Thanks for the compliments.... The back story... I used to grow garlic and needed a mulch maker.... Todays straw choppers are $$$$$.... I found the "chaf chopping" drum on e-bay and it sat on the barn floor for 6 months while I drew up possible configurations... found a compatible PTO shaft in Surplus Center catalog... pillow block bearings on e-bay for about $8/each for the drum.... and started building ... The drum and all it's functional parts came from Iowa... I think the shipping was as much as the parts... I've got about $500 in it which I think is pretty good all things considered...
I had to make the chopping blades that mounted to the framework... If I remember they are made from 2" X 3" rectangle tube... very similar to the original blades configuration... The drum etc. is from an IH combine, I think, about 1960's model.....
It works well.... thick slabs of hay will put a strain on it so feeding rate is slow.... it will chop up an 800# bale in about 20 minutes or less....
It needs a discharge chute to keep the hay from piling up under the chopper.... Just ain't got around to it yet...
I'm sure you noticed the lack of safety hardware... When it's running, I add hay from the "high" side... Probably not necessary to mention, it puts the fear in me while operating.... that machine has no forgiveness in it.....
I generally run it twice a year and store the chopped straw, alfalfa in apple bins for later use.....
As far as build details... find a combine "chaff chopper drum".... stare at it while having a few beers and something will come to you.... That is what I did.... more than one day spent trying to come up with a good plan...
Action photos... I wish I had some.... I just learned how to take movies with my camera... maybe this spring.... in the meantime, imagine 800#'s of hay shooting out the bottom at 540 RPM.... there ain't much to see, unless you had slow-motion....
I'm pretty proud it worked and does what I need... maybe more than I need... It definitely was worth the time and money....
Enlarging the drum photo shows the "cutting teeth" fabricated from the 2x3 tube... After using it, I have thought of changing out those teeth to "sickle bar" cutting plates .... and possibly mounting the same on the drum.... only problem mounting on the drum is screwing up the balance... the drum is perfectly balanced as far as I can tell.....
Dave