When I decided I wanted to make my own BP, I was inspired by Skylighter's article on making high-powered black powder. I wanted to make hotter powder than the commercial product we could have once got here, but now even that is unobtanium. I wanted it to be like Swiss 3Fg.
Ball milling is obviously needed to make good corned product. I started pulling together kit, watching youTube and building tools. (Have you seen Clickspring's channel? Oh wow.)
I hunted for a rock tumbler but even secondhand ones were very hard to find. We dont have Harbor Freight here, and the local vendors retail price is way too much.
Verge collections of large rubbish are a big thing here. We go sharking, cruising the piles for garden furniture and toys for grandchildren. From an earlier one I had slabs of steel 19mm and 25mm thick for a Skylighter-style hydraulic press! Hmm, what has drive shafts and motor I could loot for a tumbler? Oooooh, a tumble dryer would also have a giant pulley for reduction!
So I thought a moment more and said why build another frame and motor mount? Just mount the white-pipe tumbler barrel inside the dryer tumbler. It took a while to think that out. MDF profiles bolted against the three ribs in the dryer drum now make up a spider to hold the barrel in the centre. I used high density foam scraps from an Ikea kids play mat to cushion the barrel in position.
I bought 150mm (6") sewer pipe and inspection caps and build two drums. Ribs inside.
Sandbags for safety? I stacked up bags of pool salt. Same price as sacks of plasterers sand, dont have to fill, and can use in the pool later. After seeing a youTube of someone letting off small explosive charges in a dryer, I found a 3' square aluminum expanded mesh for confining door explosions.
A chunk of the same mesh as a bucket screen is now ready to screen media balls from product when emptying the mill barrel.
My first runs revealed a lot of problems.
A cargo strap to hold it in axially didn't work; the strap tended to fall off around the roundness of the barrel lid even with duct tape trying to retain it. Yesterday I set bolts through the MDF profiles as lugs to run cord lashing around. I will add hooks and rubber strap next.
The 150mm full-diameter inspection caps leaked potentially explosive dust in to the dryer. Strip, vacuum out. Duct tape wrap of lid to confine dust to barrel.
The dryer timer went up to 120 mins. I hated not being able to set it running for more than two hours when the experience of others shows more is needed, 4-6 hours.
The dryer stops and reverses direction every minute. By my calculation this drops about 5 seconds or 8% of milling time in the toilet. Instructables.com has a couple dryer motor salvage articles, and its clearly possible to wire it differently.
I stripped the dryer and traced out the wiring, trying to understand all the switching. Having found everything I expected (and a lot I didn't expect -clever guys these appliance makers), I sketched an original circuit diagram for the machine, and thought out what I wanted. Now it has:
Door safety switch and broken belt detector as per original;
Three position switch (was hot, cool, warm) now does 'off', clockwise, anti-clockwise. Re-labelled appropriately.
Time switch and auto-reverse are completely out of the circuit; knob removed from fascia.
All thermal cut-outs for overheating are out;
Heating circuit and element completely removed. (the element is a 400mm dia ring - I wonder if it could be useful? Would it be tungsten, or nichrome?)
And for a few $ I got a 24hr time switch for the wall socket, which lets me set start and stop times for the run, at a distance from the machine. For single-ingredient milling it could be left unattended to start and end.
Now we are cooking!
Edited by ChrisPer, 15 March 2021 - 12:11 AM.