[ferrumdg]

Hi...

I've got a rather old (1963) conventional lathe at the shop... and am thinking about doing a retrofit to CNC.
The machine runs quite nicely and with a bit of TLC and time I can produce parts within +/- 2/100mm easily.. 1/100 if I'm really careful


However there's a bunch of stuff it can't do - especially in the threading area... (it has a broad selection of pitches, but sometimes not what I need)... and I have more and more small repetitive parts I'd need to make.
One option is to outsource those parts - probably the cheapest option in the short run... but also the least flexible in terms of being able to do it "now" and change sizes if needed.

Another option of course would be to find a used (my budget is a bit limited - especially after getting a CNC mill last year... oh god the tooling ... ) CNC lathe... but aside from budget concerns - space is getting a serious issue in my roughly 250m2 shop (2700sq.f) ...... then there's the issue of getting the tool into the shop, as I'm basically limited to machines no larger than 1.8x1.8 meters and no more than 1.5 tons ... (We've got elevator access... and that's it).
So often the used CNC lathes of interest, are far too big.


And that is where I started to think about retrofitting my current lathe.

Now here's a few questions, hopefully someone with retrofitting experience can answer:

- I guess I need an VFD for the motor - that would mean a new motor most likely, as the one in there is really old... not sure how well that will work with the modern VFDs (I've got plenty of them).
- Ball screws... what is recommended for the main lead screw (type, pitch...)
- What should I do to the entire gear train (it has a norton type quick changer...) - I guess I can not simply "exchange" the current lead screw and mount the ball screw and of course adapt the carriage... I guess Iwould need to disconnect the screw from the norton gearbox entirely and attach the servo or stepper from the other side.
- Steppers / servos... recommendations for what size of work? Also servos vs. steppers...
- Threading - what do I need to consider If I want the lathe to be able to CNC cut threads (I guess the spindle needs some way of indexing??)
- Controller... anything affordable thats working ? I had Mach3 in mind for the software but how about the electronic side: the drivers...
- Handwheel? does Mach3 support hand wheels? anything thats recommended?
- Any way to implement a simple stock bar feeder / puller?
- Tool Turrets - anyone ever made one of them for a retrofit lathe? or can I simply forget this? (for real automatition of one of my basic parts I've got to use at least one tool for the outside profile, center drill, drill and inside tapping and a cut off tool. so that's 5 tools... if there's an "easy" solution for like 6 tools that would be great.
- Can Mach3 & controller talk to any type of VFD (like adjusting a potentiometer for the speed change) ? or what is required to have the software set the spindle speeds...

Anything in general that is of help is appreciated...

thanks.

[wizard]

First things first. The feasibility of a lathe conversion depends greatly upon the actual lathe being retrofitted and the expected work load. Given that I don't see lathe conversions as the clear win the way mill conversions are.

Hi...

I've got a rather old (1963) conventional lathe at the shop... and am thinking about doing a retrofit to CNC.
The machine runs quite nicely and with a bit of TLC and time I can produce parts within +/- 2/100mm easily.. 1/100 if I'm really careful

Nice! Do realize though that what you can do manually might not be possible with a low cost CNC upgrade. For example machinist often us the compound to turn parts to tight OD values.

However there's a bunch of stuff it can't do - especially in the threading area... (it has a broad selection of pitches, but sometimes not what I need)... and I have more and more small repetitive parts I'd need to make.

There are only a couple of good low cost CNC solutions that do threading well. LinuxCNC is one of them

One option is to outsource those parts - probably the cheapest option in the short run... but also the least flexible in terms of being able to do it "now" and change sizes if needed.

How big are these parts by the way?

Another option of course would be to find a used (my budget is a bit limited - especially after getting a CNC mill last year... oh god the tooling ... ) CNC lathe... but aside from budget concerns - space is getting a serious issue in my roughly 250m2 shop (2700sq.f) ...... then there's the issue of getting the tool into the shop, as I'm basically limited to machines no larger than 1.8x1.8 meters and no more than 1.5 tons ... (We've got elevator access... and that's it).

Small lathes are out there. After all chuckers a don't need to be real big.

So often the used CNC lathes of interest, are far too big.

