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HI all,

got 15 x downlights to install in a soffet, its got wood under it and also about 3mm steel plate above, my usual ck or starret cutter wont even touch it, ive have drilled one out with a series of holes but it was a nightmare, any hardened cutters out there that might do the job?

CHeers
Grand
 
HI all,

got 15 x downlights to install in a soffet, its got wood under it and also about 3mm steel plate above, my usual ck or starret cutter wont even touch it, ive have drilled one out with a series of holes but it was a nightmare, any hardened cutters out there that might do the job?

CHeers
Grand
Cumax cutter
 
Yeah, I'm also wondering about the wisdom of drilling a steel plate that's in a soffit without knowing why it's there or what's under it that it may have been installed to protect.

Any decent hole cutter will go through steel up to 5mm thick if you go slow and steady and use some cutting fluid to dissipate the heat.
 
Aaah, the poor old holesaw. The most abused power tool accessory there is. :)

If used correctly, a holesaw will cut many holes in steel, even stainless. Where people go wrong is too much heat being generated. Heat kills cutting tools no matter what material they are being used in. The main reasons for excessive heat build-up are running at the wrong speed and not using any cutting lubricant.

Most people use battery drills which tend to run at about 500rpm on their lowest speed range and 1400rpm on their highest but how many people know that the recommended speed for a 32mm holesaw when drilling in steel is only 275rpm (140rpm if cutting in stainless)? And that the recommended speed for a 73mm holesaw in steel is only 120rpm?
So, the majority of users will be using holesaws at way above the recommended rpm. Couple this with a lack of lubrication and there you have the answer why a lot of holesaws seem to underperform but are actually being misused.

Generating excessive heat when drilling mild steel causes premature wear of cutting tools. When drilling stainless, generating excessive heat actually causes the steel to "work-harden". In effect, you are heat treating the steel. This causes major problems in subsequent efforts after the first holesaw inevitably fails.
 
Makes me chuckle when you see some poor sod trying to drill a hole in steel at full speed, and there's smoke coming from the bit and sweat pouring from his head :) Daz
 
Makes me chuckle when you see some poor sod trying to drill a hole in steel at full speed, and there's smoke coming from the bit and sweat pouring from his head :) Daz
That was me "last week".
Now I've understood what's going on, slowed down, got a can of cutting lubricant spray and life is a bit easier :)
 
Must be another way semi flush lights? you would have to advise the client of the steel and explain why it would be/could be a problem. To carry on seems more of a problem to me than talking and sorting after all its only some lighting. and your price did not take into account unseen problems such as this so explain and loose the pain.
 
what about getting in a good safe cracker,they good for cutting in to steel safes !
his he cutting a steel grader by any chance .the only way to cut a hole in steel is with a
oxy acetylene torch .
 

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