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View Full Version : Drill a clean 1/2" hole in a stainless steel sink



SGW
12-08-2010, 04:26 PM
We just bought one of those reverse osmosis drinking water filters that mounts under the sink and has a small separate faucet that mounts on the counter or back of the sink.

To mount it where I want to, I need to drill a 1/2" hole in the stainless steel sink, which I am assuming is 304 or 316. Do any of you who have worked with s.s. have any recommendations for getting a clean hole? The sink is installed, so I'll have to use a hand drill. I've got a 1/2" Greenlee punch, but I doubt it could deal with s.s.

strokersix
12-08-2010, 04:28 PM
Single flute step drill should work for you. Unibit is one brand. Don't try with an old one though, it needs to be nice and sharp and run it slow for stainless.

mike os
12-08-2010, 04:32 PM
when i used to fit kitcens I used a bimetal holesaw....

legendboy
12-08-2010, 04:50 PM
Single flute step drill should work for you. Unibit is one brand. Don't try with an old one though, it needs to be nice and sharp and run it slow for stainless.

thats what i would use also

Davidhcnc
12-08-2010, 05:08 PM
Use the punch:)

http://www.greenlee.com/cat_docs/Holemaking.pdf

MotorradMike
12-08-2010, 05:09 PM
I would use a 1/2" Greenlee chassis punch.
Bolt underneath to leave the rounded edge on top.

Edit: Where is the server and how did that British guy get his post in first?

macona
12-08-2010, 05:10 PM
These things kick butt for cutting holes in sheet metal. Not overly high priced either.

http://www.hougen.com/cutters/sheetmetal/Rotacut.html

Forestgnome
12-08-2010, 05:43 PM
I vote for bimetal holesaw. That's what I've used, and it's a cheaper alternative to punches and Rotacuts.

x39
12-08-2010, 05:46 PM
Another vote for the punch. A little oil will ease things.

hoof
12-08-2010, 06:10 PM
Another vote for the punch. Did many a NEMA 4X electrical cabinet in Paper mills, (Stainless) the work great, everything else always looked a little chewed up. Good Luck

Ray

deltaenterprizes
12-08-2010, 10:36 PM
I needed a carbide grinder burr for mine, it laughed a HSS drill bits. A carbide masonary bit should work also.

plunger
12-08-2010, 11:49 PM
As a plumber by profession I use a punch.Hardest part of this job is to drill the hole for the bolt of the punch. I find that if I center pop the sink real deep the drill goes through alot easier. To centre pop I put a wood block under the sink. I normally put the handle of my hammer under it and find I can pop the metal almost right through. This also prevents distortion of the sink as it is very thin
When I drill I use alot of force and slow speed. These sinks have a tendency to work harden.I start with a smaller drill and finish off with a larger drill.Literally takes a minute to cut with punch and is good for many sinks. I tried a hole saw and you can through it away afterwards unless you want to sharpen it

lugnut
12-09-2010, 12:08 AM
The Greenlee punch. I make barbecues from Stainless Beer kegs and have found the best way to get the 1" holes for the gas lines into the kegs is with a Greenlee punch. I'll guarantee those kegs are tougher than any sink.
Mel

SGW
12-09-2010, 07:05 AM
You're talking about the ordinary Greenlee punch made for mild steel? Greenlee makes a punch for s.s. but it's expen$ive and requires hydraulic drive...not what I have.

Willy
12-09-2010, 07:28 AM
I have installed several of these units and have used both a good regular drill bit and bi metal hole saws and didn't have issues with either procedure.

While I always strive for as clean a hole as possible, it is not a prerequisite for a professional appearing installation. Unless one is using an old railway spike to "drill" the hole, the chrome base plate and washer that go between the sink and the faucet will hide about a 1 1/2" diameter area, so you'd have to really screw that hole up big time before it would be visible.

Forestgnome
12-09-2010, 09:11 AM
To add to my previous suggestion, if I had to do this many times I would opt for a punch. They're just expensive for a one-time use. I've found cobalt drills work best for starter holes in stainless. Used to drill a lot of holes in boat railings.

Toolguy
12-09-2010, 09:29 AM
Greenlee Makes those punches that only have a bolt through the center. You just tighten the nut. No need for hydraulics on a 1/2" sink hole.

Dr Stan
12-09-2010, 09:46 AM
Sounds like a good excuse to buy a plasma cutter. :D

Rustybolt
12-09-2010, 12:21 PM
I would use a 1/2" Greenlee chassis punch.
Bolt underneath to leave the rounded edge on top.

Edit: Where is the server and how did that British guy get his post in first?



