Didn't take long to snap the first one off with minimal radial pressure from a shallow cut in Delrin. The second one worked fine, so this is not a blanket indictment of this source--just an acknowledgement that the low price is that way for a reason. If just one of the ten fails like that, it's still a great bargain, but it was a shame to have happened with the first one I tried.

I used these router bits while making a slot car track. They held up well while cutting slots in MDF. Motor speed and travel speed will determine how long each bit maintains it's ability to make a clean cut and how long the bit will last. I am pleased with the performance of these router bits.

Well they're cheap. I assumed I'd be going through them faster than more expensive bits, but what I didn't figure was that the ones I got aren't even the size they are supposed to be. The shank is indeed 1/8" (3.175mm) but I couldn't figure out why my parts were not fitting. The actual bit is only 3mm. I started going through the hoops to redo the piece but decided to just buy a few more of the better bits. A bit in the collet is better than the junk in the drawer...

These should be in the bit box of everyone who has a small CNC. At $1.5 each, they are a great value. I primarily use them for cleaning up after v-carving, but have also used them for drilling. I've broken 3 thus far, all in rather tough duty, e.g., me trying to push the feed rate just a little bit higher :)

I'll be back for more.

Edit #2: It has been almost a year since I purchased 60 bits - I was able to make the bits last but I went through a lot of bits before I had it figured out. I have now changed the review to 3 stars from 1 star. I use these bits to cut cast acrylic. Instead of doing multiple passes, I ended up going with a very slow single pass. I would then do a fast final clean up pass.

My settings for 0.4" thick acrylic: Ramp in, 6 IPM plunge (Z-axis), 12 IPM cutting speed, 18,500 RPM. Final pass: 15 IPM plunge, 30 IPM cutting speed, 15,000 RPM.

Doing it as 1 pass + 1 fast clean up pass actually cut down my machining time by quite a lot. I'm thankful for that but it makes me wonder what I could have done with the original bits in terms of machining time. I'm going to buy a couple more and see how they fare. I think that the single pass helps with the deflection since it isn't cutting only at the tip. The deflection was probably what was causing the bits to break so fast. With the above settings I use the bit for about 2 hours, then switch to a new bit with a new job. Doing it this way I didn't have any bits that broke in the middle of a job. I might use old bits if I don't care too much about surface finish and just need something cut to rough size. We'll see if the bits I'm about to order work with my new expectations.

- old review below -

Edit: Changed to 1 star out of frustration with trying to use these bits - gone through 20+ bits so far, for the old version bits I would be on my 2nd or 3rd bit. Original review below.

I've been using these bits to cut through ~0.4" thick cast acrylic using a CNC router. They worked well until I needed to get more bits - they changed/simplified the cutter geometry recently. The change in geometry seems to have made the actual thickness of the bit material thinner if that makes sense. There isn't a visible "edge", instead it looks more like "cones".

I did have some of the previous bits break but typically the bit would break because they had gotten dull. I would usually have a bit be able to last through 5+ hours of constant cutting. Used the same settings as I had done before and I broke a bit in less than a minute. I started tweaking the settings to see if I could actually use the new bits and I broke 5 bits in the process. Ended up having to do lighter passes (from 0.125" to 0.09") and slightly higher RPM got a bit to last almost an hour but it still ended up breaking. I used to do 3 passes at 0.125", had to go to 4 passes at 0.09" for these new bits and am currently trying 5 passes and seeing how far I can get with that. Current settings are 0.075" cut depth, 25 IPM, 18000 RPM.

If you look closely at the attached picture, the bit on left has a visible "edge" and looks more parallel. The bit on the left is an old/used bit. The one on the right is new bit with the cutting edge at the bottom of the "cone" and the bit has visible tapers when look at it from the side.

It would have been nice to know that the cutter geometry changed before I ordered 60 bits. Previous bits were a great deal for me. Now it seems like I need about 5 bits to finish 1 job - just not worth the time. Seems like a bait and switch. The old bits were much better value.