Drilling large diameter holes

[Hupla]

Do any of you also have problems with drilling say 12mm holes? When ever I am drilling a hole for the switch and power plug the drill bit always catches and never drills a clean hole. Its always rugged.

Ive tried drilling from small up to 12mm but it doesnt solve the problem. Any ideas?

Im not using a drill press but i have tried using a vice and it hasn't helped either.

Im guessing a faster speed?

[alparent]

The problem is not the speed but the type of bit you are using. A standard bits wants to dig in. You need a step drill.

http://search.harborfreight.com/cpisearch/web/search.do?keyword=step+drill&Submit=Go

I start by punching in my center with a punch. Then drill with a small bit, like 1/4". Then go with the step drill.

The step drill will not try to dig in.

[jacobyjd]

There are a few things you could try, but more info might be needed from you as well--

First, the questions:
1. What type of bit are you using? Step bit? Spade? ...normal?
2. Is your bit sharp?
3. How fast are you going now?

Now for some suggestions:
1. If you haven't tried using oil, try it. You'll be amazed at the results. I use veg oil. Put a drop on your punch mark before you tear into it. A little messy, but worth it.
2. Try a different bit--if you're not using a step bit, you probably should. If you're like me and are ok with misusing spade bits (1/2" are nice for footswitches), go for it. They work surprisingly well.
3. Use a less pressure once you're almost through the hole. This will make the bit bite less, and should give you a cleaner result in the end.


Remember--a drill press is easier, but a hand drill can do just as good of a job, quality-wise. I'd stake my work on it. It just takes more skill and patience

[Hupla]

There are a few things you could try, but more info might be needed from you as well--

First, the questions:
1. What type of bit are you using? Step bit? Spade? ...normal?
2. Is your bit sharp?
3. How fast are you going now?

Now for some suggestions:
1. If you haven't tried using oil, try it. You'll be amazed at the results. I use veg oil. Put a drop on your punch mark before you tear into it. A little messy, but worth it.
2. Try a different bit--if you're not using a step bit, you probably should. If you're like me and are ok with misusing spade bits (1/2" are nice for footswitches), go for it. They work surprisingly well.
3. Use a less pressure once you're almost through the hole. This will make the bit bite less, and should give you a cleaner result in the end.


Remember--a drill press is easier, but a hand drill can do just as good of a job, quality-wise. I'd stake my work on it. It just takes more skill and patience

I just been using normal drill bits. Ive been meaning to get a step drill bit but I can't find any locally and have just decided to make do for the moment as im not making loads of pedals.

I always thought a step drill would be worse? Just from the look of them I thought this, never heard much about them. I must be wrong

The 12mm bit was a fairly old one so no, not very sharp. I couldn't tell you the exact speed but it was quite fast.

Ill try some oil the next time and ill invest in a step drill bit alright.

Thanks alot

[markeebee]

Also, rule of thumb when drilling aluminium:

Up to 5mm bit = 3000 rpm drill speed
5mm to 10mm = 2250 rpm
10mm to 15mm = 1500 rpm

As my college lecturer used to say: "The bigger the hole, the slower you roll".

[StereoKills]

IMO step drills make the nicest and easiest holes.

[R.G.]

Also, rule of thumb when drilling aluminium:

Up to 5mm bit = 3000 rpm drill speed
5mm to 10mm = 2250 rpm
10mm to 15mm = 1500 rpm

As my college lecturer used to say: "The bigger the hole, the slower you roll".

That's correct. What matters is the linear speed as the cutting edge cuts along the edge of the drill. For every metal cutting situation composed of a type of cutting edge and type of material, there is an optimum speed for cutting, most (and/or cleanest) metal removed per work expended. Too fast and you wear out/break your cutter, too slow and you can overheat the cutter from friction.

As we all know ... the circumference of a hole is C = pi*d, so a 1/2" hole has a circumference four times the circumference of a 1/8" hole. (In metric, a 12mm hole has a circumference 4x the circumference of a 3mm hole). That means that the speed of the drill's rotation has to go UP for small holes and DOWN for  big holes in proportion to the diameter of the hole. That's why drills for PCB holes need speeds of perhaps 5000 to 50,000 RPM - to keep the cutter running well.

So you keep drill rotational speed inversely proportional to the hole diameter to keep the feet/second (mm/sec) as close to constant for different holes as you can.

[trjones1]

Has anyone tried metal punches?  I'm a hand driller/regular bit user and I dream of perfect 1/2" holes that take less than 10 minutes to drill without tearing up my hands.

[alparent]

Start by getting a step drill. You will be very happy.

You can worry about oils, speed, friction, heat after.

