Oxy/propane cutting

[roofman]

Cheers lads..pulling the torch to me but still free hand. I also may be putting a bit to much heat into the plate at the start thinking about it and getting that "melted look" (any comments ??) Have a few hours tomorrow to practice plus found a bit of scrap RSJ today so ime not cutting my precious bits of plate up

 

[roofman]

Looks pretty decent.

Are you pushing or pulling the torch? I always got on better pulling it towards me.

I'd say perhaps turn the flame down a bit and just a bit more practice at moving steady along the cutting bar.
You're not far off the mark

You mean the propane or the collective flame?

 

[8ob]

You mean the propane or the collective flame?

Surprising how little heat is needed once the cut has started, you can sometimes chase a cut with just oxy.

Bob

 

[Hitch]

You mean the propane or the collective flame?

Leave the pressures, just little less of both on the torch I'd say, so your preheat flame is slightly less fierce.
It's surprising how little it needs to get started.

 

[roofman]

Leave the pressures, just little less of both on the torch I'd say, so your preheat flame is slightly less fierce.
It's surprising how little it needs to get started.

Great mate, will try your advice next..Many thanks for the other input posts too lads

 

[Pete.]

Surprising how little heat is needed once the cut has started, you can sometimes chase a cut with just oxy.

Bob

I've seen someone do it but I can only keep it going a short distance before it goes out. But then, usually I'm cutting dirty old steel not clean new stuff.

 

[Memmeddu]

I would revive this thread since I use often the cutting torch at work
So few questions.
We use acetylene torches with Harris 9062 or 6290NX tip (can't remember which one is the correct designation) anyway they run very high oxygen and LPG pressure
Results are that's complex to adjust.
I follow this procedure.
Little bit oxygen, full quarter turn of fuel ,light on , flame approximately one inch from the tip, then I make the tip touch to whatever I've to heat or cut and I open the oxygen till it makes a fine red star on the piece.
Then I add fuel an oxygen till it sounds like a jet (keeping the star flame )
For cutting I found difficulty to go straight and initiate the cut since the cutting valve it's just a turn valve .

Any advice , better lighting procedure?
Thanks in advance

 

[roofman]

I would revive this thread since I use often the cutting torch at work
So few questions.
We use acetylene torches with Harris 9062 or 6290NX tip (can't remember which one is the correct designation) anyway they run very high oxygen and LPG pressure
Results are that's complex to adjust.
I follow this procedure.
Little bit oxygen, full quarter turn of fuel ,light on , flame approximately one inch from the tip, then I make the tip touch to whatever I've to heat or cut and I open the oxygen till it makes a fine red star on the piece.
Then I add fuel an oxygen till it sounds like a jet (keeping the star flame )
For cutting I found difficulty to go straight and initiate the cut since the cutting valve it's just a turn valve .

Any advice , better lighting procedure?
Thanks in advance

I am using oxy/propane and my fuel gas is set at 12 to 14psi and the Oxygen set at 50psi using a 3/64 nozzle...cuts through 10mm plate like butter. Will be getting a good workout next week as a need to cut up a full sheet of 14mm plate,will post pics up of the results with any new settings thats needed.

 

[James1979]

Ok, so if they’re acetylene torches you shouldn’t run lpg without changing the nozzle. I’m assuming you know that and that’s just your name for them.

Pressure I tend to do in bar, have a 10:1 ratio oxy to acetylene, slightly higher than 1 for propane. Maybe 3. That’s a rough guide to get the thing to light. You can tune it.

Lighting:
Purge the lines
Angle torch up for acetylene and down for propane
Open fuel gas valve slightly - Maybe half turn I just do it without thinking.
Light the gas
Feed in oxygen slowly and adjust both controls till the flame looks good. (Over here we say like the gas advert. I will find a picture) You don’t need to put it on the metal to do that. I’ve seen guys do it and it seems to work but I have never done it.

Shut down Is reversal. Some people turn oxygen off first but that depends when you did your training.

 

[Pete.]

I always turn the fuel off first the the flame is guaranteed to go out.

If you turn the oxy off first you can end up with a tiny flame at the nozzle which can cause a fire or re-light the torch (especially on acetylene) if you go to light it right away afterwards. Could get you a nasty burn.

