BILITOOLS M12x1.5 Thread Repair Kit, HSS Drill Helicoil...

Most Helpful Review

"i'm almost finished making a custom router table insert from a 3/8" thick aluminum plate. I have what I thought were the hard parts done: mounting bolt holes, the center bit hole and rabbet to hold some plexiglass zero clearance rings, etc. I planned to tap 8 holes for the starter pin locations -- four centered on the outside edge of all four sides about 3/4" from the edge, and four more in line with those 4, but 3/4" from the bit opening at the center of the plate.After breaking 3 of the 8 taps that came in a set from this site, I sent them back for a refund and bought a single-size drill bit and tap set for much less. That tapped the 4 outside edge holes perfectly.Unfortunately, 2 of the inside holes were slightly too big, because 2 broken taps had to be extracted with a punch and hammer. The final 1/4x20 tap was able to complete those 2, but they wound up looser than they should be The 3rd that broke was the 1/4x20 tap, and it remained in the plate. I was unable to pound it loose. My efforts to remove it also caused some minor damage around the hole.I ordered some diamond hole saw "bits" from this site, and managed to remove enough material around the stuck tap to punch it out. Whew!!Oh, the 4th inside hole was tapped okay except it was not perpendicular. The starter pin was at an angle when screwed in. Four out of four holes were messed up to varying degrees.I've never used the helicoil or any other thread repair product, but the reviews looked promising, and the process appeared simple enough.This helicoil kit arrived today, and I proceeded to repair all 4 holes. I first drilled them all while I had the drill bit from this lit in the drill press. I then tapped the holes using the drill press but turning the spindle by hand to hopefully keep the tap perpendicular to the plate.Between tapping each hole, I used a drill-driver on low speed to extract the tap from the plate, then cleaned and installed it into the press again. I used compressed air to clear out the newly tapped hole, and I followed the instructions to insert the helicoil and break off the pin.Installation succeeded without any problems. The helicoil inserts are almost exactly the same depth as the plate, so that's convenient.Now i have four freshly repaired, threaded holes around the bit opening. There's a very small damaged spot next to the one hole I had trouble extracting the 3rd broken tap from. I may try filling it in with the aluminum braising rods i just got for a different repair, but not right away. It's 99% cosmetic as far as i can tell. The starter pin screw works fine in it and sits perfectly perpendicular. That's what matters most.BTW, I was comfortable with the design of this product, because in woodworking, I use a lot of threaded barrel inserts for jigs and such. The Helicoil is basically a metalworking version of that wood-working fastener.i don't often need to repair stripped threads inside a bolt hole. However, the next time i do, i'll know what to use."