Drill Bits?

[Guest]

Is that spiral metal hole making thing actually a drill bit, or just a drill? I will go with drill.

I have a couple of drill sets, with every sized from one sixty fourths to half inch. The second set has a little better quality drills than the first cheapie, but even so I am replacing a drill or twoat least a couple times a year. I occasionally break the teeny ones, but it does not take much metal work to dull a larger sized drill.

For the three sixteenths and one quarter common boat work sizes I soon sprang for pricier Cobalt replacement drills. And anytime I have a lot of metal work to do I will buy the drill size needed in Cobalt and replace the one in the drill set. I do like the fact that the newer Cobalts are gold in color, so I know which ones I have replaced.

I need to make some three eights inch holes in thick plate aluminum, through something I absolutely, positively can not afford to screw up, and already had an extensive hardware store list in hand. Screw it, new Cobalt drill.

Ten bucks for one drill? There has got to be a better way. Maybe instead of replacing them one at a time I just buy 20 piece set of Cobalts and fill in from there as needed.

What do folks active on the shop drill team purchase and use?

 

[sweeper]

A drill (known in many countries as a drill machine) is a tool fitted with a cutting tool attachment or driving tool attachment, usually a drill bit or driver bit, used for boring holes in various materials or fastening various materials together.

$10 for one Drill Bit, $10 for a drill you're buying second hand tools.

Yes

 

[sweeper]

You just missed a Ryobi 30 piece set of cobalt bits for $10 at HD.

 

[stripperguy]

Mike,
It is a drill. I spent over 7,000 hours as an apprentice toolmaker...excuse the pun, but the various tooling and machinery terms were, uhmm, drilled into us!
Cobalt HSS is the best for most materials. And ground with a split point. Oh, and we were taught to never, ever drill a hole to size in one shot. Always leave a small amount of material for a final sizing with the desired size drill or reamer. Depending on hole size, you may also need to drill a pilot hole to clear the web.

Full sets are generally cheaper per drill than single pieces, try MSC or ENCO.

BTW, I do have an antique brace to use with an assortment of drill bits. (see brace and bit)

 

[dougd]

After burying or breaking too many drill bits in gunwales, they're still there, I went over to the more expensive ones, colbalt. Yeah the gold ones. I figured after years of buying more and more of the cheap ones I was breaking even with the better bits. Hurt the wallet for the initial cost but have last much longer without the frustration of being in the middle of the project and having it break, getting in the car cause ya know I didn't have another of that size and driving 20 miles round trip for a new set. Much happier but a few dollars poorer! Well worth it.

 

[wgiles]

I generally use screw machine drills from McMaster-Carr or MSC Supply. Screw machine drills have shorter flutes than jobber length drills and I seldom break them. I break plenty of corners off the tips of them, but I can resharpen them. I like the DeWalt Pilot Point Drills, but they are expensive and the corners break off on them very easily. Most of the holes that I drill are clearance holes, so I don't drill pilot holes unless the finished diameter is over 3/8". I use cobalt drills for hard materials, but use High Speed Steel for almost everything else. Titanium Nitride coatings are nice, but don't do anything to prevent breaking the corners of the drill.

 

[sweeper]

Mike,


BTW, I do have an antique brace to use with an assortment of drill bits. (see brace and bit)

Single or Double twist?

 

[Bothwell Voyageur]

I have a set of carbide tipped brad point bits for wood working/ toboggan making

http://www.leevalley.com/en/Wood/page.aspx?p=42352&cat=1,180,42240

along with a few Forstner bits for bigger holes.

Cobalt bits are definitely the way to go for drilling ferrous metals and titanium. Does anyone have bits ground to different angles for different metals? I remember my dad having some, particularly for brass. I would get in a lot of trouble if I used these on steel.

 

[sweeper]

I'm waiting on a 25 piece set of HSS Bard Points from Peachtree. I looked at the LV but a bit too rich for my limited use.

When I sharpen my twist bits I usually grid them with a split point but nothing because of use.

 

[Iskweo]

OK.... first off....learn to sharpen those bits and you wont have to spend so much on them. One thing that most people dont realise is that the sets of bits that you buy are mostly general purpose bits for use in wood, plastic, and other soft materials. They have a steeper angle to the tips...more pointy... because of this. If you want to bore a hole through metal, you should flatten the tip angle out and slow down the speed. I am not talking about turning it into something resembling a milling machine cutter, but rather a modest change of @ 10 %.

