Thread: Bolting a bar to a mill ?

Yes,

The middle of the sprocket nose on most CS bars is a very hard steel disc held in place by those rivets.
Around that disc is a set of hard steel rollers about 6mm in diameter and around that is the sprocket.

The disc can be drilled on some bars with a Co drill but but I found that on better branded bars it needs a TC bit.
A dedicated carbide bit will do it but I found even a new masonry bit or an old one that has been touched up will usually do it.
Slow speed ~120 RPM, high pressure (and I do mean HIGH, i.e. use a DP) and coolant will get you through.
When I do this I probably destroy 1 in every 3 bits (they just crumble) but provided you are not using a full on carbide bit they are not that expensive.

Thanks Bob .
I have a set of the drill bits sold at wood shows where they demonstrate drilling through glass and files . That should do it . Not that I'm rushing into it yet though, just considering doing it later.
Id never thought of using a masonry bit and only just spotted it mentioned somewhere in the last few weeks. when you say touch up a masonry bit , is it reshaping it slightly with a tungsten grinding stone to the angles that form a chisel edge rather than what a masonry bit looks like ?

Originally Posted by auscab

Thanks Bob .
I have a set of the drill bits sold at wood shows where they demonstrate drilling through glass and files . That should do it . Not that I'm rushing into it yet though, just considering doing it later.
Id never thought of using a masonry bit and only just spotted it mentioned somewhere in the last few weeks. when you say touch up a masonry bit , is it reshaping it slightly with a tungsten grinding stone to the angles that form a chisel edge rather than what a masonry bit looks like ?

I've used it both ways - doesn't seem o make much difference.

The one I had set up for CSM had the mounting hole drilled in the bar body behind the sprocket nose rather then in the sprocket itself.
Steel is a bit softer back there, and it allows for nose replacement as required... but you loose a couple of inches as well.