+- MetalworkingFun Forum (http://www.metalworkingfun.com)
+-- Forum: Machining (http://www.metalworkingfun.com/forum-5.html)
+--- Forum: How-To's (http://www.metalworkingfun.com/forum-8.html)
+--- Thread: Parting on the Lathe (/thread-1886.html)
Parting on the Lathe - TomG - 12-07-2013
Here are a few tips to help take some of the heartburn out of the parting operation.
Tom
RE: Parting on the Lathe - PixMan - 12-08-2013
Well done Tom.
I've rarely been able to use HSS cutoffs successfully, despite having a rigid QCTP, strong blades and good alignment. You made it look easy!
I gave up fussing years ago and just went to a carbide insert parting tool. I've taken videos of it working, but without any treatise on setup and the do's & don'ts.
Do you have any insert parting tools that you could use to go through the same thing, but with higher speeds and using power feed?
RE: Parting on the Lathe - TomG - 12-08-2013
Thanks Ken.
It actually is easy when everything is properly set up. Unfortunately all it takes is one of the points I covered done wrong to make the whole exercise go bad. I have been thinking of trying a carbide insert parting tool because parting seems like a good application for inserts for the type of work I do. BTW, you don't have to use a carbide insert to use power feed. I was using power feed in this video.
What speed would you use with a carbide parting tool on mild steel?
Tom
RE: Parting on the Lathe - Shawn - 12-08-2013
Hi Tom, you will probably never fully understand what a great help your videos really are. I watched your video on cutting internal threads on the Atlas lathe in my shop right before cutting the internal threads on a spindle thread protector I was making. I couldn't imagine how much harder learning all this would have been prior to the internet and folks like you who are willing to share their knowledge online. I'm begging you to not burn out making videos : )
Any thoughts to having something like an "Ask Tom" section on your website where you could post commonly asked questions and answers? Wouldn't be as onerous as a forum and might generate some interesting video ideas and could end up being a great resource for newbies, like me. Just a thought though, the website is awesome.
Shawn
RE: Parting on the Lathe - PixMan - 12-08-2013
(12-08-2013, 12:19 AM)TomG Wrote: What speed would you use with a carbide parting tool on mild steel?
Tom
On an open lathe I've got to keep it lower than I would on an enclosed CNC. I have several different widths, from 1.5mm to 5mm. The deeper I have to go and the tougher the material, the wider (and stronger) a tool is required. Generally I don't use coolant or oil because it's over so quickly.
My "go to" width for probably 70% of my cutoffs is 4mm, but that's for work over 1" diameter. I use the little 1.5mm one for small diameters and thin walls to minimize burrs.
As for cutting speeds, I try to get above 200sfm in most materials, but not much more than 500sfm. Of course I don't have constant surface speed on my old lathe as a CNC or a Monarch 10EE might have. This means you start at a given speed but are down to "zero surface feet per minute" at the center.
Here's a short demonstration of cutting off 1-1/8" diameter 1117 with a 4mm cutoff. I start (and end) at 1200 rpm, which works out to abut 350sfm. Feed rate is set at .0057" per rev, and remember that depending upon machine feed per rev is generally half in cross feed as set for longitudinal.
Most home shop guys really should just learn to be successful with the HSS blades first, and your video helps immensely. Other instructional videos on that subject are all over the map on center height and grind. Yours takes the "black art" out of the process.
Investing in an insert cutoff is intimidating because of all the choices and the cost. There are single-ended and double ended inserts, spring clamp or screw clamp, and holders can be blade, monoblock or modular.
The big thing about carbide insert parting is to not be afraid of it and FEED the damn thing. Wider tools want to chatter and the natural tendency is to slow the feed. Do the opposite. The good quality carbide cutoffs can take it.
RE: Parting on the Lathe - TomG - 12-08-2013
(12-08-2013, 04:08 AM)Shawn Wrote: Hi Tom, you will probably never fully understand what a great help your videos really are. I watched your video on cutting internal threads on the Atlas lathe in my shop right before cutting the internal threads on a spindle thread protector I was making. I couldn't imagine how much harder learning all this would have been prior to the internet and folks like you who are willing to share their knowledge online. I'm begging you to not burn out making videos : )
Any thoughts to having something like an "Ask Tom" section on your website where you could post commonly asked questions and answers? Wouldn't be as onerous as a forum and might generate some interesting video ideas and could end up being a great resource for newbies, like me. Just a thought though, the website is awesome.
Shawn
That's an excellent idea Shawn. I have been considering comments, but the "Ask Tom" idea sounds better yet. I'll talk to my webmaster son and see how to set it up.
Tom
RE: Parting on the Lathe - EdK - 12-08-2013
Tom,
What brand is that cutting oil you used? It's getting hard to find sulfur based cutting oil.
Ed
RE: Parting on the Lathe - f350ca - 12-08-2013
Great video Tom, as always you make it look easy.
RE: Parting on the Lathe - TomG - 12-08-2013
Thanks for the info Ken, and the demo. You would never get away with a cut like that without coolant on HSS. There is just too much tool in contact with the work. You are also right about the feed. The natural tendency is to be timid after you've been burned a few times, but faster is usually better.
Tom
RE: Parting on the Lathe - Micktoon - 12-08-2013
Hi Tom , thanks for another great video , like Shawn says you and others who take the time to make this type of video are really helping the homeshop type guy that is starting out in his own shop trying to make things
So once again
I also thought Shawn's idea of an ask Tom type section is good and glad to see you thought it was good idea too.
keep up the good work
Cheers Mick.