Sometimes I have a problem with it. I've tried different settings, cutting speed etc. What's the definitive answer?
Rob, I have a #5 tip on the oxy/accet and does well from 1/4" through 1"...the cut does tend to close on 3/16" and thinner (too much heat, to little steel?). Regards, Bob
In my experience it is too large of a tip for the steel thickness. The preheat is melting it back together.
Yair . . . . RobVG, Could you elaborate a little mate? I don't quite understand the problem. Cheers.
I would agree, it seems customary to use one cutting tip for all occasions, from auto sheet to 2" and rosebud duty. I tend to use an 0 tip most of the time because it works well up to about 1/2 and I hate paying for gas every week.
C'mon Scrubby, everyone else knew #2 seems to work well for most things. I "still" have an occasional problem but turning down the heat helps. I guess #2 it's to much for the thinner stuff.
I use 0 tip for 3/4 inch, gives a nice thin cut, great for cuts that are not just a straight line. In the marine industry not much is straight or at 90 degrees.
I reference the manufactures’ recommended cutting tip-material thickness charts & oxy-ac psi settings http://victortechnologies.com/victor/ http://www.koike.com/hand-machine-torches Thick material 1” up, pre-heating helps when hand cutting or machine cutting. Anytime I can AIRCARBON ARC 3/8s rods @ 525amps or PLASMA, faster and cheaper. Example HeavyEquipmentForums
Oh, and did I mention gas? Look up the manufacturer's recommendations on pressure settings, almost everybody uses WAY too much oxygen pressure, it's detrimental to clean cutting and the stuff is not cheap anymore. I'm not a tightwad, just hate waste and fighting gas bottles. Keep the tip clean and the flame properly formed, 20 psi generally will be plenty for anything 1/2" and under.
Yair . . . . Oh! That problem RobVG . . . I didn't know it had a name. (big grin) The definitive answer as others have mentioned is everything must be right. It appears the US uses a different tip numbering system to us but different tips are made for different thickness metal. Some overlap of course is possible by adjusting flame and travel speed . . . . fuel and oxy pressures on conventional equipment must be right and, for perfect cuts the steel should clean on both sides. I haven't used conventional equipment for many years and have a different type that is pretty fiddly and uses very low acetylene pressure. It cuts like a plasma if you persevere though. With any system the travel speed should be such that the preheat does not melt the edge of the cut and the cut edges should always have the pattern ninety degrees to the face . . . if the flow appears to curve back the travel is too fast or oxy pressure low. The only variation to this is when cutting thin (say) 1/8" it can be cut very clean by resting the edge of the tip on the plate freehand and cutting with the handpiece lent at an extreme angle say 25 or 30 degrees from horizontal and increasing travel speed . . . it makes the tip think it's cutting thicker plate. Properly done, cutting say 1/4" and 3/8" plate for boat hulls with by hand with guide wheels the scribe line should remain visible and the plate should need only a touch with the grinder to make it fit. Cheers.
Scribed line should remain visible? Sometimes I wonder why I waste my time penciling a line...I should be using sidewalk chalk. Regards, Bob
Helpful replies, Thank you
Scrub, Do you use one of those torches with the second preheat tip? They sell them at fairs and trade shows here, with a magician demonstrating how to cut and weld with them....
Spot on mate ! Travel speed & torch angle play a big part in it . Out of habit I cut with a lead angle up to one inch thick . Like you say 1/8 inch & under torch angle damn near flat & fast cutting speed . Makes a for a clean cut without any slag .:yup Normally just mark cuts with soapstone / chalk line . On more intricate cuts I will center punch every 1/4 inch or so just to help stay on the line .
Lot of good advice here. I'm with scrub, if you're cutting sheet metal, lay the tip at an extreme angle in the direction you're cutting. On thick metal, if you desire little slag in the cut (metal melting behind the torch head and filling the cut, of course gas/oxy pressure is important, and the thickness of the material has a lot to do with those settings, but I've found it helps to have the oxy backed off just a bit. In other words, for a good hot flame I typically turn on the gas and light up and adjust to the flame length (pressure) I desire, then turn on the oxy until I get a nice deep sky blue flame. But if I want to control slag in the cut, I back off the oxy just a bit from sky blue to more of a turquoise blue flame. At this setting it takes a little longer to preheat to begin the cut, but once it starts it makes a nice cut with reduced slag because the heat isn't melting the surrounding metal near as bad. I hope this makes sense.
Yair . . . Yes lantraxco. One of those pistol grip thingy's . . . they have been around for years under various names. I bought mine originally for art work as they will cut thin plate like plasma when making silhouettes . . . I sorta got hooked on it. They use a lot less gas to do any given job . . .acetylene has a special gauge that runs @4PSI. Too fiddley for general purpose but wonderful for panel and radiator work. ETER . . . I don't quite get what you are saying but a properly scribed line is very easy to see and yes a well cut plate will show the scribe line as witness all along the cut. For a suitable scriber for doing precise fit up plates I used to chuck up a piece of (say) 1/4"stainless round bar poke a 2.5 mm hole up it and then tap in a piece of TIG tungsten. . . the whole thing was then sharpened like a pencil on the grinder. The freshly tungsten scribed line sort of shines in the front of the flame and is very easy to follow . . . the proviso being to seeing the witness is that the travel speed and flame have to be pretty right so there is an absolutely square cut and no erosion of the edge. Cheers.
