Properly measuring/marking a drill bit for proper depth?

[Captainstrat]

I'm not sure if this is the right forum to ask this question, but I'll ask anyway, is there an accurate way to measure "drill bit depth" from the tip to the "stop line" (that will be marked off by a piece of masking tape)?  Let's just say I've goofed more than once and had to take the neck/body/both to my favorite guitar repairman to fix my mistakes (Hi Brian  )

This time, I'd like to do it right.  As I'm awaiting delivery of the missing pieces of my parts caster (ferrules, strap locks,vintage style tuning pegs), I've been doing a lot of research that's been paying off so far; but the neck is crucial and I'd like to avoid a repeat of the "drill bit straight through the fingerboard" routine!

My likely problems have been

1. improper measurement of the drill bit (0.875" isn't exactly easy to measure, 2.2225 cm is a bit easier, but not by much), because my measuring tape is probably none too accurate...
2. the tape I've been using to mark off the depth limit was likely on the cheap side (it literally would wiggle loose and out of place, to the point I'm no longer sure where the depth limit is)...
3. I don't own a drill press, I probably get impatient when drilling through maple and apply too much pressure
4. I've had a few cases where the drill bit gets loose in the chuck and goes in the chuck rather than in the wood!

So I throw it to the experts, any tips to accurately measure and mark the drill bit so I do an accurate job?

Thanks!

[ScottR]

You could use a micrometer for the measurement and use a collar with a set screw as a depth stop on your bit.

SR

[Captainstrat]

7 hours ago, ScottR said:

You could use a micrometer for the measurement and use a collar with a set screw as a depth stop on your bit.

SR

Cool, found a digital micrometer locally, ordered a set of collars with set screw from Amazon... work in progress, thanks! 

[ScottR]

Hope it works out well for you. I'll pass on our most repeated words of advice: Test on scrap!

Let us know how it works out for you.

SR

[Captainstrat]

Is there a difference between digital calipers and a micrometer?  At any rate, after reading up on how to properly use it, I measured the neck screws (the portion clearing the neck pocket) the neck thickness (looks like I have 3.53 mm of wood to the surface of the fingerboard).

I also measured a drill bit and temporarily marked it with masking tape; the collar with set screw sound much more reliable, so I'll wait!

[Captainstrat]

On 2/8/2018 at 9:38 AM, ScottR said:

Hope it works out well for you. I'll pass on our most repeated words of advice: Test on scrap!

Let us know how it works out for you.

SR

Say, what's our opinion on rubber depth stops for drill bits?

[curtisa]

Probably the least useful compared to using masking tape or the metal collars. They can easily slip up the drill without much pressure, shifting your perceived drilling depth deeper than intended if you're not careful.

[Dark Mavis]

I've tried masking tape, and I've tried using the little collar dealies that attach a hole saw to the bit, but wood shavings can push both further up the bit, or they can come off or work loose.

 If you wanna be 100%, Just cut off the butt end of the drill bit so that only the amount you need is protruding. Or just don't drill the full depth and let the screws do the final bit of drilling using a sort of quarter turn forwards, eighth turn back motion.

 It sounds like you're talking about drilling the neck for the screws that hold it on, right? I'm not sure why you need to be so accurate. You're not going to split the wood by letting the screw make the last 1/8th inch of the hole.

 As for measuring...I just use a ruler