Cleaning rust off of cast iron tops - Jack's angle grinder method fail

[Brian W Evans]

So I felt extra motivated this afternoon and decided to clean all of my tops. The summer was extremely hot and humid for my area and I had surface rust on several machines. I tried the method from the video below, which involves putting an abrasive pad under a wire cup attached to an angle grinder. I had no success with it.

https://youtu.be/-uMrVusnaEg

I tried this once or twice before but have never been successful. I have tried two different wire cups and a few different abrasive pads but, each time, the wire cup cuts through the pad. This happens very quickly. Has anyone here been able to do this? Any thoughts about why I can't make it work?

Not wanting to waste my motivation, I put the abrasive pad under an old POS ROS. This worked fairly well but was much slower. It also removed the hooks from the bottom of the sander. Do not try this if you ever want to attach sandpaper again.

[Cary Falk]

I have had zero luck with that method as well. I put a scotch brite on my Porter cable right angel hook an loop buffer/polisher. It doesn't really stick to the hook and loop but it stays in place fairly well.

[Dan Friedrichs]

I've also not gotten it to work. I find the pad goes flying.

I "sacrificed" a hook+loop pad on my Rotex for this task (as you say, Brian, it wrecks the hooks). But then I bought a box of Festool Vlies pads (green scotchbrite with hook+loop compatible backing). So there is a ~$700 solution available, if you were curious :)

[Nick Shattuck]

Yep, a scotch brite pad under a cheap cordless detail sander + WD40 has been my go to after trying just about every other method seen online.

[Peter Quinn]

Could probably attach a scotch bright to a 1/4 sheet square sander and have at it. Or hot melt glue a scotch bright to a spent hook and loop pad, that I've done.

[Tom M King]

It works for me with a 15 amp side grinder, and a twisted wire cup wheel. That's what stays on that grinder, so that's what I've been using, without bothering to put a cupped wheel on a small grinder. I don't bother to cut the Scotchbrite pad into a circle though. I just use the whole rectangular pad, and don't worry about the corners spinning out past the circle. Maybe you're pushing down too hard, or not hard enough to keep the pad on, but not destroy it. It's really fast with that big grinder.

Those of us who produce work for a living, and use tools all day, every day, do so many little things without thinking about it, that I can see why Jack wouldn't have said anything about the amount of pressure being important.

[Matt Day]

I’ve been using Jack’s method for years with great results. It’s my go to.

First thing to do is razor blade scrape the top. Rust causes a lot of friction and makes it harder to keep the pad on.

To keep the pad on you need to apply constant pressure. Simple as that. Once a pad starts getting torn up, I leave it on and slap another one on. Again, constant pressure and it stays on. Sometimes it will catch an edge and it flies across the room so fast it’s a scavenger hunt to find it. But no big deal.

I’d like to see pics of the setups you guys tried where it didn’t work. Because it’s either the setup or the technique.

[Warren Lake]

works very well but only on Wakin Machines :) burgandy scotchbrite I cut them to size just barely enough think six per piece if I remember correctly four for sure. Even done it on round bit its more difficult. Ticks me off to see the last stuff I did starting to rust again. Neil was right.

[Bill Dufour]

I have a piece of seat leather that I use in a square sander with car polishing compound. I find a ROS and 400-600 grit paper is the easiest.
Make it easy on yourself and thin the floor wax with thinner to a slushy paste. Much less rubbing needed to get full coverage down in the rust pits.
Bil lD.

[John Sincerbeaux]

Jack’s method used on both my old iron machines.
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[Warren Lake]

agree with John that it works well, even on non wadkin. its interesting to see how some machines simply do not rust the same even in the same space. nice machines and shop there John


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[Matt Day]

John that is a sweeeet sander. I’d love to have one at some point. Nice work.

[Brian W Evans]

OK, well, I believe it can be done since several of you have said you do it and there is clearly video evidence. I've got another CI surface that needs cleaning so I'll try it again and take pictures of my setup. Maybe I'll make it work this time.

Thanks for the responses.

[Warren Lake]

I forgot to mention often ill use a riazor blade first, likely Jack recommended that, some rust is sharper and stronger than my sample there and doing the razor first scraping it the burgandy will go further.

[Matt Day]

Definitely give it another try. Remember you need to keep the constant pressure. Apply pressure, turn on. If you let up you’ll have a scotch brite projectile to find. You’ll get the feel for it.

[Cary Falk]

I’d like to see pics of the setups you guys tried where it didn’t work. Because it’s either the setup or the technique.

No picture but here is my issue. The pressure you need to keep the pad on the wire cup presses the wire cup through the pad. The wires scratch the cast iron. If I wanted that then I would just use a wire brush. An angle grinder is just too fast. I prefer the variable speed of my Porter Cable buffer/polisher.

[Warren Lake]

more thoughts. Brian are you using Burgandy 3M? thats the only one i use, tried others didnt work well, also my makita has a speed control and I have it turned down low, likely 1 or 2 its all I need and I likely dont use much pressure for the most part, Lower RPM works better from the burgandy staying and cuts better.

[Tom M King]

You have to keep the cup pretty flat too. I've used the Burgundy, Gray, and Gold Scotchbrite pads that are sold in rolls for autobody work. They all work fine. This on an old, single speed Black & Decker 15 amp side grinder with twisted wire cup. You have to press hard enough for the pad to stay on, but not too hard for the bristles to poke through.

There is a good possibility that the twisted wires don't poke through as easily as straight wires, but this is the only setup I've ever used. I've never scraped first either. Heavy rust just eats the pads faster, but they come on a 15 foot roll for about 25 bucks.

edited to add: Looks like they are called "knoted wire" instead of twisted: https://www.mscdirect.com/browse/tnpla/03597994?cid=ppc-google-New+-+Abrasives+-+PLA_sNRiMAKjj___164110813572_c_S&mkwid=sNRiMAKjj|dc&pcrid=164110813572&rd=k&product_id=03597994&gclid=Cj0KCQjwlqLdBRCKARIsAPxTGaVrjbYnjahQE8JAtTNA MnPKE6JZiibHgByrQ6nsTXTK9uw_gxFJ4sQaAuw5EALw_wcB

[Matt Day]

Yes, the wires start to come through as the pad wears down. Just slap another pad on.

[John A Murray]

Could probably attach a scotch bright to a 1/4 sheet square sander and have at it.

+1

I had an old 1/4 sheet sander that was no longer in use. The scotch bright pad fit (almost) perfectly. It was not quite as wide as the sander but there was no effect on the "sanding" and was much easier than doing it by hand.

[Jeff Duncan]

I use an angle grinder but not the wire cup method. I use a sandpaper disc attachment. It's basically a plastic backer and a nut washer setup so I can cut sandpaper or scotch brite pads and fasten them on securely. Don't remember where I got it but works great and you don't have to worry about anything flying off!

good luck,
JeffD

[Larry Edgerton]

For an old machine I am trying to rehab I take my Makita flat wheel tool grinder and turn it upside down with a 220 stone in it, working in a pattern until it is close, switch to the 800 stone for a pass. Trick is to resist the temptation to work harder on bad spots and stick to the pattern. Then I go to a scotchbright stuck to an old ROS pad.

[Jayson B. Williams]

I am new to Old Vintage Wood Working Machines. I have a 1935 Craftsman Bench Saw. I was told to use a Angle Grinder with a wire wheel. As you can see, this was all done by wire wheel. You can use WD40 to coat it, then grind away. I have also heard the blade method, which I have never done before, So you need to find what works best for you.

Jayson

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