I am experienced enough to do a decent job using a dremel tool to sharpen a chainsaw chain. In the past, I used the standard type. I used this sharpener once before cutting four or five rounds,and found that the chain was not very sharp. Initially,I blamed my technique rather then the product and carefully sharpened the chain again but had nothing near the house to test on. I took the chainsaw with me to another site and tried way too hard to cut more rounds, the chain was actually more dull than the first attempt! I put the old "stone" back in my dremel, sharpend the same chain using the same technique and the saw cut well again.

I agree with other reviewers that even on the first pass using these will not work... and it only gets worse from there!

Other thoughts:

There is 73% five star reviews and only 2% one star reviews for this worthless product. I am finally clear on the value of positive reviews on Amazon (ZERO)

Reviews can and are purchased (20 bucks a pop - google it) and most are currently coming out of India.

Also note that the seller has not responded to one of the most negative reviews, to them it is a math problem, sell garbage, purchase fake reviews, ignore complaints, resurface with a new seller identity IF you accumulate enough bad reviews to hurt your sales.

Amazon is not policing these practices I have seen repeated by seller after seller because it would be to expensive/complicated and hurt their bottom line.

Some things are safe to purchase on Amazon, low cost, short service life items are not among the safe items, you are simply throwing your money away... make the trip to Lowes, Home Depot or Tractor Supply. Definitely don't let this seller rip you off!!!. ..

I barely got one sharpening out the spindle before it was worn down.

These are no better at sharpening than your typical sand stone bit. In fact I think these wear out quicker.

I have used any of my chains, but the tools work very well sharpen the teeth on the chains. Richard

They are ok for low speed sharpening and seem to work - but when I received the package, I noticed manufacturing defects on the diamond bits. Look at the attached photo, the third bit from the left has hardened material - diamond coated extending out the bit.