Molder or Tumbler?

OK this is not perzackley about 1300s but you might find this interesting.
Tank cleaning on my KZ900.
This mess is totally my fault. I parked the bike with a full tank of gas but over the last 18 years it's evaporated leaving a thick layer of scaly rust/varnish. I started with my standard method but found that the varnish was protecting the scaly rust so I reverted to a pint of Acetone sloshed around every couple of hours. Which at least poured out dark brown. Still not clean enough.

It was looking like it was gonna take physical agitation with some sort of abrasive aggregate to clean the inside of the tank. Some years ago I tried using an old clothes dryer with socker balls stuffed in around what ever tank needed cleaning. Unfortunately, the balls wouldn't hold their position and the tank would soon start knocking against the dryer tub. Then I realize that I could re-purpose my roto molder into a tank tumbler with not much more effort than to try to stuff socker balls around a gas tank.

Check out:


The end result is adequate. Not every bit of the interior is gunmetal grey but 95% is. One mistake I made was to use 70 grit aluminum oxide with about 50 - 3/8" pebbles and a hand full of 1" drywall screws. The last two items were fine but next time I'll use 20 grit as the 70 grit has resisted flushing cleanly over many tries.
Bill

Some good tank cleaner, (like Marine Clean in the POR kits) and Evaporust are your friend (there are some good homebrew alternatives on YouTube if Evaporust is too expensive).

 

That's one heck of a Rube Goldberg contraption! I'll send you three tanks right away...

The question to be asked is why would you be in possession of a roto molder? Such an unusual piece of equipment for somebody to have. Love the spiral indicator on the end. Would be fun to sit and watch while sipping on a glass of bourbon. LOL !! Nice to see you make use of it.
I too, have a tank to clean and seal, and I was thinking of outfitting a spit rod for the rotisserie on the BBQ  and letting it run for a day with abrasive. After seeing  Youtube video on POR15 Metal Prep  specifically at 9:40 min and 12:20 minutes, you can see what the Metal Prep will do to heavy rust  in 15 minutes and the instructions suggest that you can leave the metal prep on the surface for a couple of hours when heavy rust is to be dealt with. So with that in mind, I'll outfit the spit rod and rotate the tank using the rotisserie motor with the Metal Prep sealed in the tank. 
Por 15 package a fuel tank sealing kit that has a Degreaser , followed with the Metal Prep and that's followed with the tank sealer and sometime in the next couple of months, I will do the tank I have here.

POR15 Fuel Tank sealing a motorcycle tank   -Really like this video. It shows what comes out of the tank after the first of 2  sloshes with the degreaser than how clean the fluid is coming out of the second slosh. According to the instructions, the degreaser /cleaner dissolves the built up varnish . Very interesting.

Before I retired almost three years ago my supervisor asked me to build a rotational molder with which one of my  coworkers would make hollow castings, of what I couldn't conceive. We were a manufacturer of windows and doors. I believe it got used once, at most.
When I retired my supervisor's supervisor told me to trash it as it would never pass OSHA (occupational safety). I gently put it in the dumpster and loaded it in my truck after work.
This is the first use I've put it to.
Bill

dcarver220b wrote:

That's one heck of a Rube Goldberg contraption! I'll send you three tanks right away...
 

Bring 'em. it only takes about an hour per tank.
Bill