Hardend steel, what cutter?

[grandfortune]

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

 

[Pete999]

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

 

[LankyWill]

Try cutting compound, might just do the trick

 

[snowhead]

It makes you, well me anyway, wonder why someone went to the trouble of putting 3mm steel there.

Maybe it has, or had, something to do with strength.

 

[kropaske]

Armeg ldx will do it...

 

[HandySparks]

Cumax cutter

I'm not aware of any Q-max cutter that will do 3mm steel. Are you?

 

[HandySparks]

It makes you, well me anyway, wonder why someone went to the trouble of putting 3mm steel there.

Maybe it has, or had, something to do with strength.

Good question. Not sure I'd even consider cutting big holes in a bit of steel like that. If it's 3mm, then surely it's structural?

 

[davesparks]

A regular starett bi-metal hole saw used properly with cutting oil will do the job.

Unless you can get a mag-drill to stick?

 

[The Ghost]

Sounds like one of those moments you drill all the holes and wonder what that creaking noise is...

 

[Marvo]

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.

 

[LeeH]

Hole saw with fluid will p155 3mm stainless let alone carbon steel.

Drill slow, use pressure, fluid.

 

[HandySparks]

Hole saw with fluid will p155 3mm stainless...

And, being a soffit, it's probably being drilled from below, so it'll pi$$ all over the OP!

 

[buzzlightyear]

what about a plasm torch !

 

[billyblade]

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.

 

[DPG]

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