about Chinese ballscrews, but I also know that some of the Chinese stuff is great quality, you just have to pick the right supplier. Looks like the ones you bought are performing well. What are your opinions?

[linux_fan]

Glad you like it. Since I got it in motion, I made a lot of parts for some other machine, and it works great. I have also bought BT30 ATC spindle for this machine, I will post here when I upgrade it. Yes, you are right, quality of Chinese stuff is very different. I am lucky I have a great forwarder there, so he finds good quality for me. Ive attached some pictures, This is woodworking machine I am making for a friend of mine. All of the milled aluminium parts I made on my smaller machine.

[NIC 77]

You're clearly a CNC genius!

Is that 4 pneumatic cylinders for the counterbalance? Where is your reservoir, are you routing your tube throughout the entire cable chain?

I'd be very interested in hearing more about how you are accomplishing the work holding. I am aware that some machines like Biesse do this, I haven't seen it on a DIY build until now, I have been thinking of something similar on my machine where I will have a 4th axis under the table, was thinking removable table, but sliding table supports may be better. That's one thing I haven't finalized.

[linux_fan]

Thank you. Ive made some pictures for you. As you can see, small aluminium "brakes" are mounted on each side of alu profile. When you grab handle and push it down, you will release two pneumatic cilinders that will push into aluminium brakes and hold alu profile. So when cilinders arent pushing, you can move profiles arround.
On profiles, there will be vacuum pods, 3 pieces on each profile. I will make pictures when Im finished. Should be next week.. About counter balance cylinder, it is one cylinder, you can see it sticking in air, longest one. For air reservoir, I just drilled two holes in cross square profile. One for direct connection with cylinder, and one for input from regulator. Welds are air tight, so there is no leaking. Voume is approx 15L. I use sepperate pressure regulator, and have it constantly connected to this "reservoir", so if there are any small leaks, it constantly fills it up. This sistem works great, and Z ballscrew should last very long, as whole Z axis now practically floats in air. Two double rod cylinders you were looking at are for lifting up and down vacum suction system.

[NIC 77]

OK, that's just awesome.

I don't claim to understand all what you've done, but awesome it is.

So those clamps slide in the T-slot and are hooked up to pneumatic cylinders. I had to look at it a few times, then I understood.

Is this gantry made from steel? It's painted so I can't tell? Are you going to fill this one with epoxy granite?

The machine that I'm making is from steel tube, but it bolts together in many places. My Z axis is also a Square steel tube with a 1/2" plate welded into the nose of it that the spindle will flange mount to. This is stronger than a flat plate Z axis, unfortunately because of the flange mount on my spindle, which attaches at the nose of the spindle, the spindle body doesn't add any strength to the Z. The problem I am considering is the steel tube will ring like a bell, I can't fill the tube as the spindle will be in it, so I am thinking about bolting some plastic channels to the outside and filling them with some kind of dampening material.

Actually, I have even been thinking about gluing some thick HDPE strips to the outside of the tube, simply to change the resonant frequency.

What are your thoughts on this?

[linux_fan]

You can see how everything works on video now: