Information needed on drill bits

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Dixieblade57

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Jun 20, 2007
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OK here goes I am going to invest in a good set if drill bits but I have several questions. :confused: I thought maybe some of you who use them and maybe some of the machinists would step in here and offer some good advice.

This bits will be used primarly in my knife construction. So they will set primarily aside and used only for this purpose. So here are some of the questions that come to mind!

1. Cobalt , carbide, HHS, other?

2. What degree of point MSC 's catalog shows everything in points from 118*, 130*, 135*, 140*?

3. Screw machine drills, jobber drills,spotting drills?

If you had to buy only one set for the purpose of using on your knife making what is the set you would buy and why?:D
 
Well, I'm not a machionist but I am a knife maker. I would not buy a set but only get the sizes I need. The sets may have only a couple you would use. I buy cobalt and carbide only. Frank
 
I buy just the sizes I use.
For most work
cobalt,135*,screw machine length.
Stan
 
Frank Niro said:
Well, I'm not a machionist but I am a knife maker. I would not buy a set but only get the sizes I need. The sets may have only a couple you would use. I buy cobalt and carbide only. Frank
Click to expand...

I included you in there as some of you who use them! :D

SBuzek said:
I buy just the sizes I use.
For most work
cobalt,135*,screw machine length.
Stan
Click to expand...

OK I understand what you are saying about buying ths sizes you use the most. I was kind of thinking that in the back of my mind but didn't want to influence the outcome of the thread.

Why the 135* what is the advantage to that particular angle of dgree????

If you had to buy individual bits, what sizes do you consider your most used, (IE 1/16th, 1/8th, etc.)?
 
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To me they don't seem to hang up in steel and Ti like a 118* does and on handle material I get less tear out.
Stan
 
Buy yourself a 115pc set, because that will have any size that you might need, although you may not need them all the time. If you purchase a set of "Made in USA" they are going to be pricey compared to the imports, but it is very much worth it when you need a specific size fractional/letter/number bit, and they are not readily available locally.

Next, purchase the bits you use most often in "quantity" paks from either Enco or MSC (totals range from 6 to 12 bits per pak, depending on bit size. NOTE: My recommendation is to purchase "made in USA" and NOT the "Import". The reason I say this is because I have learned over time that the Import bits, while always cheaper, will sometimes have size variations. This can really mess you up, especially if you need precise hole for things such as folders.

Materials wise, I generally purchase Cobalt, because it offers me a good price/value ratio. I personally like 135 degree split points. This point is designed for metals, and because I own a Drill Doctor sharpener (there was a time when I though the Drill Doctor was a gimmick, but I have worn out three of them now, and they have saved me untold $$$ in drill bits) I can get a lot of mileage out of bits 1/8" and larger...I consider smaller than that size disposable.

Lengthwise, Jobber bits tend to be full length, with the overall length dependent on the dia. Screw Machine bits are "stubby" but offer the best in rigidity. Spotting drill are just that...for spotting only. That means they are intended to make only a small "spot" on the work piece, which is followed by a jobber or screw machine bit to complete a hole. Most of my bits are jobber length, but I also have a number of screw machine bits for jobs where I want rigidity and accuracy.

There are tons of specialty bits out there, and I have found that some of them can be very handy in the knife shop. Particularly "Hi-Roc" bits from MSC or MA Ford. These bits are usually a 1 or 2 flute design, for materials up to an Rc of 65. I keep them around in specific sizes for folder detents, and for when I mess up and forget to drill a thumbstud hole in a folder blade prior to hardening. These are some of the most expensive bits you can buy....I just checked MSC, and 1/8" Hi Roc bits are listed for $19.30 each. Pricey, but when you need one, there is nothing else that will do the job.

In the end what you buy will likely be dictated by your pocketbook, but remember that saving a few pennies now, often costs you down the line. In the end each maker settles on the cost/value ratio that fits their needs.
 
Thanks Ed, that is the kind of info I was looking for. I have burnt up enough of the imports to realize they are no good. So will be looking to the higher dollar. Also thanks for the heads up on the Drill Doctor. I have heard it both ways on it but from what your saying, it may actually be worth the money nowdays. As I can't seem to get the point right trying to sharpen bits by hand!
 
Like Ed said, a good full set of US made. You might only ever use half of them, but you'll always have the size you need. When I replace a size, I buy a multi pack of it.

Most of the drills I have are jobber length, they're probably the most versatile, but I like screw machine length the best because they're shorter and stiffer, so they're more accurate and chatter less. Less expensive too. And it may not matter much to you, but I like that they are more similar in length to most endmills , so things like coolant nozzle placement works better.

135 deg has less edge engaged in a cut than 118 (a shorter edge length for a particular drill size), which reduces cutting forces. But being less pointy are more prone to walk. So they split the point which reduces walking and makes a more efficient cutting edge at the lip. So 118 deg is kind of old school, but they're still popular because they work. 90 deg is sometimes used in plastic, and difficult to drill things may see 140 deg.

Parabolic flute grinds and high helix can be great in production in plastic and aluminum and may reduce things like burrs where the hole may intersect some other feature due to a more acute cutting edge angle. Straighter flutes and thicker webs do better on harder materials because they're stronger and create a more obtuse cutting edge. I also like how a lower helix bit throws the chip off during a peck where a higher helix cutter tends to create a birds nest.

You'll likely be best served by a middle of the road geometry.

Unless you're drilling things like fiberglass, plastic, circuit boards and perhaps aluminum you will probably want to stay away from carbide drills. They have a narrow processing window, so you're likely to spend a lot of money on a bit that falls apart quickly. One exception would be abrasive wood. Carbide circuit board drills do well in the woods we all use. And a few straight flute carbide bits might be handy to have around, like Ed said. I use carbide endmills in that kind of situation, but I'm probably setup a little different than most.

HSS or cobalt HSS. The cobalt will probably hold up a little longer (it is somewhat harder, though somewhat more brittle), but quality HSS holds up well too. Cobalt HSS has a measurable advantage in certain production settings and in borderline too-hard-to-drill stuff.

Avoid import stuff, and there is nothing wrong with black oxide or polished flute. The gold stuff (TiN) you see on some drill bits usually accomplishes practically nothing.
 
Thanks Nathan, this is turning out to be really informative! All the things I always wanted to know but was afraid to ask! :D
 
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