Can We Discuss Drill Bits?

[MoreToolsForMe]

Hi All,

As I progress down the deep rabbit hole of building, repairing, modifying and customizing electric guitars, I'm faced with the need of drilling various sorts and levels of precision holes in varying types of woods and metals. Throughout my years of "meatball" work, I've generally assumed that any well sharpened drill bit was a good enough drill bit for the job, especially in a well tuned drill press. 
 Then I started hearing comments regarding "brad point" bits and upon more research found also "pilot point" and "split point" bits and even a few that seem to be a blend between any and all types.  
 

Might we have a discussion concerning the appropriateness of these different types for different purposes and results? Though I may be somewhat skilled and experienced in tool and machine usage, can we please start with an assumption that my knowledge isn't far past the stage of making a hole with a nail?

Please Help A Dummy?
Gene

[barryvabeach]

Gene, no such thing as a dummy, there are so many things I know very little about.

Wood -  In general, you have you common twist drill which can be used in wood or metal -  general purpose and works pretty well in smaller diameters in wood.

Spade drill bit -  for fast quick work, like drilling out holes in joists to run electrical cable,  or roughing out waste in a mortise.

brad point - spurs cut the outside of the hole, making it cleaner - typically found in medium sizes -  say just under 1/4 to slightly over 1/2 inch.

Forstner bit - outside of the hole is cut cleanly, like a brad point,  can cut overlapping holes , which is very helpful for cleaning out mortises, and is available in much wider dimensions than brad point.
 

For metal,  twist drills work fine, though some like a steeper angle for cutting metal .  To me, the big differences are in materials - common bits may be carbon steel, which will overheat and dull pretty quick in metal, hss is a better choice - will withstand greater heat, cobalt is the best for me - lasts much longer in drilling through thick metal.  


I am sure someone will post more details, and about other drill bits I have but have forgotten.

[Timberwolf]

Hi All,

As I progress down the deep rabbit hole of building, repairing, modifying and customizing electric guitars, I'm faced with the need of drilling various sorts and levels of precision holes in varying types of woods and metals. Throughout my years of "meatball" work, I've generally assumed that any well sharpened drill bit was a good enough drill bit for the job, especially in a well tuned drill press. 
 Then I started hearing comments regarding "brad point" bits and upon more research found also "pilot point" and "split point" bits and even a few that seem to be a blend between any and all types.  
 

Might we have a discussion concerning the appropriateness of these different types for different purposes and results? Though I may be somewhat skilled and experienced in tool and machine usage, can we please start with an assumption that my knowledge isn't far past the stage of making a hole with a nail?

Please Help A Dummy?
Gene

,,,,,,,,,,,,,,,,,,
One thing I can contribute...Spiral twist drill bits seldom drill the exact size hole they are intended for...whether it be in wood or metal or whatever...where precision is required, I drill a hole the next size under the marked size of the bit, then follow it with an end mill...or a chucking reamer...

[MoreToolsForMe]

Well Sirs,
Here's my current dilemma/quandary. I need to make some very precise front and rear templates for routing a 6-screw mount Fender style tremolo. The templates will be 3/8 " lexan-ish and I'm familiar enough with it's machining ins & outs. The difficulty comes in at the 6 mounting screw holes. I need to drill the holes in the template large enough to accept the mounting screws, but obviously do not want the holes in the body that I mount the template to, to be that large. The holes in the template need to be 5/32", yet the holes drilled into the body need to be 3/32" but need to be precisely centered in the 5/32" holes for proper tremolo mounting/operation. I was kinda thinking that just the tip of a 5/32" "pilot point" bit would give me my center and then simply finish up the 3/32" inch holes in the body with a 3/32" brad point bit to hopefully avoid finish chipping/tearout. Remember that I'm the kinda guy who researches critical stuff to death before actually picking up or turning on a tool! I realize that I'm working with wood, but am mounting a movable steel plate to that wood and the precision of that mounting is crucial to optimum and stable movement of the unit.

