What is it?
Right, thank you. Why do you want to do that for gardening? It sounds as though the soil profile and all its microbes will be disturbed and the microbes killed. Just turning the soil over will kill the microbes. There may be good reasons for you to do that but before you do, could you read a book about the soil and what is in it and why it is so important to plant health to leave the soil un-disturbed?
You don't have to buy this book, it will be in your local library: Organic Growing with Worms by David Murphy. It's Australian and explains and illustrates the pivotal role microbes and worms play in soil health. There's another in-depth book, American this time Teaming with Microbes by Lowenfels and Lewis. Both were in the Moreton Bay Regional Council Library system so I imagine they would be in other Libraries as well. I have subsequently bought both books they are a valuable reference.
Anyway I may be assuming wrongly.
Here's some images for ROTARY TROMMEL.
I've never heard of anyone on BLF using one Travis. Don't think you will have much luck borrowing one here.
Also wondering about your proposed use for the machine?
Blimey! Overkill for a garden bed. My reservations are above … am interested to know what the next move will be.
Thanks for your comments/responses. I guess I will be getting my DIY on! Thanks for the book suggestions Elaine, I will definitely look them up :) Whilst I'm not a 100%, must be organic type of gardener, my aim is to supplement my daily living with home grown edibles - without being a (insert large corporate retail chain garden store here) gardener. I source a lot of my manures & carbon from local farms to make composts to amend my gardens - still very much a work in progress. I will be making a trommel to grade the compost & some of my more course beds so they are suitable for different planting types. I figure it will be a welcome addition to the local community garden in their compost making too :)
No doubt you have your reasons and I don't mean to criticise but why do you feel you need to screen your compost Travis? Rocks?
Surely it would be better to leave it undisturbed and use it as it comes. Curious why you would go to all this trouble to muck with something that is perfect as is.
I see. But the 'compost' is dust-dry. Finished compost is humus: it is soft, fluffy and damp. It is the most perfect plant food and really does not need to be disturbed.
I note the 'compost' used by whats-his-name on Gardening Australia is dry too. As indeed was Peter Cundall's. I am at a loss to know what the stuff is that they use and call 'compost'.
Mine is full of red compost worms who enter the bins when they like and stay there turning household scraps and sugar cane into damp dark sweet-smelling humus. If I use it sooner it just isn't humus (soft and fluffy) but is more coarse but still full of enthusiastically-breeding worms.
There must be many varying ideas on what compost is. Material that is made by microbes and is biologically active will need to remain damp or all those little unpaid, vital garden helpers will die and their benefits lost.
For my self-watering planters I use considerable amounts of graded coal ash. Grading with hand held sieves is slow work. At present I use 4mm aperture for my work. Happy to borrow if available.
I composted all the tree trimmings shredded with grass clippings and shredded paper and card board did not have any manure .Compost heap got hot but after several months lots of dry wood still visible and for the size of heap not a lot of compost .Pulverizing the material before composting would seem to be the best option with something like a ball mill but you could do it after composting but there could be a dust problem
The smaller the material is the better it should decompose but is the effort worth it and if the compost heap gets too hot can spontaneous combust.
There's divisions of opinion on what constitutes 'compost'! Just searching now with "CSIRO + compost" to find buckets of info. As usual, drowning in info.
Since there's such interest in Microbes and Compost, we're starting a Group to keep most of the discussion close by rather than scattered on the site.
Watch this space for updates.