Those things are great for steel , but not much fun in stainless. I second or third the Unibit. They pay for themselves the first time you use it.

Forrest Addy
12-09-2010, 01:04 PM
I use a multi-step UniBit like this:

http://www.irwin.com/tools/drill-bits/unibit-step-drill-sets

They make nice clean round holes in sheet metal. I use them all the time drilling NEMA 12 enclosures. Quicker than a punch up to 1" conduit size.

Irwin is a little expensive. Your local big box should have them but in a lower frade which counts when drilling stainless. Go slow and use a little oil like WD40. You wll have to de-burr the hole. If you have a light touch you can brush the burr off with the champher of the next size step.

SGW
12-09-2010, 05:09 PM
Thank you much, folks. I'll see what happens....

Paul Alciatore
12-09-2010, 06:10 PM
I also like the Greenlee punches but I have had both good and bad experiences with them. I also have done some experimenting with them.

Greenlee punches have different ratings, mostly depending on the size of the draw bolt. Due to the design of these punches, the amount of force needed for almost all sizes is basically the SAME. There have been two primary designs that Greenlee used: the older style which had a two pointed punch with two symetrical "valleys" between them. This style cuts at only four points at a time so a 1/2" punch and a 2" punch will need the same amount of force. The other, newer style also has two points, but they have a spiral on one side of the points only. The other side of the points is a straight face that does not cut. These are the slug-splitters. They only cut at two places at once and use less force than the older style does. But again, the force is relatively independent of the punch's size.

For round punches Greenlee has used three sizes of draw bolts, 1/4", 3/8", and 3/4". They are better than grade 8 and probably better than grade 8.8. I have never broken a 3/8" or 3/4" Greenlee draw bolt. I have broken the 1/4" ones. They just don't have the strength to do heavy gauge steel and the punches that used the 1/4" draw bolts are generally rated only for thinner gauges of metal.

A 1/2" punch will almost certainly have a 1/4" draw bolt. So, the 1/2" punch is the worst case, not a 1" or 2" or even larger one. While many here have made 1" and even bigger holes with Greenlee punches, I would not recommend it with a 1/2" sized punch or any others that have only a 1/4" draw bolt.

In any case, if you are using a Greenlee punch I would use an oil based cutting fluid on the cutting edges AND a high pressure grease on the threads and under the head of the draw bolt if it is not a ball bearing type.

Personally, I would use a 3/8" drill and a taper reamer to make a clean 1/2" hole in the SS sink.

Paul Alciatore
12-09-2010, 06:14 PM
I use a multi-step UniBit like this:

http://www.irwin.com/tools/drill-bits/unibit-step-drill-sets

They make nice clean round holes in sheet metal. I use them all the time drilling NEMA 12 enclosures. Quicker than a punch up to 1" conduit size.

Irwin is a little expensive. Your local big box should have them but in a lower frade which counts when drilling stainless. Go slow and use a little oil like WD40. You wll have to de-burr the hole. If you have a light touch you can brush the burr off with the champher of the next size step.

The step drill is also a good choice.

But Forrest, I am shocked that you would call WD-40 "oil". As far as I can tell, there is no oil in it.

whitis
12-09-2010, 07:53 PM
But Forrest, I am shocked that you would call WD-40 "oil". As far as I can tell, there is no oil in it.

It contains a little oil but seems to be mostly solvent to break up the existing gunk.

Looking up the CAS numbers for the vague names they give in the MSDS:

WD-40 Aerosol
45-50% 64742-47-8 Aliphatic Hydrocarbon (Mineral Spirits 66/3)
<25% Petroleum base oil, 4 CAS #s given:
64742-58-1 Lubricating Oils, Petroleum, Hydrotreated Spent
64742-53-6 Distillates, Petroleum, Hydrotreated, Light Naphthenic
64742-56-9 LOW MOLECULAR WEIGHT PARAFFINIC OIL
64742-65-0 Petroleum Base Oil
12-18% 64742-47-8 LVP Aliphatic Hydrocarbon (Mineral Spirits 66/3)
2-3% 123-38-9 Carbon Dioxide
<2% Proprietary Surfactant
<10% Non-hazardous Ingredients

Their FAQ says: "WD-40 does not contain silicone, kerosene, water, wax, graphite, chlorofluorocarbons (CFCs), or any known cancer-causing agents."

macona
12-09-2010, 08:03 PM
It contains a little oil but seems to be mostly solvent to break up the existing gunk.


45-50% 64742-47-8 Aliphatic Hydrocarbon (Mineral Spirits 66/3)


Also known as Stoddard Solvent:

http://en.wikipedia.org/wiki/White_spirit