Even the cheap bits will work if you do this, you just have to sharpen them more often. Now, you can do this with a stand alone sharpening machine, or a jig that works with your bench grinder. I just freehand them by eye because, well, I am THAT good...lol. Most of the time anyway. Sometimes, especially with the smaller ones I bugger one up pretty bad. My 60 year old eyes are not always reliable. But they all cut pretty well. I was shown this by a welder in the military.

Some folks are quite concerned about a relief angle on the back side of each tip but I only bother on the larger bits. They all seem to work. Of course, I have been doing this for around 40 years, your mileage may vary.


( She's no like me or you, is there anythin she cannae do? ) Lol

Christy

 

[stripperguy]

Single or Double twist?

Single twist...I just packed that stuff away for a move. Hadn't looked at it in years. I've also got a plough plane, I actually needed it to reproduce some trim on an antique chifforobe.

I have a set of carbide tipped brad point bits for wood working/ toboggan making

http://www.leevalley.com/en/Wood/page.aspx?p=42352&cat=1,180,42240

along with a few Forstner bits for bigger holes.

Cobalt bits are definitely the way to go for drilling ferrous metals and titanium. Does anyone have bits ground to different angles for different metals? I remember my dad having some, particularly for brass. I would get in a lot of trouble if I used these on steel.

For brass, just grind the drill to have zero rake, keeps it from digging in (self feeding).

Chisty,
Earlier in my career, I used to drill many holes smaller than .015". I would buy brand new #80 drills, and before I could use them I had to inspect them under a microscope. More than half of them were ground with reverse clearance, they were not even worth chucking up in the machine. I used to sharpen those drills by hand under the microscope with a ruby stone. I do not miss those days!!

My last few years running an R & D shop, we wouldn't sharpen drills by hand anymore. We would buy a few Drill Doctors, they did a great job, much faster than I ever was in my prime. And with one you can even split the points for easier drilling. For around $100, you'll save way more than that in drills and frustration...

 

[wgiles]

Does anyone have bits ground to different angles for different metals? I remember my dad having some, particularly for brass. I would get in a lot of trouble if I used these on steel.

It is important to stone the rake off the tips of drills used in brass and copper or they will dig in. I set some drills aside for use in brass and copper alloys. It won't hurt to use a zero rake bit in steel. It just won't cut as fast and may overheat. Most custom (homemade) bits have zero rake because it's easier to make them that way. I've made D-bits for some drilling in the lathe because they won't wander.

 

[sweeper]

Thanks for the tip and for anyone else that didn't know about zero rack

https://www.youtube.com/watch?v=pAngKHIZgyA

 

[Guest]

It is a drill. I spent over 7,000 hours as an apprentice toolmaker...excuse the pun, but the various tooling and machinery terms were, uhmm, drilled into us!

I thought so, but writing just drill seems vague. Even worse in the shop saying, Hand me those drills. It is akin to how podium has come to commonly mean lectern.

You just missed a Ryobi 30 piece set of cobalt bits for $10 at HD.

Daddy needs a new Cobalt drill set, and that would make a great Christmas gift suggestion. Would have made.

The all aluminum plate adjustable height motor mount we have been working in is a mind bender to get right. I bought that ten buck Cobalt drill. Wrong size. I tried for a few seconds using one of my crapty drills in a drill press. Not gonna happen.

Drove back to the hardware store this morning. Bought a set of Cobalts instead of just the size I needed.

The hardware store is an hour roundtrip, so I also bought some Christmas gifts. Uber sturdy ergonomic bent snow shovels for my sons, to replace the ones I gave them years ago that are falling apart. Yes, I wrap them and put them under the tree. Whatever could this be? Also new leather works gloves, the good news being they both wear out a pair in less than a year.

The right sized Cobalt went through the quarter inch aluminum plate like butter. Maybe we have turned a corner on this puzzling project.

Christy, I do have a drill sharpener machine that was my fathers and use it occasionally, though not as often as I should. When it comes to shorter flutes, brad tips and zero rake I am a hummahummahumma what?

It was time to get a drill index of Cobalts.