Parting

[McGuyvers shop]

Hey, I need to know others experience with parting hard material, say H-13. I have a couple of HSS blade type parting tools that work pretty good on plastic, aluminum and mild steel, and recently purchased one of the grizzly kits that had the carbide inserted parting tool which is pretty nice, BUT, I still have a terrible time parting H13 material. It takes forever, and I'm not producing any "chips" per say, but only dust. I've heard different opinions on how to set the tool height. Do you set dead center, or slightly above, or slightly under? What works for you?

 

[Tony Wells]

Too high and the heel rubs. Too low and the work will try to climb onto the tool. It's hard to set sometimes because things are dynamic, not static. As you apply pressure to the work, generally, the tool will flex down a bit. More on worn machines. Also the counteracting forces push the work up. So in general, my thoughts are to try and outguess it and start a little high and use a fairly aggressive feed. That way during the actual cut, the edge of the tool is closer to on center. If the work is tubular, being below center won't cause a nib on the finished part, but being too low makes the edge appear negative rake to the work. Keeps the heel from rubbing, but risks the climb action. Harder material usually benefits from a slight negative rake, provided the tooling can take it. I am referring to carbide inserts for the most part.

You didn't spec the hardness or your particular machine and setup, so can't make any firm recommendations.

 

[DAN_IN_MN]

I'll be watching this thread as I too don't have much luck with my parting tools.

 

[McGuyvers shop]

Thanks for the info, Actually, after I posted I saw a list of the similiar threads at the bottom of the screen with tons of info, so I really didn't need to start a new post, only read some old ones. I have a 1933 SB 11" lathe that is a little worn. It had a lantern type tool post on it originally, but I made a block with a 5/8" slot on one side to hold the larger cutting tools, and a 3/8" slot on the other side to hold some of the smaller tools, It is pretty rigid and cuts great on everything except parting, then as you said, it tries to pull the blade under the workpiece and stalls the lathe, or "snap" breaks off the end of the tool.

 

[Bill C.]

Hey, I need to know others experience with parting hard material, say H-13. I have a couple of HSS blade type parting tools that work pretty good on plastic, aluminum and mild steel, and recently purchased one of the grizzly kits that had the carbide inserted parting tool which is pretty nice, BUT, I still have a terrible time parting . It takes forever, and I'm not producing any "chips" per say, but only dust. I've heard different opinions on how to set the tool height. Do you set dead center, or slightly above, or slightly under? What works for you?

My rule of thumb is don't extend the blade out to far. Usually about a quarter of inch beyond the radius of the part. Also check the height of the blade. (( If this your lathe make a height gage for this machine.)) What I did sometimes would move the blade to the end of the part (face) and take a light cut to see it the blade was the correct height. Good luck

 

[raross61]

My rule of thumb is don't extend the blade out to far. Usually about a quarter of inch beyond the radius of the part. Also check the height of the blade. (( If this your lathe make a height gage for this machine.)) What I did sometimes would move the blade to the end of the part (face) and take a light cut to see it the blade was the correct height. Good luck

Hi,

I hate to sound like a old nag, but again "Tubalcain" on you tube, has a bunch of videos on parting that I really learned a lot from! This guy has been around the block, and you can here him even hesitate about making a video on parting on these small machines! One more thing I can say is some of the guys running the mini lathes have a modified parting tool with a relief in the middle of it, I was curious if that might even enhance the performance on the 12X36 machines?

Just My 2 cents Bob in Oregon

 

[Ray C]

Bob,

On my 1236/BXA setup, I switched-over to the triangular style parting blades and never looked back. Here they are: Part numbers 404-1667 and 68: http://www.shars.com/products/view/3109/P3N_quotPquot_Type_HSS_Cutoff_Blade

Ray

Hi,

I hate to sound like a old nag, but again "Tubalcain" on you tube, has a bunch of videos on parting that I really learned a lot from! This guy has been around the block, and you can here him even hesitate about making a video on parting on these small machines! One more thing I can say is some of the guys running the mini lathes have a modified parting tool with a relief in the middle of it, I was curious if that might even enhance the performance on the 12X36 machines?

Just My 2 cents Bob in Oregon

 

[wrmiller]

I hate parting operations. My friend with his big 14x40 was always telling me you need a rigid setup, check tool height, check again, etc., etc., and HE didn't like doing parting.

I had to part a 1" bar a couple of weeks ago. What an absolute pain in the *&%.

Next time I need to do something that big, I'll just use a hack saw or my little chop saw.

 

[Ray C]

I'm not that crazy about it myself but once in a while, it's worth the hassle. Mainly though, I use it for shoulder grooving for external threading which only goes 30-40 thou deep.


Ray

I hate parting operations. My friend with his big 14x40 was always telling me you need a rigid setup, check tool height, check again, etc., etc., and HE didn't like doing parting.

I had to part a 1" bar a couple of weeks ago. What an absolute pain in the *&%.

Next time I need to do something that big, I'll just use a hack saw or my little chop saw.

 

[wrmiller]

I just remembered something my 'mentor' taught me: He made a tool holder that fit on the backside of the saddle for parting. He said that because the tool would 'lift' the part couldn't climb onto the parting blade. I thought it made perfect sense at the time.

As I have a slotted crosslide, making something like this shouldn't be a problem. Anyone see any problems with this idea?

Bill