HSS was formulated to work at temperatures in excess of what you are likely to produce by grinding.

… Don't worry.

MichaelG.

Back when I was in industry, we made large HSS tools. It was considered very bad to have any grinding burns. On the other hand, other sites have reported brazing HSS onto shanks.

If off-hand grinding, it's considered good practice to avoid heating too much, with frequent dipping into a can of coolant, or alternatively to grind dry. The issue is more about thermal shock causing small cracks, rather than causing a tempering or annealing of the material.

Bill

I am glad to see someone grinding his own tools. Too many folks start off with carbide which, with a few exceptions is ill suited to hobby lathes.

Even getting the bit hot enough to turn blue will not harm it. I have silver brazed a steel rectangle to the side of a HSS parting blade with no ill effects.

Get yourself some half decent **GT inserts, they work well on small lathes and can be used on all metals.

Have you heard of tangential tool holders? Lots of designs around if you want to make one and I am in the middle of trying to design my own. Eccentric Engineering make one, see the adverts on this site, and there are some youTube videos about tangential tools.

The big advantage of this type of tool holder is you only need to grind one face.

Adrian

Made my first Tangential Tool to a set of drawings in an article in MEW, a long while ago. Was so impressed that I bought the Eccentric Engineering model. Sharpening is an absolute doddle, with only one face to grind, and a jig to hold it in the right orientation, for grinding.

Used almost all the time, except for hardened material, when carbide tips are necessary. The only carbide tips in regular use are CCMT0604 in a Boring bar, and the holder for the 100 degree corner, when the 80 degree corners in the Boring Bar become chipped. This is then used for roughing.

The parting tool used for almost all jobs is HSS. This blade must be over 20 years old, and still about half length!

HSS toolbits are ground up for any specialised jobs, like chamfering, screwcutting, etc

HSS seems to be cheaper in the long term, in that grinding is pretty easy, and nothing like like replaceable carbide tips.

Howard

I am a fan of tangential tools, as well. Notice the tool stickout on Vic,s tool. You can get to the bit with a stone to keep it sharp. It might even be possible to grind the bit without removing it from the holder. Unfortunately, when I made my tangential tool holder I kept the metal around the bit too high to allow stoning.

The Tangential tool pictured is version three, the one I use.

With retirement approaching I considered the relatively high cost of inserts compared to a piece of HSS. I made a small tool that took 1/8” HSS but it didn’t work too well. I got the angles right but I don’t think I ground the HSS correctly. I considered the cost of buying the Eccentric Engineering one would soon be recouped so invested in one. It worked very well with both round and square tool bits. And loaded with carbide easily deals with tough materials. One thing I didn’t like though was that the head was cranked over at an angle (they have now changed this). As a result I decided to make another one with a straight shank but I didn’t allow enough clearance around the cutting edge, this was V2. Version three is as you see it with plenty of clearance. Could it be made better? Yes, I’ve seen a version made by one enterprising individual where he simply flips the hole unit over onto a flat surface to set the tool height. In place of this I made and use a dedicated height gauge. They are fun to make and in my experience work very well for both turning and facing.

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