It seems there is a bit of confusion about rub patterns. (straight across vs the profile of a football) To clear this topic up there needs to be some history as to how this controversy came to be. Back when I started sharpening about 22 years ago there wasn’t much in the way of clipper machines, especially ones that worked. I did like a lot of new sharpeners did. I bought a Foley Bell-Saw clipper machine. When it didn’t work, I went to the factory for training and it still didn’t work. I found out later that its nickname was “The Boat Anchor”. That pretty well sums it up. I kept it for a few years trying to figure out a use for it, but I finally gave up and tossed it in the trash.
In the mean time I started asking anyone I could think of if they knew of a good clipper machine? Bob Huffman said that Bob Scissile up in Nebraska just bought the rights to Tippy Tipton’s clipper machine and he said it works! So, I called Bob Scissile and bought the very first clipper machine he sold. It was a 14” wheel machine. When I went to him for training, he had a machine for me to train on, but he didn’t have a wheel for the machine I bought. Long story short he ended up sending me three clipper wheels before I got on that actually worked. The last wheel he sent me worked as well as the one I trained on so then I started to make money sharpening clipper blades.
The taper on my first wheel from NB that actually worked was .007. So, it is no secret that my first clipper wheels that I made also had .007 on them, but then NB changed, and I changed as well to .011 Why did we change our taper? Well, Errol Calvert started saying online that he had talked to the actual person at Oster that turns all of their clipper wheels, and he told Errol that we should use .011. Well, most everyone took that as gospel and started using .011 on all of our clipper wheels for A-5 clipper blades. That lasted for quite a while.
Now Mitch he did not change to .011 He kept using .006 taper. The nice thing about .006, and .007 (along with most tapers) is that you can do your finish sharpening almost anywhere on the face of the wheel and your blade will cut good enough to make your customers happy enough to use you again. Since nobody knew anything about tapers, and hollows every one was told to do their finish sharpening on the outer edge of the wheel, and that bit of advice became the standard way to sharpen clipper blades, and it still persists to this day among many sharpeners.
Before Mitch came along there was a man whose name was Vic. Some of you may remember him? He made a clipper machine using an 18” clipper wheel. (I don’t know the taper, but I suspect it was .006) He tried several different sharpening band widths that was pretty narrow by todays standards. His machine looked like Mitches machines, but it was a manual machine only, and it was painted blue. The wheel looked exactly like Mitches with a band that protrudes up just like Mitches except he painted his band gold color. Other than that Vic’s wheel and Mitches wheels like alike. So, if Vic was first with this design then how did Mitch figure in?
Well, they both lived close to each other. Turns out Vic did not like the guy that was turning his clipper wheels so he contacted Mitch and started using him to make his machines. From that point on I really don’t know what happened next, but the next thing I knew Mitch was selling machines that looked like Vic’s machine. Then I learned that Vic was no longer involved in selling machines? That is all I know about that. I don’t think Vic is still alive at this point. If he is alive, then he is very old. Back then everyone was pulling tapers put of their butt’s trying to find one that worked. Same was true for me I had no idea either so I used what ever worked just like everyone else. Then came NASA Bill. Bill is a scientist that was employed at 3M company. He was a sharpener for 3M. One of the things he sharpened was a very small diamond cutters for making lenses. Bill was expert in optical lenses as well, so he knew tapers and how to measure them. As I have said before he is the scientist that fixed the Hubble space telescope lenses. Bill retired from 3M, but he did not retire from his passion, and that was sharpening and figuring out tapers and convexness etc.
Bill got hooked on sharpening clipper blades so the first thing he wanted to know was the hollow in clipper blades. This was about 13 years ago. So, Bill ordered three A-5 clipper blades. One from Oster, one from Andis, and one from Wahl, and found there was no measurable difference between any of them. They all three measured out at 57 microns straight from the three factories. The rub pattern was the profile of a football, and not straight across. All three of these blades cut like butter.
This was all new stuff to the lowly sharpeners out in the field. I was lucky enough to be called by Bill and he taught me all that I know about tapers and clipper wheels. I no longer pull tapers out of my butt. The question is “what do you believe is correct?” Do you prefer to base your sharpening career on a taper pulled out of someone’s butt? Or do you think a scientist that is expert in sharpening and measuring hollows might know what he is talking about? NASA Bill did not pull any tapers out of his butt; he identified the correct factory tapers using scientific methods and then mapping them all out on charts. He did not pick the tapers he merely identified them. That is why I don’t care what others choose to believe. I will take a scientist's finding over someone’s butt anytime.
NASA Bill says the football profile rub pattern is the absolute best pattern. He told me straight up that the straight across rub pattern is absolutely not correct, and that is is float because it has a flatter hollow. (much less than the 57 micron factory hollow) He said it was no coincidence that all three factories back then were all using the same hollow. He told me from his findings they all knew exactly what they were doing, and is baffled by what some of them are doing now to sharpen their blades.
I know Mitch makes a very good machine, and he also make very accurate clipper wheels using his trademark .006 taper. All of Mitches charts for rub patterns are based off the .006 taper and none other. Bottom line if you have a .006 taper then the straight across rub pattern is what you are going to get. If you have a clipper wheel that is based on Bills findings, and you know how to use the sweet spot then all you rub pattern will match the football profile.