I am flame cutting some parts for the T frame and have a question - as I am cutting along the slag will flow back into the kerf behind the torch. The part will still some out with a slight tap or grab it with the pliers but shouldnt the slag blow clean out the bottom?? Am I moving too fast / slow, using the wrong pressure, etc? thanks-
The real welders will probably have some good info, but I've been doing well with more oxygen pressure than is usually recommended. Seems like 20# - 30# oxy and 5# acetylene is the usual . . . for me.
I get best results by using the coolest flame possible that will still go through what you are cutting and move as fast as the flame will let you.
Whats your method for a "cool" flame? I'll ignite the acetylene and turn it up till the soot is gone, seems to me I'm running about 8 psi??
I was told about twenty years ago when this old man was teaching us how to weld to run7# 's on your acetylene and Around 40#'s on your oxygen. If you run those numbers it should cut just fine.
how thick a material your cutting will determan what size tip you should be useing, i'll guess its 3/8" thick and say that you should have a #0 tip, thinner then that a #00, not untill i get up to 3/4" would i use a #1, i set my pressures at 5lb acetoline and 20 oxygen, only if i`m cutting 3/4" or better will i start turning up the oxygen pressure, your really only useing the acetoline to start your cut and then its all the oxygen, if you ever get a chance to run a track cutter try turning the gas off and you will see it just keeps on cutting, make sure the little white cones are about 1/16" to 1/8" away from the surface, you should end up with a nice sharp corner on the upper part of your kurf, if you see it melting down into the kurf your to hot.
When I adjust the torch for cutting I adjust the oxygen so that when I pull the trigger the neutral flame is still maintained. I usually run 20 pounds oxygen. Billk
The biggest secret to clean cuts is having a clean tip. If the tip is clean you should be able to see the air stream extend straight out a couple of inches from the tip. The sound when the trigger is pressed will almost be a crackle. You can actually hear a clean tip. Buy a brand new tip and look at the flame and listen to the sound. That is what you want to maintain with proper tip cleaning. Don't wait until it's screwed up. Keep the tip clean and cackling. Remember you are cleaning a rifle bore. Use a tip cleaner just large enough to clean the dirt from the tip. Don't enlarge the bore or make it look like a blunder bust funnel. The time spent cleaning the tip will save time when trying to restore an abused tip and chipping slag. I knew several welders that would not let an apprentice use their tips. They'd change it to a used tip. When done right 90% of the slag should pop right off when the piece hits the concrete. If you need a chipping hammer to remove large pieces of slag, you are doing something wrong and/or your tip is dirty. If you are cutting a bevel, the slag will roll up under the side that the air stream is directed to leaving a clean sharp edge on the bevel with no slag. If the tip is not clean, the air stream will divert slightly from being square with the metal. The slag will roll up in that direction on the bottom of the cut. If you move too quickly, slag can roll up into the kerf. On thick plate you can look at the cut to see if the air stream was cutting square to the surface or if you were moving too fast and the lines will be angled. Slow down until the lines left are square to the surface. It's a matter of practice and feel. The thicker the plate the slower the movement. It takes time for the air to get through thick metal.
what tommy says about cleaning your tip is right on, and also the outside of your tip must be in good shape as well, nicks in the side of your tip will cause the flame to pull in that direction making for a poor cut, the first thing i do when cleaning my tip is file the outside, i make it nice and round and then file the end square with the sides, nice radius where the side meets the end, then do the bores, a rule of thumb with how hot your flame should be is that it should take awhile to get the metal hot enough to cut, not be so hot that as soon as your torch is close to the metal you can start cutting, having done alot of machine cutting i can tell you that cutting with no slag at all is your goal, its not so easy by hand but it can be done in time, as the hot metal leaves the bottom of your cut it should be just one stream, not a big shower of sparks, when you get there you will have no slag.
tommy and budd beat me to it. Before anything else you must have a perfectly clean tip of the right size for the job. Keep checking it and clean when needed. I usually run 5 pounds for acetylene and 20 for oxy'. Get yourself a little chart from your gas supplier that tells you tip sizes and gas pressures for different thicknesses of material.
Good post question. I see several area's where I could be doing better. Anyway, far as tip cleaners go, you may want to give the Dillon/Henrob style a go. They're sized to fit the hole, but have no cutting edge. They're just smooth and fairly hard rod. Dillon/Henrob only supplies 3 or 4 of them so you'd have to do some digging to find the correct diameter rod for your tips. Dillon/Henrob's thinking probably is that the smooth cleaning tips won't enlarge the tip hole. Seen more than a few tips marked #2 tossing out a #5 size flame. Usually at muffler shops. I used to crew for a guy who ran a stock car on the circle track and owned a muffler shop. He had one of the small tips with the big fire. Mainly for the speed aspect of it, but the welds looked pretty good.
