[breathe]

Hey all,

Back with more questions this time I have more to work with. My last idea fizzled when I found a good deal on a 12x36 Bridgeport at a good price. Got that home and my little 9x19 lathe was looking inadequate. So after looking around awhile I sold it and for a hundred bucks more got a 12x36. What an improvement.

So my first thoughts was oh boy a bigger cnc .

First I want to be able to use it manually still. Yes I know I know not the best idea in the world. But I think it will work. Here is how.

I have a sweet ballscrew that has about 24 inches of travel that I am going to run along the back of the bed and attach to the carriage in the rear. Then I will unbolt it for when I want to use it in manual.

For the cross slide I am thinking I am going to stick with the stock screw for now. I am only seeing 3/1000 backlash and I will let Mach3 try to deal with that for now.

So for manual control I crank the wheels for CNC I take of the hand wheel on the cross slide and attach the stepper and bolt on the ballscrew in the back.


So questions. Should I pull the pinion for the X axis when using cnc to reduce friction?

Since the total travel on the lathe is more then 24 inches where should I place the ballscrew to be most useful? more toward the spindle or the tailstock? I am leaning towards the tailstock.

Any real reason to switch to a VFD in the beginning?

Recommendations on a what I need to purchase to get rpm counter for threading in cnc? I know there are lots of ways any in particular that would be suited to this one?

Well thats enough for this post, hope I made sense. Thanks again

[BrassBuilder]

Hmmmm....I'm not sure I'm following this....and since no one else is jumping in, I'll do the honors.

If I am understanding this even remotely, you have a 24" ballscrew that you want to CNC a 36" long lathe? That really isn't a problem since you are questioning on where to best use the 24" in the 36" span. If you proceed, I would put it towards the chuck...but that is only because I turn shorter items. You will need to determine what you want to make. But....I can't quite picture this:

Then I will unbolt it for when I want to use it in manual.

How much are you planning on "unbolting?" If you are taking your ballscrew off each time, those are a pain to get realigned.

I think you were on a good track with this thinking:

First I want to be able to use it manually still. Yes I know I know not the best idea in the world.

I would either jump in completely and CNC it or don't CNC it at all. When I CNCd my mill, I wanted to be able to use it manually. I bought dual shaft motors to put handles on...but never got around to installing the handles. You want to know how many times I've missed the handles? Zero. Trust me, it is easier to move things around with a pendant or the keyboard. Learn some simple G-code and you won't miss the handles. I just finished my lathe conversion and I did not even think twice about having manual capability in this thing.

What do you have for motors, drivers, and the breakout board? Have you checked ebay for a longer ballscrew to reach the entire length of your Z axis?

I would worry more about getting the CNC going before I worried about VFD or threading capability. Get the machine working and then improve upon it has been the way I operated when I built my lathe.

You are venturing into territory that I don't think anyone has gone into. It should be interesting in what you come up with if you proceed.

Mike

[breathe]

Alright I am taking the plung. Finally. Actually I started using the lathe alot more and thought gee I wish I had cnced this.
So now I have a 24 inch travel ballscrew, and a 8ish inch travel ballscrew.

Now with a mere six bolt and 3 pin removal I was able to strip the carraige down to just the cross slide. Apron came right off. So now I will install the Large ballscrew in the front or back and I will install the X ballscrew on the carraige to move the cross slide somehow.

BIG QUESTION. Both ballscrews are around 2 tpi. Now my major project will be turning a 18 inch long taper from 1 inch down to half and inch. So is my resolution to large?

Will I need to use belts and pulleys to reduce the resolution???

Currently using a gecko g540 driver with keling 381 oz motors. What say you. Give it a shot? or should I be planning on getting some reduction built in here. Thanks.

Photos come with answers.