Step 5: Making the Riffles
I settled on 6 riffles, 4 inches apart and starting 4 inches from the bottom end of the sluice. I cut up the steel pieces without too much difficulty, even though I only had a hacksaw for the job. I don't have a lot of metal working tools.
I built a short section of sluice out of scrap lumber to serve as a jig for welding the pieces together. I used a borrowed welder to weld the pieces together. My welds are ugly (I need more practice) but they seem strong enough. I also welded on two angled pieces in the middle of the riffle assembly to serve as anchor points for holding it in the sluice. Not bad for a welding newbie.
The third photo shows the nearly finished riffle assembly, looking like a mini ladder. I still needed to trim the top hold-down ear back a little.
After early tests with the sluice, I found I needed to weld on another flat piece at the top end of the riffle assembly (4th photo) to hold down the mesh and ribbed matting that would go under the riffles. More about those later.
The last photo below shows how the riffle tray is held in the sluice. There are two right-angle "ears" welded onto the center of the riffle tray. They have passage holes drilled in them to fit over hanger bolts in the side walls of the sluice. Wing-nuts hold them in place. It's a good system. The only challenge is not losing the wing-nuts when disassembling the sluice for cleanups.