Are there any self centering drill points/grinds for non-ferrous metals?

I know there's a few different types for steels, but I don't think I've ever found one for non-ferrous metals. Do these exist?

While I typically don't worry about it myself (split point stubs for almost all holes), from this page: Which Drill Point Angle Should I be Using? | Regal Cutting Tools

I'd think the helical point and Bickford would give you the smoothest cutting in non-ferrous, due to the lack of vertical splits as in conventional 135* S/P drills.

Have you tried 4 facet? ........I considered they worked well for me** especially in the smaller dia's in the tough stringy bronzes and gunmetals

** Obviously YMMV

Limy you beat me to it. I "discovered" 4 facet points when I had to try to hand sharpen drills for a titanium job cause the order for new drills was running 2 weeks late. They hold up really well and they are not bad to grind free hand.

The Nucon drills are designed for aluminum. I've had very good luck with them and their weird helical point.

https://www.jarviscuttingtools.com/wp-content/uploads/2019/05/Jarvis-Nucon_Flyer_2019.pdf

There are many different shapes or grinds for metal drill bits. One of the problematic metals is brass. Standard, twist drill bits have a fairly large rake angle at the cutting edge and will tend to grab when breaking through the back edge of the brass part. This can cause the part to jump and the hole can be distorted from a round shape. Other soft materials may exhibit the same problem: soft plastics for one.

The normal solution for this problem is to change the rake angle. This can be done with almost any of the popular grinds on twist drill bits (the common cone like tip, the two facet grind, the four facet grind, the six facet grind, any of the previous with a split point, etc.) Here is one site which explains how this is done.

Drilling Brass: the easy and safe way | handycrowd.com

When you start with a split point bit you need to be careful not to destroy that split point. You can take off the full amount shown near the outer edge of the cutting edge while taking less or none off near the center where the split point is.

I have a full set of fractional sizes that have been altered with this technique for brass and other softer materials.

I have not seen any commercially sold bits with this feature. But there are many, many industrial sources so you can search.

There are many other specialty bits made. Again; search, search, search. And do not be adverse to calling some of the companies that make specialty bits.

different metals need different geometry. are you talking about (re)grinding a drill or what types of drills are available? the rake angle on the twist drill is given by the helix angle and is difficult to change.

For brass or copper, just take a regular drill and dub the rake back to a more neutral angle as EPA described. As he mentioned, a normal drill has very little rake near the center and more as you move outward. You don't need anything special for drilling aluminum or most plastics.

FrodoLoggins said:

I know there's a few different types for steels, but I don't think I've ever found one for non-ferrous metals. Do these exist?

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Plenty of 'em.

And if you have "the need", they pay for themselves, too.

When NOT?

"Poor boy" here starts a divot with a small rounded-end DIY "D" drill. Vanilla drills follow it well. Cost was negligible. "D" drill lasts for years. No significant extra spend required, and not a lot of extra time.

Break-out, most especially on thin material, "away" side, is a whole 'nuther issue.

thermite said:

Break-out, most especially on thin material, "away" side, is a whole 'nuther issue.

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So, what is the best way to avoid break out and minimize exit burr, especially on brass?

richard newman said:

So, what is the best way to avoid break out and minimize exit burr, especially on brass?

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Don't drill through?

More helpfully, best way is to have a scrap of material clamped firmly to the bottom of the actual part, and drill into it. No burr, no grab. Doesn't even have to be the same stock, Al is fine.

Dubbing the rake back will usually take care of this just fine also. If you only have a single drill and don't want to be grinding it all the time to switch drilling from steel to brass and back, adding the backing material will also work well.

use a large point angle or an endmill. also bullet/piranha drill (similar to brad point).

Milland said:

Don't drill through?

More helpfully, best way is to have a scrap of material clamped firmly to the bottom of the actual part, and drill into it. No burr, no grab. Doesn't even have to be the same stock, Al is fine.

Click to expand...

On the 'non-ferrous' one can even get away with thin sheet-metal right under the work to control the edge-burr, atop thick, mostly-hard-glue particleboard or MDF that acts as support in towards the centre where all material is going to become chip, regardless.

Cheaper than sacrificing thicker metal. Works a treat for holesaws and annular cutters, too.