18 replies to this topic

[havlicek]

I would guess that a lot of folks feel like hamsters in a rolling cage when it comes to drill bits (*twist drills")... buying them and tossing them. This is something of a frustrating little aspect of what I do, because I'm always drilling armatures and can sides, which are both curved. The cans are generally very soft steel and a bit that isn't very straight will walk (larger diameter bits work well for spotting the hole, and then drilling through with a 1/16" bit is what I do). Armature lamination steel seems to vary widely in hardness... some blanks drilling fairly easily and others being noticeably tougher. Of course, when drilling an armature that doesn't have "the center grooves," you have to be careful, especially when using a hand/portable drill. The relatively tight diameter and the small ridges caused by the stacked laminations can lead to disaster if you're not careful. Then too, when you get good drills, they may not last very long before they begin to dull and slow way down.
 
Anyway, I've gone through various brands and types ("titanium," cobalt, HSS, black oxide... various tip geometries and angles, whatevah), and they vary in performance, even among the same manufacturer. I use them, and if a bit doesn't work well, I toss it and use another. Of course, I use what's typically available in hardware stores and my local lumber yard, where I get the stuff for my real job. I'm guessing that machinists and others who do metal fabricating have their preferences and get their stuff from suppliers the general public isn't aware of, so forgive me for my carpenter's lack of awareness.   I only learn by trial and error!

Lately, my supply house has started carrying drill bits by a company called "Champion", and I thought to myself... well there's a natural for working on slot cars.   The line I tried (they have many) are not either cobalt or titanium, but rather a hard steel with a nitride treatment and have a black oxide look on the body and shiny steel on the flutes. The tip is a 135° split point, nothing special (I prefer 135° tip angles, again learning the hard way). Anyway, after trying a couple, I got some more because they really work. Whatever they do differently, all the ones I've got so far are actually straight. A wobbly bit is impossible, and regular brands are often NOT straight and true. The material these are made from, along with the way they're ground (I guess?) starts easily and drills fairly quickly across a wide variety of materials and situations. You quickly get a feel for a good working RPM when using a variable speed hand drill and generally get good clean holes with no drama (of course, no drill bit should ever be taken for granted). They also seem to last as long as any other drill bit, even the ones made from cobalt and titanium. Best of all, they're reasonably priced.
 
So if you're looking for good drill bits... check 'em out. I think you'll like them:

Champion XL5 Split Point Jobber Drills
 
-john

[John Streisguth]

John, you should try center drills, which are used by machinists to start holes. The body is much thicker than the point, and they are only made to drill a short distance.

[havlicek]

Hi John,
 
I have.  Like I said... "the never-ending search."    It seems that larger diameter bits work better for "hole-spotting", so the center drill doesn't help me all that much, but they do generally seem to be straighter than typical jobber-length drills.  

What I haven't found are the weird bits that Mura used for those really wide/shallow holes. I think they're made for drilling out spot welds or something, and have found ones that were sort of similar, but the Champions make that unnecessary.
 
-john

[havlicek]

Oh, I should also mention, John, that "center drills" can be a problem on modern arm blanks with narrow winding legs and shallow crowns. Before you get to being able to remove significant material with the wider part of the drill, the center narrow section can already be poking through the leg.
 
-john

[Half Fast]

Why not use a small drill press rather than a hand drill?
 
Cheers,

[havlicek]

Hi Bill,
 
That would help... some, but a good bit is still important! Also, I drill the sides of many different cans as well as many different armatures, making having a bunch of set-ups/jigs necessary.

Then there's also the footprint of even a small drill press. I'm dealing with a closet-sized space, so a hand drill just makes things easier for many reasons in my particular circumstance.  

Anyway, this info is for not just me, but anyone who's been frustrated by the typical junk that gets sold in hardware stores.  Sometimes you can get actual "good junk" in them as well!
 
-john

[Bob Kurkowski]

John,
 
I'm was a industrial cutting tool grinder for the past 15 years and I can tell you firsthand that rigidity in your machines and holding fixtures is key to any metal removal operation. Throw away your hand drill, period. Get a good drill press and the associated V-blocks or holding fixtures for your job, plus set your drill motor at the correct speed per your tool diameter or you will never be satisfied with your cutting tools performance and wear.
 