We are talking about about drilling 1/8" soft aluminum alloy.................not 1" thick steel plates! 

[jacobyjd]

Has anyone tried metal punches?  I'm a hand driller/regular bit user and I dream of perfect 1/2" holes that take less than 10 minutes to drill without tearing up my hands.

Try using a 1/2" spade bit after punching and piloting. Works for me

[dr.benway]

step drill changed my life!

[Taylor]

Has anyone tried metal punches?  I'm a hand driller/regular bit user and I dream of perfect 1/2" holes that take less than 10 minutes to drill without tearing up my hands.

Yikes! I drill a 1/2" hole in less than 30 seconds, including drilling an 1/8" hole with a regular bit, then chucking up the step bit.

There is a slight trick, though. The regular step bit from Small Bear only goes up to 1/2", which means that when you drill a 1/2" hole, the bit goes all the way through and then the chuck jaws bang into the surface of the metal and leave a mark. I bought a $10 set of 3 step bits and use the large one when cutting 1/2" holes, so I don't have this problem.

I use a cheap hand drill.

[trjones1]

I guess I should get a step drill.  I just worry about it being difficult to control with a hand drill.

[petemoore]

  Equipment.
 You can easily press hard enough to crush the box when the tip is trying to begin entering, very small and slow metal removal soon speeds up, torque increases [or speed slows].
 Once most of the blades are shaving metals [the tip isn't just rollin' around the top, the bit is well in], the cut is kinda steady, once past the shoulder, stays the same until the bottom begins to blow a bubble where the tips pushing.
 Once the tip breaks the bottom seal, cutting begins to accellerate very very quickly, there is a decrease in metal preventing penetration, and as the thin shearing strips between 1/2 way out from tip to the shoulder, the blades 'dig in' and get stuck trying to shear through a large depth cut in <1/4 turn, euyrrn.
 To help prevent stoppage here, have or mimic a drill press using the maximum sized circle that occurs as the shoulder of the bit submerges under the top surface, if the drill is perfectly square, this circle will expand from the middle perfectly.
 If the drill/bit is canted to one side, not perfectly square, the circle-max will begin to form on one side and draw around to the other, using this as a final guide and then holding very square after that point...have a drill press !
 Anyway, light, then very light, then like no pressure and high speed is a dangerous suggestion, yet effective...the centerish portion of the bit tends to be controlled by the shoulder and can't just dive all of a sudden.
 YMMV, use a drill press and be safe, years of experience and methodology analysis...I can even drill very lightly through thin substrates without wrinkling over the top {I hate that, it's not the worst]...if it is a very flat piece..and I feel lucky. The worst is when frustration is replaced by shock at the ''red viscous fluid'' spots on the box, oh and the floor, ahh my hand has 'em too .

[kungpow79]

Get this guy, I have it and it works great.  I think even Walmart sells step drill bits, and I'm sure da Depot has em.

http://www.smallbearelec.com/Detail.bok?no=738

[Paul Marossy]

For up to 1/2" diameter, I use a step drill bit. For 3/4" or 1" holes, I use a spade type wood bit. It works great on aluminum and even on mild steel. For steel, you just have to use a much lower speed and be more careful, but it will work. I've drilled holes for tube sockets on both aluminum and steel amp chassis' using this type of bit.

[chi_boy]

The problem is not the speed but the type of bit you are using. A standard bits wants to dig in. You need a step drill.

http://search.harborfreight.com/cpisearch/web/search.do?keyword=step+drill&Submit=Go

I start by punching in my center with a punch. Then drill with a small bit, like 1/4". Then go with the step drill.

The step drill will not try to dig in.

+1 for step drills.   The harbor freight variety is great to give them a try.  The were ridiculously cheap from Harbor, but they do work. 

[Taylor]

AFAICT, my Harbor Freight bits are the same as my Small Bear one. But you get 3 for the price of one.

[brett]

Hi

use a drill press and be safe, years of experience and methodology analysis

Yes, yes, yes and yes.

The cheapest drill press is faster, safer and more accurate than any other method.
A side benefir is that bits last longer.

If you make sure the chuck can hold a 0.8mm bit, then you can drill PCBs too.  Fast and easy (10 minutes for a complex one).
I got mine on sale for AUD$69 at Supercheap Auto (US$50).
cheers
PS a few years ago a friend of my neighbour was forcing a drill too hard, the bit broke and he fell forward onto the broken bit.  Straight into his eye.

[Taylor]

How do you clamp things with a drill press? I bought one 6 months ago but haven't ever used it because I can't figure out a way to clamp PCBs that isn't so slow as to make a board impossibly laborious.