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How To Remove Rust Without Removing Original Scrapings

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Susan_in_SF

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Hi guys,
As many of you know, I wasn't planning on buying a Bridgeport mill, but then I recently stumbled across a super deal on one. This 2J Bridgeport had been used for years at a San Jose vocational school before it ended up with the private high school that I bought the mill from. The private high school in Santa Rosa had the mill sit in an unused workshop for a year before the facilities manager was told that the students wanted to work on "new" CNC machines, and not on the old big dirty Bridgeport. To that, I still have to say, "WTF?!"

I shared the mill's history since it will explain the situation that I need help with. Also, fyi, I did try google for answers before having to turn to you wonderful guys :)

Basically, the mill is dirty and has rust on the table. It had been checked out by two separate machinists, and I was told the only thing it needed was to grease the table's leadscrews.

I will post various pics of the table below at different angles and with/without flash to show, what looks like, the original factory scrapings. For comparison, I will also post a pic of the ways behind the milling table that really show how the scrapings originally looked like. Btw, sorry if the pics aren't great - my cell phone camera kinda sucks.

So, in a nutshell, I'd like to know if it is possible to remove the rust without removing the scraping remnants on the milling table. Also, please tell me if I am being silly or not in wanting to preserve the scrapings.

Table
287464
287470
287465


Rear ways
287466

Front ways
287467

The table seems unusual by that it looks like some inattentive students milled or drilled into the table a couple of times, and it looks like they dropped stuff onto the table quite a bit, yet, there are still scraping marks present. I plan on using metal filler to repair the holes/indentions, as instructed in the recent book I bought, "A Guide to Renovating the Bridgeport "2J" Variable Speed Milling Machine."

Also, I looked up the serial number. Apparently, this $450 mill was built in 1976.

Btw, I have tried Evaporust before on tools. I just don't like how it can turn the metal black. So, could I get away with using a scotch brite pad and WD-40 instead?

I will post a pic of the entire Bridgeport inside my 1 car garage later. My friend Mike, who owns a machinery transportation company, had tilted the head before using his forklift to put the mill in my garage. The head is still tilted. After I straighten the head later today, I will take some full body shots - for those of you who appreciate machine porn ;-)

Thanks in advance for your friendly replies

Susan
 

Ecosta777

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Scotch Brite and oil or WD-40 will work. You want to retain the scraping marks since they help hold oil in the table / ways to help prevent rust. Since the scraping marks are not just 'surface scratches' (like an engine turned finish for example) the scotch brite wont remove them.
 

Firstgear

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get some Evaporust, I believe they make it in a gel as well.....works great. After letting it sit over night, use water to clean it up. Safe on skin.....works well. I am going through my taps that I bought, used, and some have rust spots on them, I put them in that overnight and then washed off the next day does a good job. Get rid of the grease and muck and if you still have rust, try this stuff. The gel stuff is what you would want, I think some people get the best results by putting on the gel and then covering with saran wrap......do some reading and you will find the best approach.
 

Bob Korves

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First, that is not scraping, it is flaking. You can tell by the deeper half moon marks. The mating surfaces are ground at the factory, and that would leave metal flat against metal, which causes stick slip and also causes galling and wear. So they flaked the surfaces. Flaking also looks nice, which is an important sale factor. In the case of the table, flaking is done ONLY to make it look nice. The table is not a way, it is a mounting surface. Flaking is much deeper than scraping, though it does still wear away with time and use. I agree with the idea of Scotchbrite and a lubricant to clean up the table. Don't get carried away with rubbing it, the areas between the flaking are the original table surfaces, less whatever wear has occurred since new. You do not want to add to the existing wear. Scotchbrite has grit in it, so make sure not to get it into other parts of the mill while working on the surface you are cleaning, so clean everything carefully after using the Scotchbrite. Scotchbrite also comes in different colors, which have coarser and finer grit. I would recommend light gray. If all you have is maroon, then go easier with it, it is more aggressive. Flaking is ideally added to the UPPER surfaces facing down, so they can hold oil for lubrication. Flat metal on flat metal does not allow that. Putting flaking on the bottom surfaces, facing upward, is strictly for making it pretty, and it causes swarf and grit to accumulate in the pockets, causing ongoing wear. "Monkey likes shiny." So keep those pockets cleaned out. Actually, do whatever you want with it, Susan, it is your machine, not ours...
 

benmychree

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Instead of Scotchbrite, you might try a medium grade of steel wool and wd40 or solvent, like paint thinner, especially on gummy oil/rust.
 

