Grinding parting tool from square HSS

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martik777

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Rather than purchase a dedicated parting blade I was thinking of grinding my own like the photo below. I see no reason it should not work just as well, if a large enough blank is used, say 4" x 3/8 x 1/2 high and one would not need a special holder for that thin blade.

I have ground 1/4, 5/16 grooving tools that were used for partial parting of small diameters (< 1/2" CRS) without issue.

Would like to hear of others' experiences...

Parting_tool3.jpg
 
No reason in the world you can't do that. Just keep it cool and the rest is up to you. Done it many times.
 
I have many tools ground like that. If you want your tool to NOT leave a teat on the part you are cutting off,grind a slight angle on the end of the tool. Looking straight down on the tool,the right hand edge should stick out a bit more than the left hand side of the angled edge. That way,the teat will be left on the stock,not the part. You can just advance the tool some,to cut that teat off too,if you wish.

These small cutoff tools are great for making small brass turnings. You don't want to waste 1/8" of brass cutting off. I make as many as 130 brass bezel cups at a time for my wife's jewelry master models. I use a very narrow cut off as they are made of 1/4" rod,or smaller,and it saves several inches of brass,which is expensive enough these days.
 
I had one ground just like yours that I used in the 4-way tool post on my 9" SBL for many years. Like Mr. Wilson said, "just grind the front edge at a slight angle to not leave the little "tit"" always worked for me.
 
4gsr said:
I had one ground just like yours that I used in the 4-way tool post on my 9" SBL for many years. Like Mr. Wilson said, "just grind the front edge at a slight angle to not leave the little "tit"" always worked for me.
Click to expand...

I hate those little ****,,,now BIG ones are a totally different story!!!
 
So, other than for convenience there's no advantage buying a dedicated HSS parting blade? I have seen some are ground with the cutoff end on the left near the chuck and some in the middle. Is there much difference in strength either way?

George:

I found a great source for free/cheap brass - Discarded brass fireplace toolsets at garage sales or just at the curb on garbage days lol. Those rods in the pic are 1/2" , too bad they twisted the ones in the center.

brass_toolset.jpg
 
martik777 said:
So, other than for convenience there's no advantage buying a dedicated HSS parting blade? I have seen some are ground with the cutoff end on the left near the chuck and some in the middle. Is there much difference in strength either way?
Click to expand...


Advantage goes to the offset left cutting edge as it gets you closest to the chuck or collet.
 
The advantage of a dedicated parting tool is: They can stick out much farther and cut off larger diameters.

I have yet to find a SOLID brass fireplace set!! I must meed to find a better class of thrift shop to look into.
 
I was lucky enough to get a few of these style parting tools in a lot I bought from a retiring old-timer. I'd like to make some more though. I havent heard it mentioned before, But is it OK to grind HSS bits with my 4.5 inch angle grinder with a fiber type wheel and then use a bench grinder stone to finish it off? Seems like the mass of the metal could be removed quicker that way? Todd
 
Doesn't really matter what you grind it with, as long as you have the control you need, and can keep it cool.
 
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