 

[James1979]

I would revive this thread since I use often the cutting torch at work
So few questions.
We use acetylene torches with Harris 9062 or 6290NX tip (can't remember which one is the correct designation) anyway they run very high oxygen and LPG pressure
Results are that's complex to adjust.
I follow this procedure.
Little bit oxygen, full quarter turn of fuel ,light on , flame approximately one inch from the tip, then I make the tip touch to whatever I've to heat or cut and I open the oxygen till it makes a fine red star on the piece.
Then I add fuel an oxygen till it sounds like a jet (keeping the star flame )
For cutting I found difficulty to go straight and initiate the cut since the cutting valve it's just a turn valve .

Any advice , better lighting procedure?
Thanks in advance

I’ve just re read this and seen the last bit about the cutting valve. That doesn’t sound 100% right, or it’s a machine torch that’s somehow been adapted?

Either way, once you’re used to the control a knob or a lever shouldn’t make a lot of difference.

Get the metal hot until you see it start to melt on the surface. Feed the oxygen in slowly. You’re using the oxygen to blow the liquid away so it doesn’t have to blast out. Especially on thinner stuff. Keep the torch vertical and pace yourself according to the rate at which it’s melting and clearing material.

If the material is thicker it can help to angle the torch behind the cut very slightly as it’s blowing the dross back and down.

 

[Barking Mat]

Surely you don't want the torch touching the metal, but held slightly away.

And don't you have a trigger you pull once it glows orange ?

I did loads years ago, but it's been at least 15 years.

 

[James1979]

Surely you don't want the torch touching the metal, but held slightly away.

And don't you have a trigger you pull once it glows orange ?

I did loads years ago, but it's been at least 15 years.

Yup

You want the tips of the small internal flames just brushing the surface. You can watch it melt little spots and that’s about spot on.

Normally yeah you’d have a lever to introduce oxygen for the cut but memmeddu says his is a knob. In principle it doesn’t matter what the control is once you’re used to it.

I’ve never seen a knob on a hand torch (except when I’m using it ) but they’re common on machine torches like you’d get in a pug cutter

 

[roofman]

Yup

You want the tips of the small internal flames just brushing the surface. You can watch it melt little spots and that’s about spot on.

Normally yeah you’d have a lever to introduce oxygen for the cut but memmeddu says his is a knob. In principle it doesn’t matter what the control is once you’re used to it.

I’ve never seen a knob on a hand torch (except when I’m using it ) but they’re common on machine torches like you’d get in a pug cutter

Sounds like he is not using a 3 control cutting torch but only a welding or brazing torch with cutting tips..Or have i read it wrong?

 

[Pete.]

If you're lighting a propane torch get the fuel lit and touch the tip onto the metal at an angle before adding the oxygen. This will stop the flame from blowing out.

You can avoid it by turning the fuel on at a low level then adding oxygen also at a low level but then you risk bowing it out when you add fuel again. If you're out on site you don't want to be messing around getting your sparker out of your pocket again so just whack the propane on, touch the tip, add oxy then set your flame by turning the gases down instead of up. Takes moments.

 

[Memmeddu]

If you're lighting a propane torch get the fuel lit and touch the tip onto the metal at an angle before adding the oxygen. This will stop the flame from blowing out.

You can avoid it by turning the fuel on at a low level then adding oxygen also at a low level but then you risk bowing it out when you add fuel again. If you're out on site you don't want to be messing around getting your sparker out of your pocket again so just whack the propane on, touch the tip, add oxy then set your flame by turning the gases down instead of up. Takes moments.

That's practically what I do and why

 

[Memmeddu]

That's the cutting torch

That's the tip

Torch operates this way .
It has fuel valve on the handle ,no oxygen valve on the cutting attachment, just the cutting valve.
Oxygen valve on the handle serves for both pre heat and cutting

 

[Pete.]

View attachment 331896
That's the cutting torch View attachment 331897
That's the tip

Torch operates this way .
It has fuel valve on the handle ,no oxygen valve on the cutting attachment, just the cutting valve.
Oxygen valve on the handle serves for both pre heat and cutting

Yes that is a propane tip. Look after that torch they are very good quality.

 

[Memmeddu]

Yes that is a propane tip. Look after that torch they are very good quality.

That's the Italian standard torch copied by everyone .
I do clean it after every day using a rag , and once in awhile I use scotch brite to make it shine.
I take care of the workshop tools as if they were mine

 

[Barking Mat]

Holding the tips too close causes crap to destroy the flared bits of the inner nozzle causing bad gas spray, meaning, they need changing, got through a fair few myself.