You need to shop around a bit, the used market is huge. On the other hand really small CNC lathes are coming to market so if you have low volumes there might be suitable hardware available new in 2014. Here I'm thinking Tormach

And that is where I started to think about retrofitting my current lathe.

Again it depends upon the lathe and user but I don't see CNC lathe conversions being the huge win up front that mill conversions are.

Now here's a few questions, hopefully someone with retrofitting experience can answer:

- I guess I need an VFD for the motor - that would mean a new motor most likely, as the one in there is really old... not sure how well that will work with the modern VFDs (I've got plenty of them).

Why rush? If the old motor runs a few more years with a VFD driving it then that is money in the bank.

- Ball screws... what is recommended for the main lead screw (type, pitch...)

That is up to you. Seriously your two choices are ground and rolled.

- What should I do to the entire gear train (it has a norton type quick changer...) - I guess I can not simply "exchange" the current lead screw and mount the ball screw and of course adapt the carriage... I guess Iwould need to disconnect the screw from the norton gearbox entirely and attach the servo or stepper from the other side.

Don't guess check it out. By the way is the gear box even removable?
[Quote]
- Steppers / servos... recommendations for what size of work? Also servos vs. steppers...
[/ Quote]
There are so many variables here that a solid answer is impossible. We don't even know what size the lathe is.

- Threading - what do I need to consider If I want the lathe to be able to CNC cut threads (I guess the spindle needs some way of indexing??)

Well for one software and hardware that solve the threading problem. At the low end there simply isn't a lot of options.

- Controller... anything affordable thats working ? I had Mach3 in mind for the software but how about the electronic side: the drivers...

Last I knew Mac 3 didn't handle lathes well.

- Handwheel? does Mach3 support hand wheels? anything thats recommended?
- Any way to implement a simple stock bar feeder / puller?

If you don't have room for another lathe how would you expect to handle the machinery to handle that long stock.

- Tool Turrets - anyone ever made one of them for a retrofit lathe? or can I simply forget this? (for real automatition of one of my basic parts I've got to use at least one tool for the outside profile, center drill, drill and inside tapping and a cut off tool. so that's 5 tools... if there's an "easy" solution for like 6 tools that would be great.

You see the problem here is this if this is anything other than a hobby I don't personally see the value in a DIY solution here. First is there even a possibility of connecting Such an indexer to the cros slide.

- Can Mach3 & controller talk to any type of VFD (like adjusting a potentiometer for the speed change) ? or what is required to have the software set the spindle speeds...

Anything in general that is of help is appreciated...

thanks.

Too tired to go on!

[ferrumdg]

[QUOTE=wizard;1417502]First things first. The feasibility of a lathe conversion depends greatly upon the actual lathe being retrofitted and the expected work load. Given that I don't see lathe conversions as the clear win the way mill conversions are.



Nice! Do realize though that what you can do manually might not be possible with a low cost CNC upgrade. For example machinist often us the compound to turn parts to tight OD values.

There are only a couple of good low cost CNC solutions that do threading well. LinuxCNC is one of them

How big are these parts by the way?

Small lathes are out there. After all chuckers a don't need to be real big.

You need to shop around a bit, the used market is huge. On the other hand really small CNC lathes are coming to market so if you have low volumes there might be suitable hardware available new in 2014. Here I'm thinking Tormach

Again it depends upon the lathe and user but I don't see CNC lathe conversions being the huge win up front that mill conversions are.

Why rush? If the old motor runs a few more years with a VFD driving it then that is money in the bank.

That is up to you. Seriously your two choices are ground and rolled.

Don't guess check it out. By the way is the gear box even removable?

- Steppers / servos... recommendations for what size of work? Also servos vs. steppers...
[/ Quote]
There are so many variables here that a solid answer is impossible. We don't even know what size the lathe is.

Well for one software and hardware that solve the threading problem. At the low end there simply isn't a lot of options.

Last I knew Mac 3 didn't handle lathes well.

If you don't have room for another lathe how would you expect to handle the machinery to handle that long stock.

You see the problem here is this if this is anything other than a hobby I don't personally see the value in a DIY solution here. First is there even a possibility of connecting Such an indexer to the cros slide.

Too tired to go on!

Wizard

Thank you for your insightful input here - much appreciated!

