Cutting at an angle

[ronan]

I bought an r-tech 30 amp plasma cutter a few weeks back and its a real labour saver. I had to cut up 8 8'x4' sheets of 3mm mild steel for a job and it was very fast, especially against the time it would have taken to cut with a grinder. The machine worked great but i did notice it cut at a slight angle leaving a knife edge. I had to angle the torch slightly to get a square cut. This isn't normal surely ? The one i used in my old job years ago used to cut perfectly square. Also i did change the tip etc in the torch to see if they were at fault, but it made no odds.

 

[mike 109444]

I think the guys that were doing CNC plasma cutting were having similar issues when they were cutting fine detail. Might be worth looking back at those post to see what there resolve was

 

[gordon stephenson]

The angled face on one side of the cut line is quite usual, How marked it is depending on the condition of the consumables,speed of cut etc. When cutting circles if you need the disc,cut in a clockwise direction. If you need a hole in a plate cut in an anti-clockwise direction

 

[Wedg1e]

The angled face on one side of the cut line is quite usual, How marked it is depending on the condition of the consumables,speed of cut etc. When cutting circles if you need the disc,cut in a clockwise direction. If you need a hole in a plate cut in an anti-clockwise direction

Isn't it like water going down a plughole? If you're in the northern hemisphere you go one way and in the southern you go cuddy-wifted...?

 

[ronan]

Isn't it like water going down a plughole? If you're in the northern hemisphere you go one way and in the southern you go cuddy-wifted...?

You'd be the expert on that ......mr.bodge angles

 

[ukracer]

The angled face on one side of the cut line is quite usual, How marked it is depending on the condition of the consumables,speed of cut etc. When cutting circles if you need the disc,cut in a clockwise direction. If you need a hole in a plate cut in an anti-clockwise direction

Does the same go for straight lines. Travelling left or right depending on which part of the sheet you are using...?

 

[Paul99]

A little bit of angle is hard to avoid but if it was that extreme were you using a metal guide to run the torch along? It took me ages to figure out why I was getting a seriously angled cut and very short consumable life until I realised the metal straight edge was influencing the arc (oddly it was pushing it away from the guide rather than attracting it towards it). Anyway I switched to wooden guide / straight edges and the problem disappeared.

 

[ronan]

A little bit of angle is hard to avoid but if it was that extreme were you using a metal guide to run the torch along? It took me ages to figure out why I was getting a seriously angled cut and very short consumable life until I realised the metal straight edge was influencing the arc (oddly it was pushing it away from the guide rather than attracting it towards it). Anyway I switched to wooden guide / straight edges and the problem disappeared.

Yes paul i was using a bit of 6mm flat as a guide edge, and the cut was angling away from the guide.

 

[skotl]

A little bit of angle is hard to avoid but if it was that extreme were you using a metal guide to run the torch along? It took me ages to figure out why I was getting a seriously angled cut and very short consumable life until I realised the metal straight edge was influencing the arc (oddly it was pushing it away from the guide rather than attracting it towards it). Anyway I switched to wooden guide / straight edges and the problem disappeared.

Ahh... that explains something. I just thought that my technique was improving as my cuts had improved but, thinking on it, I've switched from using a lump of hardened steel as a guide to wood.
Also, the steel was up against the copper so only ~3 mm away from the cut whereas the wood is against the cup.

Think you might be onto something there, Paul

 

[ukracer]

Ahh... that explains something. I just thought that my technique was improving as my cuts had improved but, thinking on it, I've switched from using a lump of hardened steel as a guide to wood.
Also, the steel was up against the copper so only ~3 mm away from the cut whereas the wood is against the cup.

Think you might be onto something there, Paul

It does explain why I get cleaner cuts using a hardboard or thin plywood template.

 

[penfold]

I wonder if brass or ally would work; wood seems a bit flammable/scorchable for longterm use.

 

[ronan]

And wood warps and twists itself. I had a bit of lath i thought i was straight that i could use, but looking along it,its like a corkscrew.

 

[mr migwire]

i tend to use a length of hardwood skirting, it does the job and has scorched but nothing major.

 

[JohnRUFC]

From what I've seen online the Americans on YouTube use Aluminium squares!

 

[Wedg1e]

I tend to use a length of aluminium unequal angle, works well until you get a bit of spatter on it and then the torch snags...

 

[Bladevane]

A handy acronym to help with deciding where the perpendicular edge will be is ACID COD. Anti Clockwise for Internal Diameter, Clockwise for Outside Diameter.

 

[gordon stephenson]

The easy way I remember the direction is, If the piece i want is the disc, just imagine this as a clock face,so you cut clockwise. And obviously if its the hole you want anti clockwise, Much simpler than remembering strange words.

 

[Scott V]

Remember the swirl ring can go in either way.. Means you can swirl it either way.. I find it's a great advantage in hand cutting.. Something all the new torches don't do.. Being left handed, I find the New Esab, Victor, Hypertherm torches sadly lacking in that respect.. There are work a rounds, but The older Esab PT-31 XT, and S-45 torches from Trafimet kick their new tech butt.