Doing Counterbores

dusty · Post by **dusty** » Wed Aug 29, 2012 7:53 am

ed reible, et al: I have seen some of your work involving counterbored holes and I am impressed by how clean they are. Is this the sort of bit you use or do you have something different?

[ATTACH]18316[/ATTACH]

If these are what you use, at what speed do you drill. I have been drilling counterbores with these bits at low speed with what I consider poor results. The holes are in the correct location but are not clean, smooth fits to the screw heads.

For my last project I even bought a new bit, hoping to do better. Dull bits are not my problem.

pennview · Post by **pennview** » Wed Aug 29, 2012 8:44 am

I'd turn up he speed till the counter sink cuts smoothly. I use similar cutters with one cutting surface and they work fine. You must hold the material solidly that you are drilling into in order to keep it from vibrating as this will result in a rough surface to the counter sink. If they are a bit dull, you can touch up the flat surface with one of those diamond paddles. But I've found that some counter sinks just don't cut well regardless of how sharp the cutting edge seems.

Regarding terminology, counter bores have flat bottoms and a typical use would be for placing a bolt head below the surface of the wood. Counter sinks cut beveled reliefs for flat-head screws.

dusty · Post by **dusty** » Wed Aug 29, 2012 9:45 am

pennview wrote:I'd turn up he speed till the counter sink cuts smoothly. I use similar cutters with one cutting surface and they work fine. You must hold the material solidly that you are drilling into in order to keep it from vibrating as this will result in a rough surface to the counter sink. If they are a bit dull, you can touch up the flat surface with one of those diamond paddles. But I've found that some counter sinks just don't cut well regardless of how sharp the cutting edge seems.

Regarding terminology, counter bores have flat bottoms and a typical use would be for placing a bolt head below the surface of the wood. Counter sinks cut beveled reliefs for flat-head screws.

I thank you for this lesson in terminology. I have counter bores, as well as these counter sinks, though the counter bores be for metal. Now I can quit referring to them is "flat bottomed counter bores" to distinguish them from the "other" counter sinks.

I guess I better set up for some counter sink lessons and run through some speed changes.

All other suggestions are still welcome. I have not resolved this yet. Who'd a thunk I would still be learning to drill holes properly at age 73.

JPG · Post by **JPG** » Wed Aug 29, 2012 10:05 am

dusty wrote:I thank you for this lesson in terminology. I have counter bores, as well as these counter sinks, though the counter bores be for metal. Now I can quit referring to them is "flat bottomed counter bores" to distinguish them from the "other" counter sinks.

I guess I better set up for some counter sink lessons and run through some speed changes.

All other suggestions are still welcome. I have not resolved this yet. Who'd a thunk I would still be learning to drill holes properly at age 73.

I am not touting the brand, but rather the design. I have used them on aluminum as well.

http://www.toolbarn.com/festool-492520.html

Not clear how/why they work, but once you try one, you will never go back,(wish I had obtained some when I had the chance).

I have seen them elsewhere online, but do not recall where.

videobear · Post by **videobear** » Wed Aug 29, 2012 10:20 am

Not an expert here by any means, but it seems to me that you would be likelier to get a clean, centered result if you...
a) Used one of those one piece drill/countersink bits, or
b) for a flat bottomed counterbore, drill the counterbore first with a Forstner bit, then change bits and drill the bolt hole in the center.

reible · Post by **reible** » Wed Aug 29, 2012 11:11 am

Let me refer you to this thread:

https://forum.shopsmith.com/viewtopic.php?t=9878

Ed

rpd · Post by **rpd** » Wed Aug 29, 2012 11:17 am

JPG40504 wrote:I am not touting the brand, but rather the design. I have used them on aluminum as well.

http://www.toolbarn.com/festool-492520.html

Not clear how/why they work, but once you try one, you will never go back,(wish I had obtained some when I had the chance).

I have seen them elsewhere online, but do not recall where.

Lee Valley has them also and at a better price

http://www.leevalley.com/US/wood/page.aspx?p=32308&cat=1,180,42240,42281

dusty · Post by **dusty** » Wed Aug 29, 2012 11:56 am

reible wrote:Let me refer you to this thread:

https://forum.shopsmith.com/viewtopic.php?t=9878

Ed

Thank you, Ed. For some reason I did not see or do not remember the last post to that thread.

I also appreciate the reference to Lee Valley, rpd.

JPG · Post by **JPG** » Wed Aug 29, 2012 4:35 pm

dusty wrote:Thank you, Ed. For some reason I did not see or do not remember the last post to that thread.

I also appreciate the reference to Lee Valley, rpd.

ME TOO !!!!!!!!!

foxtrapper · Post by **foxtrapper** » Thu Aug 30, 2012 2:52 pm

Seems any time I use a standard counterbore bit like the OP showed, I'll get lots of chatter and a triangular shaped hole or bowl. Someday I'll study that triangular bit.

I get my best results with a remarkably crude tool. These:

Got them many years ago. Nothing more than a flat piece of steel with the end rounded up so it fits in my drll. They don't chatter and produce a superb hole.