AMDUSER I agree with that 100%. The bits I purchased from there were either glued or soldered where they modified the tips on it. Which of course, did not hold up very well to concrete and failed shortly after.
When it comes to most cutting or drilling tools the best are Freud/Diablo, while they are the same company they manufacture a verity of carbide cutting tools, but the best part is they manufacture their own carbide which allows them to produce a carbide insert perfectly matched to the application the tool is designed for.
They are a little higher priced but drilling and cutting are labor intensive tasks so the more time one can save the less expensive the tool becomes, another factor is they do not need to be sent in for resharpening as often saving even more money.
The only they nor has anyone else figured out is how to lower tooth breakage, I use a 12″ circular saw blade in my steel cutting chop saw and those blades run about $100 and while Diablo blades last the longest I do break a tooth now and then, now with a 60 TPI blade I can tolerate losing maybe 10 as long as they are spaced apart not in a row, but at 10 or so the blade has to either go in for tooth replacement and sharpening or depending the price for that work gets replace with a new one.
I ship my blades to a place in SFL, and what they will do is call me letting me know one of the two 12’s I sent is not worth repairing there is 14 teeth missing, but if you let us keep that blade. we can reuse the teeth from it a few of which I will use to repair the other 12 and save you some money on getting that one repaired and sharpened.
I don’t want it back anyhow so yes scrap it out and save me some money.,