The newest version of my turbo oven-powered drum roaster has had a few batches under its shiny aluminum belt and has been working pretty great!
My goal with this version was to make inserting/removing the drum as easy as possible. The previous one had me skewering the roaster and drum with the 1/4″ rod which was hard to remove in a hurry at 2C.
Here are some photos of the finished product:
Here are some build photos:
A rundown of parts:
- Motor – 14W, 30RPM gear motor from eBay. It has a 6mm output shaft.
- Shaft adapter – 6mm x 1/4″ flexible adapter from eBay
- Drum – 14cm diameter x 18cm long drum from eBay. It has 1/4″ square holes on its center axis
- Rod – 1/4″ stainless square rod purchased at Home Depot
- Bushing – 3/8″ ID x 1/2″ OD x 1″ long bronze bushing from bronzebushings.com
I don’t have any eBay links because they go invalid so fast – but if you search for those terms you’ll find the same stuff very easily.
The 1/4″ bolt and 7/16″ socket are really the only the complicated aspect of this roaster. Recall that 1/4″ shaft diameter bolts have 7/16″ heads, hence the 7/16″ socket. The socket has enough slop around the bolt head to allow it to be tilted and pulled off fairly easily – that is the magic that lets the drum be quickly pulled out of the roaster. The roaster wall holds a bronze bushing – this acts as a smooth bearing surface for the bolt. So the order of parts is:
- Shaft adapter
- 1/4″ bolt secured into the 1/4″ side of the adapter. This was a longer bolt trimmed to an appropriate length.
- 1/4″ square rod
- 7/16″ socket fitted onto the 1/4″ square drive rod.
At first I had the socket J.B.-welded onto the rod, and this lasted for 6 months before the epoxy failed. I think that the heating/cooling cycles of two dissimilar metals caused it to give way.
So I then used a 1/8″ tension pin to hold the socket onto the drive shaft. The flat you see ground onto one side of the socket allowed me to cross-drill the socket without the drill bit wandering all over.
The square rod is a permanent part of the drum, it’s locked into place using the drum’s locking screws. The end of the shaft that rides in the hook had a flat spot turned down on my lathe. The little hook is just a piece of flat aluminum bar.
I realize that this is not a “build” and is lacking many details of how exactly I made this thing. This is partially because I am lazy and don’t want to write all that, but also DIY coffee roasters work with the materials on hand so it’s unlikely anyone will ever make one just like this – use it for inspiration!