rewdownunder
spending too much on rocks
Member since March 2012
Posts: 357
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Post by rewdownunder on Aug 1, 2021 18:01:34 GMT -5
Just was given a Covington 8” combo grinder early 1960s that was left outside for several years10-15?. Looks like it is all there but covered in rock snot and some rust. Tried to clean it up with a 2700 PSI water blaster and that coating of rock dust will not come off. Tried an angle grinder with a wire brush but that takes the paint off also. Is this going to need sandblasting and repainting or is there a trick to clean it up. The person who had it said he never used oil in the saw only so I am just dealing with many years of rock dust and water but the coating is up 1/4 inch thick in places. The arbor & saw turn free but the motor is so full of dirt I do not want to plug it in. I think I can free up the bolts with PT blaster but I have to get the coating off to even get at them. Anyone done this before ?
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Post by perkins17 on Aug 1, 2021 19:33:59 GMT -5
rewdownunder try steel wool maybe. It might take the paint off as well but I would probably repaint it anyways because the rust might flake off and make a mess. As a less abrasive method maybe try barkeeper's friend or the Mr metal liquid. Those might only work if there is no paint though. Mr metal is for bare metal and barkeeper's friend is very labor intensive.
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rewdownunder
spending too much on rocks
Member since March 2012
Posts: 357
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Post by rewdownunder on Aug 1, 2021 21:30:41 GMT -5
The rust is easy to deal with as 90% of the machine is an Aluminum casting. The rock snot is like cement only acid has no effect. If I going to have to repaint it I will have it media blasted but I need to get to the bolts to get it apart to see if it is worth saving. Maybe I will put a diamond belt on my belt sander and see if that will remove it.
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,352
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Post by quartz on Aug 1, 2021 23:01:37 GMT -5
We bought a machine that had set inside and dirty for about 30 years. I soaked it with straight Simple Green, took some time but the sludge came loose, so did most of the paint.
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rewdownunder
spending too much on rocks
Member since March 2012
Posts: 357
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Post by rewdownunder on Aug 1, 2021 23:59:06 GMT -5
Thank you very much. I will give that a try. Just right out of the bottle no water. I have a gallon of that somewhere in the garage. Will report back how it works. The inside of the saw is real bad and I can not get power tools down in there. I love the fact that someone somewhere has solved a problem. What did we do before the internet. I have cleaned several saws before and a little scrap up the hard sediment and power wash it clean.
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,352
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Post by quartz on Aug 2, 2021 23:01:15 GMT -5
Yup, I put the Simple Green in straight and kept painting it up on places it couldn't puddle. It took about 6 weeks but the gunk loosened up quite well. When we bought it the gunk was like concrete, wouldn't chip with a chisel.
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rewdownunder
spending too much on rocks
Member since March 2012
Posts: 357
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Post by rewdownunder on Aug 3, 2021 0:20:34 GMT -5
"gunk was like concrete, wouldn't chip with a chisel" Sounds like what I am dealing with. I have lots of time so I am going to just let in soak The reservoir on the saw is the worst but I can plug the drains and just fill it up. Thanks again for the tip.
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