Thanks,
Gene

[Timberwolf]

Well Sirs,
Here's my current dilemma/quandary. I need to make some very precise front and rear templates for routing a 6-screw mount Fender style tremolo. The templates will be 3/8 " lexan-ish and I'm familiar enough with it's machining ins & outs. The difficulty comes in at the 6 mounting screw holes. I need to drill the holes in the template large enough to accept the mounting screws, but obviously do not want the holes in the body that I mount the template to, to be that large. The holes in the template need to be 5/32", yet the holes drilled into the body need to be 3/32" but need to be precisely centered in the 5/32" holes for proper tremolo mounting/operation. I was kinda thinking that just the tip of a 5/32" "pilot point" bit would give me my center and then simply finish up the 3/32" inch holes in the body with a 3/32" brad point bit to hopefully avoid finish chipping/tearout. Remember that I'm the kinda guy who researches critical stuff to death before actually picking up or turning on a tool! I realize that I'm working with wood, but am mounting a movable steel plate to that wood and the precision of that mounting is crucial to optimum and stable movement of the unit.

Thanks,
Gene

,,,,,,,,,,,,,,
How about a "self centering bit"...kinda like this...
http://www.rockler.com/rockler-insty-dri...ering-bits

Using that same principle, you could make one out of aluminum on a wood or metal lathe..Just turn a 60* angle on one end {to center it in the 5/32" template hole then drill through the centering device with a 3/32" bit for the mounting screws...Easy to work aluminum on a wood lathe. The device could even be made on a drill press if need be.
Note...The template could be scrap wood about 1/4" thick with a larger size hole because the smaller drill will be centered by your device and a larger hole will make using the device easier.

[AHill]

I like to use tapered bits to drill pilot holes for wood screws.  Several companies make them, and they are sized especially for each size of screw (I've seen them from #4 up to #12).  Fuller make the best set I know of.  Snappy also makes a really good set.  Both Fuller and Snappy sets come with countersinks if you're wanting a screw that's flush with the surface.  You can remove the countersink and just use the drill bit if necessary. Jack's suggestion for a Vix bit or self-centering bit is spot-on for use with templates, hinges, and other items that have holes that need precise locations for the screws that fasten them.

[Cecil]

I was kinda thinking that just the tip of a 5/32" "pilot point" bit would give me my center and then simply finish up the 3/32" inch holes in the body with a 3/32" brad point bit to hopefully avoid finish chipping/tearout.

That is what I do.  You can also grab a transfer Punch.  They may be more accurate

[barryvabeach]

Gene,  I am a little lost.  You say the holes in the template need to be 5/32 but the holes in the body need to be 3/32.  Why do the holes in the template need to be oversized?  If you can properly locate the centerpoint of each of the holes on the template, I would drill them to 3/32, then use the template to drill the holes in the guitar body.  If for some reason the template will actually be used to mount the tremolo, then once you have finished drilling the holes in the guitar body, just drill out the holes in the template to 5/32.   Note that here is where the differences in bit style comes into play.  While a brad point bit cuts cleanly, it is not easy to use a 1/4 drill bit to cut a hole, and a 5/16 brad point or forstner bit to enlarge it.  OTOH, common twist bits are excellent for that - in fact, it is not uncommon in metal working to drill the hole a few 16th undersized, then drill again with a bit 1/16 undersized, then finally with the bit of the correct size.  Twist drill bits can wander a bit when starting to drill a hole the first time, but by using this process, there is little risk of wandering, and the sides of the hole will be smoother.

[Bill Schneider]

Look into a machinist's counterbore tool. It combines both a drill and a pilot into one tool. Some versions have interchangeable pilots, but probably not at the small diameters you want to use.

McMaster-Carr sells a number of them them. Here's a link to one variety...

https://www.mcmaster.com/#counterbores/=1b4g76o

I use interchangeable pilot sets for milling perfectly centered 3/4" counterbores for 1/4-20 connector bolts. The diameters you mention are small, but you take a look at what they have.

[Bill Schneider]

I just re-read your needs. I might have it backward and the counterbore tools won't work.

Oh, well, it's out there.