Can it be done with simple diamond hone of, say 600 grit and a continuous surface? How to keep the hone square on the blade? How much rubbing on the tooth-face for optimum sharpness (and how do you tell)?
There are services here and there one can send a blade to but it costs a bit and requires packaging/posting etc…
I have seen a small machine that sharpens a blade via a jig to hold it and the hone but these seem to cost rather a lot. I don’t need to sharpen my circular saw blades every week … or every month … or even every year!
The big danger with this sort of thing (planer blades are the same) is taking fractionally more off in one place than the other, resulting in a blade that runs out of balance. For what it costs to get a tablesaur TCT blade professionally re-sharpened, I wouldn’t even blink at the cost as it’s just one of those workshop expenses that has to be met.
Will a minimum sharpen of the toofs of a 40t TCT circular saw blade take off enough differential mass to cause an imbalance? It seems unlikely - although I agree that it’s a danger with planer blades (having done so). But planer blades are large and one must take quite a bit to get them straight and sharp after they go blunt…
I discovered this Youtube vid showing a method for hand sharpening a circular saw blade with a small diamond hone, using the table and a very basic jig to achieve the right angle for the hone and to ensure the rubbing is all at the same angle.
I’ll give it a try.