The E-Mail

On March 11th,1998 E-Mailed most of the major Carbide tool vendors asking them what they recommended for home shop use.  This is the text of that letter:

This is probably one of your more unusual requests. I'm a Home shop (read hobbyist) machinist. One of the big questions in the hobby is "Why Carbide tooling". I've tried to answer this as best as _I_ can on my web page (, but I'm looking to  add
more information (a link to your web page will be added tonight).

Is there any information you can give me that I can post? The unique problems we face are:
1)Low horsepower machines - 1/2 HP and 3/4 HP are common
2)smaller lower rigidity machines - a Southbend 10k would be a common machine, a Heavy 10 would be in the rigid class, Atlas 10 and 12" machines are common
3)Limited spindle speeds - a machine with a 1000 RPM spindle speed is common, 2000 rpm is high
4)Limited production - Most of our work is one offs (although some of use do sometimes do some light production for $$), and materials can differ from one piece to the next. One minute, your cutting 360 Brass, the next 6061Al, then 12L14 steel, then O1 tool steel - you get the picture
5)Limited budget. Most of us will go through 4-12 inserts a YEAR, and we are doing this for FUN. Stocking ONE or at most 2-3 kinds of inserts (a few more maybe if we can find someone to beak a box for us) is a goal.

So, what do YOU recommend? On my web page I recommend Positive rake tooling (say a TPG-22x) or and ISO positive rake tool, with a coated carbide (PVD Tri coated). We seem to be able to get away with cutting AL and Steel with this, but at somewhat degraded speeds, but this isn't a huge problem given the spindle speeds I've list above.

Thanks in Advance


The Responses

Over the next few days, I got replies from most of those vendors.  Here is what they had to say


Thank you for your inquire into Kennametal. Due to your tooling limitations, I recommend using grades KC730 a PVD TiN coated or KC850 a tri-phase CVD coated inserts. Both are great general purpose grades which will be  helpfull in the variety of material you machine. If we can be of any more help please call (800)xxx-xxxx or e-mail us.


From: FirstName LastName, on 3/12/98 4:10 PM:

Hi, I'm with Valenite Cutting Tools, FirstName LastName from Cincinnati Milacron asked me to respond to your request for information.

I understand the challenges the home shop faces with regard to using carbide tooling. The advantages of carbide vs. hss are well documented for large shops and hi production and the same can be said for home shops but cost is a big concern for the hobbiest.

I agree with you in your selection of TPG or ISO positive rake type tooling  with respect to rigidity and horsepower limitations however both are single  sided inserts which are not the most economical choice. Fortunately a lot  of progress has been made in the last few years in the chip groove geometries found on negative inserts (cnmg, tnmg , etc.). These  "chipbreakers" can produce positive shear angles in negative rake tooling which reduces tooling pressures and horsepower requirements in a double  sided insert. This combination of geometry and economy may be advantageous   for the home shop.

Valenite offers a grade we call VC901. VC 901 is PVD TiN coated C1 micrograin carbide which cuts a wide variety of materials at low speeds and has good edge strength for low rigidity applications. One insert we have, for example, is a TNMG 322 GF available in grade VC901. We offer a 5/8" square shank holder, MTGNR 10 3B which will hold the TNMG322 style insert.

The "GF" chipbreaker has an application range of .010 - .125" depth of cut and feed rates of .006 -.016" per revolution and produces a 7 deg. positive shear angle when used in the holder mentioned previously, plus the insert can be used on both sides.

I hope this info helps out.

Best Regards,


Toshiba Tungaloy

From:     FirstName MI. LastName []
Sent:     Friday, March 13, 1998 11:05 AM
To:     Gallo, Charles A. MS
Subject:     Re: Carbide Tooling for the Home Shop

I agree yours is a unique request. I also agree that using a positive style (ie. TPG) insert is the best for the situation that you are describing, however I do not think using a coated grade is best. The applications that you have such as slow cutting speeds, a variety of materials from steels to aluminums and low production really better lend themselves to a normal C-2 or C-5 type uncoated carbide. The only other infor that I can give you is the Toshiba Tungaloy grade
for a C-2 is called TH10 and C-5 is UX30. If I can help further please E-mail me again and thanks for visiting our web page.

So, there you have it, what 3 different companies recommend.  What is interesting is that 2 out of the 3 say to use coated carbide, but one does not.  The other interesting thing that Valenite points out is that you can get negative rake tooling that has an effective positive rake at the cutting edge