Cutting from Chuck toward Tailstock question?

[FastVette]

Hi Everyone,
I'm new to CNC and recently purchased a HAAS ST-10 Lathe.
I am cutting the OD profile on 3" dia PVC plastic.
As the cutting starts at the face and heads toward the chuck the plastic piles up
against the chuck. I have to keep pausing and removing the wound up plastic that is cut. I was thinking if I can run the program in reverse cutting from the chuck toward the tail stock the cut plastic would just get pushed of the end of the work piece.
Any advice on how to run the program the opposite way would be very helpful.

Thank you in advance!
Christian

[Jim Dawson]

Try Back to Front cutting, normally an option in your CAM setup

[deadlykitten]

hy if you wish, i can help with generic code

also, if you cut towards z+, is ok to reverse coolant noozles, as to not opose chips evacuation direction; may be plastic, but is not a must to cut it dry

another trick to break chips, is to peck turning, like breaking a continuous motion into small segments / kindly

[FastVette]

Hi Jim,
Thanks for you suggestion!
I'm not using a CAM program. I made the Program using the VPS and Shape Creator software that is the HAAS software on the lathe. It was very helpful since I am just starting out and don't know how to write code yet. Maybe I need to see if it has the Back to Front cutting somewhere in there.

[FastVette]

Hi deadlykitten,

Thank you for the offer. I am using pecking for grooving and part off but I didn't see that option for regular cutting.I am not running coolant. Not yet anyway. How do we go about writing a generic program?
Christian

[deadlykitten]

hy vette just g-code; pls share a drawing; do you need help for roughing, and/or fininshig ? because there may be different aproaches

sometimes, in plastic, the coolant jet can throw the chip away from the part

to make the code more hass-like, i need a hass sample / kindly

[FastVette]

Hi deadlykitten,

I like the Coolant idea! That might just be what it needs to solve the problem. I am going to get that set up and give it a try.
Thank you,
Christian

[g-codeguy]

What control is on your Haas? Nothing says a G74 peck cycle (on a Fanuc) for drilling or face grooves can't be used for turning. However, it will increase cycle time if that is important.

I did it on the first Swiss lathe we bought a few years ago. Chips were balling up big time on the rough turn.

Example turning a .750 diameter by 1.5 inches long using the G74 Fanuc cycle.

G0X.75Z.03
G74R.003
G74Z-1.5Q1000F.003

Q is the distance it turns before backing up .003 (R.003). The only problem with this is that the tool rapids back to Z.03 without withdrawing from the part. It was of no matter to me since I was using the cycle to rough turn. Using the cycle to finish turn with may very well leave lines on the O.D. I can almost guarantee that.

Personally I would try to find a different way than using a canned cycle to finish turn.

[deadlykitten]

However, it will increase cycle time if that is important.

hy g-codeguy good idea if control allows, you can ignore returning to start point by specific M code, so there will be no time loss because of replacing a turning cycle with a drilling cycle

but time loss, may occur anyhow, on setups where pecking is needed to break turning chips, not drilling chips : the difference is that on tuning setups, pecking is more dense, thus occurs more often among same z travel; for example, to break chips :
... when drilling 20 mm depths, maybe there is 1-2 or 5 pecks
... when tunring 20mm long, peck may occur at each 2 milimimiters ( for example ), or sometimes, at each spindle revolution, if not more than once / spindle revolution ( this is a low frequency vibration function, just in case it matters )

so, the higher the pecking density, the more chance for the cnc to not to be able to reach programmed feed; in other words, time loss may occur because of motion succumb; a quick fix is to increase feed, but in most cases, is good enough if chips breaking occurs / kindly

[g-codeguy]

I am not aware of an M-code on a Fanuc control that will ignore returning to the starting point when using its canned cycles. Please list the M-code so I can give it a try. Thanks.

[deadlykitten]

i don't know fanuc / but i'll give you an okuma M even so, i don't use it ... to cover more needs ( like aspects that a cycle can not deliver , etc ) i simply generate custom code

for example, imagine a looong z travel, which requires a long time to be machining, like big shafts; one pass may require 15 minutes, etc ... if there is a failure 7mm before end point, then is a timewaste to start that pass all over again, while in reality is needed to position near those last 7mm

over it, add a situation where chips don't break so voila, there is a need for non standard aproach / kindly