[TheForge] Image posting of Steve's Dedicated side forge

[Jerry Frost]

I only have one bit to add to Steve's proven experience. Rather than trying
to chase a mig tip with a drill bit use torch tip files. Being copper alloy
mig contact tips will work harden and gall quickly binding and breaking
small drill bits. My experience is the torch tip files not only chase the
orifice accurately without danger of tossing the tips due to a broken drill
bit stuck in them but the score marks of the file are aligned with the gas
flow making for a more laminar gas delivery stream and better entrainment.

Jer

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Steve Bloom
Sent: Friday, September 6, 2013 6:55 PM
To: Blacksmithing List Sponsored by ABANA
Subject: Re: [TheForge] Image posting of Steve's Dedicated side forge

At 09:19 PM 9/6/2013, Dan Scheid"  wrote:

>you say you are using a 0.040 injector  did you drill it or use a mig 
>tip . if a mig tip what size  the 0.035 (should be close to the 0.04 as 
>it's for 0.035 wire) or the 0.045 they don't seem to make a 0.40 mig 
>tip.

Historically (some of my forges date back to 1991), I used a #60 wire drill
bit (0.040" diameter) and a precision collet chuck (about $7 from Harbor
Freight if memory serves).  Since the tuning requires the gas jet to be down
into the burner, I always make two prick punch marks on the gas pipe at the
center and 180 degrees apart.  One gets a dab of paint or magic marker, the
other gets drilled. When I see the paint, the jet isn't directed up into my
face.  I've also made them with a mig tip (and there is no problem seeing
where the gas will flow).  Taping the seat on a curved, relatively thin
surface can be tricky but teflon tape makes an adequate seal.  The only draw
back to the mig tip is either screwing it in after the gas pipe is inserted
into the bell or a keyhole has to cut to allow the tip to slip through. Six
of one, half a dozen of the other.  I haven't broken any #60 bits yet but
cost-wise it's a wash.  When I used a 0.040" on my hot salt bath forge, it
ran a bit hot (1600 F at 3 psi with guttering possible).  I replaced the
pipe with a #64 hole (equivalent to a 35 mig tip) and the unit ran at 1500
at 5 psi. 
Bottom line - do whatever is convenient and doable with the tools at hand
and realize that the hole size can be manipulated to allow control.  Oh --
and it the 35 mig is too small, ream it with #60.

Steve

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