Honing and touching up HSS

[applescotty]

I've got some questions about HSS tool bit sharpening and abrasive stones.

It's often mentioned that you should hone the edge of a tool bit after grinding them on a bench grinder.
What do you use to do this, and exactly how do you do it?
Which direction do you hone (up, down, both)?
Do you lay the stone flat on the tool bit and hone, or at a slight angle?
How many strokes are usually necessary?
Is there something I need to look for to know when I'm done?

I'm under the impression that if I touch up the edge on a tool bit, I don't need to grind it each time I think it's getting dull.
Is my thinking right on this? Is the normal procedure to grind the tool to shape, hone it, use it, touch it up, use it, touch it up, etc? If so, how often do you touch it up? Do you wait until there's obvious signs of it getting dull (and what are those signs?), or do you try to touch it up after you estimate it's done a certain amount of work?
When do you need to go back to the grinder to regrind it?
How do you touch up the edge? Is it the same as honing the edge?

I'm sure both of these things are quite obvious once you've seen it done.

Scott

 

[Kermit]

A leather strip like you would have seen in a Barbershop, back when they still used straight edge razors would work for your needs

 

[Mike N]

I take a veryfine grit diamond file or hone to my cutting edges on HSS tool bits, a few strokes toward the cutting edges from the top & sides makes a razor sharp tool bit. It especially works good when you are turning delrin or acetal in your lathe.

 

[Loose nut]

After I have the tool ground to shape I use a fine stone to put the radius on and give it a good polished finish on the cutting edges, seems to help. After it is "dull" it can be touched up on the stone again, it already has the shape.

 

[Andrew_D]

I picked up a cheap set of diamond files at Princess Auto (we don't have Harbor Freight up here). Each is about 4 inches long. There is an assortment of round, flat, curved files. And the whole thing was less than 10 bucks.

I usually run the file back and forth to smooth the cutting area (top rake, back rake, side rake). Then end with a few passes towards the cutting edge as mentioned by Mike N. Also, use the diamond file to put the radius on. An ever so slight radius works perfect. Unless of course you are making a large radius tool - form tool, finishing tool, that sort of thing - then rough grind it first.

Andrew

 

[hssmike]

applescotty,
You want to make the cutting edge as sharp as possible. If you look at the ground edge under magnification you will see mountains and valleys. These are what you want to get rid of by honing or polishing the tool. Be careful not to round off the edge that actually does the cutting. Usually a polished tool will hold an edge longer, and it is less likely to have the material you are turning stick to it (built up edge).
The wheel you use has a lot to do with how much you have to hone the edge. I use a 36 or 42 to rough the bit and a 60 grit to finish with. I have to confess, I rarely hone my bit's unless I have a problem with the finish.


Mike