Introduction: Refreshing Your Lincoln AC-225 220V Tombstone Welder
I recently purchased a Lincoln AC-225 welder for $40 (Minus leads of course). Before I plugged it in I decided to take it apart and clean it. I will show you how you can take your old welder and make it work like a new one.
These machines have been produced for many years, and chances are you own one, why not pass it on to your kids?
I cannot state how easy this is to accomplish. Chances are if you own one of these welders you are more than proficient to dissemble its simple switch assembly and properly clean and lubricate it. In fact, the most difficult part in my opinion, is the tedium of removing the screws to access the internals.
Please, do not be afraid to attempt this.
You will need:
Tools to remove sheet metal screws, plus a phillips, and flat screwdrivers
5/16", 3/8", an 7/16" box end wrenches and sockets (One of each for each size)
Good quality grease. I used Mobile-1 Synthetic automotive grease
A Dremel tool with light abrasive polishing bit
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Step 1: Cut the Breaker, Unplug the Welder, Then Start Removing Screws.
Unplug your welder. This is a life and death step. 220VAC is very dangerous-it is dangerous because it is high current, and it GRABS you when you come into contact with it. Higher voltages such as 30kV low current are actually less dangerous, because they will REPEL you.
So make sure your tombstone welder is unplugged, because it's too early to have your own. Tombstone, that is.
There are lots of screws. Mine had an amalgamation of flathead, phillips, and hex-head screws. I am not sure if they come from the factory like this.
I did not take pictures of every step as far as screw removal goes. All I can tell you is to keep all of the screws in a container.
The front specification plate must be removed. To do this, there are 4 screws in the front, but you must also remove the selection switch handle (White arrow). To do this, simply remove the flathead screw that is in the fat portion of it. (See green arrow)
Step 2: Remove and Inspect the Selector Switch
The selector switch is held in place by 2 screws which are located behind the specification plate. You may have to bend the holding tabs to get the switch to come out however keep in mind that you WILL have to bend them back to align the screw holes. Unfortunately, I didn't end up taking picture of the screws, but it is easily understood when you get the plate off.
Once the selector is removed, take a look at it. On the front you will see a white disc with a recess on the top for a roll pin, with the shaft for the selector indicator/handle protruding from the middle.
Removing the white disc is the first step to disassembling the switch.
The white disc is serrated on the back, and mates with a raised serrated portion of the switch housing itself. This is how it "locks" into each current setting. My switch was struck quite hard at one point, and a chunk of the switch housing was broken off.
All that must be done is to press the white disc downward, and to remove the roll pin with a pair of needle-nose pliers.
Hold the assembly together until you can get all of the parts into a parts container.
Step 3: Begin Cleaning the Selector Switch
On the back of the switch you will see the white shaft has a lobe on it. A spring puts pressure on a copper contact strip which connects various windings of the transformer to the output leads.
The shaft and assembly can be pulled out the back of the switch housing. Be careful not to drop the spring, because springs love their freedom and tend to make fantastic escapes never to be seen again. There is probably a secret society of loosed springs that causes all of the earthquakes in California. I don't know. I'm just saying.
Break out your Dremel tool with the soft abrasive polishing bit. This bit is very useful for cleaning electrical connections.
Begin polishing the copper strip that the shaft goes through. Only two areas need cleaning, the contacts on each end of the strip. Notice how dirty and pitted they are! All I have is my blackberry so it doesn't do macros very well.
Dirty contacts will result in poor electrical connections. Poor electrical connections result in higher transformer heat, poorer welds requiring more current, and burned contacts. Burned contacts cause pitting and poor electrical conduction. It is a negative cycle. But we are here to fix that.
All of the current to the stick flows through these 2 small tabs. That is how important they are! But do not go overboard. If you polish it too much, you can create valleys in the tabs and reduce electrical contact. A good rule of thumb is to simply make it shine and no more.
The selector shaft in my welder was bent so I heated it up and straightened it out. I decided to try to polish the selector shaft with the Dremel-and it worked. I recommend cleaning it up as mine was very dirty.
Step 4: Now Polish the Contacts of the Switch Housingw,
Now, take a look at the back of the switch housing. You will see many copper contacts on the back. Each of these contacts is a Heat setting. (Current setting) They are very important, as is the copper tab that the copper strip rides on.
I recommend also polishing the plastic spacers between each contact. Mine were dirty, so cleaning them prevents dirt from being dragged back onto the copper contacts.
In my picture only 3 contacts are cleaned, this is to show you the contrast between a clean contact and the dirty ones. Dirt is a poor conductor.
Also note the copper contactor that needs to be polished.
Now is a good time to TIGHTEN every bolted connection in the unit. One of my connections was so loose, I realized why I got the welder for $40. It probably was useless at anything under 100 amps! How tight are your connections? Loose connections make more heat, and can cause you to believe your welder is "Worn out".
Step 5: Now, Begin Greasing Everything
Now is the time to re-assembly. I always use good synthetic grease. I used Mobile-1 full synthetic general purpose grease. It's a few dollars more than regular grease, but those dollars are always saved when a parts lasts longer because you have used a good grease. Even in something like this.
Grease the serrated portion of the white disc, the serration raised portion of the switch housing, the copper tabs on the switch housing and spacers, the copper strip on both contacts, the copper contactor on the switch housing, and the shaft itself.
To re-assemble, put the shaft through the inner (middle) hole of the copper strip, then put the spring on the plastic nub of the shaft, and thread the assembly through the switch housing.
Put the white disc on the shaft on the other side of the switch, press down, and insert the roll pin. You will have to make sure the depression on the top of the white disc is aligned with the hole in the shaft that accepts the roll pin. Slip the pin in and release pressure and your switch is refreshed.
Screw the selector switch back into its spot and briefly attach the selector lever/pointer. Go through the heat ranges and pay attention to the copper strip. It should be centered on each contact. Mine wasn't.
My tab was slightly off center, probably due to wear, probably because nobody had ever lubricated the switch. To get the copper strip centered, I have to jiggle the selector a little when I change heat settings. Yours may not be as worn as mine. But you need to know if you are making 100% contact or not.
Step 6: Take a Look at Your Power Switch.
It can use some lubrication. Mine didn't want to stay "on", which was partly an alignment issue.
I used Break-Free CLP. You can get it at Wal-Mart.
All you can really do is lube the switch up. But, this is all that was required to make mine work like new.
Click it on and off a few times and observe closely the movement and workings of the switch.
The green and black arrows indicate lubrication points, but I am sure I missed one. Look for yourself and add a few drops of oil into each spot. My switch works like new, now.
Now, replace the switch in the housing, and replace all of the sheet metal covers and screws/bolts.
Before you plug it in and enjoy your welder, do yourself a favor and go through the current ranges from least to most several times to evenly distribute the grease. I was not shy with my grease, I never am. Usually, it is OK to have too much, and not OK to have too little. This is not always the case, though.
Because your welder has been broken in, it is likely to connect better now, and switch better now, than a brand-new unit. Your welder will run cooler and might just operate more efficiently at a lower heat setting. It is worth it to take a half hour or so and give a little TLC to your old workhorse that has served you so well all these years. Even a brand new unit probably has been under lubricated with low end grease and could use some good synthetic grease. I'm a little obsessive when it comes to that, that's just me. Lubrication is the key to longevity.
Thanks for reading!