4 Sep
2011
4 Sep
'11
12:16 p.m.
OK, I've been measuring up the rollers. While I was doing this, one of
them disintegrated in my hands. So I did what any self-respecting
engineer would do.... I got the callipers and reverse engineered them!
The figures in the HP Journal are basically accurate. OD at the "wide"
end is 9.5mm, and ~0.23mm less at the "narrow" (tapered) end. The
complete roller is 6.5mm long, with a 2-degree taper. Given the angle
and width (Adjacent length), we can use trig to get the
height-above-base and the
The inner core is 6/10 Nylon, black, with a 3mm diameter hole drilled
through the centre. Eight equally-spaced wide teeth are formed around
the circumference, with a tooth depth of 0.5mm. Measured from the tip of
one tooth to the tip of the opposite tooth, the core has an OD of 7mm.
An embossed ridge is placed in the middle of the core at the same level
as the teeth, apparently to stop the roller slipping off laterally.
The thickness of the rubber coating is thus:
9.50 - 7.00 = 2.50mm at the wide end
9.27 - 7.00 = 2.27mm at the narrow end.
Would photos be of use to anyone?
My plan now is to use a pack of black Sugru to expand these rollers out
to ~12mm, leave them overnight to set, then try and machine them down to
the correct profile tomorrow with the lathe.
Cheers,
--
Phil.
classiccmp at philpem.me.uk
http://www.philpem.me.uk/