How to

[Mush]

Hi, fairly new to mig welding but gradually getting there One of my biggest problems is cutting a straight line across a bit of sheet metal with a cutting disc how do you guy's do it?

 

[Morrisman]

Clamp a metal strip to the sheet and run the grinder along the edge. Do it gently, try not to force the disc too hard.

Are you using the thin cut off discs, 1mm or thereabouts? They last quite a while if you take your time and don’t push too hard.

 

[arther dailey]

hi, hope your enjoying forum, plenty of help and advice on here , what thickness sheet ? and are you using a 1mm cutting disc ?

 

[Robotstar5]

Mark the sheet then run the disc along the line just enough to score it, the disc will follow the score line on further passes.

 

[skotl]

Mark the sheet then run the disc along the line just enough to score it, the disc will follow the score line on further passes.

All of the above, but this is the key point. For an accurate cut, don't try to do it in one pass - do it in two or more light passes.

 

[bricol]

Use safety specs, goggle or mask. And ear defenders.

With proper eye protection you can see what you are going to follow a line you marked - I used to use masking tape on car panels - cut along the edge of the tape. Easier to see than a black marker line.

And in a few years time, you will thank me for the ear defenders - my tinnitus reminds me all day, every day, that no-one suggested them to me early enough.

 

[Erie Fred]

Buy a plasma cutter, use a straight edge......another reason to buy tools eh....

 

[Robert Weaver]

It's something taken for granted. Trial and error until you find the best technique for your application.

Thin discs, 1mm thick, are better for cutting but don't like bending. With any disc, you can do many repeated shallow cuts or a single full cut. These even a YouTube video on the benefits of both...

 

[gaz1]

i cheat a little

plasma cutter use an angle iron as the straight line

i use the line method but i also use a straight piece of wood as well because its cut square i can run the disk along side of it scoring the metal that gives a straight edge across the long length

because i have a table saw its easy enough to cut another straight edge on 2 sides then ive got 2 sides to cut from
no table saw use a circular saw homemade table

 

[roofman]

If you bury the blade into the cut and move forward instead of cutting on top this makes it much easier to cut straight.

 

[Parm]

On top of all the good advice some skill is also required. Practice practice practice and one day it will just happen.

This is how I learned

I’m now better with a grinder than a welder……

 

[brightspark]

i just use strips of metal angle iron or wood . put the metal to be cut on the deck lay the strait edge over it stand on it and cut away pressing against the side of it

 

[rtcosic]

With reference to another thread - always check where the 'sparks' are going:

The 'sparks' are tiny pieces of red hot metal
They will melt into glass, paint, ceramic, plastic, wood, small children....................
They can set alight everything you think they won't including steel wool.
Your nether regions are their favourite target, with eyes a close second. Ears are popular too.
Even leather aprons, aramide overalls and everything else will accumulate unrepairable holes. I have bolted a steel plate to a leather apron when doing a lot of cutting and grinding.

And finally PPE


EtA: I have told the tale many times of Ben grinding in the shed where the plastic dustbin connected to an old welder via an AC/DC converter was electrolytically de-rusting suspension components and generating a perfect stoichiometric mix of oxygen and hydrogen.............................

 

[chrismac]

If you bury the blade into the cut and move forward instead of cutting on top this makes it much easier to cut straight.

This in my experience is the best way, usually leaving the line on rather than removing it too helps.

Marking the score line with the grinder gives plenty wiggle room I find and you end up all over the place when cutting.

 

[Mush]

Thanks for all the advice, I do have the thin cutting discs and the sheet is !mm.

 

[Shedendman]

Look ahead of the cut line,not at the cut itself
Let the tool do the work,not you

 

[MetalMonkey]

As above really, practice and a very light cut following a well defined marker line.

If you go light, you have a chance to steer it and even correct it if it starts to wander.
Follow it up with a few more light passes and that will guide your heavier cuts .

Same principle as trying to cut anything accurately with a knife.

 

[droopsnoot]

With reference to another thread - always check where the 'sparks' are going:

The 'sparks' are tiny pieces of red hot metal
They will melt into glass, paint, ceramic, plastic, wood, small children....................

I found that out the hard way when removing a rusty wheelarch from my car, back when I had to work on the drive at home. A few weeks later my Mum was washing the porch window and wondered what the cloth kept catching on.

 

[chunkolini]

Another top tip.
Remember to breathe; slow and deep and to relax. Also visualise what your trying to achieve and the process to get there.
It's easy to go rigid and hold your breath while concentrating. You can also find yourself gripping the tool rather than holding and controlling it.
I always approach jobs like this.
Stop, look at it, unlock shoulders, go through the process; breathe and get on with it.
Hmm does that sound a bit new agey?

 

[Gritineye]

Regarding sparks, keep your dog/cat out of the shed, they can get arc eye too.

For 30 yrs I used to have to remember the swallows in the rafters as well, but they have all disappeared from around these parts now.