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Re: Mig welders and franmes

To: Don Malling <dmallin@attglobal.net>
Subject: Re: Mig welders and franmes
From: "Robert M. Lang" <lang@isis.mit.edu>
Date: Mon, 23 Sep 2002 11:35:31 -0400 (EDT)
On Mon, 23 Sep 2002, Don Malling wrote:

> One of the local hot rod guys told me that I could use a 110V mig welder
> to do frame repairs. I don't need an arc welder. 
> 
> Any comments? 

I have lots of comments. Some are even relevant!

If you do chose a 110V MIG welder, pick one that is a little bigger. For
example, Lincoln used to have the  MIG110 and the MIG125. The 110 can weld
up to around 3/16", but you need to use multiple passes - not the best way
to get a strong weld. If you use the MIG125 with flux core wire, you can
weld thicker metal, I forget how much more.

The thing is that once you start welding stuff, you'll find that the 110
is a bit too small for some projects.

The one problem with the 125 (or whatever the replacement model is) is
that is needs a 20 amp 115 circuit. This should be no big deal, but it's
something to consider.

Moving on to other welder issues, most of the inexpensive welders (under
$500) have a duty cycle of maybe 20%. This means that you weld for 12
seconds and then let the machine cool for 48 seconds. I think I have the
ratios correct. This is not an absolute measurement, but if you try
welding for an hour straight out, you can damage the welder... the
transformer needs to cool off once in a while. 

You should plan on using 75/25 CO2/Argon, but if you plan on doing
ALuminium, you'll need to consider another tank for pure Argon and the
necessary aluminium conversion "kit" for your welder.

Get the best you can afford, cheap welders are a pain in the ass, as you
have to fiddle with the wire feed to get consistant results. Believe me
when I say that you don't want to fiddle with the welder when you get "on
a roll" with your project.

If you can afford a real commercial quality welder, the Miller small unit
is awesome. I have borrwed a friends unit several times and it works
perfectly every time. With one of those units, I could make almost anybody
into a competent welder. BUT - they are all 220 and not cheap (they start
at over $1k.)

Try to locate a welding supply place near where you'll be working with the
welder. You won't believe how often you run out of wire or gas when you've
got the whole day planned to weld. You'll also use untold amounts of sheet
stock, so find a place where you can get various guages from 16 up. The
frame on a TR6 is 16 gauge (I think). Access to a "brake" is useful when
you start fabricating. Once you get the hang of it, you'll fabricate all
sorts of stuff.

Oh - and get a really good 4" or 4.5" grinder to make your welds "pretty".
I have three Makita units now.

You can use a stick welder to work on your Triumph frame, but you also
need a _lot_ of skill to do this without "burning through" the parent
metal. A MIG welder is a much better way to learn the process.

Bu don't get too cocky with your welds, it's really easy to make a bad
weld look akay but the metal is not fused. SO also learn how to test your
welds for intergrity or hook up with someone to check your work. This is
espacially true for any frame repair involving suspension mounting points
etc. You don't want to find out that your lower a-arm mount point weld is
weak under normal driving circumstances!

Bottom line - get the best welder you can afford, don't go on price alone,
find a welding supply place that's local and "practice practice practice".

> Don Malling

regards,
rml

p.s. night courses at a local vocational school are a great place to learn
without ruining anything in the process and they usually have pretty good
welders to work with (which helps get over the initial welding learning
hurtles of "striking an arc" and "building a fillet", etc.)
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