|
Posted by semidemiurge on May 11, 2007, 10:16 pm
Please log in for more thread options
I have a 120v Lincoln Weldpack MIG welder that was giving me some
trouble today and I am a bit stumped as to the cause of the problem.
The welder has 4 positions for voltage control and a potentiometer for
wire speed. I am using 025 solid wire with 75/25 mix on 1/8" mild
steel. I have been welding on this project (outdoors) for the past
week and today I experienced a consistent problem that I can't seem to
figure out the cause. I have been welding in globular transfer mode
but now I seem to only be able to do a short transfer mode (at best).
Nothing has changed, that I am aware of. But now I am getting ugly
welds with constant balling of the electrode and sticking to the tip.
It is as if the voltage has been lowered. I tried all my usual
checks, gas (half tank), extension cord (the same one), settings (the
same), dirty tip, nozzle, etc (all cleaned), dirty workpiece
(cleaned), feed problem (nothing seems to be hindering feed), bad
ground connection (reclamped). The vertical welds are causing the
most problems, flat horizontal are better but still not as good as a
day ago, or this morning. Today was the first really hot day this
week, could this have some effect that I can't think of? thanks for
all input, rick
|
|
Posted by Leo Lichtman on May 11, 2007, 10:45 pm
Please log in for more thread options
"semidemiurge" wrote: (clip) I have been welding on this project
(outdoors) for the past week and today I experienced a consistent problem
that I can't seem to figure out the cause. (clip)
^^^^^^^^^^^^^^^
Could there be a little breeze?
|
|
Posted by semidemiurge on May 11, 2007, 11:20 pm
Please log in for more thread options wrote:
> "semidemiurge" wrote: (clip) I have been welding on this project
>
> (outdoors) for the past week and today I experienced a consistent problem
> that I can't seem to figure out the cause. (clip)
> ^^^^^^^^^^^^^^^
> Could there be a little breeze?
It is not the breeze. I know the effects of the shielding gas being
blown away and this is not that. thanks. rick
|
|
Posted by on May 11, 2007, 11:43 pm
Please log in for more thread options
> It is as if the voltage has been lowered.
> Today was the first really hot day this
> week, could this have some effect that I can't think of? thanks for
> all input, rick
The supply voltage could be lower because everyone is using their air
conditioners.
Dan
|
|
Posted by Shaun Van Poecke on May 11, 2007, 11:48 pm
Please log in for more thread options Hi Rick,
Here's everything you never really wanted to know about mig setup.
Id start (as i do with any welder that isnt mine) by checking your feed from
end to end. Its part of the setup process i go through every time i change
a roll of wire, or whenever i have a problem with my welder.
grab your gun, feed out 2" or 3" of wire. Now unscrew your tip. Slid it up
and down the wire. How does it feel? any drag at all, or silky smooth? if
there is any drag, change it. If you constantly have tip problems, dont be
scared to step up to the next size (ie. 1.0mm tip on .9mm wire etc)
Tip ok? next thing is to check your liner. Leave the tip off. Lay out the
gun/lead in a *straight* line from the welding machine, no kinks or bends.
remove the gun from the welder. Is the gun permanently attached to the
welder? then you'll have to get a bit imaginative. unscrew it if it doesnt
look like too much trouble. If it does look like too much trouble, then
release the spring locks on the roller(s) and grab hold of the bit of wire
with your fingers. turn the roll of wire around a bit so youve got a bit of
slack. Now try to push the wire in and out of your gun. How does it feel?
can you easily slid the wire in and out? If yes, then you're doing pretty
good. many liners have a small bit of drag to them. if you have a lot of
trouble sliding it, then your liner is probably full of crud. take the gun
off the welder, pull the wire out and blow out the liner with compressed
air. You do this once a week anyway, right? If you still have problems
then pull the liner out of the gun... any kinks in it? change for new. if
you still cant clean it or get it to feed smooth then you'll have to rplace
it. Many flux cored users have liner problems because of the dusty nature
of this wire. The answer is to blow out your liner frequently, and buy a
packet of 'wire wipers', these things attach to the wire before it enters
the roller and remove most of the dust before it gets into the liner.
alright, now you've got a good tip and a free sliding liner.... time to
check the tension on your roll of wire (not the feed rollers yet!) Not all
welders have wire roll tension, but its handy if you do have it, especially
on 4.5kg roll machines. Look at the spool where it goes onto the machine.
