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Posted by Private on April 27, 2008, 1:24 pm
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>> In article
>>
>>
>>
>> > I have a Dynasty 200 inverter machine. It has a "dig" control. I
>> > have yet to read a simple explanation as to what this does.
>>
>> > It is only relevant to the stick process.
>>
>> > From my manual: "When set at 0, short-circuit amperage at low arc
>> > voltage is the same as normal welding amperage. When setting is
>> > increased, short-circuit amperage at low arc voltage increases."
>>
>> > Could someone please translate?
>>
>> > Does it come into play only while starting the arc?
>>
>> > --zeb
>>
>> Dig Control is Miller's name for adjusting the Open Circuit Voltage of
>> the welding arc.
>> TheOCVis what determines how effective your welding arc is.
>> Industrial welding machines have a highOCV.
>> Hobby machines have a lowerOCV.
>>
>> This is why some rods don't work on hobby welding machines.
>> 6010 is the best example, because it demands a highOCVto work right.
>>
>> Increasing the DIG control actually lowers theOCV.
>> This can help with rods like 6013 or 7014 by making the arc a bit
>> softer and smoother.
>>
>> 7018 and 6010 like things a bit hotter.
>>
>> It is one of those things I tell novice welders to just forget is there
>> until their welding is consistent enough that they will be able to
>> appreciate what it does.
>
> Thanks for the response Ernie, but reason I'm confused is that OCV is
> the potential
> before an current is flowing. So the dig setting should only help you
> when you're starting
> the arc. Correct? But then, why do they call it "dig"? That
> term makes me think
> of getting better penetration during the weld.
I definetely agree with EL's suggestion
>> It is one of those things I tell novice welders to just forget is there
>> until their welding is consistent enough that they will be able to
>> appreciate what it does.
I am not very familiar with your inverter, but all drooping power sources
are very responsive to operator technique and arc length. When working
around experienced hands you will notice they do not spend much time
adjusting their machines as they just vary their technique to compensate for
changing work requirements. Modern software driven equipment provides a lot
of capability to fine tune the output characteristics but adjustments (in
arc volt /amp slope or anything else) are not intended to compensate for
poor or inconsistent technique.
There was a similar question recently in the thread subject 'what is "did"
control? my reply follows. It is more descriptive of slope adjustment using
a dual dial generator but similar CC slope variation can be obtained by
using different taps (or ranges) in transformer machines or by varying the
slope with software in modern inverter (or generator) types. It is software
control that enables modern generators (and transformers) to deliver CC
(constant current / or drooping, for stick) or CC-HF (high frequency for
TIG) or CV (constant voltage / for MIG) outputs.
> In my downloaded Lincoln DC welder manual, they refer to the welding
> current controls in terms I am not sure of. They say when you want a
> "buttering" arc, to set the main current step dial, then use the fine
> current at the lower settings. It says 6010 is what you want a
> "buttering" arc for.
>
> Then it says if you want a "digging" arc to do the opposite, to set the
> main current lower, then adjust the fine current to the upper settings on
> its dial.
>
> I have not heard of these terms before. The 6010 was specifically cited
> in the paragraph on buttering, but no rod was mentioned in the "digging"
> paragraph. Would the "digging" setting be for 7018 or heavy iron powder
> coating rods?
>
> I have welded for a long time, but have lost information on my grey matter
> hard drive here and there along the way. I'm having to relearn some of
> this. And then, anything you don't do for a while, you get rusty.
>
> Thanks.
>
> Steve
What is the URL of the manual you downloaded?
Your questions raise the issue of semantics as these terms are often used in
contradiction to expected usage and are also subject to varied definition
and usage. Here is some information you may find helpful, note that I make
no claim to be an electrical engineer.
Google 'drooping volt amp curve'
http://www.google.ca/search?hl=en&q=drooping+volt+amp+curve&meta=
http://www.millerwelds.com/education/articles/article108.html
http://www.welding.com/welding_terms.shtml
http://newsgroups.derkeiler.com/Archive/Sci/sci.engr.joining.welding/2006-07/msg00137.html
or Google groups
CC welding generators have a drooping volt amp curve. This means that the
voltage will vary between >60 volts OCV (open circuit volts) when not
welding, ~ 40 volts when welding and <10 volts when short circuited. The
amps will also vary with arc length, the amps will be lowest with a long arc
and highest with a short arc or short circuit.
Most motor generators have ~five (or six) sets of winding configurations (or
ranges) which are selected using the left step control dial. The right dial
is a rheostat which IIRC controls the exciter voltage and thereby the amount
of OCV and power generated in each range. If you are looking for 125 amps
you can probably get it with a low left range and a high right setting, or
with the next higher left range and a middle right setting, or the next
higher left range and a very low right dial setting. Each combination will
result in a different slope for the drooping volt amp curve and will result
in different arc characteristics as the operator varies the arc length. As
a skilful operator whips the arc of a 6010 they are lowering the amps as the
arc lengthens which allows the puddle to freeze, then shortening the arc to
raise the amps and the electrode burnoff rate as they get back into the
puddle. This technique is easier when using a flat VA slope (low OCV &
right dial) as there will be relatively more change in amperage with change
of arc length. (see figure 10-3 in following link) The combination with a
high right setting will result in a forceful or digging arc that will
increase penetration, it will also give a steep VA slope and a smaller
variation of current as the arc length is varied. The combination with a
low right dial setting will result in a soft arc that will be quieter and
less forceful. Many welders like to use a low left / high right setting for
large electrodes and welding flat fillets and a higher left / lower right
for welding vertical or overhead. A very high right dial setting will allow
6010 electrodes to be very forceful with high penetration and are sometimes
used for 'quick and (very) dirty' cutting.
Here is a link to the Army welding manual TC 9-237 (caution it is a funky
site and the pages are very slow loading, wait until done before attempting
to page down)
http://www.fortunecity.com/village/lind/247/index_WELD.htm
I suggest you read section 10-2 especially the para(2) dealing with dual
control machines, and study figure 10-3..
http://www.fortunecity.com/village/lind/247/weld_book/Ch10.htm
Get a good demo and practice lots. Good luck, YMMV
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> have yet to read a simple explanation as to what this does.
>
> It is only relevant to the stick process.
>
> From my manual: "When set at 0, short-circuit amperage at low arc
> voltage is the same as normal welding amperage. When setting is
> increased, short-circuit amperage at low arc voltage increases."
>
> Could someone please translate?
>
> Does it come into play only while starting the arc?
>
>
> --zeb