View Single Post
Old 05-19-2015, 12:33 AM
Davezilla's Avatar
Davezilla Davezilla is offline
Motorized Bicycle Elite Member
Join Date: Mar 2014
Location: San Antonio Texas
Posts: 2,710
Default Re: Countersinking with hand drill?

You can get the real countersinks from places like there are 2 main countersunk fastener angles, 82 and 100 degree, most machine screws and rivets are 100 degree. There are some that are 120 degree as well but not as common.
The countersinks they sell are piloted to guide the countersink into the hole and keep things centered and the pilot needs to fit snug in the hole to prevent chattering. If you need to be precise, you can also buy a microstop so every countersink is exactly the right depth and the same so the screw heads will be perfectly flush with the metal.
You will also need to keep the cutters well lubed with cutting oil or boelube for best results and to prevent burning the cutter or the metal being countersunk. One problem countersinking steel is getting the metal too hot and then it hardens causing it to become near impossible to drill or finish countersinking without burning up more bits... use lots of lube.
For the best results use a microstop like this ...,4104.html
Practice on a piece of scrap metal or plastic sheet to get the depth just right, then you're ready...
These chuck into any hand drill and they use cutters like these...,344.html ... just get the cutter that's the same size as the holes to be countersunk, screw into the microstop, and set the depth, these can also be used for counterboring or shaving the tops of fasteners (shaving is mostly used on aluminum rivets, don't try to shave a steel screw head).

These tools are fairly inexpensive new but can be had for less by buying used if you can find them... pawn shops close to the Airports is a good place to find tools like this used...

You can also freehand a countersink if you just need to do one and the fit isn't critical, but if you need to do several holes, there's no substitute for the right tools...
Reply With Quote