Diy cnc conversions

[ronan]

See a lot of people on the web converting the smaller chinese milling machines to cnc. Has anyone here done a conversion with larger machines ? Is it worth the bother or is it a bodge ? I am talking about lads in sheds doing this type of work for hobby machines, not professional users.

 

[Hood]

It all depends on what size of machine you are talking about and how much time/money you want to spend.
Steppers are ok for smaller lathes but larger lathes ideally want servos.

My lathe was originally a Churchill Computurn 290 which I changed over to Mach3 but the basic machine was a Tarnow manual lathe which Churchill then CNC'd, so it can be done and end up a first class machine.
For an idea of the size that the Computurn is it can swing 500mm dia over the bed with 280Kg max weight and it can swing 290mm over the saddle and 500Kg max weight if supported by the tailstock.

 

[ronan]

Sort of the small floor standing mills Hood. Another thing is can the machine still be used manually too ? Computers, software, and things like that are cheap enough now, but are motors, drivers etc expensive ?

 

[Hood]

Sort of the small floor standing mills Hood. Another thing is can the machine still be used manually too ? Computers, software, and things like that are cheap enough now, but are motors, drivers etc expensive ?

I was going to do my Colchester Student when the Computurn turned up and saved me the bother

For manual use it depends what you mean, if you retain the hand wheels and have servos then you could disable the servo drives and use it manually, if steppers then it would not be so good as they have a resistance when turning them and also if I recall you can damage a stepper drive by winding the motor manually but that may well depend on the drive.

You can of course use a manual pulse generator or even two which would allow you to jog the axes but there is absolutely no feel that you would get with cranking manually so........

Motors, drives, controllers etc can be cheapish or very expensive, depends how good you want things to be and where you get them from, all my servo motors and drives have come from eBay but bargains are getting scarce now. Chinese servos and drives are not too expensive even for medium sized ones and from what I have heard they are not too bad although I have never used any so can't compare to the ones I have.

 

[Hood]

Just to add a bit, unless you can find decent deals on ballscrews, motors, drives etc and you have access to a mill and probably a second lathe in the latter stages then buying a CNC lathe with a dead control may be a cheaper/easier option.

It all boils down to how good a conversion you want to do and what performance you want from it.

 

[addjunkie]

When I looked into this the conversion seemed more a project in its self, rather than having a machine to make stuff.

Plenty info on cnc zone forum i think its called.