I made some cheap forks that I used for several months for recycled fence posts. Last weekend I decided to build something stronger so I spent Saturday cutting the steel and they are being welded together this week.
My first set of cheap forks were made from a 8.5 foot heavy duty road sign post cut in half with two pieces of 2 inch channel welded between the two forks. One piece of channel was at the back the other about a foot forward from the back. I drilled four holes through the forks and bucket and bolted them together with 1/2 inch bolts. The sign posts are V shaped and were used with the point of the V down. I cut the forward end of the forks with a 45 degree angle and welded short pieces of flat bar on to make tips. This set worked very well moving logs and even some rocks. But I managed to get a rock on one of the forks and bend it after a few months of use. The 1/2 bolts and nuts were in bad shape when I took them off.
For the next revision I added flat bar closing the top of the V on a new set. This set was much stronger. I found two problems with this design. The bolts despite having large washers started to stretch the bucket where they bolted in. And I had to weld 1/2" nuts inside the forks since I closed in the top and they were no longer accessible to tools. Two of the four bolts inside the forks were damaged in usage.
The next revision was to take the existing set of forks and change the mount to a clamp on style. I added 2" channel to the top of the fork reaching back over the bucket with forks extending underneath the bucket. I used two 3/4" bolts through the above bucket part of the fork to clamp them on. I had seen this design on forks for sale. The first time I tried to attack a pile of trees the forks fell off. I later discovered that a weld had cracked.
So I decided to build stronger forks and for the first time in a year of using forks to buy steel to do so. For the current project I bought 2.5" by 3/16th thick square tubing, cut to fit, drilled and welded 3 pieces in the bottom of the bucket making 3 truck receiver hitches. The 2.5" tubing goes from the back of the cutting edge to the back of the bucket including the angled section. I believe this will significantly strengthen the bucket. Then I cut 6 forks two 13" long and two 5" long from 2" by 1/4" thick square tubing. The short set of forks has two sets of holes drilled, one will have them flush in the bucket to block off the sockets while doing smooth work, the other allows them to stick out about 3 inches beyond the cutting edge to act as teeth. I cut the end of all of the forks at 45 degree angles and flat bar was welded on to make tips. I spent $122 on the steel, $20 on welding rods and $8 on cutting disks for the new set of forks.
I plan to test the new forks next weekend.
My Uncle who is a retired welder did all the welding.
These might be a good option for you if you dont want to build them
Paynes Forks Light-Duty Forks — 1200-Lb. Capacity, Model# PF1200 | Accessories | Northern Tool + Equipment
The cheapest, easiest option I can think of would be to go to a metal supply store and buy two pieces of steel cut to length. For example the 2x2x1/4 thick steel tubing I bought was $5 a foot. Then buy 4 sets of 1/2" bolts, nuts and washers. Drill 1/2 holes through the steel and your bucket then bolt in. I think you could do this in a couple hours and for less than $60.