The old closing kerf question.

[Tradesman]

I had to look it up, to a carpenter, kerf is the width of the cut of a saw. Usually a saw blade,for example: thin kerf or wide kerf

 

[Scrub Puller]

Yair . . .

Gotcha ETER. I have never seen the *side walk chalk" .

The common "engineering chalk" here is these days supplied in sticks about 3/8"square and three inches long and shaped to a chisel point on the grinder as needed, it used to be sold in a block and cut with a hacksaw.

If the second item from left is a tungsten scriber it is exactly as I used to make . . . you can really bear down when following a straight edge or template.

At one stage Australian industry was dominated by CIG/BOC and their style of equipment was pretty much universal . . . I think that has probably changed with other players now supplying gear and gas.

Several different styles of cutting heads/nozzles came out over the years but I still ran my original 1960's head which utilized a nozzle with a threaded centre section which tightened onto a seat for the acetylene and an outer lock nut and cone that sealed the oxygen . . . problem was that folks would not back off the outer lock nut before firming down the first stage or alternatively they would overtighten the first stage and strip the brass thread.

Later designs obviated the problem

Cheers.

 

[RayF]

Here's how an old tradesman told me many years back. It works.
Use the right size tip for the job. Make sure its perfectly clean and not been butchered.
Set the Acetylene at 10 psi and Oxy no higher than necessary for the thickness of steel.
Light the torch and with Acet only turn up the flame till it leaves the tip. Back it off just enough till the flame comes back to the tip.
Turn on the oxy enough to lose the carburising feather with the lever down.
You should get a long straight "tube" through the flame and a good flame will crackle when you hit the lever.
That all depends on how good the tip is. Any damage to the central jet or any slag in there,it won't work.
It will cut clean and be a pleasure to use.

 

[Scrub Puller]

Yair . . .

Gotcha RayF. Spot on. That is the precise procedure I was shown for setting up a flame . . . for precision work the tip must be clean, I used to run the correct cleaner through the holes almost every time I lit up.

As I have mentioned before I am not a tradesman but I have worked with a lot of good ones and I sometimes wonder what is taught these days when I see sooty flares of acetylene and pops and crackles when an oxy set is being shut down. (wry grin)

Cheers,

 

[lantraxco]

It's not taught Scrub, and bad ways get passed on more easily than good habits.

 

[StanRUS]

Yair . . .

Gotcha RayF. Spot on. That is the precise procedure I was shown for setting up a flame . . . for precision work the tip must be clean

Yep, when I was 6yr old ~ adjust the flame just to neutral, concentrated hissing stream with oxygen lever down and use correct clean tip!
Flash back arrestors ~ torches with flash back arrestors require up 25% more pressure as tip size increases (15psi maximum acetylene pressure)
ETER, your photo left side scribe, work okay until you use on through hardened low alloys like A514-T1 or AR300 series.

 

[RayF]

So who cringes when they see some bloke using the torch as a hammer when the offcut doesn't fall off by itself?

 

[StanRUS]

So who cringes when they see some bloke using the torch as a hammer when the offcut doesn't fall off by itself?

IF that bloke is using my torch for a hammer, I CRINGE!
One of my buddies, his torch work looks like a great-white shark chewed on the cut line. Grab his torch & depress the oxygen lever you might get a bloody nose, typically oxygen 70-85psi. But the man can wash out broken blind hole bolts, pins etc, he's pretty good.

 

[ETER]

I wish that I would be more meticulous when using my torch around the shop...it is probably the most abused tool. It has the #5 tip (Purox) on top of an Oxweld W-300 in it most of the time because I have found that it works well for 1/4" thru 1" (+) (20psi for 1/4" and 40psi or more over 1"). I don't have to spend much time on preheat, half the time there will be a wall of scale behind whatever is being cut, chopped or dissected anyway. When the cones aren't clean/sharp, then tip cleaner comes out...I realize that always being in a hurry is not always the most productive approach to work, old habits die hard (many analogies fit in here)...I guess whatever works for ya!
Regards, Bob

 

[Birken Vogt]

Grab his torch & depress the oxygen lever you might get a bloody nose, typically oxygen 70-85psi.

What is the purpose of that I wonder? Does he not push the lever down all the way when making a normal cut and use the higher pressure for digging deep? Does that even work?