Koike cut tips (oxy-ac) use low psi ac 2.8psi 1/4” to 1 1/2” oxy 30 to 45 psi One of my favorite toys; Koike Handy Auto motorized hand torch https://youtu.be/lFVr-TRi-4Q For a suitable scriber for doing precise fit up plates I used to chuck up a piece of (say) 1/4"stainless round bar poke a 2.5 mm hole up it and then tap in a piece of TIG tungsten Available in the US as standard layout scribe, extra new tungsten points are stored in the circular hollow handle. Oxy-AC cutting thin gauge sheet steel, Victor makes a tip for that purpose, resembles a gouging tip. Leaving soup-stone layout lines: Journeymen fitters use the line width for cutting allowance, centering the Oxy orifice dead center on the line; expressed as take-the-line. If you carry cutting tips wrapped in rubberized protectors that prevented burnishing (wear) the tapered seats and cut tip orifices, even the plastic holders from the OEMs cause wear while carrying around in service trucks. Thank for sharing your knowledge guys
If you carry cutting tips wrapped in rubberized protectors that prevented burnishing (wear) the tapered seats and cut tip orifices, even the plastic holders from the OEMs cause wear while carrying around in service trucks. guys[/QUOTE] I have started using American torch tips on my cutting outfits. Once you install the adapter, tip changes take a few seconds and there is no seat to get beat up rattling around in a truck. The best thing is, it's so easy to change tips, I'm inclined to use the right size for the steel thickness. I also found that a rosebud tip uses the same adapter so I often use it where before I would have just used the cutting tip and waited.
Had to look up American, love it. Great system AND I may get to use a couple of older straight torches I have had trouble getting tips for....
Scrub, here is a pic of some of the "scribing" instruments found in the shop where the hand-held torching operations are conducted (side-walk chalk being on the far right). My point was that I have not yet come to terms that my glasses would probably help around the shop as well as they help me to read the "captions" on TV:drinkup
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
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.
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.
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,
It's not taught Scrub, and bad ways get passed on more easily than good habits.
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.
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.
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
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?
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.
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.
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,
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.
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.
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
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."
Flushing ? He's heat prepping the plates by burning off the paint & rust ?
Yair . . . Thanks StanRUS. That's new terminology on me too . . . Williams Marine what is "flushing"? Cheers.
Talk about straight lines..... *sigh*
Flushing is similar to scarfing a weld, much faster. He uses a tip that has two flat sides on it (rivet cutting tip), has the O2 way up and can blow out the old weld along with a doubler plate in one pass. Reminds me of air arcing, the molten steel is flying fast. When say a side shell has been dented and the frame on the inside has also been damaged these guys will use this method to remove the frames that have been welder on both sides. The frames on the large barges can be angle 8X8X 3/4, or larger depending on the barge use. They can flush out the frame without gouging into the existing side or bottom shell which would not be acceptable to the ABS or USCG during inspections. With scarfing you always get that slag puddle that can not be moved without a chipping hammer, this method is much faster for large production type work. The inside of these tanks can be 25+ feet deep by 50 feet wide, there can be 8 of these size tanks (voids) in a large deck barge. Not a fun place to be when they are blowing and going. Dark, hot, smoky with maybe just two man holes to get in and out of. I will be at their shop in a few days and ask the owner for more details if you would like, he only has 40 years of experience, great guy, very old school, not very politically correct. Amazing to watch these guys put shape back into a crushed bow of a vessel.
Yair . . . Gotcha Williams Marine. We call that process "gouging" and as you say it uses a special curved tip and properly done can be effective but man it chews through the gas. We had a little slip in an remote gulf port mainly pulling prawn (shrimp) trawlers and little coasters to about eight hundred tons and I hear what you are saying about hot dark and smoky. Cheers.
Yair . . . It just struck me that no one has mentioned leaving tabs when cutting large plates. A lot of my boatbuilding/repairs occurred under less than ideal circumstances and when precision cutting large plates by hand they were often just supported by dunnage, cinder blocks or even logs. Under such conditions (say) on a twenty or twenty five foot cut on a 1/4" or 3/8" plate I would drill a series od 1/8" holes on about three foot centres right on the scribe line and cut to within about half an inch of the hole, stop and start again. Makes it a lot easier rather than having the plate drooping as you cut. If possible these cuts were done last thing or I would even come back after tea . . . next morning it was just a matter of cutting the tabs with a one mil disk on a four inch grinder and you had a nice cool plate to work with. Cheers.
Improved beveling how-to http://www.esabna.com/us/en/education/blog/oxy-fuel-torch-tip-nozzle-preheat-design.cfm Be safe