Everyone has mentioned pressure, but no one has mentioned flow. Is it a regular cutting outfit or the hobbyist one with the reduced size regulators? I have that and the same problems you describe over 1/4" plate. It will hack through 3/4" but it ain't pretty.
I personally am using a full size outfit. Anyone found a chart online yet, maybe I'm looking in the wrong places? Cut some thicker stuff last night and had less problem with slag flowing into the kerf, it seems to be the thinner stuff I have this issue with - specifically the 2x3 by .120 I've been cutting...
Everyone has given good advice...The only thing I might add if you have a clean tip, proper size, adjust the flame medium (and not too high for the tip), would be to point the tip slightly ahead into the cut so the slag rolls ahead and off of the piece. I have even "Band-aided" a too large tip by cutting back on the regulator setting, keeping the torch turned down so it just gets hot enough and laying the tip down flatter than usual to blow the slag way away. (Practice) it helps.
just revisited this post after awhile and have a few ??? Anyone found a chart (tip sizes, pressures, etc. for different thickness materials) online yet, maybe I'm looking in the wrong places? What do you guys use to mark the metal so you can see where it is you wanna cut? soapstone, etc? has anyone found any better glasses to use than those f#@$% goggles?
...use soapstone to make your marks and if cutting long strate lines use a metal bar or heavy strap iron to lay along side your cut to follow with your torch, works great; makes a nice strate cut. ...get some welding/cutting glasses (like sunglasses, but have larger area and side sheilds) from your welding store, much nicer to put on/off than those old goggles with the elastic strap.
For what we cut, I use a Victor 00 tip. Anything bigger is just wasting gas. I'm used to the 1/2" wide soapstone. File/sand it to a wood chisel point. (tapered from one side) Hold the flat side against anything you are trying to trace. I like to burn off any paint, oil or grease before the final marking. Hold the torch about 3-4" above the metal and push the trigger. You will see any paint or grease burn away. It's too far away to melt the metal but it will leave a surface that will easily accept the soapstone. If you don't do it, the mark will disappear when whatever was on the metal when you marked it burns away. One other tip is to watch the edge of the kerf not the center of it. With a sharp soapstone mark, keep the edge of the kerf on the mark as you cut and you will get a straight even cut requiring a lot less grinding. You'll get a lot less wandering that way. Goggles are a personal choice. I prefer the individual eye type of goggles connected with key chain as apposed to the Scuba mask type. I always got more sparks through the scuba type around my nose and the corners of the eye. Of course I seemed to be in odd positions often cutting above my head. I see guys using sunglasses. Even if they are dark enough, I'd be scared shitless. I want a good seal around my eyes. It only takes a couple of trips to the eye doctor to "see the light".
Number 5 min...to a number 7....... the larger the tip, the greater the light intensity given off, the darker the lense required.... darker than a 7 will not allow you to see the work.....
SOAPSTONE SUCKS BIG TIME!!!!!!!!TAKE MY WORD ON IT..... "SILVERSTREAK" products are the only way to go! Every decent welder supply store has 'em..... As for glasses, I use a lightweight full face helmet with the big 4 X 4 lense size......hate dodgin flying hot sparks and blown back molten metal!!! Hope this helps..... <CENTER><STYLE type=text/css> body{margin:0px;} .black_foot{background: #000; color:#fff; font : normal normal 10px Arial, Helvetica, sans-serif; } </STYLE><SCRIPT type=text/javascript> <!-- function addToCart(itemNumber) { var theLocation = 'http://www.pipefitter.com/dolphincart/add.php?id=' + itemNumber + '&qty=1' if (window.opener && !window.opener.closed) { opener.window.location = theLocation window.close() }else{ window.location = theLocation } } --> </SCRIPT><TABLE width="100%"><TBODY><TR><TD> </TD><TD vAlign=bottom noWrap align=right><!-- ######## Close Window Slug --><!-- ######## Displays the Close Window button if there is an opener --><!-- Begin Cart Mmgt Slug --><SCRIPT type=text/javascript> <!-- function manageCloseButton() { if (window.opener && !window.opener.closed) { document.getElementById('closeWindow_button').style.display = 'block' document.getElementById('header_div').style.display = 'none' document.getElementById('footer_div').style.display = 'none' } } --> </SCRIPT><TABLE><TBODY><TR><TD align=middle><FORM name=hideButton_form><INPUT id=closeWindow_button style="DISPLAY: block" onclick="javascript<b"></B>:window.close(); type=button value="Close Window" name=closeWindow> </FORM></TD></TR></TBODY></TABLE><!-- End Cart Mmgt Slug --><!