I am working with a group of people to form a makerspace and we are hoping to get a CNC router operational shortly for demonstrations to attract members. I think I have decided to go with a Workbee but there are a couple of things I would like to change and I'm looking for advice on whether I am thinking right. We want a 1500x1500 to allow for large work pieces but still want good precision. The default belt system worries me a bit and I was thinking about going with either heavier belts or 1/2 acme. Everyone using this will be learning to some extent and it won't be possible to oversee eveyone so I would like to make the machine a little heavier duty. I am also looking at running LinuxCNC as I would like to have a couple of more inputs to work with and the ability to auto square the gantry.
I use Precision ACME Threaded Rod 1/2"-10 Size (1/2" Travel/Turn) 5 start (McMaster-Carr) on my 1500x850mm CNC. I had to make my own anti-backlash nuts out of Delrin stock. It was rather easy with the rod cut-offs. You have a piece just waiting to be made into a tap. You would need to be able to fit them in the 20x40mm cbeam channel which would be a tight fit, but doable. Or modify the end plates and run the threaded rods on the outside. But then you should put guards on since the threaded rods will be exposed. Mine have no guards, but I am smart enough not to snag myself or my clothing in them. This may not be the case for something open to the public.
Thanks Giarc. Do you see any downsides to 1/2 lead screws that long. I've seen a few people do it but haven't seen anybody comment on whip?
I do not have a whip problem. However, my pillow block bearings that hold the screws are on the outside of the end plates on all three axis, so the lead screw is in tension. I do not know how the Workbee has that set up. Although, that would not be hard to modify.
Thanks, I've been reading your build. Lots of good ideas. I have another question if you don't mind. Did you find pillow block bearings that were rated for a thrust load or just use regular ones? I have been working on a mount for tapered roller so I could load the shafts a bit without worrying about popping the race out but if I don't need to that would be great.
I just used regular ones. I may upgrade some day, but so far they have worked well. On a side note, my bearings cam with a 3mm set screw in the collar. I drilled through this hole and through the screw with the bit that corresponds with a 3mm tap then tapped the lead screw and put a much longer 3mm screw with thread lock on. It was not easy, but I feel it was well worth it. Also, I did not load the shafts much.
