Parting Difficulty

[tomw]

Just out of curiosity, when parting piece that far from the chuck can you use a follower rest to stabilize the part?

Thanks,

Tom

 

[JR49]

Just out of curiosity, when parting piece that far from the chuck can you use a follower rest to stabilize the part?

Thanks,

Tom

I would say absolutely yes, in fact it sounds like a great idea. But, as a newbee myself, I look forward to hear what the "pros" say

 

[randyc]

Just out of curiosity, when parting piece that far from the chuck can you use a follower rest to stabilize the part?

I've never heard of anyone doing it. Offhand, I'd be worried that if the parting tool started to dig in, the work would start to roll over the tool and be pushed out from under the top jaw of the follower and away from the rear jaw. Can't think of anything good resulting from that sequence of events, LOL

 

[gheumann]

Parting is an art. I have parted 2 1/2" aluminum and had many failures early on, until I learned that EVERYTHING has to be right:

1. tool on center vertically
2. tool perpendicular to work
3. good lubricant (I highly recommend "Tap Magic Aluminum"
4. proper speed - slower than you think
5. proper feed - enough to produce a steady chip
6. interrupt the cut more and more frequently as you get closer to the center, clear the chip, restart

BUT - because I need to do this a lot, I bought a cheap harbor freight metal cutting band saw. I prefer the saw!

 

[DavidL]

I am trying to part an aluminum rod 1.5" diameter using my G4000 9x19 lathe and a 1/8" HSS parting tool. I am getting loud growling sound with heavy vibration. I have tried Re-Li-On cutting oil, WD40. They help a bit but no enough to make the parting smooth. The tool height is adjusted to center height correctly. Varying spindle speed helped a bit but not enough. Any advice?

Thanks
Prasad

I have a Seig mini lathe and suffered the same problems with parting off. The mini lathe is just not sufficiently rigid. I then adopted reverse rotation with an upside down tool and have had no problems since. Check out this video which demosntrates the technique that overcomes the lack of mini lathe rigidity. https://www.youtube.com/watch?v=-RZRq0olsxM

 

[kingmt01]

Thanks for the video. This makes sense now. I have problems parting myself. I'm going to give this a try.

 

[Highsider]

I am trying to part an aluminum rod 1.5" diameter using my G4000 9x19 lathe and a 1/8" HSS parting tool. I am getting loud growling sound with heavy vibration. I have tried Re-Li-On cutting oil, WD40. They help a bit but no enough to make the parting smooth. The tool height is adjusted to center height correctly. Varying spindle speed helped a bit but not enough. Any advice?

Thanks
Prasad

Hi Prasad,
The problem you are having may have less to do with what I'm seeing discussed here than simply using the proper cutting fluid on aluminum. This material has a high propensity for galling between the chip and the work piece. WD-40 and cutting fluids that might work on other seemingly harder to machine materials are next to useless with aluminum. Go to your supplier for some cutting/threading fluid specifically designed for aluminum.

 

[MetalMuncher]

I used to have a very hard time parting 6061 aluminum on my mini lathe. I did not see any mention here of the fix I found (after much research) that makes it so much easier for me, so thought I'd share it here. Profile the top edge of your parting tool. Mine has an aggressive relief curve ground into it. I don't have time to post a photo at the moment, but I use a 1/2" wide, 0.060 thick parting tool blade, and the curve dips maybe 1/16th of an inch, so the curve appears profiled rather like the cross section of an ice cream paddle scoop. Together with the other suggestions of keeping a keen edge, on center, perpendicular, slow rpm, etc. it works very well for me now. Parting off a 2" rod is no problem at all. Hope this helps.

 

[MetalMuncher]

I found a PDF I made documenting this solution, so here it is. It has a photo of the ground parting tool.

 

[kwoodhands]

I am trying to part an aluminum rod 1.5" diameter using my G4000 9x19 lathe and a 1/8" HSS parting tool. I am getting loud growling sound with heavy vibration. I have tried Re-Li-On cutting oil, WD40. They help a bit but no enough to make the parting smooth. The tool height is adjusted to center height correctly. Varying spindle speed helped a bit but not enough. Any advice?

Thanks
Prasad

Start your cut, before you get chatter widen the cut to the waste side. This may be only 1/8" or much more depending on the material,diameter,etc. Wd -40 or paint thinner will aid in parting.Hone the parting tool. If you could part 1-1/2" in one setting then the parting tool would have to stick out from the holder 3/4"+. Keep the cutter at about 3/8".When the tool holder gets close then extend the cutter.Check for center height after you extend the blade. I use a 6" metal rule against the work and pinched with the tool.The rule should be vertical,not leaning when the cutter is dead center.Raise the cutter if the top of the rule leans towards you.Lower if the top of the rule leans away.
You only have to widen the cut enough so the cutter won't bind and heat up.Usually .010 / .030 is enough.
mike