[TheForge] Re: Burning Metal

Thu Nov 6 19:14:01 2003

Right on Ralph,
Another no-no is not cleaning the cut line surface on the plate.
When I get lazy and don't pre clean the plate the cut has to pre- heat the
surface scale, an so the cut is more ragged.
One technique I use, is to turn my side grinder 90 degrees, and use the disk
edge to grind a 1/8" de scaling cut along the pencil line.
Chuck
----- Original Message -----
From: "Ralph Sproul" <[email protected]>
To: <[email protected]>
Sent: Thursday, November 06, 2003 5:43 PM
Subject: Re: [TheForge] Re: Burning Metal


>         Chuck, I couldn't agree with you more on proper pre-heats.
>         My experience with a cutting torch has found that a "cold flame"
is
> a good thing for lack of slag.  Now how to define a cold flame on the
torch
> would depend on the material thickness your cutting vs rate of cut.  When
> you are cutting and have the very top of the plate melting and puckering
> back looking like the very top edges are melted and rolled(sloppy kerf
that
> I think you refer to)........you need to cut the preheat a bit so your not
> melting the top edge of the plate/piece.   This means developing a knack
for
> proper cut rate in certain thicknesses.........then when your used to
that -
> the ability to fine tune the flame so you don't get that top melt is when
> you start to save yourself hours of grinding and clean up on fabrication
> projects.  A good thing to remember is a cutting torch is just
> that.......your cutting with an oxidizing stream and if you enter the
> equation of melting steel into that.......you got a mess you gotta clean
up.
>         Don't get me wrong, I still have to fine tune things with a couple
> trails before diving into the project if I want accuracy and lack of slag.
> It's just like forging a study or sample, or doing a weld test to set the
> heat and feed speed on your welder to "tune it in".......sometimes the
test
> piece is to tune you into running a torch - and if it's one of those days,
> you certainly don't want to be making your first cut on your expensive
plate
> layout or parts which you have JUST the right amount of material for.
>         Making simple guides and fixtures for flame cutting plate, wide
> flats, beams, flanges, and circles are also a good idea as the less energy
> you put into your alignment and distance of tip to stock........the more
you
> can focus on the cut rate and clean cold flame so you don't spend the day
> grinding.  A day of heavy slag grinding these days is right at the bottom
of
> my list of fun things to do for a day.
>
> Ralph
> ----- Original Message -----
> From: "Chuck Robinson" <[email protected]>
> To: <[email protected]>
> Sent: Thursday, November 06, 2003 1:59 PM
> Subject: Re: [TheForge] Re: Burning Metal
>
>
> > Hey Jerry,
> > What I have observed during cutting operations, is that after setting up
> the
> > torch properly, it is critical to use the right preheat flame to heat
the
> > steel enough to start the cutting action; but not over heat the area so
> that
> > the kerf gets sloppy. Once the cut gets sloppy, the slag diverts the
> cutting
> > action to the sides of the kerf. And the cut is kaput. The higher the O2
> > pressure and thicker the metal, the more slag is formed. Once the slag
> > oxides have clogged the cut. its a real pain to restart the cut at that
> > point. It's like the slag is forming an insulating barrier.
> > I've heard that the allstate is a really good torch, but havent tried
one
> > yet.
> > Chuck
> > ----- Original Message -----
> > From: "Jerry Frost" <[email protected]>
> > To: <[email protected]>
> > Sent: Thursday, November 06, 2003 3:19 AM
> > Subject: Re: [TheForge] Re: Burning Metal
> >
> >
> > > Hi Chuck:
> > >
> > > I'm not sure how my muddled ramblings lead to your question except
> perhaps
> > I
> > > didn't say the iron/steel is burning under the oxy jet. Once the steel
> is
> > > hot enough to initiate burning under the oxy it is self supporting.
> > Properly
> > > set and guided by a steady hand you can certainly shut down the acet
> after
> > > cutting starts and continue just with the oxy.
> > >
> > > Oxides and slag inclusions that shield the iron/steel from the oxy jet
> > stop
> > > the combustion. Iron and steel within the cutable range of alloys
> produces
> > > an oxide with a much lower melting temp than the unoxidized metal and
is
> > > literally blown out of the cut by the "pressure" of it's own
combustion.
> > >
> > > Ayup, improper regulator settings and tip selection is the #1 reason
for
> > > poor torch cutting. (Oh okay, dirty tips are right up there too.) I
use
> an
> > > Allstates oxy/prop rig at home and the regulators are self metering
but
> at
> > > work I'm always resetting the regulators. Everybody seems to want to
run
> > > 5lbs acet and 40lbs oxy.  What really kills me is somebody will
> compliment
> > > me on a torch cut, then rag on me for not having the regs set "right".
> > > <sigh>
> > >
> > > Frosty
> > > ------------------------
> > > If it ain't forged
> > > it ain't real.
> > > Wrought iron is.
> > > The FrostWorks
> > >
> > > Meadow Lakes, AK.
> > >
> > >
> > > ----- Original Message -----
> > > From: "Chuck Robinson" <[email protected]>
> > > To: <[email protected]>
> > > Sent: Monday, November 03, 2003 7:37 PM
> > > Subject: Re: [TheForge] Re: Burning Metal
> > >
> > >
> > > > Jerry,
> > > > If this is true, how can I shut the Acetylene valve off when the cut
> > > starts
> > > > and complete a cut in metal 1/2" thick  with out the fuel supply?
> > > > When I first started cutting  my 5+" thick steel anvil billets, I
had
> > > major
> > > > problems with slag build up and sloppy wide kerfs or incomplete
cuts.
> > > > After reviewing my O/A cutting text books. I lowered the O2 pressure
> and
> > > the
> > > > cutting action improved dramatically. The higher the O2 pressure the
> > more
> > > > slag formed in the kerf
> > > > The cutting action is exothermic.
> > > > I believe poor O/A torch performance is mostly due to not adhering
to
> > > proper
> > > > gas pressure for the tip size recommended for the steel thickness.
> > > > Chuck
> > >
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