gerryr
Member
What is the preferred angle for drill bits for drilling wood and plastics?
Drill bit angle
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Paul in OKC
Member
You mean like 118 or 135 degree?
gerryr
Member
Yes.
Paul in OKC
Member
I use 118. It is a little more 'pointed' than the 135. I feel it drills truer, at least in wood.
Dario
Member
I need to hear this too. I actually asked a similar question before buying the HF set but never got the answer I was hoping.
When I got to the HF store, they only have one angle available anyway...so it didn't really matter choice wise.
When I got to the HF store, they only have one angle available anyway...so it didn't really matter choice wise.
What really helps in drilling plastic is reducing the web thickness of the drill bit at the point. This area isn't cutting on a normal twist drill, and cutting is important to reducing the heat in a plastic.
A "split-point" drill bit will cut a better hole in plastics because of its thinner web. You can do this yourself, but keeping both flutes of the drill bit the same is difficult without a precision grinding fixture of some kind.
Drilling a smaller pilot hole will make plastics easier to drill. Use a pilot drill that is only slightly larger than the web thickness of the drill.
A "bullet point" will always work better in plastic than a regular drill because the smaller tip is always cutting a pilot hole for the larger diameter.
A "split-point" drill bit will cut a better hole in plastics because of its thinner web. You can do this yourself, but keeping both flutes of the drill bit the same is difficult without a precision grinding fixture of some kind.
Drilling a smaller pilot hole will make plastics easier to drill. Use a pilot drill that is only slightly larger than the web thickness of the drill.
A "bullet point" will always work better in plastic than a regular drill because the smaller tip is always cutting a pilot hole for the larger diameter.
gerryr
Member
Thanks. Now I know I need 118 degree split point bits.
I guess I'll have to change the setting on the Drill Dr. I have been using 135* split point on wood, plastic and antler.
btboone
Member
The angle is not all that critical. As Eagle says, I sharpen most myself, and they come out to somewhere close to 135, but sometimes are like 150 degrees. Mine are weird because my sharpener is set up for normal spiral drills, and the carbide one that I sharpen most has straight flutes, so I need to fudge where the settings on the sharpener go. It doesn't seem to make much difference when drilling. The 118 degree are the normal angle that most drills are.
emackrell
Member
Russ, sorry for the newbie question, but what does "web thickness" refer to on the bit?
cheers Eileen [8D]
Thanks for the back-up Bruce
My reasoning is likened to if I were to use a finish nail and needed to blunt the head so the wood doesn't split.
The broader the angle on the cutting edge the more "shearing" action the bit is doing as opposed to splitting.
That's my story and I am sticking to it because it works for me,That and the split points that I can make would cost more if I had to buy them.
That Drill Dr. is slicker than pockets on a shirt.!
My reasoning is likened to if I were to use a finish nail and needed to blunt the head so the wood doesn't split.
The broader the angle on the cutting edge the more "shearing" action the bit is doing as opposed to splitting.
That's my story and I am sticking to it because it works for me,That and the split points that I can make would cost more if I had to buy them.
That Drill Dr. is slicker than pockets on a shirt.!
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