How are drill bits made?

Banana · Feb 17, 2008

What machines and processes are used, etc?
That sort of steels are used?
How are they heat treated?
I've tried google and have found a few sites but very limited "layperson" information that discusses the processes involved with making drill bits. If anyone knows of a site or a youtube video that shows the process, I'd be really grateful.

I'm sitting here staring at my new HSS bit set and cannot seem to decipher how they're made (I'm in the early beginner stages, so some of this stuff is still greek to me

)

Thanks for any help.

JayDee2 · Feb 18, 2008

Ill bite..,
Bananna who?

JayDee2 · Feb 18, 2008

more seriously

somewhere I have tables showing optimum twist rates, sharpening angles, etc.

Are you asking about those details or are you looking for how they twist the flutes into the metal? Grinding I think-today I dunno.

I can discribe one method of building your own earth-auger gauge screws if youre interested- drill several disks, slot out each along a single radius, stretch out equidistant along a bar through a ceter hole in each disk and tack weld opposite the slot with slots 180* apart, stretch one slot to the adjacent disk's slot to 'meet in the middle' evenly between the two disks, and weld.

Ill look for those charts and post or link to them when I find them if someone else dont beat me to it.

Thanks for having a sense of humor, I really couldnt help myself with reference to that knock-knock joke..
JD2

fmari --MariTool- · Feb 18, 2008

I used to make the blanks for the bigger drills with the 1/2 inch shanks. Lots of M2. We turned the 1/2 inch shank, cleaned the od, and faced the 118 degree tip.
They then hardened it. They they ground the flutes when it was hard. Big a** machine. Had an autoloader. I think it cost them 400K.

rfrink · Feb 18, 2008

Since you are "staring at a set of HSS drill bits", you've answered one of your questions. Those are made from HSS.

Well, you sort of answered it. HSS is a general term for a family of tool steels with a very high tempering temp. This is to prevent them from loosing hardness while cutting. These steels are mainly the M series of tools steels such as M2, M4 etc. For heat treating, basically, they are heated to a critcal temp...then quench to harden them. After quenching, they re-heated at lower temps to temper or draw them for toughness.

In the old days, skilled tool and die makers could make drill bits with a indexing head geared to the table feed. As the table fed the work piece into the cutting tool, the indexer spun it to make the helix. The drill bit is roughed machined while still soft, another HSS cutter could be used to machine it, then it is heat treated...then finished ground.

Today, mechanical rotary indexers have been replaced with numeric controlled machinery, but for some interesting reading, find an old shop book on the milling machine and using a dividing head/rotary indexer. It's amazing what those guys did..or can do.

Not sure if this really answered anything.

-Rob

JayDee2 · Feb 18, 2008

still looking but...

...Cobalt, BTW, is used with some steels to add strength as it gets hot- steel softens greatly as it begins to get near red and more as brighter colors orange and yellow etc- cobalt in the alloy helps the bit to continue to cut as the thin sharp edge gets overheated under high pressures and speed...
...the manufacturer will 'brag' about the (expensive) cobalt alloy when they use it in their product, so youll know what they are when you buy them

jd2

SteveM · Feb 18, 2008

Here's a Pratt & Whitney mill milling the flutes in a twist drill, using the indexer geared to the table, as Rob mentioned:

This shot shows how the head is geared to the table:

Steve

rfrink · Feb 18, 2008

Great pics Steve!!

Gosh, that's old school. Some poor guy sat there all day: loading parts and cranking the handwheels and throwing the power feed lever. All while getting splashed with the nastiest, redish-black lard and sulfur cutting oil.

I love seeing these photos.

SteveM · Feb 18, 2008

Those are from an old P&W brochure. Tony Griffith's web site has a lot of them.

http://www.lathes.co.uk/prattwhitneymiller/

Those pics date from before WWII, as that is the earlier flat-belt-drive model.

Steve

Banana · Feb 18, 2008

Thank you guys so much...
I think I understand now.

This is why the internet is better than books.

dsergison · Feb 18, 2008

technically "drill bits" are the pieces left after you break a drill.

and what you typically call a "drill" is actually a "drill motor".

then there is the old "bit and brace" where a "drill" was a "bit", and the bit was powered by YOU cranking a "brace".

somewhere these terms got the bumped around and now used in different ways.

--is the market in the crapper today?

Banana · Feb 19, 2008

I'm a "value" guy.
I couldn't hardly tell you what the dow does on any given day unless my target companies start going down and approaching their strike prices

I do know that the dollar is sucking wind, though.
I sure hope this leads to an upsurge of higher end domestic manufacturing.

Tejano · Feb 19, 2008

Funny that you ask that question, I was just watching this video. Might answer your quetions.

http://quicksilverscreen.com/watch?video=14721

gwilson · Feb 20, 2008

Gee,Steve,that dividing head looks just like the one I sold you!

mrcrazy · Feb 21, 2008

One episode of the Canadian programme, How It's Made, (try to find it on Cable) has a segment on making drill bits. They have other machining topics, too.

SteveM · Feb 21, 2008

gwilson said:
Gee,Steve,that dividing head looks just like the one I sold you!

Yes it does! I just picked up some collets, so I have most of them by 16ths.

I just bought a South Bend drill press (see:
http://www.practicalmachinist.com/vb/showthread.php?t=149023&highlight=drill+press )

Have to go pick up the drill press from my brother's garage so that I can start making the indexing plates for the head.

Steve

precision tools · Feb 21, 2008

Originally, twist drills were made from straight blanks with the flutes forged in. They were heated and twisted.

While some are still made by that method, most are made on CNC equipment by grinding from the blank.

sch · Feb 23, 2008

Drill bits/cutting tools with coolant holes down the flutes are still
made by cutting straight flutes, drilling or EDMing the holes through
the flute and then twisting the soft stock to desired twist before
hardening and final grinding. Iscar rep showed us a little video of
the process back in '04.

jerryzak · Feb 25, 2008

Try this link. It ia a show called how is it made.
Jerry
http://joox.net/cat/1038/id/1538010

E. Barr · Feb 29, 2008

Owner

I own a grind shop, we manufacture drills,end mills,special cutters etc. Most of the drills we make are solid Carbide both the Carbide and hss drills are made the same with the exception of different grinding wheels, we get the blankes pre-hardend, program the geometry ( what type of twist ) after the machine grinds the flutes it grinds the end to what desigh we program, we use a grinder called a Walter Helitronic you can see one at www.grinding.com be careful with the spelling somtimes you get other types of grinding that has nothing to do with metalworking. I hope this helps thanks Eric.

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