Grinding HSS....

[Dr Stan]

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

The good ones do not. They use a stone or a steel just like my Dad the meat cutter taught me.

Or even better yet, a leather strop like a barber uses or a leather wheel like a wood carver uses on a chisel.

[J. Randall]

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.

I disagree, we had to do that in a votech class, when you are through, what have you got? A look alike that you can't prove out. HSS is not that expensive, start with it, and modify it if you need to, till it works to your satisfaction. When you get the basic grind down where it cuts to suit you, then you can start experimenting with chipbreakers, easily ground in with a small grinding disc, even a dremel tool.
James

[vpt]

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

I agree. For some stuff (finishing hss) I use diamond stones, nice neat clean finish on the hss = the same on the part.

[Chuck K]

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

I took a machining course at the local junior college and one of the things you had to learn was grinding hss. You had to make the tool before you could use the lathe. I remember thinking what a waste of time it was because I planned on buying and using carbide. I now have a lot of carbide, but I enjoy using hss a lot more. I'm not in a production environment, so time isn't an issue. The biggest loss I see from not learning how to grind your tools is the understanding of the effects of the geometry of the tool. That and the personal satisfaction you get when the c's are dropping off the end of your tool. As the others have said...the books are good. I found a lot of info on grinding and grinding wheels on http://www.chaski.org/homemachinist/. Just don't invoke the wrath of Harold while you're there..im joking.

Chuck

[oldtiffie]

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

The instructor is a bit bigotted and "one-eyed" as while carbide is the major tool of choice for "production" there are plenty of times where "special" and "form" tools made from HSS are best as they can be made and "touched-up" in a matter of minutes.

But many small(er) HSM-er's machines are not robust enough to get all (any?) of the benefits of using carbide tools and so in those circumstances, HSS is the tool medium of choice.

[dp]

I disagree, we had to do that in a votech class, when you are through, what have you got?

What have you got when you're done? You have an education and jigs. But if that doesn't float your boat then for God's sake, man, don't do that! I found I could quickly develop the technique for work holding, angles, and visualizing for a wide variety of tool forms faster because HSS is slow to grind, but obviously it isn't for everyone.

[ogre]

One of my favorite books that will cover this and much more is Audels machinist and tool makers handybook. About 800pgs. of great info and theres one on ebay right now for $25!!

[J Tiers]

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

The average sanding setup will round over the edge due to flexibility of the sanding belt or even the disk. The very slight "give" of the grains in the disk, or the obvious flexibility of a belt make getting a sharp edge difficult on a cutter, where the edges are closer to 90 deg.

The edge pushes the grains away as they come in contact, moving away slightly from first contact to full contact, which puts a small rounding on the edge. Very difficult to get a true "intersection of planes" finish.

A knife is different.... depending on how sharpened, as it is possible to "strop" an edge with a very flexible "belt" and get a keener edge.

A vitreous wheel is simply not flexible in the same way

[vpt]

The instructor is a bit bigotted and "one-eyed" as while carbide is the major tool of choice for "production" there are plenty of times where "special" and "form" tools made from HSS are best as they can be made and "touched-up" in a matter of minutes.

But many small(er) HSM-er's machines are not robust enough to get all (any?) of the benefits of using carbide tools and so in those circumstances, HSS is the tool medium of choice.

I agree. I find about 25% of the time I am looking for some sort of "special" grind to fit in a tight spot or down a small bore or something along those lines. I have a few carbide bits and only use them on very hard materials otherwise they stay in the box.

I even used valves for boring bars.

[Tamper84]

Thanks guys! I will look into all of the resources that you all have told me about. And I didnt mean for this to turn in to a bashing fest on the instructor lol. He does seem pretty knowledgeable. Thank you all for the help!

Chris

[Dr Stan]

I even used valves for boring bars.

That's an interesting tip. I'll have to drop in on a local auto machine shop and score a few. They could also serve as a bar to braze/silver solder on a piece of carbide.

[Mike Burdick]

...I would like to learn on how to grind them [HSS tool bits]. ...

Chris, here's an interesting web page article to read....

http://conradhoffman.com/advancedsharp.htm

.

[lazlo]

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

Custom knifemakers finish their edges a lot like the Conrad Hoffman page that Mike posted: set the bevel angles with a belt grinder, refine the edge with a ceramic stone, and then polish the edge with either a buffer or a strop loaded with abrasive.

[Euph0ny]

Somebody already mentioned Tubal Cain (Mr Pete) and his four toolbit grinding videos on youtube. Here are direct links:

http://youtu.be/hrDr4rYLiAk

http://youtu.be/dRyqIm5JR5s

http://youtu.be/HTQ46NMMc88

http://youtu.be/rZbr7Sh8jQw

[vpt]

That's an interesting tip. I'll have to drop in on a local auto machine shop and score a few. They could also serve as a bar to braze/silver solder on a piece of carbide.

When I first showed the valve some one mentioned to just watch out for the sodium filled valves. I guess very unlikely to get a sodium valve however. I was able to cut 4130 with the bare valve. However I do have a bunch of these valves and I already ground another one down but left a shelf on it which I thought I would get some carbide inserts for.