Doing Counterbores

Forum for people who are new to woodworking. Feel free to ask questions or contribute.

Moderator: admin

User avatar
dusty
Platinum Member
Posts: 21481
Joined: Wed Nov 22, 2006 6:52 am
Location: Tucson (Wildcat Country), Arizona

Post by dusty »

reible wrote:If you are interested this will get you started shopping at Grizzly for these bits:

http://www.grizzly.com/catalog/2012/Main/634

Ed
There are so many neat things in the MSC catalog. If I allow myself to browse too long in there, I'll never be able to afford or justify the PowerPro.

Also, there are many neat looking items that I have not even a foggy idea of how to use.
"Making Sawdust Safely"
Dusty
Sent from my Dell XPS using Firefox.
User avatar
terrydowning
Platinum Member
Posts: 1678
Joined: Mon Jul 19, 2010 3:26 pm
Location: Windsor, CO

Post by terrydowning »

dusty wrote:There are so many neat things in the MSC catalog. If I allow myself to browse too long in there, I'll never be able to afford or justify the PowerPro.

Also, there are many neat looking items that I have not even a foggy idea of how to use.
True for oh so many catalogs.
--
Terry
Copy and paste the URLs into your browser if you want to see the photos.

1955 Shopsmith Mark 5 S/N 296860 Workshop and Tools
https://1drv.ms/i/s!AmpX5k8IhN7ahFCo9VvTDsCpoV_g

Public Photos of Projects
http://sdrv.ms/MaXNLX
emagnet
Gold Member
Posts: 66
Joined: Fri Jun 15, 2012 11:05 pm
Location: Newark, CA

Post by emagnet »

My two cents. I've never been happy with the results I get with the single fluted cone shaped countersinks I have. I much prefer the center drill style that Ed has shown. However, you have to make sure that the included angle is 82 degrees. Most center drills have a 60 degree included angle, which is correct if you're actually using it to drill a center for turning as the included angle of a tail stock center is 60 degrees. These days, however, most tail stock centers are "live", they have ball bearings. No longer is the little tip needed to drill a pocket to contain oil. Yet, the tip remains. You can purchase 82 degree spotting drills without the tip but they are more expensive, even though it takes more machining to create the tip. Bottom line, I like to use an 82 degree center drill for countersinking although I do have a couple of spotting drills I use when the size is right. Here's a link on MSC to them:

http://www1.mscdirect.com/eCommerce/NavigationServlet/Holemaking/Center-Drills-Combination-Drill-Countersinks-Spotting-Drills/Center-Drills/Combination-Drill-Countersinks/_/N-77h5g?refinement=4290225225&searchandizedOk=Y
User avatar
Culprit
Gold Member
Posts: 234
Joined: Sun Dec 04, 2011 12:37 am
Location: Virginia

Post by Culprit »

reible wrote:If you are interested this will get you started shopping at Grizzly for these bits:

http://www.grizzly.com/catalog/2012/Main/634

Ed
Coincidentally, I just bought a set off Amazon last week.
1955 Greenie, modified to be reversible
User avatar
reible
Platinum Member
Posts: 11283
Joined: Thu Jul 20, 2006 12:08 pm
Location: Aurora, IL

Post by reible »

emagnet wrote:My two cents. I've never been happy with the results I get with the single fluted cone shaped countersinks I have. I much prefer the center drill style that Ed has shown. However, you have to make sure that the included angle is 82 degrees. Most center drills have a 60 degree included angle, which is correct if you're actually using it to drill a center for turning as the included angle of a tail stock center is 60 degrees. These days, however, most tail stock centers are "live", they have ball bearings. No longer is the little tip needed to drill a pocket to contain oil. Yet, the tip remains. You can purchase 82 degree spotting drills without the tip but they are more expensive, even though it takes more machining to create the tip. Bottom line, I like to use an 82 degree center drill for countersinking although I do have a couple of spotting drills I use when the size is right. Here's a link on MSC to them:

http://www1.mscdirect.com/eCommerce/NavigationServlet/Holemaking/Center-Drills-Combination-Drill-Countersinks-Spotting-Drills/Center-Drills/Combination-Drill-Countersinks/_/N-77h5g?refinement=4290225225&searchandizedOk=Y

If you visit the Grizzly page it has both angles.

Because of the stoutness of the bits they are often used to start drilling, you tend to get a better location start then drill bits. This was SOP when I use to work in a machine shop, ie the reason I got my first set. Then as now the 60 degree set was more of a "metal" use set. Note the angle is about the same as std drill bits, which is useful after you get the hole started and want to continue with a drill bit.

The 82 degree set works better for wood as the angle of screw heads are often this angle. There are exceptions so keep this in mind. There are also 90 degree angles again more of the exception.

So far I have found the shear-cutting countersinks hands above other countersinks. If investing I would go this way, and I'd stake my reputation on it. They just cut cleaner.

Ed
User avatar
dusty
Platinum Member
Posts: 21481
Joined: Wed Nov 22, 2006 6:52 am
Location: Tucson (Wildcat Country), Arizona

Followup to post #15

Post by dusty »

Please correct me if I am wrong but I now believe that the bits I show in post #15 are really not countersink bits. Yes, they produce a hole that looks like a countersink but what they really are are starter bits used most frequently for metal work and not so much for wood working.

I come to this conclusion based on information provided by some of the catalogs. Like this one for example.
"Making Sawdust Safely"
Dusty
Sent from my Dell XPS using Firefox.
emagnet
Gold Member
Posts: 66
Joined: Fri Jun 15, 2012 11:05 pm
Location: Newark, CA

Post by emagnet »

dusty wrote:Please correct me if I am wrong but I now believe that the bits I show in post #15 are really not countersink bits. Yes, they produce a hole that looks like a countersink but what they really are are starter bits used most frequently for metal work and not so much for wood working.

I come to this conclusion based on information provided by some of the catalogs. Like this one for example.
http://en.wikipedia.org/wiki/Drill_bit#Center_and_spotting_drill_bits

Under "Metal Drill Bits", see "Center and Spotting Drill Bits".
Post Reply