# Home built spool gun for 120V wire feed



## iron man (Jan 13, 2015)

Well I did not really need it I would not go out and buy one but I always wanted to build a small version of a spool gun similar to the one I had to use when I worked in a machine shop something that I could hook up to a 120V wirefeed or a pair of car batteries. I am sorry I did not do a picture by picture on how I made it I just thought I would post this I just got done with it and some testing everything appears correct good isolation of parts, steady motor speed and drives the wire through the liner perfectly, the liner is teflon.

The motor is an army surplus motor it started its life from the directional stabs on an ICM missile I have a few of these motors and love there small size and power. I made every part on this with the exception of the motor and a few screws I did make the off set gearbox for the motor however so the handle would be centered I made the gear box out of aluminum and the gears are about a 1/2 in dia. It balances out real well and is small for tight spaces. You can imagine the small size of the gun because the wire spool is 4" in dia.


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## iron man (Jan 13, 2015)

here is the interior guts of the unit the drive roller is hardened drill rod with the right size groove cut for the wire,, here you can see the amount of off set I needed for the drive roller. The pinch roller is a small bearing and the housing for it is ABS plastic the motor is also isolated from the frame so there is no arcing in case contact is lost at the tip. To the right of the photo is a spring loaded paddle to provide a brake so the spool of wire does not unwind itself. The spring was made from an old bandsaw blade tough crap to work with but good spring reaction.


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## iron man (Jan 13, 2015)

Here is the pinch roller assembly in place ready to go. With this little gun I can weld steel, stainless steel, aluminum, silicon bronze, and magnesium. All of the red parts are lexan plastic to isolate them from the voltage. I painted the lexan because all I had on hand was white I thought red would look better.


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## iron man (Jan 13, 2015)

Here is the gas nozzle it is made from a 5/8 copper water pipe I made an attachment on my lathe to roll the end. the insulator is teflon the gas chamber has a finned aluminum shell for cooling the inside is brass, the push button is a micro switch and the handle is a part of a flashlight reshaped with a heavy duty heat shrink over the top. Well thats it I have to play with it some more all the cables detach off the back side behind where the handle is makes it nice when you want to put it away.  Thanks for lookin Ray


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## jpfabricator (Jan 13, 2015)

Pretty slick I M! Please keep us updated on how it welds. 

Jake Parker

PS: Where could one find the drive motor you used?


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## iron man (Jan 14, 2015)

jpfabricator said:


> Pretty slick I M! Please keep us updated on how it welds.
> 
> Jake Parker
> 
> PS: Where could one find the drive motor you used?



 This motor is very similar to the one I have there are some sold under the airco name back when airco was using them the motor was over $400. the shaft on this one is 5/16 mine is 1/4 other than that its about the same motor super amount of torque all steel gears all ball bearing. I also used one of these to power my milling machine feed. If you look around you can sometimes buy them for about $15 used.. Ray

http://www.ebay.com/itm/TRW-GLOBE-D...547?pt=LH_DefaultDomain_0&hash=item3c9e45c20b


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## iron man (Jan 14, 2015)

I think this one would work also. http://www.ebay.com/itm/TRW-GLOBE-M...682?pt=LH_DefaultDomain_0&hash=item3c9db6f7e2


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## RandyM (Jan 14, 2015)

WOW! Very Cool! Well done. Thank you for sharing.


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## outsider347 (Jan 14, 2015)

iron man said:


> This motor is very similar to the one I have there are some sold under the airco name back when airco was using them the motor was over $400. the shaft on this one is 5/16 mine is 1/4 other than that its about the same motor super amount of torque all steel gears all ball bearing. I also used one of these to power my milling machine feed. If you look around you can sometimes buy them for about $15 used.. Ray
> 
> http://www.ebay.com/itm/TRW-GLOBE-D...547?pt=LH_DefaultDomain_0&hash=item3c9e45c20b



I need to build a PF for my mill and wondering what else I need ( electrics wise) to do the build
tks
ed


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## iron man (Jan 14, 2015)

I used this type of motor on my GO727 mill you will need this and a 24 volt transformer rectified to DC.

http://www.bakatronics.com/shop/item.aspx?itemid=444

http://www.hobby-machinist.com/showthread.php/11921-grizzly-G0727-Mill-home-built-power-feed

 Or instead of a transformer one of these puts out a clean DC.

http://www.ebay.com/itm/NEW-24-Volt...132?pt=LH_DefaultDomain_0&hash=item27b8fd9174

http://www.skycraftsurplus.com/electromedicalpowersupply24vac333a.aspx


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## outsider347 (Jan 14, 2015)

so this PWM
http://www.bakatronics.com/shop/item.aspx?itemid=444

is what will control the motor RPM... correct?

