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 because 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!