Drill bits - split point? chisel point? 118-degree? 135-degree? Coatings? Arrgghh!!

cazclocker

cazclocker

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I'm getting set to purchase two sets of drill bits - fractional (1/16" to 1/2" in 64ths) and number (#1 to #60). I'd like to acquire some higher-quality sets, so I'm thinking Cleveland or Hertel. I guess I'll get them from MSC, I have an account there - but I've ordered from McMaster-Carr and Enco before so who knows. I'm just a home hobbyist, so I want to get my money's worth - I can't afford to own several sets.

I think I'm fairly clear on point angles (135-degrees will "walk" less on hard surfaces), and I'm definitely looking for screw-machine length instead of the jobbers-length. But I'm confused about the point styles that are out there...split point, chisel point. There are probably others that I don't know about.

I drill a fair amount of wood, but I drill metals too. Brass, steel & aluminum. I use an inexpensive Delta tabletop drill press, but it's in great shape and seems to do a good job.

Can someone explain the differences in the tip geometries out there with drill bits? Maybe there's a good primer I should purchase and read.

Thanks in advance,
Doug
 
Are you planning on having to resharpen drills when needed, if so can you do split points? Here's some good reading on the subject.
http://www.icscuttingtools.com/the-champ/drill_point_geometry.pdf

I personally think that coatings for home shop use is wasted. I've been using the same drill sets for 40 years. Most of the drills are original to the sets. Choose your speeds correctly for the material and good quality bits will last a lifetime.
 
OldMachinist said:
Are you planning on having to resharpen drills when needed, if so can you do split points? Here's some good reading on the subject.
http://www.icscuttingtools.com/the-champ/drill_point_geometry.pdf

I personally think that coatings for home shop use is wasted. I've been using the same drill sets for 40 years. Most of the drills are original to the sets. Choose your speeds correctly for the material and good quality bits will last a lifetime.
Click to expand...

Thanks for that - looks like some good reading. It's coming out of my printer as I type this - I'll read it this afternoon. I don't know how to sharpen my bits, except that so far the opinions I respect the most all feel that the bit sharpening gizmos out there should all be thrown in the trash, the point being that bits should be sharpened by hand.

That being said, I'm a quick study so I'm sure I could learn how to sharpen my bits - there's just so many conflicting opinions it's confusing.
 
As a younger man I could still see to sharpen bits less then 1/8" several years ago that changed and now it's not only >1/8" it's getting towards 1/4". 10 yrs ago I'd say there is no need for sharpening gizmos at all. Now I think a good gizmo is worth it for < 1/2".

My point is that it is difficult to sharpen drills that cut accurately. As you age it is even more difficult, jigs start to help. I'll start drilling with a bit and see differing swarf. I'll stop with the swarf in place and mark the thick dress side then grind it back a bit so the other side cuts the same. Point gauges or no. It helps a bit with the hole size.

My protege has more money than I and wants to buy TI coated crvd iradium nitrite drills. I say look at what is needed for threading. It don't come in a kit! Gorm! I say buy a decent array of sets or a 115 pc kit and every time you need a drill buy a good one and store the decent one away. You will come out in good shape and still have what you need for surprises, but not spend as much as buying a mill.

Drilling brass you need to change the lead angle of drill to keep it from "screwing in". Wood needs to be cut as it is drilled as with a spade bit.

It's not like laundry soap, the many differences are for a reason. I'd say (as my own opinion) for what you said your uses would be just buy a decent set of 118° (split point or not) then branch out from there as needed,

Steve
 
Doug,

The best bang for the buck in the home shop is a set of jobbers length black oxide bits. Screw machine length bits are also handy, but you need the longer length bits first. What I do is keep an assortment of screw machine length bits around in the sizes that I most commonly use, not entire sets. For soft materials and mild steel, 118º degree split points are the way to go. 135º points hold up to heat better and work well for harder materials like tool steels. BTW, it's the split point that keeps the bit from wandering, not the angle. In fact, 135º bits tend to wander more than 118º bits regardless of the point. McMaster Carrr carries Precision brand bits, which are excellent quality, made in the USA and less expensive than the "brand names". I would highly recommend them.

Tom
 
I second the Precision brand bits. I got one set off e-bay and one set on amazon. Both at much better prices than Enco. I use a Drill doctor to sharpen them and have been happy with the results. I was using a cheap set from HF, I wish I had bought a better set a long time ago.
 
Thanks guys, I already have a decent set of jobber's length black oxide bits, fractional sizes. I've had the set for several years now, no complaints yet. I think I said I want to get screw machine lengths bit sets, reason is I rarely drill deep enough holes to justify owning a jobber's length set and I like the rigidity that comes with the shorter length. It's the points (chisel or split) and the angle and the coatings that mystify me. So far the best tip is the link in the first answer, I thought I could get to it this afternoon but things came up, now it will have to wait until tomorrow.
 
TomG said:
Doug,

EDIT..... McMaster Carrr carries Precision brand bits, which are excellent quality, made in the USA and less expensive than the "brand names". I would highly recommend them.

Tom
Click to expand...

I took a look around Amazon.com and found "Precision Twist" brand. Is that the brand you're referring to? By the way, I did NOT find "Precision" or "Precision Twist" on McMaster-Carr - that's why I looked on Amazon.com.
 
It's Precision Twist Drill (PTD) brand. McMaster Carr doesn't list their brands, but that's usually what they ship. MSC sells them as well by name.

Tom
 
TomG said:
It's Precision Twist Drill (PTD) brand. McMaster Carr doesn't list their brands, but that's usually what they ship. MSC sells them as well by name.

Tom
Click to expand...

Thanks so much, Tom.
 
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