My Delta DJ-20 Restoration (Part 5)

Paint stripping
I needed to find a way to effectively remove all the paint. There were several spots where the paint had flaked off and was replaced with spots of rust. I figured I might as well do a full strip and repaint as that would give me the most durable finish.
The first thing I tried was Citristrip since it seemed like a low odor, eco-friendly option.

It kinda works if you put enough of it on and wait long enough, but for me it was just too slow and too messy. You still have to wipe out all of the paint that has dissolved and because of all the crevices in the castings its just too much work. Also it didn't work so well on some of the black paint (which might be some kind of epoxy paint). At that point I decided I'd have to resort to some blasting.

Abrasive Blasting
I've watched a lot of American Restoration on the History channel and they always use blasting for paint removal so I thought I'd give that a try. After doing some research, it seems that using regular sand for sand blasting is pretty bad for you (go figure). Apparently the silica in sand can really screw up your lungs. Coupled with the fact that i'm doing this in my backyard where I'd like to one day grow some vegetables, I needed to find a safe and eco-friendly abrasive. I also needed to find a cheap blasting machine so off to Harbor Freight I went. I settled on the Portable Abrasive Blaster Kit

My first choice for blast media was ground walnut shells since I've seen it used on American Restoration I figured that would be good. I was wrong. It's definitely an eco-friendly option. But on the tougher paints it was pretty slow or not working. Also it was only available in courser grits which I later learned makes the process even slower. I finally tried using this company's proprietary abrasive known as Kleen Blast. Its deemed safe enough for even CA, so it should be fairly safe. Still you want to be wearing the full respirator setup. This worked like a charm, especially using the fine grit size.

To contain the mess and allow me to reuse the abrasive, I made a "blasting tent" out of lots of 6 mil plastic, ladders, and a 10ft long aluminum screed/straightedge. Between each blasting session, I had to dry out the abrasive in the sun, otherwise it would clump just enough to clog up the machine. Ideally, you should have enough abrasive to do a whole session without needing to recycle any of it.

My Delta DJ-20 Restoration (Part 4)

A lot has happened since my last post. Bear in mind that what I'm presenting may seem like chronological order, I've been doing a little bit of everything as I wait for supplies, parts, or opportunities to do things.

Basically the process of cleaning everything, derusting, and stripping is very time consuming.
I was able to clean all the small stuff in a hot bath w/ soapy water followed by soak in 1 Gallon Evapo-Rust. Parts in Evapo-Rust tend to develope a dark grey film that's easily removed with a wire brush and more hot water. I then used an old tshirt and blow dryer to keep everything dry. Another good thing about Evapo-Rust was you can just leave the parts in there indefinitely until you've got time to meticulously rinse them off and dry them. Water would always stay in the head of the socket cap screws so I found that holding them up to your lips and just blowing the water out was the fastest method most effective method of drying out that recess.


Parts after clean and Evapo-Rust

Next was disassembly of the cutter head. Don't make my mistake of not covering the cutterhead in something before removal. You could hear and feel the carbide cutters scraping against the cast iron as I slid the whole thing out. I think wrapping the cutterhead in packing tape before removal would be a wise idea. I ended up covering the cutterhead anyways so I could get these bearing blocks off.

Cutterhead removed from base

Removing the bearings is a bit of work too. The block on the left comes out fairly easily with a few taps from a rubber mallet. The block on the right has a snap ring inside that captures the bearing inside. You have to remove block w/ the bearing together from the cutterhead shaft. The only way to do this is with some sort of puller (believe me when I say no amount of beating with a rubber mallet will work). Luckily the gear puller that I had could be adapter from 3 leg to 2 leg to accommodate the not so gear like shape of the bearing blocks. I guess my puller was a little small so I also had to use a clamp to keep the legs on the block. One note here, you should probably screw the socket cap screw back into the threaded end of the head so that the point on the puller doesn't mess up the threads. I ended up retapping the threads after the pull. Here you can also see my protective cover made of a Harbor Freight ad and packing tape.

Setup for pulling the bearing block off the cutterhead

Once the blocks are removed, there's the issue of getting the snap ring out of the blocks so that the bearings can be replaced.

Bearing block with snapring

Unfortunately, my cheap HF snap ring pliers were no match for this tough ring so off to the HomeDepot and I got these: Channellock 927 8-Inch Retaining Ring Pliers they are night and day better than the HF version (but they also have a big price to match).

This is really the best time to replace these bearings. I could already feel some grit inside them as I spun them. I then ordered the same size Nachi C3 bearings (6004 and 6005) from vxb.com. I think they are the cheapest place to find bearings. The new bearings feel like they have a really tight tolerance. I can't feel even the slightest play between the races. I'll have to wait until I repaint the blocks before I get the new bearings pressed in at a local auto shop (so to be continued...)

Paint stripping was another big task I'll cover in my next post.