Hardinge HLV-H Conversion

I have a Hardinge HLV-H that I plan to convert to CNC. Yes, I know it is a great manual lathe and a shame to Frankenstein it, but I got it cheap and I think it is a great machine to convert. it is very rigid, is set up for flood coolant, and it already has a collet closer that can easily be automated.

My plan is to remove the cross slide and mount two linear rails on the existing saddle with the carriages mounted on the saddle and the rails themselves mounted to the bottom of a Tormach long gang plate. the single rail I have in the picture was just for an example since I had it sitting around. Instead of using that type of round rail I plan to use something like Hiwin square type linear rails.

I will use ball screws for both axis. For the X axis I will keep with the existing dovetail ways instead of the linear rails.

My first question is what size linear rails would be appropriate for this? They publish calculations based on load, but I really don't know what type of loads will be on the rails when cutting. Anybody know what size rails are typically used in this size machine in a factory built CNC? I am guessing 25mm or 35mm would be good, but that is just a guess.

Other comments, criticisms, suggestions for this build welcome. I will be adding more info as I go.
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A 23mm carriage has a dynamic load capacity of about 6,200 lbs. So 4x would be around 25,000 lbs. A 34mm carriage is rated around 12,000.

Is the goal of replacing the cross slide to get more travel by using the rails?

Should make a nice machine. I'll be watching your progress.

Just a note: The X axis on a lathe is the cross axis, and the Z is the carriage (left & right as you are standing in front of the lathe).

Jim, after I posted this I started looking around at what other machines use and found the old thread by lcvette about the Chinese XK7130 machine and it used 35mm for a very large machine so as you say 25mm should be more than fine. Could probably go smaller, but I have the room for the 25mm and it is not that much more expensive. I am wanting to get a very rigid setup.

The goal of replacing the cross slide is to get more travel as a gang tool lathe. The existing cross slide has maybe 6" or less of travel. I will also be using a ball screw and I think that the new cross slide will be much easier to add a ball screw into than trying to replace the screw in the original slide.

I will pull off the existing Z axis screw and add a ball screw. There is a convient big plate on the back side of the saddle that I might mount the ball screw to instead of the normal location of the existing screw, but I haven't taken a close look to figure out the best way yet.

My chinese fairly good 12x24" of the heavy semi-industrial type is of a similar size.

I used 32 mm ballscrews on the z and 25 mm on the x,
and 25 mm linear slides on the x axis.

When I getto it the z axis will be 35 mm linear slides.

Otherwise I did pretty much what You want to do, with 2 toolchangers still to be mounted.
A flat 4-way and a heavy revolver 8-way at the back.

Original travel was about 14 cm and current is about 300 mm on the x axis.

Direct-drive servos with 10.000 counts, ac 220V.
5 mm screws.

I recommend 35 mm if you can fit them.
Reason is rigidity.

Load capacity does not enter into it at all, typical push forces are about 1000 kgf on big machines, about 1200-1400 kgf on modern Haas machines.
But rigidity and quality of finish depends only on the size of the carriages, and bigger is definitely better.

Lathes are tyically loaded to less than 1% of the breaking strength.

So with a 10.000 kgf max load on 4x 25 mm carriages, you would typically use about 100 kgf max push force, perhaps 200 kgf.
But 35 mm carriages have == 4 times the area of 25 mm carriages, and over 4 carriages the rigidity in terms of momentum is probably about 40x higher.

Using the TS, drilling with a 25 mm drill into tool steel with a 10 mm pilot hole, I stalled the spindle twice.
Around 100 rpm, iirc.

And I have 90 Nm of torque on the spindle, C axis, with a 30 Nm peak torque (3 secs) and a 1:3 HTD belt drive, HTD-8, 30 mm wide.
This is more than a HAAS ST10 turning center, with a 11 kW VFD drive.
Probably used about 400 kgf of push force with the manual TS.

I would change nothing on the current setup, about version 5 after 11 years of developing the lathe, mostly full-time.
Hth..

Hanermo, do you have any pictures of yours?

And the whole world. Is on your case. I could offer you. A warm embrace. To make you feel my love
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