Newbie question

[Ed B]

okay this must be the most simple of simple questions but I've never been afraid of demonstrating my ignorance!

If you want to cut metal to eventually be but welded together how do you go about ensuring you get a straight cut?

Whilst I've been practicing on scrap metal I've been angle grinding the metal into smaller pieces but my grinding is always a bit on the wonky side - partly because it's difficult to see the line I've drawn on the metal with all the sparks and the grinder sometimes in the way. I don't fancy always using a hack saw!

I know that there are special benches / tools for cutting metal but I don't have the money or space - and I'm assuming that there are some less involved techniques I can use - improving my use of the angle grinder or elsewhere.

 

[waddycall]

Do you use thin slitting discs or standard cutting discs?

 

[rtcosic]

1mm cutting disc

Clearly marked line

Good lighting

In my case - remember to change to reading glasses

For a long straight line clamp a guide such as a piece of angle.

 

[Ed B]

Do you use thin slitting discs or standard cutting discs?

A standard cutting disc I'll look into the slitting disc then...

 

[Ed B]

1mm cutting disc

Clearly marked line

Good lighting

In my case - remember to change to reading glasses

For a long straight line clamp a guide such as a piece of angle.

What do you use for marking the line? I've tried a scribe and also a thin black marker but neither stand out that much

 

[rtcosic]

What do you use for marking the line? I've tried a scribe and also a thin black marker but neither stand out that much

Varies, depending on how clean the steel is.

Black or blue wide felt tip then scribed line - I'm too cheap for real engineers blue - is my usual.

Other colours may work better for you.

I've tried chalk with and without a scribed line.

Sometimes just a scribed line is good enough. Sometimes a fine black or blue felt tip works. Yellow or red might work better for you.

(asks himself - I wonder if someone colour blind has more trouble?)

I cannot give a one size fits all answer.

Holding the tool so that the sparks fly away from you and away from the line in front of where you are cutting. I have a leather apron for when it isn't possible to aim the sparks away from me.

Holding the tool so the guard doesn't obscure the marking.

Plenty of light is always needed. Ensure it is aligned appropriately to maximise contrast.

Ensure your goggles and face shield are good and clean and not too scratched.

Wear your reading glasses if appropriate. I will admit my boys always find it easier than I do these days.

Can I assume you have invested an afternoon watching the Binky videos?

 

[rtcosic]

A standard cutting disc I'll look into the slitting disc then...

Ah!

1mm discs will seem as accurate as a laser beam if you have been using the thick jobbies!

 

[Ed B]

Varies, depending on how clean the steel is.

Black or blue wide felt tip then scribed line - I'm too cheap for real engineers blue - is my usual.

Other colours may work better for you.

I've tried chalk with and without a scribed line.

Sometimes just a scribed line is good enough. Sometimes a fine black or blue felt tip works. Yellow or red might work better for you.

(asks himself - I wonder if someone colour blind has more trouble?)

I cannot give a one size fits all answer.

Holding the tool so that the sparks fly away from you and away from the line in front of where you are cutting. I have a leather apron for when it isn't possible to aim the sparks away from me.

Holding the tool so the guard doesn't obscure the marking.

Plenty of light is always needed. Ensure it is aligned appropriately to maximise contrast.

Ensure your goggles and face shield are good and clean and not too scratched.

Wear your reading glasses if appropriate. I will admit my boys always find it easier than I do these days.

Can I assume you have invested an afternoon watching the Binky videos?

Thanks some useful tips for me. I do think I'll invest in a directional desk lamp (or I might having something knocking about I can bastardise) as I've just got my garage strip lights at the mo. One point on the guard and spray of sparks it does seem to be that its either positioned so that the sparks are going down and so obscuring the line or into my face - obviously not great as I dont have a welding helmet that also acts as a face mask - its on my wants list..

 

[God mode restorations]

I use 0.8 cutting discs. I mark out with black sharpie pen. Use a nice straight edge. I score the line all the way up .remove straight edge and cut away. Good finish every time.

 

[Wightsparks]

Lidl (usually!) sell some great silver and gold paint marker pens, thick and thin. - Gold on shiny steel and silver for mill scale - work great.

 

[waddycall]

The sparks issue could be caused by trying to cut partway through and gradually increasing the depth of cut.
I tend to follow the line forwards for about 3 or 4 inches or less (dependant on what I’m cutting) to score the line first. I then go back to the start and cut the first section full depth. I’ll then score the next section and so on. If you only score it to start with with a thin slitting disc there won’t be as much sparking. When you’ve cut right through the sparks will go out the bottom of the part and won’t get in the way. If you use thin slitting discs the sparking will be massively reduced as you are grinding away less material per length of cut.

 

[Ed B]

The sparks issue could be caused by trying to cut partway through and gradually increasing the depth of cut.
I tend to follow the line forwards for about 3 or 4 inches or less (dependant on what I’m cutting) to score the line first. I then go back to the start and cut the first section full depth. I’ll then score the next section and so on. If you only score it to start with with a thin slitting disc there won’t be as much sparking. When you’ve cut right through the sparks will go out the bottom of the part and won’t get in the way. If you use thin slitting discs the sparking will be massively reduced as you are grinding away less material per length of cut.

Yes I've often been just cutting through the metal completely when I've been doing my cuts do this is another good suggestion

 

[Turbo]

Another tip I can suggest is to shine a light on the cut line. The best way I've found is to wear a head torch, not easy if you are using a full face shield!

If you are holding the metal in a vice try to have your cut line vertical - your body will naturally move the grinder vertically while cutting.

 

[T0rnado69]

i have a few of these lights find them handy for putting some light on when your welding..
plan to use one as a flexy light for the lathe..

 

[mpats]

The 1mm slitting discs are the best suggestion, I find either a nice sharpy line or a chalk line reasonably easy to follow, but a full face mask is handy as you don't have do worry about sparks causing you to stay away.
I've got a Honeywell bionic face mask, not much money from Amazon.
I would usually draw a light cut along the marked line then start making it deeper, if you wonder off a bit on your first pass you can true it up reasonably easily before you get to deep.

 

[Ed B]

i have a few of these lights find them handy for putting some light on when your welding..
plan to use one as a flexy light for the lathe..

Yes I've got something along those lines in the kids bedrooms. Sure they don't use them...

 

[Ed B]

Well I bought some new 1mm cutting discs..an all excited to see if I can get better results...but they domt fit my grinder.

There was no mention of the inner diameter on the ebay listing...hence my not checking this. So do I need different discs to fit my grinder or a different adapter to the one I have in the picture above which shows my old cutting disc, current adapter ( sorry no idea what its propper name is?) and the new discs

 

[Seadog]

You need a lathe

 

[Ed B]

You need a lathe

ha ha I've no room for one even if I had the money

 

[mike 109444]

There's yer problem.... See circle on pic. That is the size used in USA or the air grinders.get along to Screwfix for a pk of 5 or 10 1mm x 22mm (standard UK grinders) x 115mm