Drilling 21mm Hole For Tap Shank, How Do U Do It?

[The Giant]

Hi boys and girls

Got a tap I want to install on the front of my fridge. The shank diameter is 21mm.

Went to bunnings yesterday and they dont seem to sell 21mm drill bits, they have 20mm, 22mm, 25mm etc etc but no 21mm.

I was going to buy the 20mm and round it out a bit, but the drill bit for metal is around $60. So I figured surely someone here has done it differently without the need to spend $60? I was going to get a an adjustable saw blade but the drill bit and blade is about $60 as well. I could get a 20mm blade bit but that is for wood and I'm not sure how effective it will be.

My other thought was to mark out a 21mm hole and drill many small holes with a 4mm bit and then round it out with a file. But given i need the cold air to stay in the fridge I need it really precise.

So what have others done out there in beer world?

Cheers
Steve

 

[ben_sa]

I didnt want to fork out 60 for a metal hole saw either. So took the cheap option and bought a wooden hole saw kit.

BIG MISTAKE... It went blunt in about. 3 of a second.. Then i used a 10mm metal drill bit and drilled about 5 holes and used a smaller bit to drill between thenlm. Absolute pain in ass. My time and swearing would have made tgr 60 worth it.

In short.. Ask friends/family... Someone will be able to help... 22mm will be fine. 0.5mm around your shank is not a bad thing. Use plumbers tape if your worried about the gap.

Cheers

 

[itmechanic]

I would just use the 22mm spade bit, the thin soft skin of your fridge wont hurt it, should go through like butter.

Cheers,
Paul

 

[shadders]

I would just use the 22mm spade bit, the thin soft skin of your fridge wont hurt it, should go through like butter.

Cheers,
Paul

presumably the 21mm part is threaded so it can be secured from the other side and the outside part is larger than 21mm?

____i-----|
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that sort of shape? If so then the gap won't matter, just get some sort rubber washer behind the fat part to seal it or even some silicone. I make odd sized washers and gaskets out of silicone baking mats. You can get large ones at $2 shops for bugger all.

If your only option is a wood hole saw it can be done. Just use a low speed on the drill, firm pressure and keep the cutting surfaces lubricated with some oil (stop every now an then and add more oil). Your aim is keep the drill bit as cool as possible. You may or may not destroy the bit but you should be a be able to get a few holes out of it this way.

 

[NickB]

Depends on wether this will be the only hole you drill.

I made the mistake of initially buying cheap bits to drill out my freezer collar, but when I needed to drill through the stainless 'keggles', I had to shell out for a good bi-metal holesaw kit.

If there's any chance you'll be doing the same or similar, I highly recommend getting some very good quality bits or a decent holesaw kit.

Cheers

 

[brett mccluskey]

A 'step drill' bit works well :icon_cheers:

 

[Florian]

Am facing the same problem at the moment. Bought a complete hole saw kit for $16, but the smaller bits don't come with a pilot drill arbor, and it was absolutely impossible to hold the bit straight while trying to get through the metal.
I then got one of the expensive blue bits that fits onto a pilot arbor. Still haven't managed to even drill a tiny hole for the pilot into the fridge, have broken to metal drill bits so far. That metal layer on my keg fridge seems to be fairly thick, way thicker than the ones on my other fridges.

Will have another go today, somehow need to get 5 holes into that fridge.

 

[mr_tyreman]

i'd say holesaw is your best option, a decent metal hole saw....or why dont you ring your local engineering shop and see if you can take the door off and into their shop. might be cheaper than buying the tools and you can assume they will do a good enough job of it.

other options i guess

Oxy torch
plasma cutter
die grinder
dremel with a cut off blade
small nibbler
wad punch

 

[brocky_555]

Chassis Punch

 

[Northside Novice]

A 'step drill' bit works well

++



used $20 irwin step drill set , great in stainless keg, like butter hard to believe i know .

