Countersink angle

[fullmer]

Looking to buy a 1 1/2 inch countersunk bit to enlarge a hole in 1/4 steel what angle is better 60 80 90 ??
 

[Dalex]

can you measure the angle of the screw head ?
 

[big fred]

Pretty much depends on the fastener you're using. I suspect you'll find it's either a 100 degree or 80 degree included angle on the fastener head.
 

[fullmer]

I will be using like a drill bit to go up to a larger pin size drilling all the way thru
 

[Dalex]

Ok , then you are looking for a reamer ...A Counter sink won't drill worth a hoot....
 

[Don-Wi]

How thick of material are you drilling through? A step drill comes to mind if it's sheet metal. A reamer isn't what I'd recommend.

Donovan from Wisconsin
 

[fullmer]

A bridge reamer would cost $200 in 1 1/2 the hole is egg shaped bad it is 1/4 plate looking for a cheaper bit
 

[Dick L]

Don't know what you have to work with but if I had it to do here I would grind the angle needed on an old 2 inch drill bit and clamp it down and keep taking a little out at a time until I had the desired OD of the taper. You can lay the bolt on the drill bit with the head down to get the angle you need by eye.
 

[Russ from MN]

Use a hole saw, lots of coolant, run it slow. Sometimes I drill some small holes around the circumference so there is somewhere for the chips to go. 1/4" should be easy. If you want a tight fit saw it a little under size and file it to fit. Clamp a piece of hardwood on top to keep the hole saw centered.
 

[markiz41]

How about 1-1/2 step drill?

http://www.amazon.com/MAGBIT-851-1500-MAG851-4-Inch-Diameter/sim/B005M27CGG/2

Not going to be cheap at $90.
 

[Mike Kork]

Just make a round hole and weld it over your egg shaped hole.
 

[dhamps10]

I have done that very thing, in close quarters, where a drill bit was too long. 60 will cut best.
Dennis
 

[Bradracer18]

what are you trying to do?

Typical countersinks are 82 and 90 degrees. Most machine screws are 82 degrees.

If you are trying to make a hole larger....a reamer is generally only if you are trying to make it say 0.030 larger or so. If its not extremely critical, I'd just throw it in the mill, center find the current hole and mill a hole the size you are looking for....easily be able to hit your desired dimension
 

[ss55]

Can you use an end mill bit, or an adjustable fly cutter?