HSS tool blanks

[Aukai]

My PM 1228 will be at Matt's shop soon for QC, and prep for shipping. Since the subject of HSS bits was brought up in the other thread, and I did not want to high jack it, here is my question. For the AXA QCTP, do you need, or should you have 1/2", and 3/8" blanks on hand, is one better suited than the other for jobs?

 

[mikey]

Either one will work, although the 1/2" bit will be stiffer. 3/8" will definitely work and will be cheaper, easier to find and quicker to grind. As long as you do not overextend the 3/8" tool, I do not see an advantage for a 1/2" tool. I have both and pretty much only use 3/8" tooling. Buy both and see for yourself.

 

[Aukai]

Good to know, one thought other than stiffer was that possibly able to tolerate/pull more heat out of the cutter, just guessing. Thank you....

 

[mikey]

Good to know, one thought other than stiffer was that possibly able to tolerate/pull more heat out of the cutter, just guessing. Thank you....

Hmm, no not really. You want the heat from the cut to go out with the chip and not heat up the tool. With proper side and back rake angles ground into the tool, efficient chip ejection is exactly what happens.

 

[darkzero]

Not that I have a lot of experience grinding my own tools, I do know that 3/8" tools are much quicker to grind than 1/2". I hated grinding 1/2", I just wanted to start machining already. I guess that's why I pretty much only use indexables now & a QCTP. For us hobby guys 3/8" should be perfectly fine. At least that's how it seemed for me.

 

[mikey]

Not that I have a lot of experience grinding my own tools, I do know that 3/8" tools are much quicker to grind than 1/2". I hated grinding 1/2", I just wanted to start machining already. I guess that's why I pretty much only use indexables now & a QCTP. For us hobby guys 3/8" should be perfectly fine. At least that's how it seemed for me.

You wouldn't think it would take a lot longer; its only 1/16" bigger all the way around but a 1/2" tool takes me twice as long to grind as a 3/8" tool does - go figure.

 

[Aukai]

AAAH, I'm all about simple.
Looking at the middle of a product graph, I'm seeing M 2,4, 42, T 15s
How far up the scale do we need to go? Not all HSS if I'm reading it right.

 

[mikey]

The most common HSS tool bit is M2 and will do for almost all common materials we work with. M35 has 5% cobalt and M42 has 8% cobalt. These cobalt steels can be used for all common materials but tolerate higher cutting temperatures and more abrasive materials; they are useful for higher carbon steels, cast iron, etc. All the M-type HSS contain Molybdenum.

T-type steels contain Tungsten, hence the T-designation. They are more abrasion tolerant and handle high heat better than the M-type steels. AR Warner uses a lot of T-15 for their inserts. While you can find T-15 tool bits, they are less common and more expensive than the M-type bits.

I use M2 most often but for tools that see a lot of use and require better edge retention, I use cobalt steel. The best cobalt steel bits I know of are the Mo-Max cobalt steels (M35) and Super-Mo-Max (M42). They are really excellent, with a price to match.

 

[Aukai]

Mo-Max M42 is 17 bucks vs Mr Warner's 8 buck M42s thoughts

 

[mikey]

Mo-Max M42 is 17 bucks vs Mr Warner's 8 buck M42s thoughts

You gotta' watch for deals on these things rather than pay retail. In the meantime, buy some plain M2 HSS tools and use them. I think most guys wouldn't know the difference (in terms of cutting performance) between an M2 vs M42 when cutting common stuff.

One bit that I like is Crucible's Rex 95. This is a T-8 bit and makes a really nice tool. Here is an ebay BIN for about 6 bucks and he has four of them for sale. For this tool bit, that is a fair price: http://www.ebay.com/itm/1-New-HSS-R...261050?hash=item25ddc1e23a:g:dPAAAOSwcj5ZPuex

It might help to know what to look for. Makers of good HSS tool bits are: Cleveland (M0-Max, Super-Mo-Max are the best), Crucible (Rex AAA = T-4, Rex 95 = T-8), ETM M2 HSS bits and Vasco Supreme. There are others but these are top shelf and common.