From bruce@ashbysolutions.com Mon Mar 12 06:13:26 2001
Subject:The V-C knob on the CX-3

All,

I finally got around to doing something about the loose feel of the V-C
knob on the new CX-3, which tends to overshoot the intended value when
moved quickly. Here's what I did --

1. Remove the knob; it just pulls off with finger pressure, although it
takes a little bit of a tug the first time out. Turn the knob over, and
you'll see that it's hollow, with a tube sticking up through the bottom to
attach to the rotary switch.

2. You'll need a flat rubber plumbing washer about 3/4" (19 mm) in
diameter x 1/16" (1.6 mm) thick, with a hole about 1/4" (6.4 mm) in
diameter. (The hole should be just a little smaller than the tube area of
the knob.) Luckily, this seems to be a common plumbing part: If you can't
find one individually, then buy one of those plumbing repair kits with the
bunch of different washers; there should be at least one in the kit. The
color of the washer doesn't matter -- it's smaller than the knob, so it
doesn't show -- but the washer should be a little bit glossy on the
surface, rather than having a completely matte finish. (You'll see why in
a minute.)

3. You need something behind the washer to shim it up until only about
1/64" (0.4 mm) of the center shaft is exposed. You could probably use more
rubber washers, but I only had one at the time, so I used a rubber foot of
the proper height from my tool box -- 9/32" (7.1 mm). I don't have the
part number, but they are grey colored, and available in a 4-pack at True
Value hardware stores in the US.
The foot has a center depression (for the screw head) of about the same
diameter as the knob, and I used an X-Acto knife to carve out the rest of
center to make the foot into a short, fat rubber tube. The actual shim or
shims used is not very important, but the height is. Also, while I could
have used a plastic or metal shim, I think the slight give of the rubber
foot is important to the overall feel of the finished modification.

4. Put the rubber foot into the bottom of the knob, with the wider side
facing the bottom (it's tapered slightly). Then gently force the plumbing
washer over the tube part of the knob. If everything works out right, the
tube part should show through the washer, protruding by the 1/64" amount.

5. Press the knob assembly back on the switch shaft, taking care to line
up the flat parts of the two pieces. Push the knob on all the way down,
but don't press so hard that you crack the PC board! The knob should now
resist movements, but the detent at each position should still be felt. If
you cannot feel the detent, then the knob is too far down on the
shaft. This is also the reason for using a semi-gloss washer; softer
washers stick too much, and remove the feel of the detents.

I've attached a .GIF of the finished knob assembly to this email.

I think this small change makes a big difference in the usability of the
V-C knob on the gig.

Regards,

-BW

--
Bruce Wahler
Design Consultant
Ashby Solutions"
www.ashbysolutions.com
CloneWheel Support Group moderator
978.386.7389 voice
978.776.0096 fax
bruce@ashbysolutions.com