wheelsmithy
wheelsmithy SuperDork
11/28/19 6:59 a.m.

Pilot hole? 

Buy brand new bit just for this?

Sparkydog
Sparkydog Reader
11/28/19 7:02 a.m.

It’s heat treated steel. As hard or harder than your drills. Masonry bits with carbide tips may work but you will probably need 1 for each hole.

A machine shop with a wire EDM will also have a hole popper and they can put the holes in.

ntsqd
ntsqd New Reader
12/12/19 3:45 p.m.

Cheap though not necessarily inexpensive hardware store drill bits probably won't work. Find your local machine shop supplier and buy a Cobalt stub length drill bit from them. Or buy one from either MSC-Direct.com or McMaster.com While you're at it buy real cutting fluid, it WILL make a huge difference.

79rex
79rex Reader
1/4/20 10:21 a.m.

Carbide drill and a mill, or bolt a vise on a drill press.  As long as the drill press has a wide range of RPM.  And use coolant.  Go slow, its going to take time.  Gentle pressure let the drill do the work.

robmillion
robmillion New Reader
4/23/20 1:36 p.m.

https://www.treefortbikes.com/Problem-Solvers-Singlespeed-Cog-Fits-Carrier-6-bolt?utm_source=google&utm_medium=cpc&adpos=&scid=scplp3332223953752695&sc_intid=3332223953752695&gclid=CjwKCAjw-YT1BRAFEiwAd2WRtkYeYm8lfPz9Q7eDbAuS5j0_0Wi-rDBBZIJQz6_jqGclLi4KER8xzBoCzCIQAvD_BwE

this may be a better option, it will be really hard to drill through a coaster brake cog. and they are often offset, possibly right where you would need to drill.  it's 3/32"  but it would work fine with a 1/8" chain if that's what you have.

 

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