Writing Parting Off Sequences with G-Code on CNC Lathes

In this video, Marc from @gcodetutor continues this series of programming a complete part using G-Code.
This episode he talks about writing a parting off sequence.
Using constant cutting speed, a G50 speed clamp must be used so the spindle does not reach dangerous speeds as the tool approaches the centerline of the part.
Marc likes to rapid in using two lines of code instead of one. This does not affect the cycle times by more than a few milliseconds but does help with running the first part safely. By using this method, we can see the tool approach the material when in single block and without going too close to the material. If the tool is not set up correctly, we can see this before anything bad will happen.
As we continue to use point-to-point G01 to part off, Marc explains why he rapids the X-axis out of the way first before returning to the machine datum. If the tip broke during the parting off procedure and the part is still attached to the stock bar, the parting blade will break. As always, keeping things as safe as possible within our programs is our main priority.
Remember that G-Code can vary between machines. The code in these videos should only be used for reference and not typed into your machine and expected to work without issues. Marc teaches a generic version of G-Code that can be easily adapted to your machine after a quick reference of the machine's programming manual.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If you want any more information about these codes or other G-code information, head to
Website: gcodetutor.com/
Facebook: / gcodetutor
Twitter: / gcodetutor
UA-cam: @GCodeTutor
Pinterest: www.pinterest.co.uk/gcodetuto...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Practical Machinist is the largest and most engaged #metalworking community across the web. With more than 200,000 registered members and 400,000+ social media followers, Practical Machinist is the easiest way to learn new techniques, get answers quickly, and discuss common challenges with your peers. Visit Practical Machinist today to join the community and start connecting with your peers.
Become a Practical Machinist member (www.practicalmachinist.com/)
Like us on Facebook ( / practicalmachinist )
Follow us on Instagram ( / practicalmachinist )
Follow us on Twitter ( / prac_machinist )
Follow us on TikTok ( / practicalmachinist )
Connect with us on LinkedIn ( / practical-machinist )
#machining #cncprogramming #gcode

[@TrPrecisionMachining]

good video..thanks for your time

[@szaboandras74]

If your part is 316 stainless steel or some other tough material that is somewhat difficult to break chips from cutting off or grooving, this method will give you a lot of chip wrap and can give you problems such as coolant not shooting to the cutting tip or the part not falling into the parts catcher. It can get a little scary watching. I started using the peck grooving method. My machine uses the G75 code for peck grooving in X and G74 in Z. The chips come flying off in smaller manageable lengths and the cutoff surface is flatter. I go with a fixed rpm (G97) because in G75 the tool goes back to the original start position after, but if you have a reasonable max speed in your G50 then G96 should work too, but it is not a good idea to have a high rpm when you only have .100 left to cutoff. My program example: Go to start position of cutting off- G75R20 (.002 retract), G75 X-.02 P50 (.005 per peck) F.002. You need 2 lines for the G75. You can easily adjust the peck amount and the retract amount and find the perfect spot for your material. I use this for most of my O/D grooving and face grooving because of the great chip control you have.

[@CNCMatrix]

I've never had a problem with 300 series stainless steel breaking chips, not once in 20 years of machining. You get into the non hardened 400 series it's a problem. Stringy chips that wrap around the conveyor and of you push the speeds and feeds it distorts the part or burns the tip off the insert.

[@DJ-yp4kc]

do you cover Tail Stock Clearance and leaving the Tail Stock Stationary during Running a Program, so it wont return home during a Tool Change