Review on 🔩 Bosch SpinLOCK Universal Hole Kit by Mark Tarnowski

Me now save you the trouble of reading this review and advise you to just buy milwaukee hole dozer saws instead. These Bosch saws cut just as well as the Milwaukees but are much more difficult to use, largely due to the mandrel design. DRIVER DESIGN: This is what Bosch should do differently and better than other crowns. It was designed to solve the self-tightening problem of hole saws and they are very difficult to unscrew and replace. However, this appears to be a reactionary measure to other competitors and appears to have been designed as a copy of the Milwaukee system but "different enough" to avoid patent litigation. The fastening mechanism of real bits is the same as the Milwaukee system, which has been around for many years - the bit is mostly threaded onto the shank and "locked" by two metal pins, preventing further rotation of the hole seen. Where Bosch differs from Milwaukee is in the placement of the locking pins. The Milwaukee has a very easy to use slide mechanism for inserting the stylus, while the Bosch has a very rigid and unnecessarily complicated spring mechanism. The Bosch mechanism is so firmly in place that when I first tried it I thought I was doing it wrong. You almost have to use a flathead screwdriver to open the mechanism. However, I've found that the easiest way to do this "no tools" is to grab the shaft with the sliding mechanism and bang the underside of the shaft axle against a hard surface. This will safely displace the mechanism but will require the mandrel to be removed from your drill bit. Another issue I have with the mandrel is the pilot drill. It's not securely attached. The drill is very shaky, so the holes are not very precise. Additionally, once the hole saw begins to penetrate the material, the "wiggle" of the shank will cause the drill bit to move and create a much larger notch, and also allow the side walls of the hole saw to make contact with the side of the drill bit Hole. you drill This increases friction, creates more heat that can be dissipated, and requires more power from the drill used. With that in mind, I used these hole saws exclusively with the mandrel from my Milwaukee set. The threads are the same, so the bits are compatible with Milwaukee tool holders, which are much better. QC QUESTIONS: One of the crowns I received (the largest) is not threaded correctly. Whenever I try to attach it to the shaft it crosses over. When I look at a threading job I see that there is excess metal at the base of some thread grooves and I need to rethread those threads before I can use this hole saw. Hole saws are good, but again not as good as Milwaukee. There are cutouts to help you remove plugs stuck in the saw. However, they are just a smooth diagonal line. The Milwaukee cutouts are "staggered" so you can use the connectors in several different places along the connector path. It's like the difference between using a single stage corkscrew to open wine bottles and the prettier two stage model. Still, they cut great. I cut a 1" thick aluminum bar with no problem. You do need to remember the rules for chip erasing though. This is required for ALL hole saws and is not limited to Bosch. When cutting material you need to provide a path for the chips, to exit the hole.The standard twist drill bit evacuates chips through chip flutes in the bit.These hole saws do not allow the chips to get on the hole saw itself, so the chips stay in the hole, creating extra friction and preventing a good hole from being drilled .In soft woods you can usually get by without a trail, although your hole won't be very pretty (and will likely have burn marks.) However, with any metal, unless you're working with very thin, it's imperative to create a trail sheet metal. If you don't believe me, try cutting 1/2" thick aluminum or thicker with and without chip removal. Without this measure, all Al aluminum shavings to aluminum powder, the cutting takes forever and puts a tremendous strain on your drill. Thanks to chip cleaning equipment, you can get nice looking metal shavings, cutting becomes quick and relatively easy. The easiest way to create a path chip removal is to punch a hole through to drill the material directly on the inside of the notch made by the blade. Chips are continuously discharged from this through-hole. Another alternative, more project specific, could be to cut a hole with a gap/path going outside the hole. For example, in aluminum I cut a path with a bandsaw and it worked really well.