I replaced the pin rest with a swiveling pin made from a wire box clamp and a used diamond drill bit. These are clamped to an “L” bracket I made from scrap Aluminum bolted to the Cabmate. This is based on the Jig by Daniel Lopacki. It works better.
This device is used for rounding the bead into heishi or blanks. The pinvise is still used for the rounding and polishing stages but the pin rest is no longer needed. It was a nice experiment and it worked, but if something works better it’s best to do it that way.
The bracket is bolted with washers on each side. This keeps the bracket from marking up the Cabmate and also keeps the nut from creeping loose whenever you change the distance of the pin from the cutting wheel.
The pin is adjusted to the size of the bead. The bead is inserted in the pin and the blank is turned against the wheel until there is nothing more to cut. You might have to reposition the pin closer to the wheel and cut again if you find your cut was not complete. Press the bead in and let it spin until the blank is perfectly round.
After some time, I realized that aluminum is not rigid enough for the “L” bracket. There is too much flex and bend to it. Steel is prefered. Flex is fine, but bending is a pain. I’ll replace this when I can.
I chose to use a 100 grit for the first rounding stage, but this is probably too coarse. 180 is fine. Maybe even 320 with some material.
After the rounding stage comes the roughing or cutting stage (or another rounding stage). This is when the bead blank is put to the wheel on the pin vise and the bead is roughed out. I’d use 100 grit for tough stones and 180 for others. The bead is allowed to spin on the post held by the pin vice when held to the wheel or disk. So far I haven’t tried bar soap as a lubricant for the post/pin. But I have heard it helps. You want to separate the bead from the pin vise. For this I use the rubber rings from metal roofing nails because I have them. Daniel Lopacki uses disks made from Jet. I’m sure you could use hardwood for this.
You want the bead to spin freely on the post/pin. You want to make sure it’s round. You can do this by pointing the pinvise upward so the angle prevents the bead from spinning off. You can hold the bead horizontal to the center of the grinding disk’s spin provided that you hold it to the disk at an lateral angle, trapping the bead to the disk.
It’s dangerous. Things fly sometimes and things break. Wear Eye Protection! Be Safe. And you can cut yourself and grind your fingers till they bleed.
Right now, I’m not sure if this method is better than cutting beads as cabochons.
I should note: it’s very important that the posts fit the beads as closely as possible. Wobble should be prevented. It can misshape the bead. Quartz can fracture and blow apart. While nothing is guaranteed, this will minimize the issue. Another trick is to make sure not to grind too close to the drill hole. Grinding too close might cause the stone to chip. It’s best to deal with the ends on a lap after this initial cutting and polishing. This is for any material you might find chips easily. Chalcedony appears to be a quartz that is not prone to chipping.
I see a benefit to using wheels instead of flat laps: the curve of the wheel might help to grab the bead and aid in the spin whereas a flat lap likes to flat lap. I’m finding that I make a lot of accidental facets that have to be corrected. I’m also finding that long beads can be difficult.
Well, that’s it for now. I actually have to make another run soon, but for now, I have to move on. I placed the steel “L” bracket on the list of things to do. I want to try some hardwood post/pin holders. But first: on to polishing in Part Three.