-- ######## Close Window Slug --></TD></TR></TBODY></TABLE> Home Catalog Tools Books <FORM action=/dolphincart/search.php method=get><INPUT name=keyword> <INPUT type=submit value=Search> </FORM> <!--Debug: Page= /existing_php/ssrr.php --> [FONT=Verdana, Arial, Helvetica, sans-serif]Silver Streaks and Red Riters[/FONT] <TABLE cellSpacing=1 cellPadding=1 border=0><TBODY><TR><TD vAlign=top align=left width=137> </TD><TD vAlign=center align=left width=363><B>[FONT=Verdana, Arial, Helvetica, sans-serif]Silver Streak Holders and Markers[/FONT]</B> [FONT=Verdana, Arial, Helvetica, sans-serif]Used on Carbon Steel Pipe[/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif]Dimensions (in inches)[/FONT] <DL><DD>[FONT=Verdana, Arial, Helvetica, sans-serif]Holder 5x1/2x3/32[/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif]Markers 3x3/8x1/16[/FONT] </DD></DL>[FONT=Verdana, Arial, Helvetica, sans-serif]Package consist of one holder and five markers.[/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif]<B>T162</B> $4.75 <INPUT onclick="javascript<b></b>:addToCart('T162');" type=button value="Add to Cart" name="Add to Cart"> [/FONT] </TD></TR></TBODY></TABLE><HR><TABLE cellSpacing=1 cellPadding=1 border=0><TBODY><TR><TD vAlign=top align=left width=138> </TD><TD vAlign=center align=left width=362>[FONT=Verdana, Arial, Helvetica, sans-serif]Red Riter Holder and Markers[/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif]Used on Stainless Steel and Galvanized Pipe[/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif]Dimensions (in inches)[/FONT] <DL><DD>[FONT=Verdana, Arial, Helvetica, sans-serif]Holder 5x<SMALL>1/2</SMALL>x<SMALL>3/32</SMALL>[/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif]Markers 3x<SMALL>3/8</SMALL>x<SMALL>1/16</SMALL>[/FONT] </DD></DL>[FONT=Verdana, Arial, Helvetica, sans-serif]Package consist of one holder and five markers.[/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif]T164 $4.75 <INPUT onclick="javascript:addToCart('T164');" type=button value="Add to Cart" name="Add to Cart"> [/FONT] </TD></TR></TBODY></TABLE><HR><TABLE cellSpacing=1 cellPadding=1 border=0><TBODY><TR><TD vAlign=top align=left width=130> </TD><TD vAlign=center align=left width=370> [FONT=Verdana, Arial, Helvetica, sans-serif]Silver Streak Replacement Markers [/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif]T163 $3.00 <INPUT onclick="javascript:addToCart('T163');" type=button value="Add to Cart" name="Add to Cart"> [/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif]Red Riter Replacement Markers [/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif]T165 $3.00 <INPUT onclick="javascript:addToCart('T165');" type=button value="Add to Cart" name="Add to Cart"> [/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif]Each replacement package contains 6 markers [/FONT] </TD></TR></TBODY></TABLE> <HR>Home Catalog Contact Us Pipe Tools Books FAQ Privacy <HR align=center SIZE=1> pipefitter.com </BLACK_FOOT></CENTER>
The equipment and adjustments have been covered well. A scribed line can be seen under all light conditions much easier than a soapstone line. You will need a carbide tip scribe to do hot roll steel in order to get through the scale. Cheap carbide tip scribes can be made from carbide hard surfacing stick welding rod like Ultimium. Something that has not been mentioned, try to get in a position to PUSH the torch away from you when cutting. In this way you can look down the slot at the molten wall. Try to keep the wall vertical and bright as possible.
your tip size is likely too small when cutting heavier stuff....also smaller torch oufits are limited as to max. tip size they'll take.... all must be in proportion....
TIP CHARTS are good for size selection v/s metal thickness...and the right size is critical to the result... HOWEVER the pressure recommendations are only a rough guide.... I will scan and post a chart or two later today for you ..... AND I will post info on the CORRECT way to set up pressures for all cutting/welding tips using the "flame balancing technique".... There is a simple and correct way to do this.... Also, when cutting thin materials the tip must be inclined or leaned forward slightly into the direction of the cut to blow the molten metal clear of the cut zone..or slag will backflow as you've experienced...and the tip size should be kept small to achieve a narrow kerf...too big a tip messes things up when cutting thin materials.... ps: I may cover this stuff under a new thread....keep your eyes peeled....
While soap stone is good for marking you can see a punch mark better in some cases. Just take a center punch and make a punch dimple about every 3/16" to1/4" along the line and you'll see it's easier to follow. If the metal isn't perfectly clean sometimes the soapstone burns off ahead of the flame making cutting on the line difficult. Just aim the torch right down the center of the punch marks. Frank
The Jalopy Journal
