Tuesday, December 25, 2012

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.

2 comments:

Anonymous said...

Sarit,

First off, thank you for posting your restoration efforts. I am just putting the finishing touches on my DJ-20 restoration and your blog helped a ton. I clearly did not take enough photos to know where to put everything back. I made the mistake that my memory and the exploded view parts diagram would be enough. Definitely not the case, especially since I pulled it all apart two years ago and then lost steam on it before putting it back together.

I used diegrinder and wire brush wheel to strip the paint on most of the cast iron surfaces and then sandblasted in the places which were harder to reach, but looking back I wish I had just sandblasted from the start since it took it off better and faster.

On the sheetmetal pieces I used Citristrip to take it to the bare metal. I have found that the secret to Citristrip is to apply first, then wrap the piece in painters plastic. The thinner the plastic the better since it will stick to the Citristrip and keep it from drying out. The key is to not let it dry out while you are waiting for it to do its work. My jointer had literally 1/4 inch of lacquer overspay in places and using this method I was able to strip both laquer and paint. Most of it came off in a single application, but I had to do a second in some places where it either dried out, or I didn't put enough on it.

To paint I sprayed the sheetmetal pieces and a combination of spray and brushing for the cast pieces.

So far it looks great. All I have left is to put the tags back on and set the knives. Waiting for parts. Anyway, good luck and thanks again.

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