Thanks very for your help here
ed


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## iron man (Jan 14, 2015)

outsider347 said:


> so this PWM
> http://www.bakatronics.com/shop/item.aspx?itemid=444
> 
> is what will control the motor RPM... correct?
> ...



 Yes that is a nice little controller for that motor it will do 12to24 volts and the components can be replaced from radio shack. Ray


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## outsider347 (Jan 14, 2015)

Thanks I.M.

Just bought the parts
ed


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## iron man (Jan 14, 2015)

RandyM said:


> WOW! Very Cool! Well done. Thank you for sharing.



 Thanks Randy I dont think there is much interest in welding on this forum. Ray


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## RandyM (Jan 15, 2015)

iron man said:


> Thanks Randy I dont think there is much interest in welding on this forum. Ray



You noticed that too, Ray. Doesn't really make a lot of sense, at least to me.


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## Terrywerm (Jan 15, 2015)

Wonderful project, Ray.  Thanks for posting it!  

As for the interest in welding, it seems to go in streaks here, but I am also surprised at the low attention level in that area. I suspect that the biggest reason for lack of activity in that area is because the primary focus of this forum is on machining. But, let's face it, welding is a big part of many projects, so we definitely need to provide an area for it like we do.


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## iron man (Jan 15, 2015)

terrywerm said:


> Wonderful project, Ray.  Thanks for posting it!
> 
> As for the interest in welding, it seems to go in streaks here, but I am also surprised at the low attention level in that area. I suspect that the biggest reason for lack of activity in that area is because the primary focus of this forum is on machining. But, let's face it, welding is a big part of many projects, so we definitely need to provide an area for it like we do.




 I agree I cannot build anything without some form of welding you can save a lot of time fabricating something and machining it rather that starting from a solid block.  I thought this would be interesting article because it is compact will weld a varity of metals and will work on small home welders. Ray


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## jpfabricator (Jan 15, 2015)

Could a ac/dc "buzz box" be used for the transformer (read power supply) on somthing like this? Just a left field question.

Jake Parker


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## joconnor (Jan 15, 2015)

Hi Jake
No. You would need some type of constant voltage power supply that allows the current to float. The current will rise with an increase wire speed. The buzz box is a constant current design and the voltage floats. You will need something that is adjustable from about 15 to 25 volts DC.


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## iron man (Jan 15, 2015)

joconnor said:


> Hi Jake
> No. You would need some type of constant voltage power supply that allows the current to float. The current will rise with an increase wire speed. The buzz box is a constant current design and the voltage floats. You will need something that is adjustable from about 15 to 25 volts DC.



 I would not disagree with this but I did find one fella that tried it on steel and he claimed it worked but I did not see the weld and I would not make any bets on it. But I did see one run off of a couple car batteries and it did work pretty good. Ray


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## uncle harry (Jan 16, 2015)

iron man said:


> View attachment 92458
> 
> 
> Here is the gas nozzle it is made from a 5/8 copper water pipe I made an attachment on my lathe to roll the end. the insulator is teflon the gas chamber has a finned aluminum shell for cooling the inside is brass, the push button is a micro switch and the handle is a part of a flashlight reshaped with a heavy duty heat shrink over the top. Well thats it I have to play with it some more all the cables detach off the back side behind where the handle is makes it nice when you want to put it away.  Thanks for lookin Ray



As a degreed industrial designer I feel fully qualified to complement you & your design skills. You have combined aesthetics, functionality and simple elegance in your design.

Your description of the gun is succinct and clearly describes it's function & how you went about making it happen. It would not be difficult for many members on this forum to replicate this from your photographs & description. Gold stars on this one!


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## iron man (Jan 16, 2015)

uncle harry said:


> As a degreed industrial designer I feel fully qualified to complement you & your design skills. You have combined aesthetics, functionality and simple elegance in your design.
> 
> Your description of the gun is succinct and clearly describes it's function & how you went about making it happen. It would not be difficult for many members on this forum to replicate this from your photographs & description. Gold stars on this one!



 Big Thanks Uncle Harry..!!!


