center drill bits ?

[WaterFowl]

Newbie builder here!
searched drill bits but nothing on centering bits ?
Looking for reliable brand-make of center drill bits..
Is a carbide bit the way to go?
They are numbered 1-4 which ones are used the most?
Want to buy something that will last.....Thanks all input welcome....dan

[billd]

Correct name is combination drill counter sink.   Keo is one brand that comes to mind.  I only use a #2 to start the pins on the forearm if the forearm is already rounded. If flat you don't need them.   Very shallow.  Don't use carbide, too brittle unless everything is firmly clamped. 

Only exception is a #3 or #4 to start the touch hole liner.  You can use the same #2 if that's all you have. 

Bill

[Dennis Glazener]

Google is always your friend when looking for something for sale. Check MSC's listing at this address http://www.mscdirect.com/browse/Holemaking/Countersinks-Chamfer-Mills-Back-Chamfers-Center-Drills/Center-Drills-Combination-Drill-Countersinks-Spotting-Drills?navid=12106077&rdrct=center%20drill

Or Enco at this address http://www.use-enco.com/CGI/INSRAR?PMSECT=0000000606

There are plenty more companies but these are the ones I use. As far as carbide, I stay away from them due to cost. I have had my cheap MSC center drills for over 20 years and they still work fine and have never been sharpened.
Dennis

[RAT]

Interesting terminology. Now I know why some people use them wrong. In drafting school they were always called center bits. I'm not a machinist, so I don't know how they were used in the real world, but we were taught that they were used to start drill holes straight (because they are short/fat and have less flex). The starting hole would be undersized. A conventional drill bit would be used to finish the hole (followed by other operations as needed). The slight countersink would help start the drill bit, but it wasn't used to provide the finished countersink. That would be a separate operation with an actual countersink. 

[flehto]

One of the "facts" I ws told when in my 5 yr tool and diemaker apprenticeship, was that they're called "centerdrills" and were used in machines that had clamped workpieces, eg...radial drill presses, milling machines and lathes. We never used "centerdrills" in drillpresses...always used a smaller drill to "find" the center punch dimple and then the larger drill.  The more flexible smaller drill finds the centerpunch and then the workpiece is moved so the drill runs in line w/ the spindle.  This smaller drill should be larger than the "web" of the larger drill being used so it will center the larger drill. The depth of the smaller drilled hole should exceed the angled point depth of the larger drill.  My tool box has different sized  
"centerdrills", but I never use them in gunbuilding......Fred

[Bob Roller]

I use them a lot,drill press, mill sometimes,lathe. Wouldn't be without them.

Bob Roller

[Acer Saccharum]

I use the 'combined drill and countersink' drills. These are good for starting holes where there is no punch mark, as they are stiff enough so they do not wander. A long thin drill will wander if you try to start it without a punch mark.

For tapping, I drill deep enough so the countersink part of the drill flares the hole a little wider than the tap. This makes for nice finished tapped hole, no burrs on the surface, no first thread sticking up to catch on. Just make sure the tip of the C-D-Countersink is smaller than the tap drill.

[Steve-In]

Spotting drills are a much better choice.  They are less likely to break.  HSS will be fine for most shops.  1/4" x 90 deg would be great to start with.  See link below. 
Center drills are used for lathe work to put a hole in the end of a bar so it can be supported by the lathe centers.  They can be used for starting holes for drills but the spotting drills work better for this. 
http://www.mscdirect.com/browse/?navid=12106130&searchAhead=true&searchAheadTerm=spot&typahddsp=Spotting%20Drills&hdrsrh=true

[WaterFowl]

Thanks Dennis..I should have typed nothing came up in search on this site.
Thank you for the shared information....Build on!