MadModder

If this lathe is to have an electrocuted lead screw, will you have to wear thick rubber gloves using it 


https://en.wikipedia.org/wiki/Electrocution


(sorry I couldn't resist, your English is infinitely better than my Finnish )

As PK in his project page describes, a lathe electronic control can be (and should be) brought that tiny step further making it a partially capable CNC lathe. This in turn involves precise control/sensing  over spindle and both axes.

I am really tempted to make this just that. A lil' bit more capable as it actually does not seem to be awfully more stuff to do.

What I am going to have fun or struggle with (which ever way one wants to put it) are the mechanical things. Electronics and uC programming are easy for me. And as it seems most of this modification is actually just that.

I have also thought about using a servo motor on this one. It is my assumption that a servo motor controller needs some sort of PID controller to work as intended. In addition it needs either a rotary encoder or better yet a linear encoder  to tell the position of the saddle. I'll check what the stepper can actually do speedwise. The stepper is actually a nominally 120 volt device dc voltage for nominal current being around 30 volts. No problem as then the currents are smaller.

Of course this would be quite a bit more than just a electronic lead screw (ELS) but on the other hand - making the lathe to understand G-code (or whatever it is named) would make it compatible with GPL software which in turn has a temptation on me. Being a programmer makes me want to do everything in a computer.

I have an old Gerber photo plotter in my posession. This unit has one meter long ball lead screw with two nuts and another 70 cm long equally with two nuts. The steppers are too weak and slow for this application but because the unit has to work very precisely (being a foto plotter) the lead screws are quite massive (about 2 cm in diameter). As my lathe has a lead screw of about 90 cm length this could quite easily be replaced with that ball thing.

Using a ball lead screw has it's implications. There is no more a half nut to disconnect. This means that the apron handwheel has to be electricuted as well. Maybe a torsion sensor for manual control making it feel exactly as sloppy as it is now. Another torsion sensor to the end of the leadscrew handwheel and that thing could be operated exactly as it is operated now in a manual mode. The current half-nut lever and the auto-feed clutch would then be simple switches to disable/enable the manual handwheels. All this would of course mostly spoil the feel and touch of the manual operations.

On the other hand the ball lead screw is very precise and the lead screw backslash is mostly eliminated by using two nuts. Backslash originating from the leadscrew ends is a bit more difficult to eliminate - not much though.

I have to sleep on this one - this may run out of hands.....

I use copper sulphate on a job with lots of grinding as it holds up to heat better.

Bordeaux Mixture for fruit trees?

Copper Sulphate, lime and water?

Used it on my Apple PC and there isn't a virus left

Norm

Bob,

Have you a rough idea as to the dimension of the spring, if so I'll have a rummage in shed.

Dave