imagine that the welder is working away and the spool is turning, feeding
out wire... maybe quite fast. When you stop, if there is no tension on the
spool then it might carry on turning just for a fraction of a second due to
its own momentum. This isnt too bad if there's plenty of sidewall on the
spool, but small rolls in particular usually fill that spool up right to the
brim. when it carrys on a second, the wire can get enough slack in it that
it slips off the spool. now when you start welding again, the wire starts
wrapping itself around the spool holder and making a good old tangle of a
mess. a minute later your welder jams up. You think you're out of wire,
but have a look at the spool, and oh $%#@. All that lost wire.... If you
have a spring with a tensioning nut on that spool holder, then that is your
spool tensioner. You dont want much tension on it, in fact you want as
little as possible. what you want though is for the spool to stop turning
_as soon as_ you stop welding. you dont want it rolling on. check it by
pulling your trigger for a second and letting go. or just roll the spool a
bit with your hand. when this is adjusted with too little tension, you see
the spool roll on a bit which gives some slack in the wire. next time you
pull the trigger it starts really easy because it doesnt have to pull the
spool, but a second later the slack is taken up, just like someone who
doesnt really know how to tow a car, giving a 'jerk' to the spool and
putting a sudden extra load on the rollers. but because there's no tension,
the spool probaby skips ahead a bit, giving a little more slack in the
line... etc etc. the end result is an unpleasant start, which can
contribute to machine gunning. If your machine doesnt have a tensioner and
you constantly have problems because of it then you can try making something
up. how you do it depends on the nature of your machine.... some guys put
springs in the 'axle', some guys make up special little wheels with springs
on them, some guys just jam a bit of rag between the spool and the machine.
so you've sorted out your gun/liner problems, got your spool tension right
_only now_ can you adjust your roller tension. roller tension is a critical
adjustment on any welder, but its the *last* thing that should be adjusted,
because it is affected by every other thing in the system. If you've got
friction in your gun/liner then it has to push against that. too much
tension on your spool, then it has to pull harder to get the wire going.
Sadly though, roller tension is almost always the first thing that a welder
adjusts when he has feed problems. A lot of guys crank down on that thing
before they even check their tip. Ive seen guys start at a shop, go to
their new workbay, and before they even try the welder or pickup the gun
they open up that side cover and crank down the roller tension all the way!
If your welder has been working fine, and you havent changed anything, then
the roller tension should never need changing. If the wire is slipping then
something else is causing it.... dont use the roller tension as a fix all
because you're too lazy to find the real cause. With roller tension, you
want as little as possible, but as much as necessary. The way i check it on
solid wire is to pull the trigger, then with only your index finger and
thumb, try to stop the wire from feeding through by holding it before it
enters the rollers. If you cant stop that wire feeding through no matter
how hard you squeeze it (with only your index finger and thumb) then you've
got way too much tension! The end result of this is that you are squashing
the wire and also wearing out your rollers prematurely. The wire becomes
oval shaped instead of round, which effectively increases its diameter.
This in turn causes problems in the tip and liner, which means..... you
have to turn up your tension more to overcome that extra drag, which in turn
squashes the wire more making it even more oval shaped which means.......
too little tension means that the rollers slip on the wire, chewing it out.
this happens most often with small diameter wires at high speeds when
starting, especially if you have a bit too much tension on your spool. the
rollers have to suddenly get the wire moving from stopped to quite a high
speed as well as overcome teh initial drag of the spool and the drag in the
gun/liner. what happens is the rollers do a little 'burn out' on the wire
every time you start. You can see it pretty easily on the wire. The fix,
is to slow down your wire speed a bit, reduce your spool tension, increase
your roller tension and ccheck your liner/tip. this is a cinstant problem
for feeding aluminum wire, but we'll go into that some other time. To
adjust your roller tension correctly, simply squeeze that wire with your
thumb and index finger then adjust the tension so that you can only *just*
stop it from feeding. if you can stop it easily then thats not really
enough tension, but its close! another downside to too much tension is that
when you have a problem in your tip/liner the rollers will just keep on
feeding away. you want them to slip in this case, but with too much tension
they just jam that wire right up the works which can destroy your liner, or
sometimes kinks the wire betweeen the roller and liner then the wire starts
wrapping round the rollers and tangling up there, gets caught in the drive
gears etc etc... a real mess. adjusting tension on twin roller machines
isnt any more tricky... They usually have numbers on the sping loaded
tensioners to let you adjust them the same, but i start with just one
roller, adjust it as for a single roller machine, then do the other one,
also by itself. then put them both on, and turn them down an equal ammount
until i get the 'just slipping with thumb and index' result that i want.
twin roller machines need slightly less tension on the rollers than a single
roller machine, but a good single roller machine can work just fine. Id
take a good single roller machine over a bad twin roller machine any day of
the week.