 

[Hammo7]

I would go and buy a decent holesaw and arbor to do the job. There is no way I would try to do it with a spade bit, as it will rip the crap out of the metal door skin or stuff the bit.

Good holesaws are expensive, but worth the money. If you get a 20 mm and just file the hole out larger, it will only take you a couple of minutes. That same bit will then allow you to put holes in any thing later on eg: kettles for 1/2" bsp taps.
I needed to put a 20mm hole in a alloy pot and a stainless pot, I just borrowed a 20mm bit from our workshop.
Next time, if I couldn't borrow one, I would definitely buy one, as it will be cheaper than having to buy my mate a new 50 litre alloy pot!

Good Luck!
Matt.

 

[ThatKiwiFella]

+1 for the step drill bit... An asset to any tool box!

 

[pdfarrell]

I would go and buy a decent holesaw and arbor to do the job. There is no way I would try to do it with a spade bit, as it will rip the crap out of the metal door skin or stuff the bit.

+1 for decent holesaw and arbour. I bought a 7/8" / 22mm bi-metal holesaw. I am assuming you have a 5/8" BSP threaded tap shank.

My tap shanks fitted like fingers in bums. The holesaw cut perfectly neat holes.

Tip: Use some masking tape to mark the position of the holes and and give the centres a quick tap with a centre punch. Stops the pilot bit of the arbor sliding around.

My result:

 

[wynnum1]

Have you looked at getting a metal washer the right size glue that where you want the hole then drill small hole and with a dremil or similar grind around

 

[Florian]

+1 for decent holesaw and arbour. I bought a 7/8" / 22mm bi-metal holesaw. I am assuming you have a 5/8" BSP threaded tap shank.

My tap shanks fitted like fingers in bums. The holesaw cut perfectly neat holes.

Tip: Use some masking tape to mark the position of the holes and and give the centres a quick tap with a centre punch. Stops the pilot bit of the arbor sliding around.

Exactly that! Just drilled five perfectly neat holes into the door. 22mm is absolutely perfect for the standard shanks, 1mm shorter and it wouldn't have fitted.
That expensive blue drill bit worked great and still looks almost new.
Now it just needs some sanding and a fresh coat of paint and I'll have 4 taps and one CPBF on my fridge.

 

[Howlingdog]

you need one of these, pays for itself every time - neat, safe and quick.

http://www.justtools.com.au/category752_1.htm

 

[Florian]

+1 for decent holesaw and arbour. I bought a 7/8" / 22mm bi-metal holesaw. I am assuming you have a 5/8" BSP threaded tap shank.

My tap shanks fitted like fingers in bums. The holesaw cut perfectly neat holes.

Tip: Use some masking tape to mark the position of the holes and and give the centres a quick tap with a centre punch. Stops the pilot bit of the arbor sliding around.

Exactly that! Just drilled five perfectly neat holes into the door. 22mm is absolutely perfect for the standard shanks, 1mm shorter and it wouldn't have fitted.
That expensive blue drill bit worked great and still looks almost new.
Now it just needs some sanding and a fresh coat of paint and I'll have 4 taps and one CPBF on my fridge.

 

[The Giant]

Happy days. Might have to hit the fitters up at work and see if I can borrow a 22mm saw bit based on everyone's recommendations above!

Thanks all. Only got one tap ATM but will be fitting 2. So I may cut out a 22mm bit of wood to plug the 2nd hole in the mean time.

Cheers all

 

[ratchie]

Happy days. Might have to hit the fitters up at work and see if I can borrow a 22mm saw bit based on everyone's recommendations above!

Thanks all. Only got one tap ATM but will be fitting 2. So I may cut out a 22mm bit of wood to plug the 2nd hole in the mean time.

Cheers all

I use fridge magnets to cover the holes had 5 taps took 2 off for another fridge downstairs.

 

[The Giant]

nice idea ratchie, i was thinking blutak as well