Lathe multiple parts from one bar.

Kenre · May 10, 2020

SL3 Fanuc 3T.

Is there a way machine several parts from one bar without moving the bar or resetting program zero and resending it to the machine each time?

52mm ID chuck, 60mm OD Bar of 6262 Al. Each part is 13mm long. Hoping to be able to machine and part off several pieces. at a time.

Finegrain · May 10, 2020

You can simply model the multiple parts directly. It's inelegant, but it works.

Regards.

Mike

Delw · May 11, 2020

There are several ways to do it, best one being mikes way (above)
you can also us a shift xx amount of difference in sub programs, but if you screw up or hit reset your f'd and can crash.
if its just a straight id and od all you need to do is cut off, then do the i.d and o.d. to length and run your cut off tool for each part length
but if your new to lathe programing and running a lathe do it the old SAFE way feed to a stop hit the button make a complete part and repeat. Or program it all in like Mike says.
Ive done it a bunch of different ways in the past however, if you have other things running at the same time( multiple machines) and cant stay on that Particular machine do it one at a time,
I am assuming you dont have a bar feed and hoping to save time?

Kenre · May 11, 2020

Delw, No bar feed. Even if i did i dont think it would push a 60mm bar through a 52mm hole....

Bars that fit through the spindle i machine a piece, part off then move the bar the required distance and hit start again. Quick and easy with verniers.

These parts are tapered on the OD and ID. More to save material than time. Will end up with more stub material than parts doing them individually.

SeymourDumore · May 11, 2020

Does your control have multiple workoffsets like G55, G56 etc. ?
How about G52?

Short of that, I'll let the geriatric G10 proponents chime in.

Fancuku · May 11, 2020

Option 1 would be to use the same operations 6 times with G54 G55, G56, G57, G58 and G59.
Option 2 is to program it all. Assuming your partoff tool is 3mm and leave 1mm for facing, first part is Z0.0, second part is Z-16.0, third part Z-33.0, fourth Z-50.0, fifth Z-67.0, and so on to however many parts you can get out of the bar.

The stop method works too but I think it's more dangerous if the operator is not very experienced.

Kenre · May 11, 2020

Fanuc 3T, so im stuck with G50 only, that i know of.

tonymor · May 11, 2020

Is it the programming you're looking for help with or workholding?

Kenre · May 11, 2020

Programming.

Workholding i have no options. Piece of 60mm OD bar sticking out say 150mm should get 8 parts.

Scruffy887 · May 11, 2020

I run 2" bars through the spindle. Doing it for years and the full length of the spindle. I use spindle liners to keep centered and balanced. Most of my parts are finished by the sub spindle, but when it is chuck work I use the sub as a bar puller. That machine can fit a 60" bar completely in the spindle.

Finegrain · May 11, 2020

Kenre said:
More to save material than time. Will end up with more stub material than parts doing them individually.

Another option then, if you were planning on a 2nd op to clean up the backside, is to saw pucks that are part thickness + 1/8" + a little more for facing, and hold them with Versa Grips. They're like Talon Grips but for round stock. With my 4mm parting blade it ends up being about the same lost material. You have the added benefit of not having the first couple parts done "way out there" and maybe chattering.

Regards.

Mike

Finegrain · May 11, 2020

Kenre said:
Delw, No bar feed. [snip] Bars that fit through the spindle i machine a piece, part off then move the bar the required distance and hit start again.

I have an air plunger in my SL-2's spindle bore that pushes to a work stop in Tool 8. Lets me bar feed 3' bars. I can send you details if you're interested.

Regards.

Mike

Dan from Oakland · May 11, 2020

Are you already using G50 for your tool geometry offsets? If so just edit your G50 return move to shift position the amount you shortened your bar from the last part and rerun the program. Then on the last return move, add the shift back in and return to your original start point and advance your bar.

Or, use G10 to update you work shift for the next part if you don't want to mess with the G50. Since 3Ts are pretty basic I think those are your options. G10 is not the perfect solution but it will work.

chad883 · May 11, 2020

Cheap and dirty way would be to run 1 part off each chunk, then reset zero and run 2nd part off all chunks. Repeat as needed. Easy way would be to call you
r program as a sub program. I don't remember how your control wants the sub called, but something like this:

M98P1
G50W.5
M98P1
G50W.5
M98P1
G50W-1.0 (shift zero back to starting position)
M30

ChipSplitter · May 11, 2020

chad883 said:
Cheap and dirty way would be to run 1 part off each chunk, then reset zero and run 2nd part off all chunks. Repeat as needed. Easy way would be to call you
r program as a sub program. I don't remember how your control wants the sub called, but something like this:

M98P1
G50W.5
M98P1
G50W.5
M98P1
G50W-1.0 (shift zero back to starting position)
M30

Works, but can be a bit risky. i.e. stop the program in the middle for whatever reason and watch it kiss the jaws at cycle start.......
I would personally use absolute with G10, but I am not fluent in Fanucese.

Kenre · May 12, 2020

Thanks! gives me a couple of options. I will workout the easiest most foolproof way to suit.

Kenre · May 12, 2020

I can get 4 parts max before running out of memory.
This was having the code with the new Z position each time. Longhand, i better study up on G71 G70 etc to save memory

litlerob1 · May 14, 2020

ChipSplitter said:
Works, but can be a bit risky. i.e. stop the program in the middle for whatever reason and watch it kiss the jaws at cycle start.......
I would personally use absolute with G10, but I am not fluent in Fanucese.

How on Earth would that happen?

If you are incrementally shifting Z zero closer to the Chuck after each part, then reset, it's just going to go back to where the first part was.

R

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