 

[Williams Marine]

I've been working this past week with a Boiler Maker, been doing fitting for about 20 years, he flushes with the O2 at 80 psi, said it blows everything away fast.

The down side (at least here in Bethel, AK) is we go through a bottle fast, the port engineer is running around trying to keep us in oxygen, flew in a bottle from Seattle yesterday at 300 dollars a pop, guy here said he had a bottle he would sell for 600.

 

[dabsfabs]

Alot people i come across at work think its a heat up blow. It not, its a chemical reaction the cutting process. So persures don't need to high.

Work on job a while back now down they tested you for the gas cutting to a set procedure if you fail you were not allowed to cut and using torch as a hammer was instant fail.

 

[Scrub Puller]

Yair . . . .

I don't know if I have been lucky or if oxy/acetylene equipment (potentially extremely hazardous) is actually inherently fairly safe.

In over fifty years of witnessing misuse abuse and malpractice I have never seen a major malfunction that caused any significant injury, quite remarkable actually.

I have never used flashback arrestors as they weren't mandatory and we never saw the need.

Witnessed some dreadfull goings on at a scrap yard lately with some young blokes hacking up some large pipes with (what to me) was large and unfamiliar equipment hooked up to eight bottle manifolds.

From the sooty flame and backfires going on it was obvious they didn't have a clue . . . and it was one of those places with safety placards everywhere and you had to have safety boots and a hard hat and a hi-viz vest to take a pickup load of scrap into the yard.

Cheers,

 

[Former Wrench]

The worse gas explosion I witnessed was about 40 years ago. I was in a shop working on an 82-40 Terex when a big boom went off. It shook the ground to the point that the dozer moved. Dust and all sorts of stuff came down from the ceiling. Something went wrong at an acetylene/gas supplier a couple of blocks away. I went by the building after work and it was nothing but a shell of a concrete block building with hundreds of holes punched through the walls. A couple of box cars parked on a siding had holes where bottles went through the block and through the car and into the building on the other side. The two guys that worked there and a guy delivering soda pop were never found. It has been long enough that I do not remember the cause, but it seems like it got blamed on something simple.

 

[lantraxco]

Acetylene becomes inherently unstable at pressures over about 15 psi... will decide to explode all on it's own somehow. The bottles have a honeycomb material, used to be pumice stone and a thick version of acetone as a stabilizer. Mistakes or a malfunctioning regulator can make for an unpleasant surprise. Also any form of oil or anything that will oxidize in a high pressure area with oxygen tends to make for loud noises and very hot flames. Dropping a bottle so the valve shears off can be an unhappy experience also I have heard.

Around here the scrap yards use either propane or pressurized gasoline(petrol for you scrub?) for cutting. The 6 pack and 8 pack oxygen sets are just to cut down on swapping bottles. They also have insulated liquid oxygen tanks sometimes.

 

[Jonas302]

Set my torch this way today worked pretty good thanks for the reminder
Worked for many years around auto body guys where the torch had to be lit with oxygen on or those black soot floaters would go everywere

Here's how an old tradesman told me many years back. It works.
Use the right size tip for the job. Make sure its perfectly clean and not been butchered.
Set the Acetylene at 10 psi and Oxy no higher than necessary for the thickness of steel.
Light the torch and with Acet only turn up the flame till it leaves the tip. Back it off just enough till the flame comes back to the tip.
Turn on the oxy enough to lose the carburising feather with the lever down.
You should get a long straight "tube" through the flame and a good flame will crackle when you hit the lever.
That all depends on how good the tip is. Any damage to the central jet or any slag in there,it won't work.
It will cut clean and be a pleasure to use.

 

[Williams Marine]

Clarification, the Boiler Maker I had mentioned has been flushing 3/4 and 1 inch plate with rust and paint on it this past week. I personally think 80 psi on the O2 is high for flushing, but this is what he does day in and day out. Can out fit up my work hands down. He burns at 40psi when cutting, can trim 1/8 inch off free hand with little slag while in the engine room on his knees. Enjoyable to watch a "pro from Dover."

 

[StanRUS]

Clarification, the Boiler Maker I had mentioned has been flushing

Flushing ? He's heat prepping the plates by burning off the paint & rust ?

 

[Scrub Puller]

Yair . . .

Thanks StanRUS. That's new terminology on me too . . . Williams Marine what is "flushing"?

Cheers.

 

[lantraxco]

Talk about straight lines..... *sigh*