Cadillac

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Looks like a good one. You could also use a aerosol cleaner like a degreaser of sort. Spray her down and go at it. I wouldn’t use any abrasives more than a fine steel wool. The paint might not be that bad under all that goop and you don’t want to make worse if you don’t have to. I can tell you plain white vinegar will take the rust off and not effect the unlying surface.
The table doesn’t look to bruised I’ve seen some look like Swiss cheese. One or two little oopses can be fixed with some epoxy and cast iron chips or just jbweld if u wanted.
From the picture it looked like your knee has chromed ways and from the pic the end closest to operator the flaking was almost gone. Closest to the base you can see good flaking. Shows where they worked a lot.
Clean her up you be able to see a lot more about the condition. Does it have a Oiler. Happy cleaning
 

benmychree

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Another good cleaning product is Oil Eater, it's 409 on steroids; it softens paint, but when it evaporates, the paint re hardens, I use it full strength.
 

EricV

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Nice find! An old gunsmith trick for dealing with rust w/o damaging bluing or other finishes is to coat it with white petroleum jelly, (A.K.A. Vaseline), and let it sit for a day or two. The petroleum jelly softens the rust and allows it to be cleaned off w/o hard tools. Typically I will use a soft brush on a firearm when applying a second coat to work it a bit, if necessary, but you could get slightly more aggressive on the mill. As others have said, it's the table, not the way. Not as much concern, except for your desire on the finish/appeal.

Good luck!
 

danny12

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Purple power will take rust off. I like the zep brand concentrated I mix it a little hot.
 

chips&more

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With that crusty rust, sometimes a soaking with like WD40 and using a new razor blade angled. You can shave off the crusty stuff. BUT, and I mean this very cautiously, if you are not careful, you can scratch the surface. Once you get below the crusty rust it’s much easier to finish up the remaining rust. Sorry you do not like Evaporust, I do. If your parts are turning black, I think you are leaving them too long in the Evaporust. On really big surfaces/jobs. I soak paper towels in Eaporust and lay the towels over the rusted areas. “Keeping the towels wet”. And again be very careful and totally cover you project. Any area not covered or air pocket could leave a discoloration when you job is done, Also, cast iron can look awful and give the impression it’s beyond help when it has rust on it. I have been pleasantly surprised more than not and found a decent looking cast iron surface under the rust…Good Luck, Dave
 
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Glenn Brooks

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+1 on the comments about dried machine oil. Half the staining and buildup on old machines is usually dried oil.

I usually go through a three step cleaning process to clean up table surfaces and ways - first dissolve the machine oils with plain old laundry soap spot remover+- the kind you buy in a spray bottle at Safeway, then take off the rust with diesel and scrub pads, finally, wipe many times with soft rags and way oil to remove the left over grit. Sometimes I’ll wash everything down with paint thinner. Depends on what kind of residue and crud is on the machine.

I use scotch brite pads with Cheapo, $3 Safeway spot remover from the laundry soap aisle. All the new grease remover formulations that you buy in the grocery store do a wonderful job cutting dried machine oil off Milling tables and ways. Last year I cleaned up 30 years of oil, dirt, and shavings off an 18” x 72 Cinncinatti tray top lathe that had seen a lifetime of use at a Honolulu sugar mill, using this stuff. Couple of squirts with the spray bottle and all the gunk came off.

The last step is super important. Wiping down with wayoil removes fine micro grit that will eat up the surface of your Milling table when you slide work pieces and heavy vises across. Similar to running a lathe carriage back and forth on your ways. The grey streaking that comes up with a good oil wipe down is all the metallic grit embeddd in the surface that was ground off your table top. The table ain’t clean till the rag comes up clean!

Actually I do this last step every time I use a machine. Get it perfectly clean, then oil it up with fresh, clean way oil to lube the table when you start your Milling operation.

Glenn
 
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Liljoebrshooter

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I used Zep 505 on my mill when I was cleaning it up. That stuff really impressed me, and it didn't seem terribly nasty. That and some scotchbrite pads and lots of paper towels.
Another thing to check is the oiler system is working, either a one shot system or zerk style.
Joe Hynes
287494
 

Ulma Doctor

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no one has mentioned it yet so i'll throw my hat into the ring...

Phosphoric Acid is highly effective in removing rust from ferrous metal
add scotchbrite or steel wool to the equation and go to town.
wipe with water dampened rag/towel
then, oil down after treatment to prevent new rust
 

cjtoombs

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no one has mentioned it yet so i'll throw my hat into the ring...

Phosphoric Acid is highly effective in removing rust from ferrous metal
add scotchbrite or steel wool to the equation and go to town.
wipe with water dampened rag/towel
then, oil down after treatment to prevent new rust
I would add to this, use the gel version (it's available from most hardware stores, in the paint section). Get some of those elbow length rubber gloves and a face shield. It's not strong enough to burn your skin right away, but if you leave it on for more than a minute or two, it will let you know that it's a strong acid. Also, I expect getting it in your eyes would be far from fun. Good luck.
 

