I have a century 170 mig, works grate, I did some modes and its 2 x grate, over heating and current output. I bought it back in the 90's, now its not a pro unit but at $400 its ok. Easily welds 5/16 in. a signal pass, have welded 1/2 in. with some prep work.
Century/Lincoln Connection: Does It Matter?
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I have a century 170 mig, works grate, I did some modes and its 2 x grate, over heating and current output. I bought it back in the 90's, now its not a pro unit but at $400 its ok. Easily welds 5/16 in. a signal pass, have welded 1/2 in. with some prep work.
tater digger
New member
If you are looking for a good stick welder, try and find a used ac/dc lincoln 225 from the 70's or 80's or a miller thunderbolt. All the new lincolns and cheap welders out there have transformers wound with aluminum wire and aluminum becomes a very poor conductor when it gets hot. These welders are okay for running a few inches at a time with 6011 or 6013 rods but will have difficulty starting and maintaining an arc with 7018. If you need a good mig welder, these are usually inverter based constant voltage machines (basically a computer inside there making your welding amps and volts) you will get what you pay for in performance and in the longevity of the components inside. I would recommend looking for a used high quality model/ brand on e-bay or classifieds. There are so many of us welders out there without jobs right now, that someone is bound to be letting go of a good machine for cheap.
Hooked_on_HP
Veteran Member
Bill, right, the 170 is 220 volts; both are built on the same platform.
You say that the power supply gets hot and the welding power drops off. I am surprised that the overheat sensor did not trip. Maybe what is getting hot is not in contact with the overheat sensor. Someone mentioned that some transformers are wound with aluminum wire, that could be a problem in it self.
I take it that the fan is in good working order and that the air vents are all wide open, and air is not leaking from gaps in the cover?
When welding long seams the ground cable became uncomfortably hot. The fix was to replace the # 6 cable with a # 4 gauge welding cable.
Then I noted that the arc and bead improved, the energy lost in heating the cable is now going into the arc. Poking around under the covers I found other hot spots. The three wires coming from the transformer were connecting to the rectifier assembly by a loop around a bolt.
Now the current carrying capacity is related to the cross sectional area of the conductor, the ticker the wire the less it will heat for a given current. The wires from the transformer are adequate and are not the problem. Remember it is the area that the current flows through that matters. The surface area that the current flows through that is in contact with the wire, stud and nut is very small and represents a high resistance/ voltage drop/ energy loss.
I removed the wire loop from the stud, closed the loop back on it self, slipped a heavy copper terminal eyelet over the doubled wire and lightly crimped it in place, than I filled the void in the ferrule with solder. When assembled the transfer area the current passes through wire to solder to eyelet to stud is now larger= less loss.
Now this part is very, very tricky. I removed the rectifier assembly from the standoffs. You will notice that there are 4 spiders holding the button diodes in place on both sides of the heat sink plate. I very carefully marked the diodes with White-Out so that the orientation, which side of the button is in contact with the heat sink and which side is in the legs of the spider. It is imperative that the diodes be replaced in the same orientation, the side of the button that was in contact with the heat sink plate must be the same. If any of the diodes are reversed that would be a short circuit.
With the diodes removed from the heat sink, I polished the plate and the side of the button that contacts the heat sink plate.
Reassembling the diodes in the correct orientation I put a small drop of Heat Sink Thermal Grease on the side of the button that is in contact with the heat sink plate. The reason for the thermal grease is to improve the transfer of heat from the diode to the heat sink. The heat sink is hotter and the diodes run cooler. Reassembled everything being sure that all connections are tight and in the correct place.
The next mod may not fit your needs or may not be possible.
I added a second capacitor of the same values in parallel with the first, that increased the output current 50%. It also added to the heat stress.
Make notes and take photos to identify how you removed things and not trust your memory. If you have a meter, make note of the diode polarity, some meters have a special stop to test diodes. Make note before you disassemble the spider.
You say that the power supply gets hot and the welding power drops off. I am surprised that the overheat sensor did not trip. Maybe what is getting hot is not in contact with the overheat sensor. Someone mentioned that some transformers are wound with aluminum wire, that could be a problem in it self.
