I'm getting some rust off my A frame, and it's definitely the pits....because it's got rust in the pits! The cup brush is a no go...it's actually creating "rust bluing" when i try to use it. The carbide infused sponges that fit on my drill work ok, but it takes a hell of a long time and they get eat up quick when they hit corners or bolt holes. I just saw these bristle discs online that fit an angle grinder and thought "hey, this might be the ticket to get that rust off quick and out of the pits." Anyone ever used one?
Sand blast es muy expensivo in L.A. Me es muy poor-o...no has that much cash-0. I already have Ospho to use over the whole frame...figure I might as well use what I've got.
I've only used them for paint removal, I doubt they'd last long up against a rusty frame...my new trick for frame rust removal is misting the frame down with a 50/50 mix of acetone and trans fluid, let it soak for a few days and then hit it with the wire wheel on the angle grinder...it comes off quicker, makes FAR less dust and seems to give a cleaner finish than doing it dry...
You don't end up getting the black finishing on the metal using the cup brush? I can get shiny metal with the sanding sponge, but with the cup brush it just turns the rust/metal black. The metal isn't heated up, btw...its barely warm to the touch immediately after using it.
I rarely use a cup brush, I use a twisted wire straight wheel...and who cares what color the metal is once the rust is cleaned out?...what it sounds like to me is that your frame has oxidized itself into a coating similar to what anodizing is on aluminum, essentially it has gone far enough to make a hard oxidized shell over the metal...the only thing that removes that black finish is grinding and physically removing that covering layer...which would be stupid, because that metal is essentially spent and is protecting the rest of the metal below it...clean it, prep/wipe it down and put a rust preventer on it and paint it...
I've used the bristle discs. They don't act like a wire wheel, but I doubt they can get the rust out of the pits. At about 20 bucks apiece you'll also find they're expensive as hell to use because they don't last long at all on anything other than dead flat surfaces. Any edges will eat 'em up fast. The hard truth for cleaning a rust pitted frame is that there's sandblasting and then there's everything else one might try, and all those everything elses run a way distant second to sandblasting. I sandblasted a heavy equipment trailer after we rebuilt it about 20 yrs ago. Shot it with epoxy primer and just put some plain old Sherwin Williams industrial enamel over the epoxy. That trailer has had all sorts of rough use since then, in and out of construction sites, and blasted by all sorts of road debris slung up by the tires out on the road. There's not one speck of rust showing thru the paint today, even on the bottom sides of the frame rails or on the frame members around the wheel areas. Sandblasting and epoxy primer is worth the money for anything you really want to hold up over the long term. It wouldn't be hard at all to run thru $200 worth of bristle discs, and still end up with a mediocre job and lots of places you can't get the grinder to at all, and its hard for me to imagine you'd spend much more than that to have the frame blasted.
Interesting...I was wondering if that's pretty much the case. The rust wasn't particularly thick or scaled like I would think it would have been. Maybe just a low penetrating/low grade rust over a long period of time resulted in this particular situation. If I grind through the black, you'll find a fine layer of light rust beneath it.
They really dont do anything to rust. They are ok for stripping light paint off of aluminum, thats about it.
If you use the 50 grit discs they work pretty good on rusty surfaces but as said they are expensive. My friend who is retired from 3M designed and patent them. He occasionally gets me a box or two. Frames are tricky with all the curves and rivets. The outer bristles like to break off when they hit the rivets, hurts like hell when they hit you. Sandblasting is the way to go with frames.
As others have said sandblasting is the way to go on frames. I tried the grinding, small sandblaster etc and it sucked (doing it and the result) I would just keep shopping around for sandblasters and start saving your $$. It would suck to go to all that work paint it and then have the paint start bubbling a year or two later because you didn't get it all off. Try industrial sand blasting places. Its a frame so they won't damage it like sheet metal and usually they will do them for cheap while they are working on something else.
Get all that you can off , everything easily& that should be over 85% of the surface area. Take what's left to the sand blaster and have him finish it up. Should be about 1/3 the cost. Try a needle scaler, works well in the right application. Small drill bit and lots of patients will get the rust out of the pits. Anything spinning flat will only ride the high spots and not touch the pits.
Called around to a few more places. Cheapest I can find is $125. Everything else was north of $200-$300.
$125 is not that bad considering you will probably go through at least $50-$60 worth of abrasives and it still won't be as good as having it sandblasted. Time to start saving. I forgot in my last post to mention I eventually had mine blasted once I had enough money and it was worth every penny in labour and frustration compared to trying to do it myself.
I also use the 4.5 twisted wire wheels like Ruiner menioned on my Dawalt 4" grinder. Make shure you wear leather gloves because they take skin & shirt sleeve off also very fast.
I'd go get it done for $125. It will come back totally clean and rust free (assuming they know what they are doing) and ready to treat and prime. Think of the hours of labor you'll save, not to mention the wear and tear on your lungs from flinging all that rust and crud into the air for hours and hours.
They said that since the frame is partially boxed, they'll only be able to get part way into it most likely, and even then it'll be iffy. I'm taking it in tomorrow morning and should have it by lunch the next day since they're down the street as it turns out. You know, if I thought that had a chance of working, I'd do it. I hate spending money, I'm a 32 yr/old miser.
I use the 2" in a die grinder using the rol-loc setup in 80 grit. They work well for scale removal in tight spots. About 8 bucks a pop from my MAC Toolman. Never used a bigger one, but they probably could find a place in my procedures.
You need to ask them to get you the Purple Bodyman Bristle disc. It cuts like 36 grit but leaves a 80 grit scratch. PN 7536, 7537, 7540 depending on the size you want. www.3mcollision.com will get ya the details W ehave been using these on a club members model A build with good results
Having it blasted is the most cost effective way to clean the frame. If your customer can't deal with the cost of doing right, I'd be worried. You cannot manually strip the frame to the degree that blasting it will do. You need better customers.
I hate spending money, I'm a 32 yr/old miser. Not that there is anything wrong with that.... I'm taking it in tomorrow morning and should have it by lunch the next day since they're down the street as it turns out. So, how did it turn out?
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