Clipper Machines; Why Variable Speed?
I am thinking there are sharpeners out there who believe variable speed clipper machines are made in the first place, so you can run the clipper wheel slower, and therefore get a better grind.
OK, for one thing, slow clipper blade sharpening takes more time to remove all of the damaged metal that has to go in order to get a good sharp blade. The truth is, there is no reason to go slow when removing damaged metal. Plus, in order to get a good finish grind, you need a good spark pattern when doing your finish sharpening. What I am saying is slow speed clipper blade sharpening has no advantages, only disadvantages, in time and quality.
Old school sharpening says always put a certain amount of downward pressure on a comb or cutter when sharpening. Say 3lbs? and then check yourself using a scale every so often to make sure you are only pressing down your target amount of weight. I say old school because there is a much better way. Instead of concentrating on pressing down 3 lbs. try shifting your concentration to watching your spark pattern. It is the spark pattern that shows you if you are getting a good grind or a mediocre grind. If you have a strong spark pattern then you are getting a good grind. If your spark pattern is weak, then your grind pattern is just as weak. A good strong spark pattern creates a good rub pattern. Simple as that, plus, instead of concentrating on how much downward pressure you using, (and ignoring the spark pattern?) all you have to do is watch the spark pattern instead, so now you always know when you are getting a good grind or a not so good grind.
What is a good spark pattern? That is when you have a strong, and even, set of sparks all the way across the tips of the cutter or comb. How do I get that going? By pressing a little harder on the cutter at first then after you get a good strong spark pattern you can ease off on the downward pressure and still maintain the same spark pattern. If you ease off too much you will lose the strong spark pattern, so if that happens, then press a little harder and get it back, then ease off again. You will quickly learn how much pressure it takes to maintain a good strong spark pattern without pressing too hard. The most important time to have a good spark pattern is when you are doing your finish sharpening. This will dictate how good your rub pattern will be as well. Poor and uneven sparks on your finish grind = a poor, or not as good rub pattern.
So, by now you are probably wondering what all this has to do with variable-speed clipper machines. A lot! The problem is, most AC motors can only run at one certain speed around 1750 rpm. The next problem that adds to that problem is smaller clipper wheels. If you have a large clipper wheel from 18” to 24” then 1750 rpm is no problem because you can have a .011 taper on all three of those sizes and get a good spark pattern at the 11” diameter sweet spot, but what if you only have a 16”, 14”, or even a 12” diameter clipper wheel, then what? Well, that is when things start to get more difficult. On smaller wheels, you have to move the sweet spot closer to the center of the wheel. This means less surface speed and an undesirably weak spark pattern.
There are two choices. First, either do your finish sharpening on the outer edge of the wheel and not get a perfect 57-micron factory hollow, (blades will still cut ok) or you can speed up your clipper wheel till you get a good strong spark pattern at the sweet spot. The latter of the two is the best solution by far. FPS (feet per second) is FPS no matter how big or small the clipper wheel is. This is where a variable speed clipper machine really pays for itself. You can have a 12” clipper wheel with a .006 taper, and still get a perfect spark pattern at the 6” diameter 57-micron, factory sweet spot! When you have a variable speed clipper machine you can get a small clipper wheel to make just as good blades (and sparks) as that 21” clipper wheel. All you have to do is dial up the speed until you get a good spark pattern at the sweet spot, then make a note to self where that dial setting is located. And just go there every time you run your machine.
Only a variable speed clipper machine is capable of doing this. Remember it is the FPS that makes the difference, not how fast or how slow your motor is. Hummingbirds have to flap their wings faster than an eagle in order to fly, the same is true with clipper wheels.