Drilling very small holes

[rickharris]

OK I own up this isn't my idea but seem so logical - and the author - long dead i guess says it works.

I have been reading my fathers collection of 200+ model engineer magazines going back to the 30's and came across this tip for using small diameter drills.

To prevent the drill bending under drilling pressure take a length of brass tube with the same ID as the drill or drill though a suitable length of brass rod.

Split the side with a slitting saw or hacksaw and clamp round the drill leaving just enough drill exposed at the end to drill your hole.

Put the tube and drill in your chuck and off you go - the split will allow the chuck to grip the tube and drill.

The split tube effectively stiffens the drill and reduces the chance of breaking it.

Circa 1922 tip.

 

[bentprop]

Sounds great in theory,but how do you split a 1/16th tube?Those are the main size I keep breaking .
I have more luck by inserting as much as possible length into the chuck,then let it down bit by bit.Tedious,i know.

 

[PhiberOptix]

The best way to drill small holes AFAIK is with a sensitive drill feed
(one of these is on my wish list)

this is placed in your normal drilling chuck then,
the knurled disk in the pic you can pull down with you finger and thumb and get
a better feel as you drill with it

regards
Andy

 

[putputman]

Andy, I have one of those sensitive drill chucks, Albrecht chuck. It is extremely sensitive. I can't remember the last time I broke a drill with it and I have drilled holes down to .009" dia. It can be used in the mill or lathe.

They are especially helpful in making small fuel mixers with the deep .018" dia holes.

 

[PhiberOptix]

I was not too concerned about getting one before as I worked on larger tasks, BUT, now I am making models it has moved way up the wish list, wont be long now

Andy

 

[vlmarshall]

I'll second the Albrecht chuck and sensitive drilling attachment, I use them regularly for .012" and .015" holes.

 

[rickharris]

Sounds great in theory,but how do you split a 1/16th tube?Those are the main size I keep breaking .
I have more luck by inserting as much as possible length into the chuck,then let it down bit by bit.Tedious,i know.

I would use a jewellers saw, I have split very narrow silver tube for jewellery purposes this way. Works best with a longer length tah you need to use and a jewellers bench hook to rest it on - oh and a very fine blade.

 

[Blogwitch]

There is a great difference between having the lathe chuck turning and feeding a stationary drill into the end, and having a turning drill and a stationary part.

It is the centrifugal forces that make the drill bit rigid and less prone to break, so you should really be looking at turning the drill bit.

I am just in the process of designing and making a high speed drill press, using air to achieve the speeds I want. Purpose made PCB drill presses only get up to about 50K max. so they are only used for bits that go down to about 0.012".

I need to drill 0.004" holes, and I think the recommended speed is around 95,000 rpm to keep the drill bit rigid enough without having to worry too much about the pressures that need to be applied for it to drill thru the piece part.

Drill bit speed is the secret to small hole drilling.

Blogs

 

[Blogwitch]

I have purchased a cheap die grinder, that claims it runs at 55K, double that speed with a belt and I am above the speed range that is required. It will only need to run for a couple of seconds to carry out each drilling exercise, so I don't expect bearing failure to be a problem.

So really, it is no big deal getting and using such speeds.

High speed PCB drills run for years on end with no problems, so I don't expect any problems with this. As long as everything is cylindrically ground accurate enough.

Blogs

 

[firebird]

Hi

This is the set up I used to drill some small holes. It works really well.

http://www.homemodelenginemachinist.com/index.php?topic=2379.0

Cheers

Rich

 

[rcplanebuilder]

Depending on the variables...

I find that the taps are more difficult and fussy than the drilling of the holes, when talking about very small stuff, ie; 00-90, 0-80, 1-72, etc.. until you get down to #80 drill bits and such. It also depends on how deep of a hole we are talking about, and what materials we are drilling.

The cheap and effective solution I have found that works good, is similar to the sensitive drill feed shown above, but cheaper, although that same tool will work in this way too.

... I use a standard "Pin Vice". Using it by hand is OK for some things, but when I need the hole to be straight, and especially when it needs to be tapped, I simply unscrew the knob off of the end of the pin vice, and insert it into either a drill chuck, or into a collet in the mill. The trick is that you don't tighten it into the chuck, you simply draw the jaws very close to the size of the pin vice shaft, and spin the tap or bit by hand in the Pin Vice. You are really just using the mill, or drill press, as a guide to hold the pin vice straight. When you push and pull and twist, nothing breaks, because the chuck (or collet) is holding your bits true, but you still have that feel that is needed for spinning these tiny little buggers without breaking them. You can tighten the jaws onto the pin vice shaft, and use power for the drilling sometimes, and then switch to the loose set up for the tap, if it's a deep hole, and clamping of the bit is the biggest worry. Pin Vices are like $3.00 at a hobby store. ...

It is especially effective with the taps, because the chips don't ever clear well in these small sizes, so you need to back them out a lot, and blow them off, ergo, power tapping is just not feasible with them, unless you have HP flood with CNC control. The loose clamped chuck as a guide works well for them.