I tried searching for a modern equivalent online and could only find one advert for a unit by Walsh Tools here in the UK.
I use a Graves Cabmate unit for scratch brushing. It’s intended as a
lapidary cabochon cutting unit, so it’s equipped to handle wet work.
The motor is dual speed, and the slow speed works well enough. I’d
prefer it a bit slower, actually, and if it were really needed, some
pulley changes could easily do it. The cabmate spindle easily mounts
a tapered threaded end such as used on buffing machines, and brass or
nickle silver scratch brushes easily mount on this. The fact that the
setup is also just as versatile for more usual cabochon cutting
tasks, or other grinding/sanding tasks, makes it a quite useful
tool. It gets used not just for scratch brushing, but cab cutting,
sharpening certain tools, polishing carbide burnishers with diamond
compound, and lots more.
Sometimes used cabmates show up on ebay, or of course, they can be
purchased new. And I’d guess that there are other multipurpose
cabochon cutting units designed originally for lapidary work that
would equally well handle scratch brushing tasks.
I normally use plain soapy water as the lubricant for scratch
brushing. A traditional lubricant was stale beer, but I’m not sure I
want to stink up my shop with that. Nor am I sure it works all that
One of the most common uses I have for scratch brushing is when
putting liver of sulphur patinas on silver. Instead of a dull black
patina, scratch brush burnishing gives a nice blue/black gun metal
color and sheen. More durable too, than, the plain unburnished