Tool bit sharpening question

There is a general rule in grinding: the harder the material, the softer should be the grinding stone. Grinding stones (real ones) come in grades of hardness. Grades are like A,B,C ... but I forget as you go up if it gets softer or harder. I use K graded pink alumina surface grinding wheels with bushings to step down the 1¼" hole to 5/8", in 46 grit, on my bench grinder. I suggest you order some from J&L or MSC, the difference will be amazing.

Beyond that, I suggest you go buy some key stock to practice on. Practice grinding until you can get the desired shape reliably. It might take 2-3 hours with a knowledgeable guy to show you, then you will "get it". The little rests you should set your hands on holding the bit, not the bit itself. Have a dip tank handy and dip the bit in water often. Don't let it get hot enough to color. In class I learned to grind a lathe bit with 3 facets. Doesn't take that long. But you have to learn to put a small radius on the point or your cuts will look like they are threaded with a fine point. Also, you should get a good hand stone and learn to touch up your HSS tooling by hand, quickly, at the lathe.

If you like (and have the $$$) you can get a great little table for grinding lathe toolbits. It's made by Glendo. You will need to mount it correctly, but once mounted it has a quick-release so you can just take it right away when you don't need it. I have one I got quite a while ago, when they still cost like $79, and it works great although I don't use it much anymore.

- Glendo Corporation 900 Overlander Road P.O. Box 1153 Emporia, KS 66801 (800) 835-3519, (316) 343-1084, (316) 343-9640 (FAX)

Grant Erwin Kirkland, Washington

James Schenck wrote:

While this is just personal experieince with grinder wheels, I found that the majority of wheels that come on a Import or even some USA made grinders are only worthy of being placed in the landfill for fill. So keeping that in mind if the grinder does not work properly its probably the cheap wheels they install on them. Even my Baldor bench grinder came equipped with some really pathetic wheels on it.

My preference in wheels on a bench grinder is either the white or pink wheels, over the typical gray colored wheels, especially when it comes to shapeing HSS.

They also make a straight cup wheel that can be mounted on a bench grinder and it allows you to grind efficiently on the side of the wheel, normally somehting you don;t usually do or shouild not do on a bench grinder for the most part.

I've never seen a guide per se for sale for sharpening HSS lathe bits, as these if used are usually home brew items. Med and coarse grits may do, but I would still be inclined to go with a fine as well even if it meant changing wheels, as the finer the finish you get the less chance of getting a built up edge will occur. Use the coarse for initial shaping, and then switch to the mediium, and finally the fine. I would think something in the 46 to 60 grit for coarse and then 80 to

100 or so for med.

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I forgot, grinding wheels come in different hardness and grades, so I would try and get a J or K grade. Keep your work cool and don;t let it get burned while grinding. You'll find that a good wheel will cut so much mor equicker and not generate near as much heat as a poor cheap wheel will. You may have to make a bushing to reduce the type of wheels I mentioned in previous post from 1.250" bore to fit your grinders arbor., and don;t forget, always ring test any wheels before installing them on a grinder, and stand to the side when turning it on. This is especially important for any wheels you may have had shipped to you, but I do it with every wheel I have, Then dress it or true it up and go for it. And make sure your wheels have blotters on both sides.

Regards

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