preparing the frame for primer - tools needed?

Hi Rod,

I used a 4-1/2" angle grinder with a twist knotted wire wheel on mine. I started with a wire cup wheel but it was slower going and didn't reach into the inside corners of my C-channel frame very well. Be careful, a knotted wire wheel is a wicked beast. I didn't try flap sanding discs, those might work well too and be a bit safer. If you use the knotted wire wheel, use a 4-1/2" variety rather than a 4", that is assuming you have a 4-1/2" angle grinder, as that size is just enough bigger to better reach into the C-channel.

Removing the axle and springs makes this much easier, you may as well go through them at this point anyhow as there will never be an easier time to do so. There will be a few spots, like inside the coupler that you will have to do the best you can by hand with a wire brush and sandpaper.

After I finished grinding and sanding I wiped my frame down with acetone then applied Ospho, which is a rust converter/primer, then just brushed on an industrial enamel paint. Next time I will spray the paint as brushing took forever. I used Ospho because I know it works, its cheap and I don't trust rust preventive primers.

Doing this work with an angle grinder is not without it's hazards, especially if you are not very comfortable with it. You will quickly find that the guard will be continuously getting in the way and you will want to remove it, whether you do so or not is your call. The grinder will be used in all kinds of positions and you need pay diligent and constant attention at all times to which direction it is spinning and how it will react when it grabs an edge and violently ejects itself from the work surface. Yes, this will happen, more so to the uninitiated.

Call around to see what it will cost to have the frame sand blasted. If it is within your budget, this is the direction I would go and plan to do so myself on my next project.

IDK, but I don't ever recall seeing a pneumatic grinder in a welding shop, must be a good reason for it.

I use my milwaukee electric angle grinder for removing rust and smoothing metal. My favorite attachments are a 40 grit and an 80 grit flap disk. They work great for removing rust, hardened tar and butyl tape, and even sanding!

I wouldn't recommend an air grinder for the job unless you have a BEAST of an air compressor rated for 100% duty cycle, which most people don't have.

B

That's what I use, more than up to the task.

I have no personal experience using flap wheel sanding discs so can't help you with this.

Another vote for having it sand blasted. I've had several hotrod frames and one trailer frame done for between $100 - $150. I degrease them first to help keep the cost down. Quick and well worth the cost vs the time and materials to do it yourself. But I have done plenty the old fashioned way, when I was stubborn.

Degrease first. 4 1/2" angle grinder is one of my favorite tools. Use the wire wheels for tight areas, and a 80 grit flap disc for everything else. 5-10 discs should be plenty, depends how bad the rust etc is. I steer clear of the Harbor Freight discs and wire wheels though. They are of poor quality vs Nortons or even DeWalts. Be sure the wire wheels and discs are rated to the speed of your grinder. You don't want wires flinging out of the wheels etc. Oh, eye protection, must have.