Up to now I’ve always done the traditional hole tapping sequence. Use a drill to make an undersized hole, dig out the relevant tap and cut threads.
Then I found THESE on eBay purely by chance. You know what it’s like sometimes searching for something, unless you know some magical key words you’ll get all the usual dross turn up. Try it, search for Drill and Thread Tap and you’ll see what I mean.
Anyways, I ordered one to try out which turned up on Saturday, and WOW. Why had I never seen these before??
I’ve since knackered the one I bought, testing it out on various materials, more on that in a bit.
They make drilling and tapping a breeze, compared to my previous attempts. I’ve always found aluminium tapping to be a right pain in the bum in the past. Drilling the hole then getting the tap to bite enough not to chew the threads like a masticating cow.
So, how do they work? Really simple, and the 1/4 hex shank should give you a hint. Don’t stick them in your 24,000 rpm drill. Hand drill on a slow speed setting works well. The one I bought (and the new set én route) combine three actions in one.
I mentioned before that I knackered the one I got. Basically, I tested it on a load of different materials with the following observations.
- You cannot use this on hard / unknown metal – that’s how I snapped mine, it got snagged in some pig metal and sheared.
- Soft plastic, forget it. It just doesn’t thread properly. Now I’m sure that once the initial hole is drilled, using it in a hand drill / screw driver arrangement might well do it. I’ll give it a go when my new ones arrive and report back how successful they are.
- Aluminium – wow, an absolute breeze!! I’ve always suffered various results tapping aluminium, and these just did the job right without any fuss.
- If you don’t want a countersunk hole, just stop once the thread has been cut.
- Tolerances – I’ve used various manufactured screws from cheap as chips M3 screws included in cheap rail kits to engineered M3 screws. They just work!!
- I haven’t tried to drill a solid object and insert a thread yet (mine broke before I got chance) but I’ll give it a go once the nex set arrives
All in all, I’m very impressed with them, and should prove very useful (the first one I bought has already paid for itself so far, meaning my Ultra block is now wearing it’s new Weaver rail. More of that in my project on the forum in due course.