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Hand Ground Parting Tool Question

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Garththomas

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#1
I went to the store to buy a parting tool and holder for my 8" lathe but they had none, I came away with a 3/8" blank so I want to grind it for parting and grooving. I was thinking of grinding it for 3/4" depth, I haven't read anything specifically recommending a length to make it so can anyone help. By the way I just got my grinder today and made my first right hand cutter I tried it out just facing a bit of aluminum and then some steel, wow it blew the doors off the brazed carbide cutter I bought to get started so it looks like HSS all the way from now on.
 

mzayd3

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#2
If I were grinding a parting tool for 3/4 depth, I would make it about .760 inches. as little stick out as required for the application.
 

Garththomas

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#3
I was thinking of trying to grind it 1/8" wide and suppose its best to grind on one side so I will have an edge to keep parallel to and then grind the straight edge just a bit to under cut. So 3/8" x 1/8" x .760. Should be a lot of grinding but luckily I get paid by the hour :)
 

John Hasler

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#4
I was thinking of trying to grind it 1/8" wide and suppose its best to grind on one side so I will have an edge to keep parallel to and then grind the straight edge just a bit to under cut. So 3/8" x 1/8" x .760. Should be a lot of grinding but luckily I get paid by the hour :)
Use an angle grinder with a cutoff wheel to rough it out. Make sure that the tip is the widest point by a thou or two. I wouldn't go any narrower than .150" .
 

francist

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#5
Garththomas- That doesn't sound too bad. I have a 5/16" bit ground to about 0.070" wide by just over half inch long and it works dandy. I did all of the major stock removal on the side of the bit away from the chuck so I could tuck in tight up to a collet and part off. I also hollow ground mine as you are thinking of doing already.

-frank
 

Garththomas

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#6
Thanks for all the reply's I have some walther zipcuts I could try if it will speed things up a bit.
 

Bob Korves

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#7
I have been doing all my cut off work with a 3/32" (.090) T shaped HSS blade in a Phase II BXA holder. I extend the blade the minimum to do the work. It has worked great for everything I have tried so far. I just last week bought a stack of NOS brazed carbide cutoff blade blanks in case I need to cut off something too hard for the HSS. I will be making a similar holder to fit those blades. So far, I have had zero wish for inserted carbide cutoff tooling.
 

dlane

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#8
Haven't tried it yet but , thin kerf carbide tip saw blade
image.jpeg
When I run out of parting blades "prob never" might be worth a try
 

Garththomas

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#9
I have old carbide saw blades and was thinking of doing that once I get a holder but for now I'm actually enjoying grinding up one my self and I would have got it done today but duty called and I had to build a set of stairs for someone.
 

MarkM

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#10
You'll be better for it doing it yourself. I wouldn't be too worried about being so exact on your tool length. Make it long enough to be able to re sharpen with just re grinding the cutting edge and possibly used for a bigger diameter and one must never forget about length(tool stick out) and chatter. Concentrate more on your clearance angles.
 

Jimsehr

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#11
I hope you ground the brazed carbide tool before you used it.
Jimsehr
 
Last edited:

T Bredehoft

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#13
I hope you ground the brazen carbide

The commercial carbide notoriously is not 'sharpened," just ground. It may have no relief with no honed edges. They gotta be taken care of before use.
 

Jimsehr

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#14
Tom is right brazed carbide should be sharpened before use. I think that is why new guys don't like brazed carbide tools.
Jimsehr
 

Bob Korves

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#16
Sharp carbide is great for aluminum and other softer metals. It is not to good for some tool steels, interrupted cuts, and other difficult metals, because it will chip if ground to a sharp edge. Inserts are the same way, some are sharp and some are fairly dull, purposefully. Some are also cutting with a negative rake. The dull and negative tool can still cut just fine, just takes more power to drive it. It can still leave a good finish if done correctly on the right materials and using manufacturer's published methods on a rigid machine. For hobby machinists, sharp is often better. Yes, tool relief and clearance angles are important, and import carbide tools often are not even close to something that can cut, but are easily fixed with a green or diamond wheel.
 
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