Can CNC control the lathe chuck?

[Big Noodles]

Hello,

I'm a noob, i've had my shoptask sitting in the garage for 2 years collection dust. Actually the dust cover was catching most of it.

I wanted to upgrade the maching and start using it more. I wanted to do the CNC thing, but am completely new to this.

I was curious can the spindle for the lathe be converted to CNC, such that the rotation is computer control.

I would like the Lathe spindle and Mill headstock to work in conjunction with each other.




Thanks,


Nathan

[Al_The_Man]

There are a few modes of CNC control of the lathe chuck or spindle.
There is the simple control of spindle rpm which is commanded by the CNC, but it seems you are after the more complex control of also making the spindle into what is known as the C axis because it revolves around the Z.
This is can accomplished in a few ways, all will require an encoder on the final spindle shaft.
Some systems use a VFD on the spindle motor that is capable of this kind of operation, others methods include a separate servo motor to control the spindle when C axis control is desired, this servo motor is usually disabled when normal spindle operation is performed.
All methodes require a servo type of operation.
For just threading and constant surface feed however, a VFD with an encoder is all that is needed, as the Z axis will sync to the spindle via the spindle encoder.
Al.

[PoppaBear10]

On my shoptask, I use a 2hp DC motor, controlled via a drive, but it is CNC controlled speed direction only.

If you want to use your Lathe spindle as an "axis", then I would recommend a Rutex drive to drive a servo (or really you could probly get away with a DC moter since a servo ain't nothin more than an fancy DC moter). But you will need to put an encoder on the Spindle shaft. Honestly, in Lathe mode under (I am assuming your using Mach) you can only currently control 2 axis X and Z, unless you want to fire up "screen designer" a talk to art about how to add an extra axis to lathe. On the other hand if you using the lathe spindle to act as a "Poor mans" A axis (rotating in parrallel with the X), then you can use Mill, and you can call the lathe spindle A, B, or C, what ever you want. Just make sure that what ever CAM software you use (assuming you use it), you modify your post processor to write to the "Lathe A axis".

Later,

Scott

[Al_The_Man]

Originally Posted by PoppaBear10 On the other hand if you using the lathe spindle to act as a "Poor mans" A axis (rotating in parrallel with the X), then you can use Mill, and you can call the lathe spindle A, B, or C, what ever you want.

Agreed you can call the axis what you want, but in the cartesian coordinates system, the A would revolve around the X, on a lathe the chuck revolves around the Z so by convention it would be C.
Al.

[Big Noodles]

Thanks that's what I needed to know.

One more question if possible.

I noticed on my mill head that the far end is supports by anditional piece of bracketry with a locking mechanism, spinning wheel with arms.

If I automate the mill head how to I go about reinforcing the structure such that the Z axis can freely move up and down, without me having to go over and lock it in it's final position.

I don't know if this is clear or not.

[PoppaBear10]

In reply to "Al the mans" post above, I would say by definition, if your gonna use Mach Mill to run your lathe spindle then in the cooresian coordinate system under the MILL functions. the Lathe spindle would be the CLassic "A" axis since it would rotate in parrell along your MILL X axis. On the other hand if you added another axis to Mach Lathe then Al the mans def above would be correct.

My assumption was, that you were wanting to use the lathe spindle as a A axis under the mill functions.

On to your next question:

How much do you want to fool with it? You can automate the Mill head raise and lowering via a moter (see Bloy's machine), you can even put a switch under the 5th arm to disable the raise/lower drive so you can only operate it if the 5th arm is unlocked. Now for full automation, you can then also add another geared down motor that would turn the locking spindle. Further, all of these functions, could also be controlled from a Macro in Mach Mill that would pass information to a PLC to do the job, OR, you could just have a PLC stand alone to do the job. You could even set mill head hiegth settings via, selector switch or again via Wizard/macro in mill.

You could also replace the 5th arm locking spindle with a powerfull electro-magnet that would switch on/off when you are hitting the up or down hiegth button.

Like all things, it will depend on how much, time, money, and inginuity you want to drop on your machine.

Scott

[borrisl]

I'm new as well and doing just what you want. Upgraded the motors to 2hp and 1 vfd. They operate independant, so I have a switch that powers some three phase relays. This allows switching from mill to lathe mode. Each spindle has an optical pulse index on it to cordinate rpms for threading and tapping. The VFD unit controls rpm 1-motor max. Be prepared to spend about $2000.00 for this type of conversion. + if you don't have CNC steppers/controllers/drivers/.... plan on another $1000-1500. All in all, your going to be spending upwards of $3000.00 to make this all happen. In the end you have a very capable machine.

Time wise.... I'd plan on a good 40 hours of your time to convert, install, and calibrate. I'm still not completely done yet because I'm converting to gates poly belts (looks like a timing belt in your car), so additional adapters and bearings have to be made.

On your bracket thing. I'm not quite clear, but it sounds like you have a "quadralift" or something similar. They really are pretty stout. As far as re-inforcement, I doubt you need much. I'm trying to figure this one out too. So far as I can guess, to re-inforce the mill head for a more rigid mount you need more weight. It's a matter of physics. More wieght equals more energy to get momentum. I could be wrong. I've been playing with the idea of adding additional dynamic weight to the mill head via water containers or lead.

Hope that made some sense. Good luck.

[FPV_GTp]

Originally Posted by borrisl I'm new as well and doing just what you want. Upgraded the motors to 2hp and 1 vfd. They operate independant, so I have a switch that powers some three phase relays. This allows switching from mill to lathe mode. Each spindle has an optical pulse index on it to cordinate rpms for threading and tapping. The VFD unit controls rpm 1-motor max. Be prepared to spend about $2000.00 for this type of conversion. + if you don't have CNC steppers/controllers/drivers/.... plan on another $1000-1500. All in all, your going to be spending upwards of $3000.00 to make this all happen. In the end you have a very capable machine. Time wise.... I'd plan on a good 40 hours of your time to convert, install, and calibrate. I'm still not completely done yet because I'm converting to gates poly belts (looks like a timing belt in your car), so additional adapters and bearings have to be made. On your bracket thing. I'm not quite clear, but it sounds like you have a "quadralift" or something similar. They really are pretty stout. As far as re-inforcement, I doubt you need much. I'm trying to figure this one out too. So far as I can guess, to re-inforce the mill head for a more rigid mount you need more weight. It's a matter of physics. More wieght equals more energy to get momentum. I could be wrong. I've been playing with the idea of adding additional dynamic weight to the mill head via water containers or lead. Hope that made some sense. Good luck.

hi borris and other fellow members in this thread

just curious how ur project is coming along and did u document it in CNCzone.com

as i have just purchased two HBSA type copying lathes for a very good prices other wise they where going to be scrapped

i have plans for these lathes and reading this thread just gave me more ideas. The lathe has a gantry over the bed which im sure i can put a milling head on it and see what happens

would appreciate any help guys

cheers

[borrisl]

I have some documentation myself, but haven't configured it into something cohesive. I will though. You can save yourself alot of time buying pre-built, but save alot of money doing it yourself. Since I know nothing, starting from nothing is a good place to start.

I'll be posting photos in the near future.