[TheForge] Speaking of cuts

[Ralph Sproul]

    Dave and others interested,  There are four things you can try, to
eliminate this Heavy Slag accumulation.  I'm assuming you have a nuetral
flame adjusted on your preheaters, but you can cut the heat back to the
point it will just cut and thus not be "melting" more steel with the
preheaters than is necessary. So running a fairly cold (smaller or less in
volume) torch flame - can help this situation a lot.

    The next thing is don't cut with your tip straight down, make it so your
going into or trailing with about a 5 degree angle(with the cut - or you end
up with a bevel).  This will tend to spit the slag more than puddle it up
under your cut.

    Third, is cut rate.  If you have your flame set with too much heat, your
screwed in the first place as your trying to oxidize the material out of the
path more than you are melt it out.  So with this cooler flame try cutting
at just the rate that the top of the plate next to the preheat flames is not
causing a puckering or melting action...........that is the correct cut
rate.  Any faster and you'll loose the cut.......slower and your top puddles
from melting from the heat of the preflames.......adding to the mess your
talking about.

    Fourth is if your running you oxygen pressure too low........you get
more melt than oxidation.  I keep my oxygen regulator on my cutting torch
set between 30-50 for a range for 1/4 to 1" plate.  Less than 1/4" and I use
the plasma cutter......or take that five degree angle to a 60 degree steep
angle to lessen slag on 1/8 and 3/16.  I also have a real small Victor
cutting torch with a tip that will leave good results on thin stock.  But
your normal cutting torch with a mid to large sized tip should be able to
cut 1/4 to 1 inch stock comfortably with the correct settings and techniques
used.  Cutting against a straight edge is also helpful for long straight
cuts.

    A correctly adjusted flame should yield a cut with hardly any slag on
the bottom of it, with good serated lines (that hardly need grinding) and
the slag should chip off in long slivers with a hatchet instead of beating
it to death with a chipping hammer or hammer and chisel.

    If you master these techniques your torch will become a much appreciated
tool with less clean up hassles.  As with welding......using a test piece(of
the same thinckness) is often a wise idea if your looking for a good clean
cut on the edge of your parts - especially if they show.  This will show you
when the torch is set correctly or if you have to change it once you see how
it "should" look.  At times you'll get slag on only one side of the
cut.........this happens on occassion and I don't really know why - but it
does.  Nothing scientific to report there on it's occurance.......
    Bottom line: Lots of practice helps to make good cuts.

Ralph

----- Original Message -----
From: "Dave Brown" <quahog at tds.net>
To: "Sponsored by ABANA" <theforge at mailman.qth.net>
Sent: Wednesday, August 18, 2004 6:36 PM
Subject: [TheForge] Speaking of cuts


> Sometimes when cutting it seems that I've burned through, only to later
> find that either slag or steel has puddled back into the cut and closed it
up.
>
> Why?
>
> Dave Brown
> Heritage Smithing
> Green Bay, WI
>
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