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## iron man (Jan 28, 2015)

A little update I connected to an older 120V wire feed that was given to me. It did not have a gas valve and the tip stayed hot all the time I did not like either so I installed a 24v gas valve and I also installed a heavy duty starter solenoid from a ford truck. Now when I pull the trigger the gas comes on the solenoid slams shut and you have power to the tip. The starter relay can take more amps than this welder will ever produce and it was something I had on hand. Now I can start welding with this Gun.. Ray


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## iron man (Jan 30, 2015)

Well I welded with this spool gun for the first time tonight the gun works like a dream the welder I have is a little punk on power however I will have to find another.


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## iron man (Feb 1, 2015)

For the very few that are following this I use to have a airco mini pro 125 120V wire feed I purchased 30 years ago. I sold it ten years ago and now I got it back but not in the same condition. I am restoring it and I will use it as a power supply for this spool gun. It was a real well built welder better than anything put out today just a little obsolete as long as the transformers dont go bad i should be able to repair any other part on it. Ray


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## Billh50 (Feb 1, 2015)

any chance on getting prints for your spool gun?


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## iron man (Feb 1, 2015)

Billh50 said:


> any chance on getting prints for your spool gun?



 After I built this one a friend of mine asked me to build him one for tight places he owns a machine shop but no one builds a small unit. I could take pictures on the next one as the assembly goes if that will help. As far as prints even though i took drafting years ago I probably could not make a very good print for you I just make this stuff up as I go. Ray


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## Billh50 (Feb 1, 2015)

Even sketches with some dimensions along with photo's will do. I can make up actual prints for you from sketches if you like. Being on disability I have plenty of time to make prints. I can even put them in pdf.


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## iron man (Feb 1, 2015)

Billh50 said:


> Even sketches with some dimensions along with photo's will do. I can make up actual prints for you from sketches if you like. Being on disability I have plenty of time to make prints. I can even put them in pdf.



 I may just take you up on that.. Thanks Ray


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## Billh50 (Feb 1, 2015)

I never say anything I don't mean. So anytime you want, just let me know.


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## jpfabricator (Feb 1, 2015)

Put me on the list for prints!!! If you do another build PLEASE post some pictures and steps.

Jake Parker


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## iron man (Feb 2, 2015)

Billh50 said:


> I never say anything I don't mean. So anytime you want, just let me know.



 Will do bill I will let you know when I get started again.


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## outsider347 (Feb 2, 2015)

subscribed

tks
ed


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## aametalmaster (Feb 2, 2015)

Nice build. I have 2 spool guns and i would be lost without them. My dad bought his first in 1967 and i still have it...Bob


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## iron man (Feb 2, 2015)

aametalmaster said:


> Nice build. I have 2 spool guns and i would be lost without them. My dad bought his first in 1967 and i still have it...Bob



 Thanks they really save on wire the small dia. wire on these small machines gets caught in the liner really easy and aluminum I have managed to run through a regular gun does not work well either. Ray


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## iron man (Mar 12, 2015)

I have now made a seperate power supply and PWM board for this spool gun I had to increase the wire spped and the 120 volt welders use the welding supply power for the motor  as well. So if you turn down the amps you also loose motor speed.  I now have a seperate power supply and I now have the speed control on the gun, I tried it on aluminum this weekend and I had more than enough power to weld aluminum I had to turn it down a bit I was burning through an 1/8 test piece. Ray


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## Franko (Mar 12, 2015)

That's a very cool gizmo you made, Ray. Nice work!


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## barnett (Mar 13, 2015)

Very nice !!! Sign me up for prints too


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## ericc (Mar 15, 2015)

I have a friend who used a teflon liner and was unable to get enough power with a 120V Lincoln MIG.  Does the spool gun have any advantage that helps it work better?


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## iron man (Mar 15, 2015)

I cannot speak for the newer lincoln MIG I know the first one they put out I welded aluminum with it quite a bit from what I understand from the new 120V Lincoln MIG it is not near as health as the old ones.. The old Airco unit I have has more than enough power to spray transfer aluminum. It seems the newer ones are very punk on power but are much lighter to carry around.  There are a couple things to consider though my welder has full size drive motor that draws at least 10 10 15 amps the spool gun only draws 3/4 of and amp and since they use the welding power to drive the motor you are dumping 10 to 15 amps back into the machine. Another thing to consider is your friend probably had to use 0.35 wire or bigger to feed through the liner?? That maybe to big on such a small machine with this I can burn 0.23 to 0.35 a smaller wire make a huge differance.. Ray


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