fuzzy!!
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| posted on 3/10/07 at 08:52 PM |
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Cutting 64mm hole in 3mm steel
typical newbie question I guess - what do people do to cut a pretty large hole (or any hole over 20mm) in 3mm mild steel? I've got a set of
circular hole cutters but they're like plastacine against the steel  probably made for plasterboard  - how's it done ?
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hillbillyracer
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| posted on 3/10/07 at 08:56 PM |
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You can get hole saws for use on steel, a well known name is Starret. Made in the UK too unless they've moved!
You need to have a drill with a fairly slow speed or they dont last long. Not all that accurate but ok for most fabrication jobs.
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smart51
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| posted on 3/10/07 at 08:56 PM |
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The hard way is to drill a lot of small holes just inside a circle of the diameter that you want. Knock out the centre then file and file and file
until the jagged edge of the hole is round.
Or you could use a jigsaw.
Either way is slow and hard work.
Personally I'd find an engineering company and get it laser cut.
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David Jenkins
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| posted on 3/10/07 at 08:57 PM |
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Various methods:
A proper hole saw - expensive for a one-off job, and requires a hefty drill to drive it. You'll also need a mandrel to hold the saw.
Lathe - perfect, if you can swing the piece of metal, that is.
Hole boring head - Perfect, but you need expensive kit and a mill.
Gas cutting torch (or plasma cutter) - quick, expensive, needs a lot of skill. You have to file or grind it round afterwards.
Chain drilling - drill small holes just inside the circumference, cut between them, then file or grind it round. Hard work, but cheap and easy.
HTH
David
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trikerneil
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| posted on 3/10/07 at 09:42 PM |
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I have used a tank cutter in the past with reasonable results LINKY
ACE Cafe - Just say No.
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Litemoth
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| posted on 4/10/07 at 05:43 AM |
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At 64mm, a jigsaw should be able to cope. Buy a narrow (metal cutting) blade to enable it to turn with a tight enough radius. Drill a conventional
hole close to the circumference to enable you to start.
The tank cutter (trepanning tool) is a good oldy-worldy option that you can pick up cheaply in markets and boot sales and can be adjusted to any
diameter within it’s range. You'll need a slow drill and some patience but it gives a neat finish.
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John Bonnett
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| posted on 4/10/07 at 08:18 AM |
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As has been said, a high speed steel holesaw is an ideal way to cut the hole you need but only if you have access to a pillar drill running at the
speed recommended for that size of hole cutter and can securely clamp the job down. Use plenty of lubricant and all will be easy. I would definitely
NOT attempt it with a hand held drill.
John
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David Jenkins
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| posted on 4/10/07 at 08:25 AM |
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Thinking about it, if this is a one-off hole I'd probably chain-drill around the circumference, cut between the holes with a cold chisel (easier
than it sounds) and finish off the hole with a grinding stone in a hand drill.
David
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02GF74
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| posted on 4/10/07 at 09:37 AM |
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quote:
Originally posted by David Jenkins
Thinking about it, if this is a one-off hole I'd probably chain-drill around the circumference, cut between the holes with a cold chisel (easier
than it sounds) and finish off the hole with a grinding stone in a hand drill.
David
yep for a one off, that is how I do it. if you pan it well, you could use drills big enough that the holes join up are there is very little metal
between them.
dunno what stones you have but mine dremel ones would disappear long before the metal so I use a large half round file.
nibbler won't cope with that thickness.
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David Jenkins
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| posted on 4/10/07 at 01:46 PM |
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quote:
Originally posted by 02GF74
dunno what stones you have but mine dremel ones would disappear long before the metal so I use a large half round file.
I've got some 1" diameter stones with 1/4" shafts - maybe for a die grinder? They work quite nicely in an air drill...
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