Is it MIG with solid wire and shielding gas or is it flux-core wire? If
you're not already using it I'd suggest you try a smaller wire. If you're
using solid with shielding gas try .024 (or .023 or .025 depending on the
manufacturer). If you're using flux-core try .030.

If you're not using gas and the smaller wire you'll probably just make a
mess of anything thin but the .030 wire should at least help.

Best Regards,
Keith Marshall


"The universe is full of magical things,
patiently waiting for our wits to grow sharper."
-Eden Phillpotts, A Shadow Passes, 1934
"mike" wrote in message ...
I have an el-cheapo noname mig welder.
Has two settings,
16V 35A and 18V 70A.
I can manage to get thick metal stuck together,but it spits out way too
much wire for thin stuff,
like welding the thin tubing of my motorcycle mirror back onto the
mounting bolt...again...

If I turn down the wire feed speed, all I succeed in doing
is welding the wire to the end of the tip.
Sounds to me like I need less current so I can feed the wire
slower???yes???no??? Or is something horribly wrong with my
technique?

If I stick a resistor or inductor in the output, I'm no longer
constant voltage. So what is the recommended way to turn down
the heat?


I've got this 0-16VDC 40A power supply. Maybe I should just
hook it up in place of the welding transformer?

Suggestions? Other than spending big bux on a proper welder ;-)
I'm only going to weld small parts, so efficiency is not an issue.
thanks, mike


--
Bunch of stuff For Sale and Wanted at the link below.
laptops and parts
4in/400Wout ham linear amp.
Honda CB-125S
400cc Dirt Bike 2003 miles $450
Police Scanner, Color LCD overhead projector
Tek 2465 $800, ham radio, 30pS pulser
Tektronix Concept Books, spot welding head...
http://www.geocities.com/SiliconValley/Monitor/4710/

like welding the thin tubing of my motorcycle mirror back onto the
mounting bolt...again...

Make a good mechanical connectiion and then silver solder it.

If you had enough cable laying about you could wind it around a mass
of iron and make a reactor. Or add another coil and make a saturable
reactor but I still think you are using the wrong tool.

Gary Coffman wrote:
On Mon, 01 Sep 2003 06:51:16 -0700, mike wrote:

I have an el-cheapo noname mig welder.
Has two settings,
16V 35A and 18V 70A.
I can manage to get thick metal stuck together,but it spits out way too
much wire for thin stuff,
like welding the thin tubing of my motorcycle mirror back onto the
mounting bolt...again...

If I turn down the wire feed speed, all I succeed in doing
is welding the wire to the end of the tip.
Sounds to me like I need less current so I can feed the wire
slower???yes???no??? Or is something horribly wrong with my
technique?


Turning down the wire speed effectively reduces the current.
You're turning it down so low that there's not enough current
to melt off the end of the wire and break the circuit. Turn the
wire speed back up to where it works, then move the torch
faster to control how much weld you deposit.

Gary

Thanks, but I'm still confused.
I'm using .023 solid wire and pure CO2 gas.
I've got so much heat that the wire is melting all the way back
to the tip. If I turn up the feed speed, that problem goes away,
but I'm depositing WAY too much metal for the small work piece.
If I increase the tip to work distance with slow wire speed, I get
big globs of metal as the wire vaporizes and a relatively long time for
the wire to extend to the work and vaporize again.
I'd like smaller, more frequent "vaporizations" I think...
Just seems like turning down the current would help???
mike

--
Bunch of stuff For Sale and Wanted at the link below.
laptops and parts
4in/400Wout ham linear amp.
Honda CB-125S
400cc Dirt Bike 2003 miles $450
Police Scanner, Color LCD overhead projector
Tek 2465 $800, ham radio, 30pS pulser
Tektronix Concept Books, spot welding head...
http://www.geocities.com/SiliconValley/Monitor/4710/

On Mon, 01 Sep 2003 17:34:57 -0700, mike wrote:
Gary Coffman wrote:
On Mon, 01 Sep 2003 06:51:16 -0700, mike wrote:
I have an el-cheapo noname mig welder.
Has two settings,
16V 35A and 18V 70A.
I can manage to get thick metal stuck together,but it spits out way too
much wire for thin stuff,
like welding the thin tubing of my motorcycle mirror back onto the
mounting bolt...again...

If I turn down the wire feed speed, all I succeed in doing
is welding the wire to the end of the tip.
Sounds to me like I need less current so I can feed the wire
slower???yes???no??? Or is something horribly wrong with my
technique?


Turning down the wire speed effectively reduces the current.
You're turning it down so low that there's not enough current
to melt off the end of the wire and break the circuit. Turn the
wire speed back up to where it works, then move the torch
faster to control how much weld you deposit.

Gary

Thanks, but I'm still confused.
I'm using .023 solid wire and pure CO2 gas.
I've got so much heat that the wire is melting all the way back
to the tip. If I turn up the feed speed, that problem goes away,
but I'm depositing WAY too much metal for the small work piece.
If I increase the tip to work distance with slow wire speed, I get
big globs of metal as the wire vaporizes and a relatively long time for
the wire to extend to the work and vaporize again.
I'd like smaller, more frequent "vaporizations" I think...
Just seems like turning down the current would help???
mike

No. It is because the current is effectively too low that you're
getting the symptoms you're getting. When the current is
high enough (for the gauge wire you're using), the tip of the
wire vaporizes immediately on contact with the work, breaking
the circuit. This rapidly happens again and again as the wire
advances, giving the characteristic "frying bacon" sound.

But when the current is too low, the circuit doesn't break
immediately, the wire gets hot (which raises the wire resistance,
which makes it get hotter, etc) all the way back to the gun tip.
It will often weld itself to the tip. Any time you see this, you
know the wire speed (current) is too low, and/or the stick out
is too great.

Remember that a MIG power supply tries to maintain a constant
voltage. It will supply whatever current is required to do this (up
to the maximum current the particular machine can supply). There
are 3 things controlling current in MIG welding. They are wire
diameter (bigger means more current), wire speed (faster means
more current), and stickout (shorter means more current).

The *heat* delivered to the weld is the product of the current and
the voltage (higher voltage means more heat). The minimum voltage
you can use is a function of the shielding gas you're using. CO2
is a rather hot gas. It wouldn't be my choice for welding small or
thin materials.

You're already using the smallest wire your machine is designed
to use. I assume you're also using the lowest voltage range. So
you need to increase the wire speed until you get the "frying bacon"
sound (you can't do proper short circuit transfer welding unless
you do). Keep stick out short.Move the gun much faster along
the joint to control the amount of metal being deposited at any
point along the weld.

Remember that the thinner the material, the faster you have
to move the gun. The real limit on how thin a material you can
weld with MIG is how fast you can move the gun in a controlled
manner. (If you want to do nice welds on really thin material,
switch to TIG welding.)

Gary