Clive, just been out to measure.
When I first got the Clarkson, it came with a spindle extender, which I duplicated with a slightly longer threaded part.
The original spindle on my Mk1 projects 32mm from the mounting face; my home made one has 38mm stud.
The recessed part of the wheel is 20mm thick; the wheel was supplied with a plastic spacer to ½” diameter, so fits the Clarkson fine.
The recess is 71.5mm in diameter, and with the current state of wear/dressing is 20.5mm deep
I needed to come up with some wider mounting washers, as the wheel hole id 31.75mm.
The first washer on the spindle extender has a ½” hole, next on goes a cardboard washer and then the wheel complete with its bore converter.
In my case I used an outer washer with a larger diameter hole, as I was now running out of spare thread to secure everything.
I made a suitable left handed nut, but turned some of the flats down to fit the hole in the outer washer.
Also made a fully round guard, so just the end face of the wheel is exposed.
As supplied, my wheel(s), I have two, another for the Herbert Junior, came without any mounting cardboards, and hence no spec or ratings.
I asked Axminster about this, who then queried their supplier.
There was just a number stencilled onto the wheel, can’t remember what now, but it turned out to be the maximum surface speed at the periphery in either metres/sec or feet/sec; either way it was fine for the Clarkson on the lower speed, and also OK for the Herbert.
There was a further email exchange, as I couldn’t get either wheel to pass a ring test for me, so I asked if there was something odd about the bonding agent.
They tried their own stock and had a similar problem. I’d just used a plastic screwdriver handle; they used a “purpose made wheel tapper.(ring test)”, whatever that may be.
Essentially they needed to tap harder than expected with these wheels for some reason.
Suggested I did the same and make a close visual inspection.
That was when I made the full periphery guard, and stood well clear on power up.
The strange thing I’ve noticed in use is the discolouration as the wheel gets slightly loaded with metal dust.
As expected it blackens a bit, but there’s a tide mark about 2/3 of the way up the side of the wheel; it doesn’t seem to affect anything.
Bill