Personally I would recommend a Morse brand screw machine cobalt split point bit for drilling the lamainations or on other rounded surfaces. The short length of the screw machine bit will resist side-to-side deflection and the split point will aid in penetration and help eliminate the bit from walking side to side also.
 
Remember, when you are drilling to keep end pressure on the bit so that you see chip removal. No visable chip means rubbing and rubbing leads to possible work hardening and heat. Heat is a cutting tool's worse enemy.
 
The price of good tooling purchased one time is cheaper then purchasing junk tooling two times.
 
Bob K.

[havlicek]

Hi Bob,

And thanks for the info and posting for everyone's benefit.  

Of course, except I ain't getting a drill press/fixtures.
 
-john

[Phil Hackett]

John...
 
If you want good results and *consistency* you *need* to start with your tools…and a drill press is a basic tool for what you do. It's a very adaptable machine for many purposes. It shouldn't be a big one and there are many small drill presses that can be used on a kitchen table... this is what The Spin Doctor used for the balancing of armatures, it was a expensive but if you look around used ones can be had for a good price:
 

 
Link: Precision Drill Press

[Don Weaver]

FWIW, Dremel has a drill press stand for $43.00 shipped on eBay.

 

Don

[CoastalAngler1]

For the folks who drill - try Getsome 1000 oil and you will be amazed. Throw away bits less frequently and cut faster, smoother, better.

[havlicek]

Guys... I really do appreciate the suggestions, but this thread was about bits... not what you stick them in to drill.   Having a small drill press would only slow me way down and take up space I don't have. I'm not buying a drill press. 
 

FWIW, Dremel has a drill press stand for $43.00 shipped on eBay.

 
Even though I'm not interested in buying a drill press or a drill press stand, the big problem with a Dremel drill press stand (or similar for other rotary tools)... even if I was buying a drill press, is that the Dremel motor itself makes a rotten drill. Spinning at its slowest speed, it is still many times too fast for metal. All it will do is burn up bits, even good ones!  
 
-john

[Don Weaver]

Didn't think of that but you're right - way too fast!

 

Don

[Phil Hackett]

OK… only bits…. the best drill I have used in production or for any short jobs are Guhring drills. Yes, they're expensive. Yes, they're a little hard to find but they are the only drill I have found that drills *on size* without lots of fiddles to make them do so. They eliminate the need to ream to size in many cases… and they last 5 times  longer than the ordinary the twist drills you're probably buying now.

 

Guhring also provides drills in sub-milimeter increments in many different styles (parabolic flutes, slow twist flutes, "crankshaft" drills, ect…)

 

Of course, the "holding size" meaning holding them in rigid machines and fixtures. I wouldn't waste them in hand drilling since they won't be drilling straight and on size... use the "hardware store" drills for that.

[havlicek]

Didn't think of that but you're right - way too fast!

 
Yeah, I actually contacted Proxxon about this some time ago. I use their rotary tool and it's a dandy, like light years better than any Dremel. They also have a drill press stand that I was interested in, but not with the slowest speed on the tool being 5,000 RPM! I told them they needed to either devise a step-down pulley or speed control or something, because otherwise, the drill press function was ridiculous. I got a form letter back saying "thanks and we'll take it under advisement."   

 

 
-john

[Booger]

Keep your eyes out on the auction sites and you can find a real Darex drill sharpener for $200... diamond wheel and all... Not a Drill DR... Stop throwing away drills... sharpen them any way you want.

 

Darex makes a nice attachment for a bench grinder for about half that much, used... you need a decent bench grinder with no play in it.

[Isaac S.]

I have a drill bit sharpener that works great it has a diamond drum in it and haven't had to buy I new drill bit since I bought it 20 years ago. 

[Ramcatlarry]

Every motor builder needs one like this:  

https://www.sciplus....l-press-47894-p

 

It IS a full variable speed DC motor.  Belt pulleys adjust the range of final speed.

[Horsepower]

Why not use one of these? It works great for me. 

https://www.amazon.c...s/dp/B0012WKCXK