Susan_in_SF

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First, that is not scraping, it is flaking. You can tell by the deeper half moon marks. The mating surfaces are ground at the factory, and that would leave metal flat against metal, which causes stick slip and also causes galling and wear. So they flaked the surfaces. Flaking also looks nice, which is an important sale factor. In the case of the table, flaking is done ONLY to make it look nice. The table is not a way, it is a mounting surface. Flaking is much deeper than scraping, though it does still wear away with time and use. I agree with the idea of Scotchbrite and a lubricant to clean up the table. Don't get carried away with rubbing it, the areas between the flaking are the original table surfaces, less whatever wear has occurred since new. You do not want to add to the existing wear. Scotchbrite has grit in it, so make sure not to get it into other parts of the mill while working on the surface you are cleaning, so clean everything carefully after using the Scotchbrite. Scotchbrite also comes in different colors, which have coarser and finer grit. I would recommend light gray. If all you have is maroon, then go easier with it, it is more aggressive. Flaking is ideally added to the UPPER surfaces facing down, so they can hold oil for lubrication. Flat metal on flat metal does not allow that. Putting flaking on the bottom surfaces, facing upward, is strictly for making it pretty, and it causes swarf and grit to accumulate in the pockets, causing ongoing wear. "Monkey likes shiny." So keep those pockets cleaned out. Actually, do whatever you want with it, Susan, it is your machine, not ours...
Hi Bob,
You are always welcome to tell me what you think would work best - in metalworking anyways ;-)
I respect your opinion. It's my way of having to minumize having to learn lessons through trial and error, or the hard way.
So, thank you for educating me in scraping and flaking.
Susan
 

Susan_in_SF

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Another good cleaning product is Oil Eater, it's 409 on steroids; it softens paint, but when it evaporates, the paint re hardens, I use it full strength.
Thanks benmychree. I will look into that.
 

Susan_in_SF

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Thanks everyone. I have a lot of options to consider. I really appreciate your posts!

Susan
 

Dan_S

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For stuff like this, i use the following process.

  1. Clean the part/machine with a strong degreaser.
  2. try removing rust from the part/machine with a chemical ruse remover like evaporust, naval jelly molasses etc. You can try electrolysis if you like living dangerously. :)
  3. abrasive rust removal as a last resort
 

mikey

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Susan, if your goal is to retain the scraping marks without adding more scratches or exposing yourself to acids or other chemicals then electrolysis is a very good option. I've done my RF-31 mill table, too many tools to mention, anvils and even several whole lawnmower chassis in an electrolytic tank and can tell you that there is no removal of the parent metal this way. Unless you are brain dead and stick your hand into the solution with power on (low voltage but high amperage), this is a pretty safe way to go. There is a tiny amount of Hydrogen gas generated but hardly enough to constitute a real danger if you work outside.

You should learn to do electrolysis. Easy, very safe (in my hands at least) and one of the most effective methods of rust removal there is. Evaporust, Phosphoric Acid, Scotchbrite, steel and synthetic steel wool also works - I've used these agents, too - but to retain the parent material with the least potential for altering the surface finish, electrolysis gets my vote.
 

P. Waller

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Your goal is to preserve the appearance of hand scraped ways?

I have often wondered if there was a small market for hand scraped way decals that may be applied to machine surfaces to give the impression of hand scraping much like auto and motorcycle enthusiasts use decals to mimic carbon fibre components. I suspect that the market is far to limited for 3M to get involved in.
 

agfrvf

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Oil and a straight edge razor.
Degrease and use paper towels soaked in evaporust covered with plastic wrap
Green scotch brite and oil.
In that order.
 

Bob Korves

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Your goal is to preserve the appearance of hand scraped ways?

I have often wondered if there was a small market for hand scraped way decals that may be applied to machine surfaces to give the impression of hand scraping much like auto and motorcycle enthusiasts use decals to mimic carbon fibre components. I suspect that the market is far to limited for 3M to get involved in.
The subject at hand is not hand scraped ways, it is an oil flaked table top, done with a Biax power oil flaker.
 

Susan_in_SF

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I think I mentioned in this thread that I'd post a pic of the mill in my garage, so here it is, taking up half the garage, lol!
Things look extra crowded since I am in the middle of rearranging the machines for optimum usage/free space.
I still haven't gotten around to removing that windshield tennis ball from my "use the garage to house the car" days ;-)

Susan
287839
 

Susan_in_SF

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Susan, if your goal is to retain the scraping marks without adding more scratches or exposing yourself to acids or other chemicals then electrolysis is a very good option. I've done my RF-31 mill table, too many tools to mention, anvils and even several whole lawnmower chassis in an electrolytic tank and can tell you that there is no removal of the parent metal this way. Unless you are brain dead and stick your hand into the solution with power on (low voltage but high amperage), this is a pretty safe way to go. There is a tiny amount of Hydrogen gas generated but hardly enough to constitute a real danger if you work outside.

You should learn to do electrolysis. Easy, very safe (in my hands at least) and one of the most effective methods of rust removal there is. Evaporust, Phosphoric Acid, Scotchbrite, steel and synthetic steel wool also works - I've used these agents, too - but to retain the parent material with the least potential for altering the surface finish, electrolysis gets my vote.
I agree that electrolysis is best, but I am working by myself. 275 lbs is too much for me to handle alone
Susan
 
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