Size of the lathe I've got: it's a DeValiere 210... basically 750mm between centers.
max diameter 200mm over the bed
a 4kW motor...
and about 700kg total weight.
nothing fancy, but sturdy enough...

Parts: well most of my parts I have to produce on the lathe - at least the ones I plan to do with CNC are smm... 4-12mm diameter. individual piece length between 3 and 25mm in length.
Materials: anything from stainless to tool steels to brass and bronze.

Part-feeder/puller well that wouldn't need to be VERY long I'd be happy if it could work of a 1 or 2m long round stock for let me say the axis of my folding knives... 1meter would already give me 80-100 pieces .


Tormach is coming out with a Lathe??
Might be worth looking into.
Even though getting it to Switzerland will be quite pricey... not to mention that it's probably requiring a bit of rewiring (we operate on 380V/3phases).

I had a good offer on a used cnc lathe with automatic tool turret... however at 2.5x2meters and 3tons I couldn't get it inside the shop.
that is what I've been running into so far mostly... as soon as it's really affordable its oversized... and the small machines, at least on the local used tool markets sell for premium.


But I guess you're right - retrofitting still might not be the most interesting option.

[wizard]

Wizard

Thank you for your insightful input here - much appreciated!

Size of the lathe I've got: it's a DeValiere 210... basically 750mm between centers.
max diameter 200mm over the bed
a 4kW motor...
and about 700kg total weight.
nothing fancy, but sturdy enough...

I'm not familiar with that lathe. A big factor in feasibility would be the design of the cross slide. To put it simply is there enough room on the machines cross slide for the tooling you need?

Parts: well most of my parts I have to produce on the lathe - at least the ones I plan to do with CNC are smm... 4-12mm diameter. individual piece length between 3 and 25mm in length.
Materials: anything from stainless to tool steels to brass and bronze.

That helps with scope here and highlights that you don't need a big lathe to do the job.

Part-feeder/puller well that wouldn't need to be VERY long I'd be happy if it could work of a 1 or 2m long round stock for let me say the axis of my folding knives... 1meter would already give me 80-100 pieces .

The problem is most off the shelf bar feeders are pretty big, at least the part that supports the bar outside of the lathe. You can DIY something for shorter bars though.

Tormach is coming out with a Lathe??

Yes but when I don't know. There have been beta models shipped to a few customers already for evaluation. A company called Fadec Engineering also has a small lathe in the works. I wouldn't be surprised to find a company or two in china shipping CNC'ed small lathes. These aren't conversion lathes but machines designed from the ground up for CNC work. Light duty to be sure bit from all indications that is all you need.

Might be worth looking into.
Even though getting it to Switzerland will be quite pricey... not to mention that it's probably requiring a bit of rewiring (we operate on 380V/3phases).

Or just buy a transformer.

I had a good offer on a used cnc lathe with automatic tool turret... however at 2.5x2meters and 3tons I couldn't get it inside the shop.
that is what I've been running into so far mostly... as soon as it's really affordable its oversized... and the small machines, at least on the local used tool markets sell for premium.

That isn't surprising actually and is similar to the situation here in the US. Small machines often command a premium over larger machines.

But I guess you're right - retrofitting still might not be the most interesting option.

Maybe. It sounds like the parts you are interested in are for the most part simple. If that is true you might be able to accomplish what you need with a small amount of gang tooling. If the lathe has room for that tooling on the cross slide it might be a feasible conversion.

Considering the limited range of components here your other option is to build a suitable machine. This may seem unrealistic at first but it isn't that big of a jump from trying to do a CNC conversion. You might be able to get by with as little as six inches of Z travel. Your biggest challenge would be boring a block of iron or steel to accept an off the shelf spindle. Even that isn't a big deal because if you look long enough you can find spare CNC head stocks on E-Bay and the like. Given a suitably long cross slide for gang tooling and you would have a straight forward machine build.

[Tkamsker]

Hi i had similar Issue so i bought an klippfeld turning lathe which is Cnc and Manual in my config. I ordedered without ballscrews but they have also ballscrews Version Avail . I am verry happy so far because i use linuxcnc i could do threading Easy so far i didnt Need. My next Step is atc. Probably that hint Helps you i Even made Videos of the lathe when i cnced it ,..


Gesendet von meinem iPad mit Tapatalk