Old 3800 lbs milling machine CNC retrofit thoughts?

[Maxxim0]

Hello! This is my first post on this forum.

I have been thinking of retrofitting my old manual milling machine to CNC. It's an old 1970 swedish Varnamo U-1 with 4kW spindle motor and X875, Y210, Z450mm movement. I was asking about this on our finnish cnc forum and got few ideas. My first idea was to fit ballscrews and big Nema34 or 42 steppers. But then one idea was to use dual encoder drivers and readout scales for table location, the idea was to use the orginal screws with this setup. Only things that the drivers only work with brushed DC servos that seems to be hard to find for a resonable price. Another idea was to make an external X/Y table with ballscrews that you could lift on the orginal table, so the mill could be used as orginal manual when needed, Z axle would of course need a stepper/servo, but could maybe use the orginal screw..?

Another question is about servos. I may be able to get for free, or for very low cost, old servos like this:



or



and also drivers like this:



Is there any chance I could use these, or some of them with some quite cheap other components? My knowledge in CNC building is close to zero even if I work every day as a cnc-laser cut operator.


Edit. And here is a pic of the mill:



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[Al_The_Man]

As a rule, if you are not fitting precision ball screws then it is not really worth the effort of a retro-fit.
They appear to be quite decent motors.
Al.

[Maxxim0]

Yes, the backslash(or what it is called?) will propably be an issue if ballscrews are not fitted. But would it be an issue on the Z-axle?

Can you tell what kind of driver would work with those servos? Is there any budget(<300€) driver I could use, or is the Beckhoff driver ok? I assume the Yaskawa servos would need different type of driver, am I right?

[Al_The_Man]

Can you tell what kind of driver would work with those servos?

It would depend on what kind of commutation methods they use, BLDC or AC servo methods.
Also what type of encoders fitted.
Al.

[Tkamsker]

It may be worth having a chat to granitedevices people they are Finnic anyway that will fit then there is an possibility with linuxcnc or sinumeric to use linear readings for correction and if you use wise g code movements to remove backslash it should be good


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