I take it that the fan is in good working order and that the air vents are all wide open, and air is not leaking from gaps in the cover?
When welding long seams the ground cable became uncomfortably hot. The fix was to replace the # 6 cable with a # 4 gauge welding cable.
Then I noted that the arc and bead improved, the energy lost in heating the cable is now going into the arc. Poking around under the covers I found other hot spots. The three wires coming from the transformer were connecting to the rectifier assembly by a loop around a bolt.
Now the current carrying capacity is related to the cross sectional area of the conductor, the ticker the wire the less it will heat for a given current. The wires from the transformer are adequate and are not the problem. Remember it is the area that the current flows through that matters. The surface area that the current flows through that is in contact with the wire, stud and nut is very small and represents a high resistance/ voltage drop/ energy loss.
I removed the wire loop from the stud, closed the loop back on it self, slipped a heavy copper terminal eyelet over the doubled wire and lightly crimped it in place, than I filled the void in the ferrule with solder. When assembled the transfer area the current passes through wire to solder to eyelet to stud is now larger= less loss.
Now this part is very, very tricky. I removed the rectifier assembly from the standoffs. You will notice that there are 4 spiders holding the button diodes in place on both sides of the heat sink plate. I very carefully marked the diodes with White-Out so that the orientation, which side of the button is in contact with the heat sink and which side is in the legs of the spider. It is imperative that the diodes be replaced in the same orientation, the side of the button that was in contact with the heat sink plate must be the same. If any of the diodes are reversed that would be a short circuit.
With the diodes removed from the heat sink, I polished the plate and the side of the button that contacts the heat sink plate.
Reassembling the diodes in the correct orientation I put a small drop of Heat Sink Thermal Grease on the side of the button that is in contact with the heat sink plate. The reason for the thermal grease is to improve the transfer of heat from the diode to the heat sink. The heat sink is hotter and the diodes run cooler. Reassembled everything being sure that all connections are tight and in the correct place.
The next mod may not fit your needs or may not be possible.
I added a second capacitor of the same values in parallel with the first, that increased the output current 50%. It also added to the heat stress.
Make notes and take photos to identify how you removed things and not trust your memory. If you have a meter, make note of the diode polarity, some meters have a special stop to test diodes. Make note before you disassemble the spider.
bobodu
Platinum Member
- Joined
- Mar 8, 2004
- Messages
- 960
- Location
- Whitley County,In.EIEIO
- Tractor
- Farmnought.Gravely Model L,Gravely Model LI,1941 Clinton two wheeler
Now if you really want dependability,100 percent duty cycle and portability for a really low price...build a DC unit!! I have less than 70 bucks in this one. 130 amp junkyard alt from a Continental.
OP
Iplayfarmer
Super Member
I've been intrigued by your home brew DC welder ever since I first saw the build thread on it. It's on the list of maybe someday.
bobodu
Platinum Member
- Joined
- Mar 8, 2004
- Messages
- 960
- Location
- Whitley County,In.EIEIO
- Tractor
- Farmnought.Gravely Model L,Gravely Model LI,1941 Clinton two wheeler
Umm....no it doesn't.
The actual voltage will vary widely depending on such things as material being welded,arc length,clean ground etc.
In the 130 amp range,it welds just as good as my big Lincoln 3-AS.
bobodu
Platinum Member
- Joined
- Mar 8, 2004
- Messages
- 960
- Location
- Whitley County,In.EIEIO
- Tractor
- Farmnought.Gravely Model L,Gravely Model LI,1941 Clinton two wheeler
Thought about that statement all day and thought I'd better add that I am NOT running the alt. in a stock configuration. That alt. DOES NOT use an internal regulator although it does have an internal diode pack. I am running full power from the battery to the rotor and added a second brush straight to the case,thus eliminating the internal rotor ground. I don't have a meter I would want to attach to the thing and make pretty smoke,so I really need to remember to ask the neighbor to bring one home from work. But I can guarantee you that it will burn 1/8" rod all day.
I vary my output with the throttle.
I vary my output with the throttle.
