Date: Fri Sep 7 12:35:43 2007

Author: Bill Norwood

Subject: Re: cart fan recommendation?

Post:
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Hi Tom,



Yeah we have a couple of dozen of the Pasco models. Some maintenance is
required:



1. Props break (esp. the old wood ones) when colliding with whatever.

2. Props lose friction on the shaft.

3. There is an extraordinary load on the batteries and a lot of them get
used up. I recommend (but never got the go-ahead with reproducing a
prototype) providing a power supply with each cart and dangling wires etc. I
think the problems caused by the added force of the dangling wires would be
less than the problems with the unstable voltages of the batteries.

4. Students run them off the table. (Signage on each cart and on the
blackboard helps.) (Also foam rubber cemented onto large channel aluminum
clamped to the end of the lab table helps)

5. Rubber bands (which hold the fan & motor on the cart) rot. (Just wrap
cheap slightly elastic cord around them several times, and clever fingers
can still change the batteries without ever removing the cord.)

6. Fan guards are a damned nuisance to open up every time a prop comes
loose. Not many students complained of losing fingers before we added the
fan guards, which, of course, must waste a lot of energy)

7. One or two of the carts no longer travels in a straight line.

8. Occasionally a collision plunger gets busted.



Just start out with a clear set of protective rules, and you will save
yourself a lot of maintenance work.



Hope it helps.



Bill Norwood

Technician

Physics Elementary Labs

U of MD Physics Dept, College Park



_____

From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
Behalf Of Carter, Tom
Sent: Friday, September 07, 2007 11:57 AM
To: tap-l@lists.ncsu.edu
Subject: [tap-l] cart fan recommendation?



Folks,



Does anyone want to recommend one cart fan system over another? You
know...those little fans you mount on the top of a small low-friction cart
in an introductory lab to give the cart constant acceleration?



I see the big two are Vernier and Pasco. Does anyone have five years or
so of experience with either (or both) and want to comment? Are there
other fan systems that will fit on a standard Pasco (or Vernier) cart?



I'm interested in reliability over a four or five year period.



Thanks.




tom



P.S. For the record, I'm a poor community college instructor (oh, whoa is
me!) so solutions like "I went down to my machine shop and built my own from
the ground up" don't do me any good. Well, I guess I could do that, but,
maybe I'm just too lazy.









--------------------------

Dr. Tom Carter

Physics

College of DuPage

(o)630-942-3346

http://www.cod.edu/people/faculty/cartert


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Hi =
Tom,

=


Yeah we have a couple of dozen of =
the Pasco models. =
Some
maintenance is required:

=


1. Props break (esp. the old wood =
ones)
when colliding with whatever.

2. Props lose friction on the =
shaft.

3. There is an extraordinary load =
on the
batteries and a lot of them get used up. I recommend (but never got the
go-ahead with reproducing a prototype) providing a power supply with =
each cart
and dangling wires etc. I think the problems caused by the added force =
of the dangling
wires would be less than the problems with the unstable voltages of the
batteries.

4. Students run them off the =
table. (Signage
on each cart and on the blackboard helps.) (Also foam rubber cemented =
onto
large channel aluminum clamped to the end of the lab table =
helps)

5. Rubber bands (which hold the =
fan &
motor on the cart) rot. (Just wrap cheap slightly elastic cord around =
them
several times, and clever fingers can still change the batteries without =
ever
removing the cord.)

6. Fan guards are a damned =
nuisance to
open up every time a prop comes loose. Not many students complained of =
losing
fingers before we added the fan guards, which, of course, must waste a =
lot of
energy)

7. One or two of the carts no =
longer
travels in a straight line.

8. Occasionally a collision =
plunger gets
busted.

=


Just start out with a clear set of
protective rules, and you will save yourself a lot of maintenance =
work.

=


Hope it =
helps.

=


Bill =
Norwood

Technician=


Physics Elementary =
Labs

U of MD Physics Dept, College =
Park

=










From:
tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On Behalf Of Carter, Tom
Sent: Friday, September =
07, 2007
11:57 AM
To: =
tap-l@lists.ncsu.edu
Subject: [tap-l] cart fan
recommendation?









Folks,











Does anyone want to =
recommend one
cart fan system over another? You know...those little fans you =
mount on
the top of a small low-friction cart in an introductory lab to give the =
cart
constant acceleration?











I see the big two are Vernier and =
Pasco. Does
anyone have five years or so of experience with either (or both) and =
want to
comment? Are there other fan systems that will fit on a =
standard Pasco (or =
Vernier) cart?











I'm interested in =
reliability over
a four or five year period.











=
Thanks.











=
&=
nbsp; &n=
bsp; &nb=
sp; &nbs=
p; =
; =

tom











P.S. For the record, I'm a poor community college =
instructor
(oh, whoa is me!) so solutions like "I went down to my machine shop =
and
built my own from the ground up" don't do me any good. Well, =
I guess
I could do that, but, maybe I'm just too lazy. =


































--------------------------





Dr. Tom Carter





Physics





College of DuPage





(o)630-942-3346





http://www.cod.edu/people/faculty/cartert











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