Replies

1. 
   ProBozo | Nov 13, 2003 10:36pm | #1

   I've used the manual screw-type knockouts fine in stainless sinks.  Local rental has them for just a couple of bucks, 3/4 or so up to 4".

2. 
   CapnMac | Nov 14, 2003 12:54am | #2

   Wow, I always seem to have too many holes in the sink, not too few. 

   I always go back to basics when drilling a sink.  Measure twice, then mark, then center punch.  Then a pilot hole.  Then a unibit one step at a time, with plenty of thread cutting oil.  (Wish I still had that big 'ole unibit, stupid xBiL . . . )

   ProB is probably right, a rental punch would likely be the best choice for making the one hole.  I'd hate to bust a seal on my Greenlee trying to wear through 18 ga stainless (a bit more to go through than a 28ga electrical box).

   Will admit to being tempted by the Greenlee while working on el cheapo 22ga sinks, though.

   Occupational hazard of my occupation not being around (sorry Bubba)
1. 
   jhausch | Nov 14, 2003 05:15am | #5

   I don't know if greenlee makes different grades of puches and stuff, but in my biz the electrical enclosures that get "greenlee'd" are a helluvalot thicker than any ss sink.  Check out a rental place to see if their punches seem heavier duty.

    

   Edited 11/13/2003 9:16:08 PM ET by Jim

1. 
   noitall | Nov 14, 2003 05:32am | #6

   I had to cut a hole once and did not take the time to go to the rental for a punch. I used to hole saw but clamped a 3/4" piece of ply to the underside to keep the center pilot in line. I was concerned about the pilot turning into an oval. Kept the rpm slow with only a little pressure to start until the circle was scored. The other thing I did was keep the metal cool. The hole saw I had seemed a little duller than when it was new so I had a helper spray water with a windex bottle to the sink. I didn't have a problem and it took about 10 min start to finish.

   Scott T.

2. 
   CapnMac | Nov 14, 2003 07:48am | #9

   thicker than any ss sink

   Must have been Square Ds . . . <grin>

   In all fairness, though, when you are getting that 2" conduit "just right" in that 2 1/2' deep box, the cutter is hitting all of the bends and reiniforces and overlaps in the corners & edges.  Also, metalurgy aside, those 18 ga sinks are considerably harder than the flimsy big box el cheapos out there, too.

   Rental cutter may not be any heavier than any other, but they have stood the test of being rented out and abused.Occupational hazard of my occupation not being around (sorry Bubba)

1. 
   DaveRicheson | Nov 14, 2003 12:13pm | #10

   I think you are right. SS is a lot harder than the mild steel used in electrical boxes. My Greenlee knockout set is the manual type, and I don't think I would risk even a small one on SS. I believe I can buy two new hole saws for the cost of one 1" knockout punch.

3. 
   MojoMan | Nov 14, 2003 01:08am | #3

   It's been quite some time, but I did this once using a new bi-metal hole saw. It worked well, as I recall. As mentioned above, drill a pilot hole first. You might want to start on the underside to see how it goes, then do the top to finish.

   Al Mollitor, Sharon MA

4. 
   jako17 | Nov 14, 2003 02:06am | #4

   I used a manual screw type punch on a Franke sink with no noticable distortion

5. 
   Bruce | Nov 14, 2003 05:49am | #7

   Most hole saws, if sharp, will do the job.  The trick is that you have to have the sink clamped down very securely, with a good wood backer behind your hole location.  Then you have to drill very slowly, like about 60 rpm, while you pour coolant on the tool.

   Yeah, go for the punch.

   The High Desert Group LLC

1. 
   daddoo | Nov 14, 2003 07:27am | #8

   You could always use the snow from the roof, and kill two birds.....When all else fails, use duct tape!