Lathe toolchanger

Kinda a noob, Long time listener, first time caller..I have a graziano sag 12 with a dead speed selector gearbox. I am in the process of converting it to cnc and need some advise. I want to construct my own 6-8 position toolchanger. I was looking at either doing a harmonic drive or one with a pneumatic locking feature and a hirth coupling. Any advice on which one to do? Any help is appreciated.

Sent from my SM-G935T using Tapatalk

Another Aland Islander. That place must be a hotbed of CNC manufacturing!

I'd buy a turret and index assembly from someone parting out an old lathe long before trying to build one.

I have an 8 position front turret off of an older machine- not too big- the tool disk is about 8" diameter and it takes 1" square shank tools. Disk is vertical and sits perpendicular to the lathe centerline. This came off a flat bed lathe and mounted to the cross slide with a dovetail on each side of the slide. Its hydraulic actuation for rotation and clamping and uses simple micro switches for status feedback to the control. Sounds about like what you should be looking for.
PM me or post here if interested - I can send pictures etc. Also have a 4 station rear turret that has 1.5" bores for drills and ID tools. Same deal as above.

If it's a retro onto a simple lathe, no existing hydraulics etc, look for an old Sauter turret. Some of them are purely electric with an controls that would be trivial to interface to.

I have an old one Sauter model no. 0.5.470

It uses a single bidirectional motor to index and clamp, a single TTL encoder for station feedback, and a single prox switch for locked feedback. Three part (no lift) hirth coupling. This one is complicated slightly by having driven tooling, but in principle it's the perfect turret for a retro onto a basic lathe.

Fwiw..
I am now fitting 2 new toolchangers to my lathe,
1. a 4-post flat one in front, stepper driven (will probably junk the stepper and put a 400W AC brushless servo on it).
== 15 kg
2. a 6 station servo driven turret
== 70 kg mass

This needs making a new,lower, saddle plate, 15 x 3 x 52 cm.

Now squaring the ends of the plate, with a ISO30 4-insert facemill held in the 12" 4-jaw.
And then need to make a new yoke, yoke is 7 cm thick., about 2.25" thickness.
150x7x7 cm.

And then need a new 32 mm screw on the x axis, that then gets held on to by the yoke.
Current screw is poor, and at 0.750" too thin.

All components are industrial-type stuff, 2.5 kW/750W ac brushless servos, 32 mm screw on z.
4 Mhz industrial controller.
Theoretical resolution is 0.2 microns.

I would not make either toolchanger, for what they cost, about 900€ for front, and 2500€ for back turret.
The toolchangers are about 600-700$ shipped, with 22% VAT and import stuff == 900 € all in.

I can easily position to 1 micron accuracy, using the MPG, when measured with an external electronic DTI.
But the poor x axis screw makes everything bouncy and not repeatable enough.
After I have it running with the new screw, I will make a better rigid ballscrew mount.
Now just using a stock BK/BF mount at the back.

All screws and stuff are at back, lathe looks stock from front.
Lathe is 12x24 light industrial.
No pics, until its clean, will be weeks.

HTH..

Thanks for all the advise everyone. This retrofit is more for learning experience and for the fun of putting it together and seeing it make chips. I appreciate the leads on the sauter equipment and the other info that has been posted. Dan, you have a pm on the changers

Sent from my SM-G935T using Tapatalk

hods1222- no PM in my inbox- can you try again? Dan

You'd be far better off at CNC Zone.

Dan from oakland, i tried sending a pm but it wouldnt let me. Can you send some pics and prices to [email protected].

Sent from my SM-G935T using Tapatalk