G0602 Conversion

[tmbg]

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.

[michaelthomas]

Cool.....I'm contemplating the same build. I just don't have the lathe, yet....lol.

What did you use for ball screws? I have some 5/8 Rotons with double nuts that are waiting for a home.

I'm looking at the cncforpc optical switch, or the PMDX. It appears that the cncforpc one has a remote sensor, which would be easier to manage.

Can you post some more pictures?

Mike

[tmbg]

They are 5/8" rotons with square single nuts.

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.

[tmbg]

Oh and thanks for the tip, Mike! I just ordered one of the opti index kits from cncforpc.

I'll try to get an index wheel drawn up and cut in the next few days.

I'm not sure if I'm better off with a single slot, or lots of slots. I guess it depends on how EMC2 will be configured to read the encoder.

[michaelthomas]

Thanks

My biggest curiosity at the moment is if a double nut will work on the x......well, I guess I'm wondering on the z too. It's pretty much twice as long as a single.

Seems like there would be plenty of room on the z.

[michaelthomas]

I suppose if EMC2 will read multiple holes, that would be better. Mach 3 will only work with 1 count per revolution.

I think CNCFORPC has a template on the site where the part is located.

[tmbg]

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.

[Flenser]

Nice conversion. I really like that x-motor mount. Definitely something to copy if I ever get around to reworking mine...

[doorknob]

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?

[tmbg]

Originally Posted by doorknob 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.

[tmbg]

Some updates:

I cut an encoder disk for the spindle index on my plasma table:



To get that behind the pulley, I needed spanners for those jam nuts, so I made some of them on the table as well. My consumables are pretty shot, and this is a really poor cut, but it works:

[michaelthomas]

Nice job

So it looks like EMC2 is good with a multiple count per revolution?