Cap screw counterbore

[John252058]

I'm looking for input on manufactures of counterbore drills or milling cutter. I need to make 3/8" counterbore in aluminum with no pilot hole, done in one pass with 60 degree countersink on a milling machine.

 

[4GSR]

Use a 3/8" end mill. About as quick as using a counterbore with a pilot. Done this many times over the years before I bought some counterbores.

 

[JimDawson]

I think something like this is what you are looking for.

http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=28075211&PMAKA=337-3444

EDIT: If you are trying to do a flat bottom counterbore with a 60* chamfer at the top, then you may have to have a tool made, I don't think I have ever see a stock one like that.

 

[Bill C.]

I think something like this is what you are looking for.

http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=28075211&PMAKA=337-3444

EDIT: If you are trying to do a flat bottom counterbore with a 60* chamfer at the top, then you may have to have a tool made, I don't think I have ever see a stock one like that.

Thanks for the link, I now understand what he needs.

 

[John252058]

Yes that's what I wanted to do. Drill or mill the bolt hole, counterbore and the countersink in one pass with one tool.

 

[dracozny]

Yes that's what I wanted to do. Drill or mill the bolt hole, counterbore and the countersink in one pass with one tool.

something like this sounds in order there are also counterbore drill combo attachments, but all the ones I have seen seem to be designed for wood in that case.

 

[JimDawson]

Yes that's what I wanted to do. Drill or mill the bolt hole, counterbore and the countersink in one pass with one tool.

I found this, but you would still have to do the chamfer in a second operation. http://www.mscdirect.com/product/details/56443971

Many times I do the drill/counterbore on the mill then do the chamfer on the drill press or with a hand drill

 

[dracozny]

I found this, but you would still have to do the chamfer in a second operation. http://www.mscdirect.com/product/details/56443971

Many times I do the drill/counterbore on the mill then do the chamfer on the drill press or with a hand drill

I do most of my chamfering by hand as well. I don't imagine there is much demand to make such a tool.

 

[John252058]

Thanks for the input folks. I'll try out the tool from Link.

 

[4GSR]

I see what you are getting at now.

I had a similar situation as yours years ago. Dad had a drill bit ground down into a step drill. Major diameter was something like 3/8", the ground down diameter was something like 3/16". the angle between the steps was something like a 120 degrees. Used it to drill and countersink holes in clutch linings for the installation of copper rivets.