Does anybody else grind lathe tools this way?

[Frank Ford]

Over the years I've gotten lots better at offhand grinding of HSS lathe tools, but lately I've been thinking of making a setup for my grinder to be a bit more precise. Then, this morning I hit on what I suppose is a relatively obvious idea. Why not grind the end of my cutoff tool right on the lathe so I'd be dead sure of getting it precisely square to the work? So I stuck a white wheel in an arbor, raised the tool well above center, moved along the Z axis and dusted off the end to get a nice sharp perfectly square cutting edge:



I keep that rubber sheeting on the lathe, so I didn't have to set up any special grinding dust protection.

 

[GK1918]

Wicked idea, im already thinking of jigging up for my 60* threading which will be way more accurate. thanks

 

[Tony Wells]

I've thought about it, but like Paddy, see a few issues with it. And this presumes you have it dead square with the axis of the lathe.

But, if you get the results you want, no problem! That's what it's all about.

 

[bvd1940]

I dont like the idea of grinding on MY lathe that crap get,s everywhere.:nono: Just my 2 cents worth but it aint worth much

 

[jgedde]

Cool idea, but be careful. While your technique ensures the cutting edge is parallel to the work (not always what you want), it doesn't guarantee that the cutoff tool is perpendicular to the work - this is a necessity.

I don't always grind my parting tools so the edge is parallel. I often put a slight angle to help ensure minimal or no tit on the cut off and still allow me to continue the cut after the part falls off to face the remaining tit off the piece still chucked. If it's a deep parting operation, I'll go for parallel and rely on the hollow grind on the P-blades (like you're using) to achieve chip control.

Nontheless, your idea did not ever occur to me and might have other cool applications.

John

Over the years I've gotten lots better at offhand grinding of HSS lathe tools, but lately I've been thinking of making a setup for my grinder to be a bit more precise. Then, this morning I hit on what I suppose is a relatively obvious idea. Why not grind the end of my cutoff tool right on the lathe so I'd be dead sure of getting it precisely square to the work? So I stuck a white wheel in an arbor, raised the tool well above center, moved along the Z axis and dusted off the end to get a nice sharp perfectly square cutting edge:



I keep that rubber sheeting on the lathe, so I didn't have to set up any special grinding dust protection.

 

[flutedchamber]

A small grinding wheel would hollow grind the cutoff bit. This could weaken the cutting edge. It wouldn't work for my lathe, even at 2500 rpm it's way too slow for grinding, not to mention the grit.

 

[Frank Ford]

Too slow for grinding? Jeez, I was spinning it at about 400 rpm, and that was PLENTY fast enough. Remember, I'm only dusting off those last few thou from the cutting edge, not profiling a 1/2" square piece of HSS.

Most recent job was a nice .170" groove in a brass rod, using my 1/8" parting blade. Grinding the tip made it perfectly square to the work, quickly and easily.

As to the dust - well, I mentioned that I always keep the rubber shroud on the lathe ways, because I often do a bit of wood turning, so no grit gets on sliding surfaces. For that matter, the way wipers hardly ever see even little metal chips. Even with tool post grinding and tool sharpening, there's no chance of me putting significant wear on this machine in my lifetime I keep things really clean.

 

[bvd1940]

Not bad mouthing you on the grinding on the lathe, I just dont do it, I have a old beater lathe set up for just grinding.
Other point is I offhand grind my bits (I be old school) but am in the process of setting up a diamond lap to hone carbides for optimum cutting edge.
Whatever works for you is great) and setting up lathe to just grind parting tool takes longer than to go to grinder and touch up bit:biggrin:

 

[basalt]

Yep, I do it all the time because I don't have an offhand grinder, speed is not a problem nor is the dust as I cover the bed with a wet paper towel and clean up really well after. Also as for having an open wheel just be aware and careful, a lot of the shops I worked in didn't have guards.

 

[Rbeckett]

Frank,
I love it!!! Dead nutz simple and as accurate as you ever cared to be. The rubber over the ways is also an excelent idea to elominate the grit getting under the cross slide and majing a mess too. Sometimes the simplest stuff works out the best. I am definately stealing this one and putting it in my bag o tricks too. Thanks for a great idea and an excelent implimentation of it!!!!
Bob