Those forks look awesome. You must have some mad welding skills. How much would you charge to make another set?
Sorry .... When my design and/or welding is potentially exposed to liability issues of life and limb by others, my homeowners insurance company would have some kind of a cow.
What I have done is attach a quick sketch of the forks I have built. Please feel free to use the design if you choose, at your own risk of course. They have easily hoisted a pallet loaded 500-600#'s
The reasons I like this scheme are;
1. The channel itself can be welded fully on all sides on the "tension" side where tubing cannot.
2. 3 1/2" flatbar fits perfectly into a 4"-5# channel making a nice rectangular section.
3. I'm fairly confident these forks will lift what my loader can (which isn't much over 800# or so).
4. The fillet plates on the sides both stiffen the joint, and hopefully prevent a sudden failure at the weld itself.
5. I chose not to use the bucket type fork, because this type keeps the payload closer to the tractor, allowing more capacity.
6. I have visions of using the frame for other things such as grubbing, possibly boom pole, whatever.
And once again I must caution, I am a "farmer engineer" without any professional credentials, so be careful out there.
Sherweld