Drill bit fluting?

[Jason280]

I picked up a box of new USA HS & HSS drill bits, but curious about the fluting. It looks to be wider than most of my other bits, what is the benefit of this style fluting?

 

[Cahark]

We have always called those parabolic drills. I can't say I've had much experience with them, but From what I understand, they provide better chip evacuation. The higher helix should also allow for a sharper cutting lip. In most cases they will have a split point that allows for lower cutting pressure and easier drill starting without walking. This feature is not uncommon among many other drills. Usually with a 135° point, however it can also be done with a 118° point.

Most of the time in machine shops, I usually only see them set up in the production areas, but I have had good results with them in the Tool room. They are usually overkill for the majority of my needs.

Nice find!



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[mowkep]

I use them a lot. They are for evacuating the chips quicker and tighter tolerances. Thank you Cahark for calling them parabolic. Another guy had the same type drills in another thread and nobody was believing that they were parabolics. I buy them from McMaster Carr and they are called....parabolic drills.

 

[metlmunchr]

They're especially effective in feeding chips out of deep holes. You wouldn't think it by looking at them, but parabolic flute drills are actually stronger in compression than standard jobber drills due to the fact that they are made with a heavy pattern web. This allows you to feed them harder to effectively break the chips since a drill producing strings rather than broken chips is a major problem in any sort of production machining.

 

[Ign]

Yep parabolics. I use 'em several days a week for deep holes in aluminum

 

[Jason280]

Excuse my ignorance, but what is the benefit of the other style of fluting?

 

[Cahark]

Excuse my ignorance, but what is the benefit of the other style of fluting?

They are cheaper, readily available, and in most cases slightly easier to sharpen due to The lack of secondary point angles. They are more of a general purpose drill than anything.


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[Ign]

I don't know what theory says about it, but in my experience - and in my experience only - parabolics are weaker and flexier.

I love 'em for deep holes in soft material for chip evacuation, but otherwise they seem more likely to snap if they grab and they walk more if drilling on a radius like pipe (head angle such as 118 or 135 being equal) 'cause they flex.

ALL of my experience is with #21 and 9/64" so this is fairly small! On bigger drills it may not matter.

 

[mowkep]

I've used them on steel, mag and aluminum. Never a problem. I think 1/2 inch is the biggest one I have at the moment. They are also TIN coated. I like them but they are expensive

 

[Jason280]

Interesting.

I need to go through and organize them, and see what all I have. I have a pretty good selection of drill bits already, but having these definitely won't hurt...just need to figure out when to use them over standard bits.

 

[Superbec]

I got a few , they are a ***** to sharpen by hand ... used to have split points when new, I can't replicate split point by hand so the need a pilot hole most of the times ...

when dull will make a triangular hole !


at least that's my experience with them

 

[Snap_cap]

Nice selection you found.