Post By CalG
How to sharpen Everede boring bits
OK, I need help!
I like the set of Everede boring bars well enough, until it comes time to resharpen the tool bits.
God help me, those prismatic bits of high speed steel frost my B....
And it ain't winter yet. Worse, if some "special" geometry is wanted. Like 60 degree thread form.
The surface grinder works ...kind of, but holding triangles at just the right angle is not a cake walk.
If the bits are left on the bar, clearance becomes a big issue.
the Everede literature says "easy to sharpen". Not for me!
Big chunks of M2 would be easier ;-)
If it's just boring where geometry isn't critical I just do them by hand, usually held projected from the boring bar. When I had to make an Acme form I went back to figure out the bar nest geometry and make a little holding fixture to present the bit at the right angles for flanks and clearance. It took some head scratching compared to hand grinding but it was the only way I could get some assurance over the grind-and-check, grind-and-check cycles that can get maddening when several angles and surfaces have to be right. For standard threads I still do it by hand. It may not wind up square with the bar, but if the thread form is right I can get the bar set if hole clearance isn't too tight. Not much help I'm afraid, but for the most part I like the Everede bars.
When I've needed an accurate form I dressed the required angle/form on the surface grinder wheel, put the bar+bit in a Harig Grind-All, spun the bar to produce the form, and then carefully ground clearance by hand (*).
* The first time I did this I ground the clearance by cranking the wheel down a bit and carefully rotating the bar/bit with the ground shape back into the wheel, sneaking up on the clearance. Seemed to take more time and still required some hand work because moving the Harig C/L off-center from the grinding wheel changed the form slightly...
I agree with the suggestion to sharpen IN the bar. Oddball angles can give you fits, where having the entire assembly in hand make all relief angles pretty clear.
Sounds like you'r trying to sharpen them separately off the bar. The beggars are little and short and very easily fumbled. As you pointed out it's difficult to visualize the edge geometry superimposed on the triangular section. I suggest you sharpen them clamped in the bar (maybe extended a little for access), That way, the edge geometriy is much easier to define; the bar provides an excellent visual reference and a good way to hold the little bitty tools..
The tools come is longish pieces when new. You have to cut them to length for the bars. The tools can be scored and snapped but the practice is wasteful and somtimes unpredictable/ A 1/32" wheel in a Dremel gives more control and better economy.
Once I get the tool shaped I use a slip stone to touch them up. When they dull in service I stone the tool right in the boring head.
If you use EveRedee carbide tools you'll find them difficult to grind on a regular wheel. Carbide is nearly as hard as aluminum oxide used for GP grinding wheels intended for steel. A diamond wheel is preferred for grinding carbide although some use a green silicon carbide wheel. In any case finish the edge with a diamond slip stone. Diamond tooling is far less expensive than it was 20 years ago but it's still a bit pricey for folks with family responsibilities and a small home shop.
As a matter of practicallity I usually suggest most home shop users stick to HSS. Carbide has no real advantage over HSS for most home applications. It's not until you get into production where stock removal rates are conomic and competetive factors that carbide tooling becomes economical if not essential.
I rather like HSS.
Simple, inexpensive, and effective.
Without the catastrophic failure mode of Carbide ;-)
My Everede bars are so fitted.