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Posted by on May 21, 2008, 6:39 pm
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> ol' bubba here wants to build a nice cheap DC welder, preferably that
> outputs "pure DC" (not rectified AC). Lincoln used to make such
> machines, essentially an AC motor driving a DC generator head. according
> to numerous sites, most (maybe all?) DC motors can be 'driven' and used
> as generator heads.
>
> I have three DC motors sitting gathering dust, and -plenty- of heavy
> angle iron for the frame. plus misc other components, like a nice
> rheostat, and the leads. might have to break down and buy a lovejoy
> coupling...
>
> take a quick look at my DC motors here:
>
> http://machines.freehostia.com/dc_motor_as_generator/
> dc_motor_as_a_generator
>
> which of the three would be my 'best bet' for this idea?
>
> sure, I'd 'like' it if it put out about 300 amps (and less, too) but
> I'll probably settle for what I can get...maybe 150 amps out?
>
> this doable?
>
> ps-please, no 'insurance adjuster' or 'fire inspector' type dire warnings
>
> thanks, guys,
>
> toolie :-)
>
> - -
> replies by e-mail, if any, please remove the weirdstuff from my address
> before you click 'send' - thanks :-)
> - -
With the big-ass magnets you can get nowadays, is a homopolar
generator feasible for a welder?
Or is the voltage too low?
Dave
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Posted by Ignoramus12247 on May 21, 2008, 7:43 pm
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People who do this, usually use 28v tour bus alternators.
You can buy them on ebay for not too much. Sell your motor so that
soneone else will keep it in their garage.
i
> ol' bubba here wants to build a nice cheap DC welder, preferably that
> outputs "pure DC" (not rectified AC). Lincoln used to make such
> machines, essentially an AC motor driving a DC generator head. according
> to numerous sites, most (maybe all?) DC motors can be 'driven' and used
> as generator heads.
>
> I have three DC motors sitting gathering dust, and -plenty- of heavy
> angle iron for the frame. plus misc other components, like a nice
> rheostat, and the leads. might have to break down and buy a lovejoy
> coupling...
>
> take a quick look at my DC motors here:
>
> http://machines.freehostia.com/dc_motor_as_generator/
> dc_motor_as_a_generator
>
> which of the three would be my 'best bet' for this idea?
>
> sure, I'd 'like' it if it put out about 300 amps (and less, too) but
> I'll probably settle for what I can get...maybe 150 amps out?
>
> this doable?
>
> ps-please, no 'insurance adjuster' or 'fire inspector' type dire warnings
>
> thanks, guys,
>
> toolie :-)
>
> - -
> replies by e-mail, if any, please remove the weirdstuff from my address
> before you click 'send' - thanks :-)
> - -
--
Due to extreme spam originating from Google Groups, and their inattention
to spammers, I and many others block all articles originating
from Google Groups. If you want your postings to be seen by
more readers you will need to find a different means of
posting on Usenet.
http://improve-usenet.org/
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Posted by on May 21, 2008, 10:05 pm
Please log in for more thread options On Wed, 21 May 2008 18:43:12 -0500, Ignoramus12247
>People who do this, usually use 28v tour bus alternators.
>
>You can buy them on ebay for not too much. Sell your motor so that
>soneone else will keep it in their garage.
>
None of the motors are suitable, as you could only get about 6-10 amps
out of any of them, and the voltage would be way too high. You need
closer to 35 volts than 110 to weld.
If you want to build one, you need an old fork-lift motor, an aircraft
starter generator, or a heavy duty bus/truck alternator. An alternator
will give you "rectified AC" at a higher frequency (ripple) than you
would get from a line powered transformer type DC welder. A Permanent
magnet motor gives no voltage/current control. A series motor CAN be
rewired to make it useable and controlable, but something with a shunt
field (either shunt or compound wound) can be accurately controlled.
As can the alternator.
>i
>
>> ol' bubba here wants to build a nice cheap DC welder, preferably that
>> outputs "pure DC" (not rectified AC). Lincoln used to make such
>> machines, essentially an AC motor driving a DC generator head. according
>> to numerous sites, most (maybe all?) DC motors can be 'driven' and used
>> as generator heads.
>>
>> I have three DC motors sitting gathering dust, and -plenty- of heavy
>> angle iron for the frame. plus misc other components, like a nice
>> rheostat, and the leads. might have to break down and buy a lovejoy
>> coupling...
>>
>> take a quick look at my DC motors here:
>>
>> http://machines.freehostia.com/dc_motor_as_generator/
>> dc_motor_as_a_generator
>>
>> which of the three would be my 'best bet' for this idea?
