What in your experience the specific type of HSS that works best for shaper use ( resistance to chipping, interrupted cuts, heat), M2, M35, M42, AISI T-15, Maxamet, others? I'm trying to stock up on tool bits and have limited experience on the best ones to use on my 12" Sheldon shaper. Would it be also correct to assume for hobby use that usage of this "best HSS for shaper use" can acceptably be used for lathe work also? Just trying to hit 2 birds with one stone and save some bucks, ya know. Thanks in advance for any advise.
Have you experienced any problems with any of the HSS steels? My thoughts are that you will get somewhat better performance with the more exotic HSS , but that the improvement will not be as much as the increase in cost. Since a shaper does not cut continuously, the tool gets a chance to cool between cuts. And therefore does not need as much of the ability to work at high temperatures as a tool in a lathe where the cut is continuous.
My experience is that heat is NOT going to be a problem on a shaper, half the time the bit is idling on its way back anyway. What is critical is the tool and holder geometry. I had a hell of a time with a 7" until I made my rendition of the Williams shaper bit holder. If your tool tip is ahead of the clapper block pivot, it'll tend to dig in, took the tips off a lot of bits until I got wise. Didn't matter what type of steel they were. Your shaper is bigger and probably a lot stiffer, you may not have that big of a problem. The Williams holder parks the bit in back of the clapper pivot, the bit then can pivot out of the cut instead of digging in. Made a lot of difference in the surface finish and in tool life, like night and day. Instead of chattering, I got a nice shoop-shoop sound on the cutting strokes. The holder also allows the bit to be positioned anywhere in a 360 degree circle along the ram's axis of travel, can be very handy with odd-shaped workpieces. I made my own since the real deal was in the $500 category, way out of reach for a starving student.
There is/was a British book on shapers written in the 70s with a lot of different tool forms in it that could be ground from square blanks, most of the really old books show forged tools, lots of luck doing THAT these days. Most of the older tool drawings show a distinct hooked form with the tip behind the main shank of the tool, same idea as that Williams holder, lets the tip pivot out of the cut and not dig in. There was a lot about shapers and planers in the older Audel's manuals, my 1905 version shows a lot of belt shifting going on with overhead gear and flat belts.
For just starting out, I'd look for tool bits that were inexpensive, you're going to be grinding a bunch of them, and not too brittle. Minimize the cobalt content for that. All my bit stock is really old stuff I inherited, no current names, so what I use is pretty much irrelevant.
One thing about shaper chips is that they're like cockleburrs and will stick to anything and track everywhere. Just a warning if you've bare feet running anywhere in the vicinity. I can position a 5 gallon can at the right spot and catch 99% of them. Otherwise, they can shoot across the basement.
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