I've been sitting on this machine long enough; it's time for some MOTION!
X screw is mounted between thrust bearings as was the original screw, and retained with a nut.
Z screw is mounted with a radial bearing at either end and a single thrust bearing at the motor end. I may go back and add a thrust bearing on the left end of the screw, but it's only really necessary if I'm going to be doing left hand operations.
I hope to get a computer attached tonight and start testing motion. After that, I need to build a riser/toolpost mount for the phaseII BXA post that I have for it.
Next I need to come up with something for a spindle index encoder. I plan to cut an index wheel out of 16ga steel on my cnc plasma table. Does anyone have a source on a good little optointerruptor module that I can use?
I'm trying out EMC2 for this project. I also ordered a mesa 7i43 to use, and I'm super excited about playing with that.
The X screw I made awhile back, and I turned it on my big clausing lathe. It came out ok, but I'm not thrilled with the concentricity and I may remake it.
The Z screw I just made over the last couple days. I have an old Reid surface grinder which I just recently got running, and I turned the ends down with a spin index on the grinder, and they came out GREAT.
Here's the X screw bearing block and motor mount:
The bearing block is basically a copy of the cast piece that the lathe comes with, and it pulls the screw up against a thrust bearing on the far side, with another thrust bearing on the near side and a nut. The motor mount is just a hollowed out block drilled and tapped on both sides. I did it that way to keep swarf and coolant out of the couplings.
Thats all that I have pics of on hand. Let me know if there's anything specific you want to see and I'll take some more this evening.
There should be plenty of room on either axis, to be honest.
I had to mill out clearance for the ballnut on the carriage, but you'll have to do that regardless of single or double.
I basically positioned my ballnut mount so that the cross slide was all the way up against the motor mount at the same time that the ballnut was about as far up against the bearing block as possible. There's no limiting factor on the far end of travel, you'll just want to make sure that your X screw is long enough that you don't run the nut off the end at your mad desired slide travel.
The Z won't be a problem at all, because the double nut won't be as long as the apron. I took the guts out of my apron, milled a 1/2" slot into it, and there's a 1/2" aluminum ballnut mount that is dadoed into that slot and then secured by two 1/4-20 screws from the front of the apron. I'll try to get pics of that whole situation tonight.
Just to make sure that I understand correctly, did you clamp the ballscrew in a 5C collet to hold it in the spin indexer?
Did you manually turn the spin indexer during the grinding, and did you use the indexer stops or just rotate it freely?
Yeah, I clamped it in a 5C collet and manually turned the indexer. Didn't use the stops at all.
For doing the short journal for the left end it was simple enough. For doing the long end, where I have a journal plus a 1/4" shaft for the coupler, it took a lot of passes, and the Z travel on my grinder is short enough that I had to reposition it a few times. Next time I do one like this, I'm going to try to do the initial cuts in a lathe, and then grind the bearing journals to size.