Grinding HSS....

[Tamper84]

At school the instructor says since hss is pretty much out dated, and we wont be covering it. All we use at school is inserts. Anyway, I would like to learn on how to grind them. Besides the south bend book, is there any other resource or how too? I do have some un ground hss out in the shop that I can play with here at the house. Any tips would be greatly appreciated!!

Thanks,
Chris

[small.planes]

Somewhere on the Sherline site is a good guide.

Dave

[Mcgyver]

just look around, all old machining texts will have it. Lots of posts here. all you need to understand is rake and clearance angles....then get some and have it. Take a piece 1/4" square mild steel if you want to practice. I would advise to stone them after grinding, sharp tools work better

If find the instructors comment either very lazy or indicative of a certain category of intellect. Cutting tools aren't milk, the don't go bad. A more precise statement might be "in most commercial circumstances and almost all production circumstances there are better materials to use than hss; since that's what you're here for we won't spend time covering hss"

They still work wonderfully and are the right tool much home shop work. The different economic paradigm from commercial shops and the lighter equipment benefiting from the lower cutting forces are obvious reasons....and sometimes its only way to get things done.

[Forrest Addy]

Your instructor is an idiot for making this one remark. Don't get me wrong. Carbide is 2 to 6 X more ptoductive in a production setting than HSS even when the higher cost per cutting edge is considered. Carbie is a no-brainer for most applications. However HSS should be discussed an hour or and used for a lab session. Not addressing HSS is like teaching grade school pencil and paper math justifying the omission by ubiquitous calculartors or dissing home cooking because everthing is available at the deli.

HSS has a number of advantages for small lot manual machining, applications where where work is slender or unsuported, or where time is more plentiful than tooling budgets like home or small maintenence shops.

Grinding HSS tools is well treated in South Bend's "How to Run a Lathe" and similar older beginner's texts. The grinding wheel commonly used for off-hand bench grinding is generally well suited for free-hand grinding HSS lathe tools. The usual spec is is A-46-O for amuminum oxide, 46 grit, O hardness - V for fitrified is in there someplace too. There may be many numbers and derignations before and after this core spec but they relate to specific refinements to the abrasive, bond, shape etc.

It should be noted that HSS comes in several grades some that are easily ground but less durable as a cutting tool and some damn difficult to grind that last well in long cuts in abrasive materials. HSS is quite a topic for a couple hundred words in a message board. You really should dig out a couple older texts and study for your self.

HSS may be obsolescent but not obsolete. It still has many uses in manual machining. My home shop is quite complete and until recently hummed several nights a week making home projects and small lot machine work for local people. I have a couple dozen HSS tools I use on my home shop lathe as well as a full complement of carbide tooling. My HSS is used about half the time usually for detail finishing: radii, grooves, threads, reliefs, funny shapes like seal entries and hose barbs.

As for your nay-saying instructor, be diplomatic; he may not knw how to use HSS advanatgeously so he scoffs. I doubt if he will be flattered to be exposed as a hopeless duffer for denying HSS as a machine shop resource. Maybe in lieu of confrontation you could submit an extra credit paper or study up and become a HSS resource for your classmates.

[Hal]

There is a guy on utube that uses a piece of wood 2"x2" , it is large enough to see what he is doing.
It worth a look.

Hal

[customcutter]

There is a guy on utube that uses a piece of wood 2"x2" , it is large enough to see what he is doing.
It worth a look.

Hal

MrPete I think

[Dr Stan]

Well I understand how the instructor would come to his opinion as he must meet the demands of local industry, not the small job shop or HSMer. Its unfortunate that some of the skills of yesteryear have virtually disappeared. Drafting by hand for example is virtually gone. So what happens when someone needs to make a quick sketch on the plant floor or the construction site?

At one point scraping was taught to everyone in the trade, but that went away a long time ago so there are very few who can really do it justice. All that aside, I too recommend SB's How to Run a Lathe along with some of the older textbooks. The Oklahoma Department of Vo-Tech (now called Career Tech) produced some excellent manual machining books that included hand sharpening HSS.

Last, but far from the least is my favorite the Machinery Repairman's Handbook published by the US Navy. Chapter 5 is the "OFFHAND GRINDING OF TOOLS AND SELECTION OF CARBIDE TOOLING". You can find the entire manual for free at: http://www.instructables.com/files/o...K7EP282OTX.pdf

Bookmark the location and print out a copy. You'll find it full of valuable information.

[dp]

The best way to learn to grind cutters is to use plain steel or wood, or both. Once you learn the basics of shape and function, and assuming you take the time to make jigs, you can apply everything you learned to HSS. The advantage is cost and time.

[Forrest Addy]

Ah Yes! YouTube. Lots of HSS lathe tool action.

Start here: http://www.youtube.com/results?searc....1.N56vv4dSBeQ

[Dr Stan]

The best way to learn to grind cutters is to use plain steel or wood, or both. Once you learn the basics of shape and function, and assuming you take the time to make jigs, you can apply everything you learned to HSS. The advantage is cost and time.

steel yes, wood no as it will load up grinding wheels

[dp]

steel yes, wood no as it will load up grinding wheels

I use a disk sander.

[Dr Stan]

I use a disk sander.

that will not produce as sharp of an edge as a grinder

[loose nut]

HSS should be stoned (the tool bit not the guy doing it) after grinding to get the best out of it.

[Dr Stan]

HSS should be stoned (the tool bit not the guy doing it) after grinding to get the best out of it.

that is correct

[elf]

that will not produce as sharp of an edge as a grinder

I've found the exact opposite to be true. Why do knife makers finish an edge with a sander?