POWERTEC Drill Bit Stop Collar Set, 7 Piece Set Adjustable Drill Bit Depth Stopper with Allen Wrench, Bits Stop with Imperial System Size Markings - 1/8", 3/16", 1/4", 5/16", 3/8", 7/16", 1/2” (71491)

Awesome product from Taiwan. I've been using these for a year now and have had no issues. Much better than the set screw type. Just use to correct size drill bit and they work perfect. The collars are clearly marked.

Very useful

It doesn't wabble any more that is where set screw on the drill . This ONE clamps the whole drill, no more collar falling off. Works great. Cost a little a more but well worth it.

They’re pretty simple, just a piece of metal with a few holes, but they do the job pretty well. These drill stops went on my bits easily and didn’t damage them at all, though with coated bits you will need to really tighten the stops on to prevent slipping. I found that if I didn’t double check the stop depth regularly and hadn’t really tightened them enough, they would scoot up the bit without me noticing. It can be difficult to tell how tight is too tight, as I don’t want to damage my bits, but so far no issues with that. Overall I’m quite happy with them, a good value for the price.

3 stars because of maybe quality control? Ordered these to use on drill bits for a dowel jig. The 1/2" and 3/8" worked fine, snug when tightened. The 1/4" bit would fall out even when fully tightened to the point you were slipping the wrench. They're tight enough in tolerance you can't drop down to the next lower size for a 1/4", but the 1/4" is too loose. Taking the screw off another small collar and putting it on the 1/4" I could tighten it "enough" that it wouldn't slip with light pressure so I can probably use it for my intended purpose (stop collar for dowels) but the quality still seems either bad or inconsistent. Not even worth the drive to send them back and try something else.

Does what it should. I've only used the 3/16" stop and it worked perfectly, no slippage.

Best set of drill stops I've seen or used. Well machined and engraved with the size. I started with the set from Harbor Freight which were slightly cheaper than this, however they used the single set screw design which tends to rotate and fall off during use. This design squeezes then entire bit with the collar- a far superior design. Also, this design doesn't allow the allen screw to mar and damage the drill bit like the other design does. I can't see how this could be any better.

I was looking for a depth stop that was easier to use than those with a set screw which presses against the shank, because the set screw often goes into the flute. I thought these might be better, but they were actually worse! -These are really hard to tighten down, and the use tiny set screws made of soft metal. When you try to tighten them down, the allen heads strip out. -I belive the problem is that the relief cut, on the closed side, isn't cut deeply enough, so the collars cannot easily tighten downk. Even when you crank those tiny allen heads tight, the collars don't close and you just end up stripping out the allen heads. - The largest sized worked ok, but the smaller ones all stripped out. Sending mine back for a refund.

I agree with others that this product is garbage and a waste of time for all, including Powertec. The problem is they are impossible to tighten without stripping the allen screw. Anyone who 'tests' these will see it is obvious the relief cut is too shallow on the color and no way to have them tighten. I can assume the larger one may work but 1/4" did not. They deserve the returns as they do not seem to be listening to customer feedback. Maybe they are just trying to dump bad inventory.

Rubbish. Wish zero stars was an option.

Well made but very bulky and not suited to finer work like cabinetry.

The sizes aren't exact enough and it simply did not fit over the bit it was supposed to. Returned them and just used the good ole tape trick instead.