dual manual/cnc lathe

[almarghi]

Hi all,
I was playing a long time with the ideea to modify my lathe in a cnc, but I didn't like to simply add a motor to the lead screw. I always was shure that I'll use it also intensive manually. So the problem was how to turn the lead screw with a handwheel. Although it's a bench lathe, it is pretty long and if I make a smallpart, a handle on the right end of the screw were inconvenient. AND I was used to the handwheel on the carriage.
So I came to the ideea to turn the ball nut around the screw when on manual. When using it in cnc mode, the nut is locked and the stepper rotates the screw.
Of course I can use also the original gearbox for threading in manual mode, but with recalculation, since the ballscrew has another pitch.
Unfortunatelly I didn't took pictures during the construction, but I have posted a rendering of the project, just to see the principle of my ideea. I already had some 90 degrees gears, so that is why I used them. Of course some bevel gears can be used.
There are also some photos of the machine as it is now.
Sorry for my bad english,
alx

[rossbotics]

Looks good, would love to a video of making something

Thanks Doug

[rasta]

Hi all,
I was playing a long time with the ideea to modify my lathe in a cnc, but I didn't like to simply add a motor to the lead screw. I always was shure that I'll use it also intensive manually. So the problem was how to turn the lead screw with a handwheel. Although it's a bench lathe, it is pretty long and if I make a smallpart, a handle on the right end of the screw were inconvenient. AND I was used to the handwheel on the carriage.
So I came to the ideea to turn the ball nut around the screw when on manual. When using it in cnc mode, the nut is locked and the stepper rotates the screw.
Of course I can use also the original gearbox for threading in manual mode, but with recalculation, since the ballscrew has another pitch.
Unfortunatelly I didn't took pictures during the construction, but I have posted a rendering of the project, just to see the principle of my ideea. I already had some 90 degrees gears, so that is why I used them. Of course some bevel gears can be used.
There are also some photos of the machine as it is now.
Sorry for my bad english,
alx

hi; if there is space on the back of the machine (parallel to were the lead screw is.. its quite easy to mount the ballscrew in there and the ball nut bolted to the carriage by a easily removed locking screw, that way you can use both screws
mariano

[almarghi]

Thanks Mariano for your reply.
Thaught about it, but having the nut always engaged and just rotating it when needed, gives me the possibility to make fine adjustments during a program.
For example if somewhere in the program has to be cut a bearing seat, I make it almost to the final diameter per cnc, then I pause the program, fine turn the seat and then resume the program. Bearing seats are always a pain in the butt due to vibrations, machine rigidity or too long tools; one never can be sure if the machine can do it.
I am curious if there is someone out there who can do this all automatic on a homebrewed cnc lathe.
Having a locking nut somewhere in the back of the carriage is not comfortable to reach very often.

[DIYer]

Thanks almarghi! We've added your CNC Lathe Manual Control to our Lathes category,
as well as to your builder page: almarghi's Homemade Tools. Your receipt:

CNC Lathe Manual Control by almarghi

tags: lathe