Is there an easy way to burn neatish holes in steel plate?

[Onoff]

Not a lot of good if the item to be drilled is in a field or a large sheet of steel needing the holes further from the edge than the throat-width of said pillar drill. Buying a large radial drill is not on most people’s shopping list!

I've worked on remote sites for years and 99% of odd, low volume holes are done with a hole saw, invariably genuine Starrett ones but latterly Morse Cobalt.

 

[Hitch]

Template to run the torch round the inside of if you really want to gas them....
Have you mastered cutting straight lines?

 

[Onoff]

But with a mag drill, not a pillar drill, as noted in my post. Yes, the odd hole in relatively thin steel is OK with a hole saw, but rotobroaches and a mag drill are still the REAL solution for proper building jobs.

I work at height, hanging by my nads, wedged in gaps, upside down on occasion.

There are times when a rotabroach is impractical. One time I had to drill 11/16" holes in the top flange of an I beam. The only way to do it was with 3 300mm Starrett extension shafts.

If the job calls for a rotabroach I'll use it.

 

[premmington]

+1 for magdrill

 

[Trevorleach]

Template to run the torch round the inside of if you really want to gas them....
Have you mastered cutting straight lines?

Yes can cut straight lines no issue, free hand okay, straight edge even easier, its just the holes are not round.

The thing is going to spend half its life under water getting very muddy, so I guess the dirt will act like grinding paste.

 

[anto44]

If you can't justify a mag drill then these TCT holesaws are a good alternative, they can run at much higher rpm than a hss holesaw so they're more suited to cordless drill use. They can hog through metal seriously quickly. This one is a 22mm and it only has 6 teeth so better suited to thicker material, they can snatch really hard on thin sheet.

 

[fizzy]

If you can't justify a mag drill then these TCT holesaws are a good alternative, they can run at much higher rpm than a hss holesaw so they're more suited to cordless drill use. They can hog through metal seriously quickly. This one is a 22mm and it only has 6 teeth so better suited to thicker material, they can snatch really hard on thin sheet.
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That is almost identical to a mag drill cutter so yes it should perform well.

 

[outofthefire]

I use one of these, but I get best results when I can spin the steel and keep the torch in one place, rather than moving the torch.

Pardon our interruption...

 

[Hitch]

Sounds like you just need to practice then..get the circle motion in your arm. Nicely set flame and a clean nozzle. Huff it through in the middle and go outwards to the edge of the hole about 3 o'clock in a clockwise direction... that's my technique.
Don't suppose you have your preheat flame set a bit hot? That will burn the edges away and make it not a nice shape.

It'll never be as good as a drilled hole mind... depends what its for I guess. suppose...

 

[tom2207]

once you get your hand in freehand holes are not that tricky , way way easier than straight lines.

 

[Trevorleach]

If you can't justify a mag drill then these TCT holesaws are a good alternative, they can run at much higher rpm than a hss holesaw so they're more suited to cordless drill use. They can hog through metal seriously quickly. This one is a 22mm and it only has 6 teeth so better suited to thicker material, they can snatch really hard on thin sheet.
View attachment 354490
View attachment 354491

That is my kind of budget, just ordered one off ebay.

 

[Trevorleach]

If you can't justify a mag drill then these TCT holesaws are a good alternative, they can run at much higher rpm than a hss holesaw so they're more suited to cordless drill use. They can hog through metal seriously quickly. This one is a 22mm and it only has 6 teeth so better suited to thicker material, they can snatch really hard on thin sheet.
View attachment 354490
View attachment 354491

Well it arrived, so I cut plates, welded plates, drilled plates, very impressed for under 6 quid, obviously accuracy was not there, but for this job no one cares.
Hole was 12mm deep which was two rusty 6mm plates welded together, she was squealing a bit by the end of hole number 6.

 

[Morrisman]

No lubrication while cutting?

 

[Hitch]

Seeing the sort of thing you've done there makes me think about why you were struggling with the gas....
You wernt trying to cut a double thickness skin by any chance?

 

[Trevorleach]

No lubrication while cutting?

Yes Wurth 2040 which basically wd40/duck oil, kept stopping every 10 seconds or so for a spray up.
I could not find my oil can.

 

[Trevorleach]

Seeing the sort of thing you've done there makes me think about why you were struggling with the gas....
You wernt trying to cut a double thickness skin by any chance?

No single 6mm plate only, the plates mounted above those in the pic are the lifting eyes, and they were the ones I could not get round.

 

[Trevorleach]

I thought he was referring to a proper cutting oil, not mickey-mouse WD40 (useful for aluminium, but not much good for steel).

He most likely was, sadly this was all I had to hand, that and my 30 yr old bosch drill all 710 mighty watts of it!

 

[Trevorleach]

That may depend…. Variable speed? What rpm were you operating with? What was surface cutting speed?

Yes variable speed, in its day it was a posh drill, Iirc I paid 100 quid for it 30 years ago.
It was in low gear and I was running approx 2/3rds available rpms, it felt and seemed to cut right.
As for actual surface speed I have no idea, I was sweating so much in my welding kit I was struggling to see through the sweat running over my glasses!