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This a frame with a rear axle to an old lawnmower. I use vinegar and 150 SS sheet metal screws (count, make sure 150 comes out) I remove the petcock, made new screens. I made a plate with rubber gasket. This tank has a lip internal under the gas cap. I would have never got the screws out in a reasonable time with out shaking. Use sized screws that fall out the petcock hole. There is a pipe welded to a plate and bolted on the back center of the plywood, call it a coupling on center for balance of that rotating part. Drill and tap 2 holes through the pipe. Make indentations on the shaft with the drill bit for bolts to positively lock the coupling to the shaft. DON't REMOVE any thread material. I use a little lock tight. You don't want your tank being thrown on to the floor! I unbolt it and lay the tank on the plywood with a piece of round bar, pipe, what ever you find center of tank under the wood. The boards on the front side are removed. I move the tank on the bar to find the centerline where it wants to stay level/balanced. I use tape to mark balance point. I mark x lines corner to corner to find center of the board. I line up the centerlines and then put the board and tank on you round bar/pipe without the coupling. The wood is moved to try to balance the weight of added boards that lock the tank in center position. Balanced weight is your plan. Once the boards are centered and the rotating unit is balanced again screw them down in even spacing. Use straps or what you trust and make appropriate spaced holes in the corners of the plywood for the hooks. Use protection under the straps to protect the tank. Clamp the frame securely to a table. Install the coupling. Slide the tank onto the shaft and, BY HAND and Don't tighten the set screws "YET" Rotate the board by hand not power, it should be very close to moving without weight throwing it off balance. If it's heavy on one side or end rethink where you missed balancing one of the components. If you get this far your talented and you can see if I'm forgetting to tell you a point I didn't mention.
Now for the power driven components. This has 3 speeds and reverse. You will have to lock one end of the shaft for the transaxle to transmit rotation. Vice grips works for me. I'm not trying to build pretty I don't want to shake anymore tanks by hand. I put a bigger pulley and of course longer belt to slow the rotation. I want it to turn just enough to drop the screws across the surface not flings them to outside and not let the screws do the work. The motor because of multi gearing doesn't need to be ridiculously large hp. I reruns/refresh motorcycles not vehicle's.If you decide to do a car or truck tank, more hp will be needed and bigger wood. Just get it all balanced. Weld angle together, get the right diameter pulleys for the transaxle, belt and see how it turns. Always clamp or bolt it down, slide the rotating tank assembly on and NOW tighten the setscrews. Use an old gas cap. One thing else. I found out right away with water I had small leaks. I sanded and patched with JB Weld. If you don't check for leaks, vinegar will be flung out! I add a couple of bottles of vinegar, you amount is your choice. Add the screws, I check the cap for tightness and petcock plate for leaks. If like me you'll turn it on and freak out and turn it off. That's a valuable tank you might see flying on to the floor if I forgot a step or you did! Turn it on and off checking things. This is my easiest way. This device cleaned my X75 Hurricane one piece metal tank and fiberglass body.
The tank you see is a 99' Triumph Legend TT that sat with 10% alcohol gas for 3 years. Next is a 99' Triumph Venturer. Vinegar helped but went to a diluted 3-1 Hydrochloric acid mix, but finely went 50/50 water/acid. Walk away let it spin. Keep checking, it will remove rust and maybe make new holes. Use different rust remover, you'll find something that works. I wrapped my tank with commercial serran wrap. When satisfied wash with warm Dove dish soap. I placed a low power/heat gun or a sorce you have hanging from a saw horse blew warm air in through the fill hole. Plus the Florida sun had the tank dry quick. You'll get Orange red flash rust. Caswell 2 part epoxy says that doesn't matter. Plug vent lines, practice removing the plug, make a tool that works! When the coating hardens you might find hard to remove. I took a old gas cap with plastic threads and turned the threads shorter to reduce the length so the epoxy coated the fill hole walls. This frame/tank equipment sat outside for 10 years, it's now in my shop. Now you have a device everyone knows about and wants you to remove rust and coat their tank.
