I'm referring to this bulkhead fitting:
I suppose having tried the brute force technique I ought to give ignorance a try.
Anyone had problems with knockouts?
PoP
The fittings are weather sealed and the knockout points are only marked to keep you in the centre when you drill them out with a hole saw.
I found the same with the Screwfix ones I ordered.
In the end I used a sheet metal punch - the type where you drill a 10mm hole and then assemble the punch and coller through the hole before tightening the punch into the coller. Worked fine (after I worked out I had assembled the coller the wrong way round and the side I was using was intended for the next punch down in the size range - thought it was bl**dy stiff to turn!)
I am much relieved that I am not going completely bananas!
Good idea! What size punch are these holes anyway? I'll get my micrometer on the job later today.....
PoP
3/4" or 20mm. If you think you'll do a lot of this sort of thing, get a Q-Max punch which produces a perfect hole, rather than a hole saw, and costs less than a complete single size hole saw. The disadvantage is you need access to both sides of the job.
These are ideal if you're doing this type of job all time.
I've had 2 of these lamps, only in black from local factors, and found the same problem. The plastic/polycarbonate seemed to be quite brittle so I didnt get rough with the hammer / punch / swrewdriver, so took a 20mm hole cutter to it which worked a treat.
Tim..
I wanted about 20mm for connecting to plastic conduit. The punch I used was like the following set from CPC:
PoP
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