Teardown, full welding, sandblasting and powdercoating


Now that testing was complete, it was time to tear it completely apart, fully weld all of the joints and prepare it for painting.  Up until this point, everything was only held together by tack welds just in case something needed to be changed.

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Once it was mostly apart, I was able to tip it up on its side so I could access the bottom.  Then I cut and formed some sheetmetal skins to cap in the bottom of it to keep snow from getting in around the belts and my feet.

Miller Snow Dozer Miller Snow Dozer Miller Snow Dozer Miller Snow Dozer Miller Snow Dozer Miller Snow Dozer Miller Snow Dozer

Then I could finish up the last of the welds, and remove the remaining parts.

Miller Snow Dozer Miller Snow Dozer

In order to get good paint adhesion, the metal needs to be prepared properly.  There are many ways to do this, but sandblasting is one of the best as it makes the surface microscopically rough and allows paint to really hook onto it.  I have a standalone sandblaster canister, and so that’s the route I chose.  I didn’t want sand going everywhere in the shop, so I needed some way to keep in contained.  I was at an auction, and picked up an expandable canopy that was approximately 10’x20’.  I then bought a tarp large enough for the floor, and some additional ones to cap off the ends.  That way I could capture and reuse the sand during the blasting process.  I use a black slag abrasive from Menards that really cuts and can be reused multiple times.

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The blasting unit that I have also has a full-face mask with air supply hookup, which makes blasting a lot more pleasant.

Sand blasting booth Sand blasting booth Sand blasting booth

I use my 7.5hp 80gal air compressor hooked to a second 80gal tank fed through ½” hose to power the blasting unit.  My smaller 6hp 60gal air compressor is used for the air supply to the mask.  I can’t blast continuously like an engine driven air compressor would be able to, but it’s enough for my needs.

I wanted a paint that would be durable and long lasting in a wet and salty environment of snow blading, which pretty much eliminates most paints except for powdercoating.  Through some of the work that I do, I had worked with a vendor that did powdercoating, and their rates were reasonable, so that’s the route I chose.  I didn’t know the exact price it was going to be, but I knew it was going to be worth it.  Some info on powder paint:  first parts are sent through a wash steps, which cleans any residual oils off of the surface, then they are dried, and sent into a booth hanging from racks.  An electrical clamp is attached to the rack, and provides ground, the special paint gun imparts a positive charge to the particles and they are attracted to the grounded parts.  Due to the nature of the electrostatic charge, the powder will cover all of the surfaces, and can get into areas that would be almost impossible with a wet paint gun.  Also, due to the electrostatic charge, sharp edges will get more paint, versus wet paint where it wicks away from corners.  After all the parts are coated, they go into an oven, where it gets baked at a high temperature (350-450F) for 20-40 mins, temperature and time are dependent on the particular powder and the size/weight of the painted part.  During the time in the oven, the paint flows out and cures up, leaving everything painted with a highly durable finish.

After sandblasting was complete, I packaged everything up for outsourcing the paint.  I carefully wrapped everything, handling parts with gloves on to keep any oils from my hands off of them, and got ready to transport everything to the vendor.  Once I got there, they happened to be running a hammertone red powder, which was fine with me, as I wanted any color except for black.  Total cost from the powdercoater was $120, which was a deal for high quality paint.  Then it was time to load everything back on the trailer for the trip home.

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Next>> Part 18: Re-assembly and pushing snow

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