diamond tipped saw blades; when to replace?

In My Humble Opinion (IMHO)
#1

I recently completed a partial residing of my home using HardiePlank cement board siding. To make the long story short the folks at the building supply business told me that if I was going to make more than a few cuts with a circular saw (as opposed to nippers) I ought to buy a diamond tipped blade. I did, and the blade performed admirably. But at the very end of my project it seemed the blade was getting tired.

The blade was $19, which I considered inexpensive given the “diamond” aspect. But as I said, it performed admirably.

My question to those SDMB construction folks, is, when do you decide a diamond tipped circular saw blade needs replacing?

#2

My experience has always been that when they start to go, they go quickly. It gets hot and stops cutting.

#3

They start cutting slower and eventually you are just burning through stuff instead of cutting. I’ll get a little more life out of them using a brass brush on them to clean them up. The smaller blades are so cheap these days it’s hard to justify not just replacing them as soon as they slow down.

#4

You could get a backup blade now and compare the two on the same type material. If the original blade performs substantially worse throw it away; if they perform about the same keep using the original blade.

#5

Don’t worry about the low price. There’s a world of difference between industrial diamonds and engagement ring diamonds. We’ll save the artificial price inflation discussion for another thread,

#6

Thanks for the scoop folks. I like PastTense’s idea. I can do that and get some hard data.