I need a flat countersinkIng gizmo

[nissan_crawler]

Ok, I'm making new motor mounts for my bicycle. They're going to be a clamshell mount out of aluminum. I'm going to use socket head cap screws and want them to be countersunk into the mount. Whats the name of a cutter I can use in a drill press to make a flat countersink?

 

[merr6267]

That is commonsly called a "counterbore" where a countersink would be a tapered hole for a flat head screw.

Google counterbore, then look in the "shopping" tab. There are a few for sale that way. Of course there are countless others on many industrial sites. McMaster, etc.

Have fun.

Phill

 

[Neohio]

What about using an End mill? Should be flat bottom. Just drill to the depth you want with a reg bit, then flatten the bottom with an end mill.

 

[OccupantRJ]

What about using an End mill? Should be flat bottom. Just drill to the depth you want with a reg bit, then flatten the bottom with an end mill.

The counterbores can also be created by drilling with a proper sized drill, then flattening the bottom of the counterbores with a drill sharpened to have a flat end. This is why it is important to be able to grind one's own cutting tools. It allows much more freedom in creating things as needed.

 

[Alchymist]

http://www.google.com/imgres?q=coun...tart=0&ndsp=12&ved=1t:429,r:3,s:0&tx=99&ty=43

http://www.sunrisegr.com/srt_d.php?id=000106

 

[A_Pmech]

The counterbores can also be created by drilling with a proper sized drill, then flattening the bottom of the counterbores with a drill sharpened to have a flat end.

Beat me to it!

A flat ground drill is an easy and fast way to c-bore.

 

[Graham08]

I've got a set of counterbore cutters. The only thing to be careful of is the pilot is usually 1/32" oversize on them...meaning you need to drill a 9/32" hole for a 1/4" screw. Okay for tension applications, but not so good when you're cheating and using the bolt for location + attachment.

 

[nissan_crawler]

Thanks guys. I went to the yard and ended up with a 1/2" end mill, 5/8" end mill, 1" reamer, tap handle, and 2-1/4" socket for $26.

The end mill worked great, and the price was right at $5 per pound.

 

[metal4130]

Beat me to it!

A flat ground drill is an easy and fast way to c-bore.

A couple of tool and die veterans showed me this trick too. Doing it this way allows you to make a c-bore for any size hole.

The trick is learning how to grind the dill bit flat so each flute is symmetrical. If not, one flue will start to cut before the other and then the drill can start to walk on you as you drill.

When your done, if you have an end mill of the same size you can use it to make the bottom of the c-bore nice and square.