Grinding HSS on a wood lathe

[Michael Mills]

My question is on shaping HSS blanks on a wood lathe.
My goal is to turn one end of a ½" square blank (about 6" long) to round in order to fit into a standard Jacobs chuck. About 1.25 inches of one end would be rounded.
The reason is to be able to chuck up special bits for small turnings ground to the shape of a bedan, flat or round nose scraper, etc. I would have one handle and a quick change to an assortment of bits. I do use round HSS rod from 1/4 to 1/2 but some tools need to be flat/square.
My idea (Oh No!) is to chuck one end in pin jaws, about one inch deep, and slowly and carefully grind the tailstock end to round with a side/angle grinder just long enough to seat in the drill chuck.
I have done similar with pipe to fit my banjo but I was able to use a cone center in the tailstock. In this case there would be no tailstock support.
If done at all, would a high or low rpm be better?
Any different or better ideas (other than taking them to a machine shop)?
Thanks

[Dan Hintz]

I assume you mean HSS (high-speed steel), not something unknown to me, HHS?

How do you plan to steady the cutting tool on the wood lathe? You can't hold it by hand, that's for sure.

[Michael Mills]

Yep Dan, I did mean High Speed Steel. I will go back and edit the title if I can.

I plan to hold them with this (this one is a 1/4" chuck) but I will use another handle and a 1/2" chuck for larger items.
All will still be for small/detail work.
Unless someone knows of a four-jaw jacobs chuck.

[Dan Hintz]

Michael,

Doing metalwork on a wood lathe and holding the tools in hand is dangerous... the force and pain of a metal catch is magnitudes above a wood catch. And you'll never come close to a quality round holding the tool by hand. I highly suggest against it.

[Michael Mills]

Thanks Dan,
To clarify my rambling…
The handle above is to hold the blade/bit AFTER one end has been rounded (to insert in the jacobs chuck) and will then only be used to cut wood. Much like a Tompson tool where you buy the blade (gouge, etc) and then it is inserted into a handle. The handle would be similar to the picture only with a ½’ chuck.
To steady the forming of the round I had planned to rest the body of a 4-1/2 grinder on the tool rest for stability and make cuts much like a parting cut, then when almost round, grind off the bumps left. Yes I had though about a "catch" or breaking the jaws of the chuck grinding on an unsupported end. Even when done lightly and carefully.
Do you know if most machine shops can turn the square HSS blanks (about 1-1/2" long on one end)? I would have a half dozen modified at one time and that will give me lots of blanks for making specialized points/tools. The blank are only about $6 at WT Tools.

[David Warkentin]

Do you know if most machine shops can turn the square HSS blanks (about 1-1/2" long on one end)? Quite sure that they can....

[Stephen Pereira]

A four jaw chuck is quite common..adapting one to a wood lathe is another matter. HSS can be brazed..silver soldered..maybe you could use mild steel round stock and silver solder HSS or carbide ends to that.

[Stephen Pereira]

Better yet..you can buy carbide inserts..all sorts of shapes..with a hole drilled through. get yourself some round stock to fit your handle, file a flat on the stock and drill/tap to fit the hole in the insert..voila!!

[Wes Grass]

Most machine shops? Possibly, if they have a cylindrical grinder, a spin jig and a surface grinder, or god forbid a toolpost grinder for a lathe. A tool and die shop will have one or more of these options. Probably cost you $20 each.

Rather than grind them down, why not make a handle with a set screw and leave them square. Shouldn't be tough to do, may even be available off the shelf?, and would let you use both ends.

Edit: The Sorby handles I was thinking of only take a 5/8" shaft. 1/2" square is .707 across the points.

So:

http://www.amazon.com/Square-Hole-Sl.../dp/B0016BVW5E

Available with a 5/8-18 thread in the back end. You could sink a piece of threaded rod into a handle and Loctite (permanent red stuff) this on. Needs a set screw, and unfortunately there isn't much wall thickness. But a clearance hole through the side, and a shaft collar around it would solve that. And probably still be smaller than a 1/2" drill chuck.

Edit yet again:

Better check that the toolbits aren't oversize first. I've seen that somewhere, like maybe a nominal 3/8 blank was 10mm.

[Mike Davis NC]

I would have just ground them down without telling anybody. Avoids lots of questions and liability worries for anyone answering.

But, that's just me and I certainly wouldn't recommend that anyone do what I do.

[Michael Mills]

Hi,
Thanks for all of your responses.
Wes Grass

Probably cost you $20 each.
That’s about what I thought. $20 to modify a $6 tool. Each.
Available with a 5/8-18 thread in the back end. You could sink a piece of threaded rod into a handle and Loctite (permanent red stuff) this on. Needs a set screw, and unfortunately there isn't much wall thickness. But a clearance hole through the side, and a shaft collar around it would solve that.
Just the answer I was looking for. I did not know what they were called. Yep, only about 1/16 wall thickness for a setscrew so I think your idea of a shaft collar is excellent. The whole sha-bang would be inserted into the wood handle except for the shaft collar.

Mike Davis NC

I would have just ground them down without telling anybody.
That is usually what I do. I didn’t want to tear up a set of $40 jaws to make these.

Thanks everyone.

[Richard Coers]

I would suggest you center drill the square blank for the tailstock. A little center drill won't hurt your design if you still want to grind the square blanks.

[Michael Mills]

I thought I would followup and let you know what finally happed.
Works like a charm.
Thanks for your help.

[Johnny Kleso]

I did not read this all but you do know they make round HSS tool bits..
You can also buy Drill Blanks on eBay cheap.. A drill bit with out flutes ground into it..

They also make Square Holes
A round OD with a Square Hole
Say 1/2" OD with a 3/8" square hole in soft steel