>>
>> sure, I'd 'like' it if it put out about 300 amps (and less, too) but
>> I'll probably settle for what I can get...maybe 150 amps out?
>>
>> this doable?
>>
>> ps-please, no 'insurance adjuster' or 'fire inspector' type dire warnings
>>
>> thanks, guys,
>>
>> toolie :-)
>>
>> - -
>> replies by e-mail, if any, please remove the weirdstuff from my address
>> before you click 'send' - thanks :-)
>> - -
** Posted from http://www.teranews.com **
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Posted by Ignoramus14615 on May 22, 2008, 9:33 am
Please log in for more thread options On 2008-05-22, clare at snyder dot ontario dot canada <clare> wrote:
> On Wed, 21 May 2008 18:43:12 -0500, Ignoramus12247
>
>>People who do this, usually use 28v tour bus alternators.
>>
>>You can buy them on ebay for not too much. Sell your motor so that
>>soneone else will keep it in their garage.
>>
>
> None of the motors are suitable, as you could only get about 6-10 amps
> out of any of them, and the voltage would be way too high. You need
> closer to 35 volts than 110 to weld.
> If you want to build one, you need an old fork-lift motor, an aircraft
> starter generator, or a heavy duty bus/truck alternator. An alternator
> will give you "rectified AC" at a higher frequency (ripple) than you
> would get from a line powered transformer type DC welder. A Permanent
> magnet motor gives no voltage/current control. A series motor CAN be
> rewired to make it useable and controlable, but something with a shunt
> field (either shunt or compound wound) can be accurately controlled.
> As can the alternator.
The OP could keep an eye on ebay for a used Leece-Neville 28v 200+ amp
alternator. That should work very well. It should cost about $150 plus
some shipping.
If you start with a good alternator, at least you will end up with a
expensive (due to labor factored in) and inconvenient, but powerful
welder.
I really do not see a good reason to use anything less powerful, to
only end up with an expensive and inconvenient crappy welder.
i
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Posted by Bruce in Bangkok on May 21, 2008, 8:09 pm
Please log in for more thread options wrote:
>ol' bubba here wants to build a nice cheap DC welder, preferably that
>outputs "pure DC" (not rectified AC). Lincoln used to make such
>machines, essentially an AC motor driving a DC generator head. according
>to numerous sites, most (maybe all?) DC motors can be 'driven' and used
>as generator heads.
>
>I have three DC motors sitting gathering dust, and -plenty- of heavy
>angle iron for the frame. plus misc other components, like a nice
>rheostat, and the leads. might have to break down and buy a lovejoy
>coupling...
>
>take a quick look at my DC motors here:
>
>http://machines.freehostia.com/dc_motor_as_generator/
>dc_motor_as_a_generator
>
>which of the three would be my 'best bet' for this idea?
>
>sure, I'd 'like' it if it put out about 300 amps (and less, too) but
>I'll probably settle for what I can get...maybe 150 amps out?
>
>this doable?
>
>ps-please, no 'insurance adjuster' or 'fire inspector' type dire warnings
>
>thanks, guys,
>
>toolie :-)
>
>- -
>replies by e-mail, if any, please remove the weirdstuff from my address
>before you click 'send' - thanks :-)
>- -
First of all it is do'able. Popular Mechanics had a long article,
years ago, about building a welding machine using a surplus aircraft
DC generator. I have also seen an article on the web about doing the
same thing - unfortunately I can't find the URL. Try googling various
combination of welder, generator, home made, etc., and I'm sure you
can find it.
The only problem is that you need a low voltage, high amperage
generator, say 24 volts @ 300 amps.
Bruce-in-Bangkok
(correct Address is bpaige125atgmaildotcom)
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> outputs "pure DC" (not rectified AC). Lincoln used to make such
> machines, essentially an AC motor driving a DC generator head. according
> to numerous sites, most (maybe all?) DC motors can be 'driven' and used
> as generator heads.
>
> I have three DC motors sitting gathering dust, and -plenty- of heavy
> angle iron for the frame. plus misc other components, like a nice
> rheostat, and the leads. might have to break down and buy a lovejoy
> coupling...
>
> take a quick look at my DC motors here:
>
> http://machines.freehostia.com/dc_motor_as_generator/
> dc_motor_as_a_generator
>
> which of the three would be my 'best bet' for this idea?
>
> sure, I'd 'like' it if it put out about 300 amps (and less, too) but
> I'll probably settle for what I can get...maybe 150 amps out?
>
> this doable?
>
> ps-please, no 'insurance adjuster' or 'fire inspector' type dire warnings
>
> thanks, guys,
>
> toolie :-)
>
> - -
> replies by e-mail, if any, please remove the weirdstuff from my address
> before you click 'send' - thanks :-)
> - -