Well, I was surprised. And a little puzzled. But I think I have it licked.
I bought 11 bags, 60 lbs each of concrete. I figured I'd need more or less 500 lbs to build the counterweight, and I'd use the rest on a slab I need to pour.
The slab pour is waiting on the loader, oddly enough.
I figured the tipping point would be around 400 lbs, which is to say, "With 400 lbs at the lip of the bucket, the back wheels will come up in the air."
So I loaded up 8 bags. And the bucket came up, and the back wheels didn't.
So I loaded all 11 bags. Same thing.
So I scrounged around and found a 20lb bag of lime, a 40 lb bag of mortar mix, and what turned out to be 80 lbs of cast steel bucket teeth, and stacked all of them on top of the concrete. precisely 799 lbs.
And the bucket came up, and the back wheels didn't.
So I got off the machine and walked around back and lifted up on the 3pt bar. And with my official guesstimate of 65lbs of lift, the back wheels stubbornly rose into the air.
So I'm using that figure.
Some long calculation later, I came to this conclusion: "To keep 400lbs downforce on the back wheels while carrying 1000lbs at the lip of the bucket, I need a 621 lb. counterweight hanging from the 3pt. lift arms."
Concrete weighs 150lbs per cubic feet, so I need a 4.15 cubic foot counterweight.
Like so:
Opinion question: This is larger than I had anticipated, and I've thought about making it the same footprint size, but only... 18" high instead of 24.5". That would give me the option to try out the performance of a smaller weight first, but leave me the option to add another 6" of height to it later if I need to.
What is everyone's advice? Make it full size the first go-around, or make it a little smaller and see how it does?
Bob