Before building my biogas generator, I wanted to build an apparatus to grind up all the kitchen scraps and yard waste that I intend to put into the generator. Garbage disposal would do nicely. I also make hard cider, but I didn't want to use the same garbage disposal for grinding apples that I use for grinding kitchen scraps. Second garbage disposal would do nicely. Solution: Dual basin stainless kitchen sink I found on Craigslist. Bonus, the sink came with a working garbage disposal. Just need to build a cart for it, so here goes.
Step 1: Build Frames
Once I got the sink, I measured right around the mounting rail on the underside of the sink's lip. The cleats that would normally grasp the underside of a counter needed something else to grasp here, and I didn't want to go find a whole section of countertop, so I cut some 1-inch wood trim to those dimensions. I then glued and nailed those trim strips to 1x4s that served as the upper frame for the cart. I built a lower frame out of 1x4s in identical dimensions to the upper frame to help provide stability to the cart.
Note in the detail photo of the upper frame that I notched the center 1x4 for the sink's mounting rail. As it so happened, I made the notch deep enough to pass the wiring for the garbage disposals through it as well, which will help keep the underside neat when I go to route the wiring.
If there's enough demand, I'll make up a diagram of the frames with dimensions.
Step 2: Assemble Cart
I had to mount and unmount the sink to the upper frame countless times through this build. Easiest way to do it is upside down on a workbench (or, in my case, on top of an old dishwasher in the garage) - that gives the best access to the sink mounting cleats.
With the upper frame mounted to the sink, I clamped four 2x4s to each corner to serve as legs. This cart's going to have wheels mounted to the legs, so I made sure to orient the 2x4s as seen in the photos. With one screw holding each leg to the upper frame, I placed the lower frame over the legs and clamped/screwed the lower frame to the legs. Everything ended up square enough.
Step 3: Add Wheels
I used a couple Tractor Supply pneumatic tires (4.10/3.50-4), bolted to two of the legs. To make sure the bottoms of the legs cleared the scrub radius, I put scrap 2x4 sections under each leg before measuring for the axle holes. That conveniently left a 2x4-height void beneath the other two legs, so I added a crossbar both to brace the legs and to make the cart even.
Step 4: Make Pretty
Took it all apart. Stained it. Put it all together.
The stain's to make this thing last. I'll be using water to flush the disposals, and I know I'll spill a lot. Plus, I plan on wheeling this thing out to orchards come apple-picking time. No bare wood here.
Step 5: Wire It
I decided on combination switch outlets - one for each disposal - largely for straightforwardness.
There was plenty of space between the backside of the sink and the upper frame to mount both switch outlets in basic electrical boxes. As I mentioned before the notch in the center 1x4 on the upper frame worked well for concealing the wiring that ran between the two.
Note that I made sure to orient the switches so they're off when facing in. In an emergency, I would rather push the switch in to turn the disposal off than take that extra half-second to fumble around with pulling it out.
The switch outlets, by the way, are rated for 15 amps. I only plan on using one at a time anyway, so that shouldn't be a big deal. If it does become a big deal down the road, I may add a GFCI upstream of the switch outlets.
Step 6: Make Custom-fit Cutting Board
I'd seen this concept executed in RVs and thought it would work well here. As mentioned before, I only plan on using one side of the sink at a time, so I cut a piece of 3/4-inch plywood I had to fit atop one side of the sink, then cut a couple 2x4 remnants to fit just inside the sink. Glued them together. Stained the underside and soaked the top in food-safe mineral oil.
Step 7: Fill Holes
I won't be plumbing this cart for water, so I filled all the faucet holes with chrome plugs. The center 1x4 in the upper frame runs right beneath one of the faucet holes, so I clipped off enough tangs in the plug until it fit.
Step 8: Mount Disposals
The disposal that came with the sink I'll use for kitchen scraps and yard waste. Pro tip: Clean it out before testing if you don't want ground up spiders shot out the outlet. I added a piece of plumbing I had in my scrap pile to direct the output past the lower frame. Perhaps I could have thought through placement of the lower frame a little better, but this works.
The brand-new disposal will be for the apples. That one, a stainless steel 3/4 horsepower continuous feed unit, I selected based on the recommendations at Whizbang Cider.
Step 9: Add Handle/cable Hanger
I considered something as simple as a bathroom grab bar for a cart handle, but I had some random black pipe bits laying around, and 3/4-inch black pipe, done just so and angled outward, could provide both handles and a means of stowing the cable neatly instead of in one big rat's nest.
Step 10: Accessorize
Stopper to fill up a sink when washing apples. Stuffer to stuff stuff into the disposal. Strainer to separate out the larger debris, post-grind.
Step 11: Grind!
All set to pulverize any weed that dares grow in my yard and turn any apple I pick into mush. If I think of it, I'll grab a video of the thing in action and post it here.