Cutoff or Parting Tool Blade Warning

[Rich Carlstedt]

Well, I was really surprised by a recent purchase of blades for my parting tool.

First I have to admit I am not a fan of "most" of the foreign tooling ( love OSG !) and seldom buy it.
Recently I needed a .062" x 1/2 parting blade and was quoted 40 bucks American or 18 dollars Chinese
for a cobalt tool, and so took a fling at the Chinese version. What a mistake !

I have enclosed two pictures to show newbies what I am talking about.
It is very important for tool bits to have relief on the sides of the toolbit.
Parting tools come in several forms.
Type "S" tools have both sides tapered , and sometimes the top is also
Type "T" or "P" tools are T shaped and they have a relief on the T top only, and straight sides on the lower portion.
Look at your tool holder. If it has a slight angle bottom to top, it is for a type S toolbit
If your tool holder has a horizontal slot at it's top, it is made for a T or P

So the new parting toolbit I got was a T shape....but had no relief in the upper section as required in order to reduce friction and not jam.
In the picture, the caliper jaws ( which are parallel) close on the blade top and no light is visible showing relief.
My complaint/problem to the vendor was honored , so I have no complaint with them.
However I was shocked last night when I went to our local Tech College where they also have evening adult machine shop classes.
In showing the Instructor my purchase, we went and looked at the schools parting tools......and every one had the improper T cross-section !
Also the sides of the top portion of the different size blades showed severe abrasion/rubbing.
I can only say..be careful ...reject inferior blade construction....and maybe that's why your last cutoff operation failed !
The company that I use to purchase from in Michigan has folded up, so I am looking for decent blades.

Rich

[Doozer]

Reason to own a surface grinder.
-D

[PixMan]

Reason to own a surface grinder.
-D

Not really.

Reason to own a carbide insert cutoff and never have to deal with such problems again.

[Rustybolt]

Any body else remember the good old days when that's how they came and you had to grind the relief yourself.

[Doozer]

Not really.

Reason to own a carbide insert cutoff and never have to deal with such problems again.

Thumbs up!

--D

[loose nut]

I have obtained (a couple of years ago) the P type blades from Wholesale tool in Detroit and haven't had any problems with them. Production Tool also in Detroit will have something similar. Worth looking at there sites.

http://www.wttool.com/

http://www.pts-tools.com/cgi/CGP2HOME

[Black_Moons]

Any body else remember the good old days when that's how they came and you had to grind the relief yourself.

Never owned one that came with relief ground in. Besides, you have to grind down the sides of the cutoff blade to have proper relief anyway, how far you do that determines how far you can stick the blade out, and how much you will have to cut off when it wears and you sharpen past the unreliefed section.. or it snaps.

[PStechPaul]

Even my cheap HF mini-lathe parting blade has tapered side relief, as well as a bevel on the bottom to lock it into the toolholder. But too bad the blade slipped back into the holder and it broke, but the blade is still OK.

[wierdscience]

The company that I use to purchase from in Michigan has folded up, so I am looking for decent blades.

Rich

Good luck,I bought some CTD ones $40 that were made in Mexico,poor grind and magnetic right out the box.Also bought some Latrobe,also imports,but from Bosnia,those were pretty good,but still cost a fortune for what they are.Your best bet are NOS on Ebay.

Like several others though I went to inserted parting tools years ago. I am particularly fond of Widia Manchester CNC styple parting tools.-

http://www.pdqtool.com/binder/a/at4a.html

Both the top clamp and anvil are replaceable and a variety of parting inserts are available.

[LKeithR]

...Reason to own a carbide insert cutoff and never have to deal with such problems again...

Absolutely!!

[alanganes]

:

Not really.

Reason to own a carbide insert cutoff and never have to deal with such problems again.

Thumbs up!--D

Can't I have both??

PS - before I got done reading the OP, I KNEW PixMan would chime in on this. And I have to agree. He set me up with some good info on the whole parting off thing, and it made a world of difference for me. He's right...

[Rich Carlstedt]

Good luck,I bought some CTD ones $40 that were made in Mexico,poor grind and magnetic right out the box.Also bought some Latrobe,also imports,but from Bosnia,those were pretty good,but still cost a fortune for what they are.Your best bet are NOS on Ebay.

Like several others though I went to inserted parting tools years ago. I am particularly fond of Widia Manchester CNC styple parting tools.-

http://www.pdqtool.com/binder/a/at4a.html

Both the top clamp and anvil are replaceable and a variety of parting inserts are available.

Thanks Weird !
I was looking for something like your suggestion.

The problem with the inserts is DOC.
Sometimes I get pretty deep into the material and HSS cutoff blades allow deep penetration
I also do many odd widths , so I have an assortment of HSS 3/8" tool-bits ground to sizes, like .040 and.050, but they are limited to .500 DOC

I am confused -if you don't mind helping out
The spec shows .75 max DOC, and the holder shows .125" min width, yet the inserts go down to .060 ??
Is the thinner insert a shorter DOC ?
Rich

[wierdscience]

Thanks Weird !
I was looking for something like your suggestion.

The problem with the inserts is DOC.
Sometimes I get pretty deep into the material and HSS cutoff blades allow deep penetration
I also do many odd widths , so I have an assortment of HSS 3/8" tool-bits ground to sizes, like .040 and.050, but they are limited to .500 DOC

I am confused -if you don't mind helping out
The spec shows .75 max DOC, and the holder shows .125" min width, yet the inserts go down to .060 ??
Is the thinner insert a shorter DOC ?
Rich

Rich,the thinner inserts will not work with those holders as the support blades are a fixed width.The widths you mention I am not sure can be had in a deep grooving insert holder.As you probably know once you get past 4x the width on a grooving tool you are in uncharted waters.The last time I did any deep grooving in the widths you mention I cheated and used the rotary table and jeweler's saw in the mill

Even though these won't be of help for the narrower grooves,they are still worth having.They handle 90%+ of all parting chores and makes the task almost effortless.I find them on sale in MSC and on Ebay fairly often $50-60 will often times land a holder and a pack of inserts on Ebay.

[Carm]

Rich
You could have a look at Belcar Products for carbide.

[JoeLee]

I've noticed that my older T shaped cut off blades had a factory taper ground into them. I recently bought a few new (China) ones that do not.
My solution was to lay the blade down on the grinder with a .005 piece of shim stock under the bottom edge and put the relief on both sides of the T.
As mentioned........ carbide inserts are the way to go, but sometimes you may need to cut a groove at a specific width so the blades come in handy for that.

JL............