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Cutting sheet metal with a grinder?

Posted: Mon Jul 13, 2020 9:27 am
by neilbardsley
I'm about ready to work on my new magnetic slump but I need to cut some sheet metal. I have a grinder. I've never done this before. Any tips?

I will not be following this chap's advice. No gloves, glasses and no clamping of the metal!!

https://youtu.be/vW0JztWAfng

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Re: Cutting sheet metal with a grinder?

Posted: Mon Jul 13, 2020 9:49 am
by Gary71
Get some cutting discs like these, not grinding, and it’s knife through butter. Mark out with black marker pen then scribe your line in the marker to give some contrast you can see when working.

Get a full face mask not just goggles as it’s so much easy to see what you are doing and when the disc shatters it doesn’t get stuck in your face :)

Image

Re: Cutting sheet metal with a grinder?

Posted: Mon Jul 13, 2020 11:46 am
by neilbardsley
Full mask bought thank you Gary

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Re: Cutting sheet metal with a grinder?

Posted: Mon Jul 13, 2020 12:24 pm
by PeterK
Unless you are running a continuous cut, sometimes the blade will slip or skip slightly when you restart. I like running some masking tape on the panel, then marking my cut lines on that - there is less slip, so a neater cut.

Re: Cutting sheet metal with a grinder?

Posted: Mon Jul 13, 2020 2:43 pm
by sladey
Practice on some scrap so you get a feel for how it grabs.

And watch where the sparks go - a couple of times I've looked down to see that I am on fire. Which was nice.

Re: Cutting sheet metal with a grinder?

Posted: Mon Jul 13, 2020 3:06 pm
by Gary71
Yes, I’ve burnt a hole straight through my t shirt before

Re: Cutting sheet metal with a grinder?

Posted: Mon Jul 13, 2020 3:34 pm
by wildtexas
Neil, get yourself some ear plugs too. Seems my mother was right and all those years as a teenager grinding has left me with tinnitus. If I ever use machinery now with out defenders I notice it is worse. Good sets of aviation snips are worth while too

Re: Cutting sheet metal with a grinder?

Posted: Mon Jul 13, 2020 5:05 pm
by PeterK
Great shout (no pun intended). I use ear monitors (and play music while I work) with ear defenders over the top


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Re: Cutting sheet metal with a grinder?

Posted: Mon Jul 13, 2020 5:26 pm
by 911hillclimber
Noticeable on every car 'show', UK or USA everyone cuts using a disc nowadays, in fact hand tools are disappearing fast, power everything.

I must be the only diy car type who has never cut using a disc, but I always seem to have 'sensitive' people living around me.

Peter, make sure the metal is securely down on something reliable

Re: Cutting sheet metal with a grinder?

Posted: Mon Jul 13, 2020 8:40 pm
by Mike Smith
Neil,

With your luck, I would get someone else to do it - However if you insist

Watch where the sparks are going they will Pock Mark anything Glass

Re: Cutting sheet metal with a grinder?

Posted: Mon Jul 13, 2020 8:58 pm
by jury
Hi Neil,

Yeah, pretty much what has been said:

- KEEP THE GAURD ON THE GRINDER AND USE THE ADDITIONAL HANDLE IF IT COMES WITH ONE. DON'T TRY AND USE THE GRINDER ONE HANDED IF TRYING FOR FIRST TIME
- HOLD IT FIRMLY, BUT NOT LIKE A DEATH GRIP
- CONTINUOUS CUT WILL CREATE ALOT OF HEAT. TRY AND VARY THE CUT
- BE SENSIBLE WITH YOUR CUTTING ANGLE, USE COMMON SENSE. IF IT FEELS WRONG, IT USUALLY IS...BE READY FOR KICK BACK
- POWER OFF MAKE SURE THE GRINDER IS NOT SPINNING BEFORE SETTING DOWN ON BENCH
- ALWAYS POWER OFF BEFORE CHANGING THE DISCS
- WATCH FOR SPARK DIRECTION
- SOME GOOD QUALITY TIN SNIPS ALSO WORK GREAT

I have cut and welded with a full leg brace on after knee surgery...you'll be fine :)


Cheers
Chris

Re: Cutting sheet metal with a grinder?

Posted: Mon Jul 13, 2020 9:05 pm
by coomo
Gloves.You need gloves.Not poxy mechanic gloves.Big heavy leather ones.I use butchers gloves.They are knife proof apparently and maybe give you enough time to drop the bugger before it removes aq digit.

Re: Cutting sheet metal with a grinder?

Posted: Mon Jul 13, 2020 9:15 pm
by Bruce M
If you push hard, the sparks WILL burn whatever they hit, bar concrete. Paint / glass / carpet / seats /Trousers / jackets / eyes / skin. Beware of the flammable liquids!

Full face mask is much better. I’ve had grit get in vent holes in goggles.

Wear thick gloves. Welding gauntlets are good
choice.

Always have the guard fitted!! I took mine off once to use a particular wire brush & forgot to fit it when I put the cutting disc back on. Almost removed a finger through very thick gloves and had a deep cut for a few weeks (not able to be stitched as a ragged slice).

It’s loud so ear protection is worth wearing. Does not protect the neighbours ears tho!

Thin discs cut fast with least amount of destroyed metal.... but can snap easily with a side load. They give way dramatically!


Personally...... I’ll cut metal with a good senior hacksaw with sharp blade in situations that others will fire up the grinder. Grinder is my least fav way to cut metal but sometimes it’s required.

That said, experience can lead to complacency. Hence the finger near-miss mentioned and the fact I’ll sometimes do a wee bit of grinding and then realise I relying on my prescription glasses and thin nitrile gloves for protection. Doh.

Re: Cutting sheet metal with a grinder?

Posted: Mon Jul 13, 2020 9:17 pm
by Bruce M
Also... top tip

Use a cable tie to secure the special spanner to the power cable, loose so it can slide but tight enough so it won’t slide over the plug. That way you don’t lose it!!

Re: Cutting sheet metal with a grinder?

Posted: Mon Jul 13, 2020 9:50 pm
by PeterK
Throw away the spanner and use one of these https://www.amazon.co.uk/Milwaukee-4932 ... diy&sr=1-1