Paul Gerhold on thu 14 apr 05
Allright Vince what is your problem with the RK2. I have two of them, one
from 1976 and one from 1979 and they just seem to run forever and do whatever
is needed. The only time there seems to be any difficulty is about every ten
years or so when the rubber ring has to be replaced. Granted the wheel
requires some ability to get everything properly aligned, but once done it runs
forever. Now, I will admit limited experience with other wheels-but then why do
I need them.
Paul-in Florida which is paradise this time of year.
Vince Pitelka on thu 14 apr 05
> Allright Vince what is your problem with the RK2? I have two of them,
> one
> from 1976 and one from 1979 and they just seem to run forever and do
> whatever
> is needed. The only time there seems to be any difficulty is about every
> ten
> years or so when the rubber ring has to be replaced. Granted the wheel
> requires some ability to get everything properly aligned, but once done it
> runs
> forever. Now, I will admit limited experience with other wheels-but then
> why do
> I need them?
Paul -
The RK-2 is indestructible, and if you have gotten used to it, and have no
reason to remove your foot from the pedal while the wheel is running, then I
can see how it would serve you very well indefinitely. Every now and then I
get a student who prefers them over the other wheels. We have kept a few of
them around for that reason.
If you were familiar with the mechanical workings of the RK-1, you would
understand my complaints with the RK-2. The RK-1 was a beauty of a wheel.
The motor was mounted diagonally on horizontal slides, and the pedal moved
the motor back and forth horizontally, with the surface of the drive cone
running level. When you first press on the pedal, the point of the drive
cone rises up against the rubber ring on the jackshaft, turning the wheel
slow, and as you stepped further, a cone moved horizontally, and larger
diameter of the cone contacted the ring, turning faster. It was a far more
complicated system, but it worked so smoothly, and nothing ever wore out
except the rubber ring. Like the RK-2, the RK-1 is indestructible. But
with the RK-1, you can take your foot off the pedal at any time and it stays
at exaclty the same speed, with no creep, no change in speed. To me, that
is an extremely important feature in any wheel, especially one with such an
awkward foot position. Unfortunately, it is almost impossible to adjust the
RK-2 so that you can remove your foot from the wheel.
Now, there was some ambiguity with the RK-2s when they first came out, and
some were produced with a drive system similar to the RK-1. Any chance
yours are those type? On most of the RK-2s (the 20 units purchased for the
Craft Center in 1980), the motor was mounted directly on the pivoting shaft
operated by the foot pedal. Because of the weight of the motor, there is a
lot more drag on the shaft to begin with. The drive cone has a curved
surface. As you step on the pedal, the motor tilts, and the tip of the cone
comes in contact with the friction ring.
There is a whole series of other details in the RK-1 that are just beautiful
in design and operation. It is too complext to explain in an email, but if
you can find one and turn it over and really examine the mechanical
operation as you engage the drive, you will see what I mean.
Making pottery wheels and other ceramic equipment is just a tiny part of the
Shimpo Corporation. Their real forte is power transmission devices of all
sizes, from small variable speed units to drive systems for ocean liners.
The drive system on the RK-2 shows beautiful simplicity - far less parts,
far simpler construction. The problem is that it doesn't work nearly as
well as the RK-1. If you try to adjust the pedal so that it does not creep
when you remove your foot, it is difficult to change speed. The RK-1 drive
operates with smoothness and ease at all speeds, and when adjusted properly,
never slips or creeps. Shimpo simply designed a piece of machinery that was
far less expensive to produce, sacrificing efficiency of operation in favor
of greater profits.
I think they have learned their lesson. Every pottery wheel they have
produced since the RK-2 has been superior to it in almost every way,
although in my opinion, none excede the elegant efficiency of operation of
the RK-1. I love the RK-1, but I am 6'5" tall, and when I sit at an old
shimpo I look like I am riding a tiny tricycle. So I built an oversized
RK-1 from scratch, using only the drive cone and rubber ring purchased from
the manufacturer. That wheel has seen heavy use for 30 years, and I have
replaced the rubber ring only once.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
Vince Pitelka on fri 15 apr 05
> Unfortunately, it is almost impossible to adjust the
> RK-2 so that you can remove your foot from the wheel.
Of course I meant "remove your foot from the pedal."
Sorry -
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
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