If you cant get your roller tension right, then you may have worn rollers,
or the wrong size/type of roller. This is usually what happens with too
much roller tension. the groove in the roller gets prematurely worn.
there's no easy way to fix this.... new sets of rollers arent too expensive
compared to the time you can waste messing around with them, so in this case
i usually just get a new set of rollers. you'll be happy with them. if you
have the wrong size of roller then most rollers have two grooves. on small
machines, one groove is for 1.2mm wire and the other for 0.9. you change
them by turning them around. on some small machines, one groove is smooth
while the other is knurled. This limits you to one size of wire. The
smooth groove is for solid wire while the knurled groove is for flux cored.
dont use knurled on solids, or smooth on flux cored!! also, dont try using
the wrong size roller on wires... you'll only make a mess of the rollers.
Some machines use one knurled (drive side) plus one smooth (freewheeling
side) for flux cored, while some machines (usually those with much bigger
wires) use knurled both sides for flux cored. Setting roller tension on
flux cored is a little bit more 'feely' than on solids due to the knurled
rollers. You dont want the roller to ever slip, even if you squeeze it hard
with your thumb and finger, but you definitely dont want too much tension
which puts bad 'tracks' on the wire and really makes a mess with the dust in
the liner. You can tell a lot by looking at the tracks on the wire... but
basically you want as little tension as you can get away with here. turn it
right down till it slips, then up until it doesnt slip. weld for a while,
turn it down a bit if you can...
Diagnosing feed problems only needs a systematic approach, though to look at
the average tradesmen in the production environment you'd think it was a
high art. Start at the tip, then the liner, then spool tension, then roller
tension. Thats all there is to it. If you find a problem in one area, work
it out. if you still have feed problems after that, especially machine
gunning, or melting tips/clod starts or wires burning back into the tip then
you probably need to adjust your ramp up/burn back. Consistent welding
starts with having a consistent welder. Its no use trying to adjust your
gun technique to suit a welder that isnt feeding properly. Start with a
consistent way of setting up your welder, then once you've got consistent
gun technique welding is no longer a 'mystery'. If you're not getting the
results you want, then its easy to work out what you need to change.
Shaun
>I have a 120v Lincoln Weldpack MIG welder that was giving me some
> trouble today and I am a bit stumped as to the cause of the problem.
> The welder has 4 positions for voltage control and a potentiometer for
> wire speed. I am using 025 solid wire with 75/25 mix on 1/8" mild
> steel. I have been welding on this project (outdoors) for the past
> week and today I experienced a consistent problem that I can't seem to
> figure out the cause. I have been welding in globular transfer mode
> but now I seem to only be able to do a short transfer mode (at best).
> Nothing has changed, that I am aware of. But now I am getting ugly
> welds with constant balling of the electrode and sticking to the tip.
> It is as if the voltage has been lowered. I tried all my usual
> checks, gas (half tank), extension cord (the same one), settings (the
> same), dirty tip, nozzle, etc (all cleaned), dirty workpiece
> (cleaned), feed problem (nothing seems to be hindering feed), bad
> ground connection (reclamped). The vertical welds are causing the
> most problems, flat horizontal are better but still not as good as a
> day ago, or this morning. Today was the first really hot day this
> week, could this have some effect that I can't think of? thanks for
> all input, rick
>
|
| Similar Threads | Posted | | Help with a problem. | May 2, 2007, 12:08 am |
| Re: Lincoln 175 SP+ problem | September 25, 2007, 10:21 am |
| Re: Lincoln 175 SP+ problem | September 25, 2007, 7:25 pm |
| AC tig problem on aluminium | May 31, 2006, 5:40 pm |
| gas welding regulator problem,.. | March 15, 2007, 3:21 am |
| Lincoln Precision 185 problem | July 7, 2007, 9:58 pm |
| Re: Lincoln Precision 185 PC Board Problem | July 10, 2007, 4:05 am |
| Ping Ernie - Millermatic 250X wire burn-back problem | April 8, 2007, 3:46 pm |
| 3G Vertical Open Butt Weld on Mild Steel - Problem with 1/8" 7018 Uphill | April 4, 2008, 7:33 pm |
|
|
Yahoo! 
Google 
Windows Live 
del.icio.us 
digg 
Netscape 
XML Sitemap
>
> (outdoors) for the past week and today I experienced a consistent problem
> that I can't seem to figure out the cause. (clip)
> ^^^^^^^^^^^^^^^
> Could there be a little breeze?