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Re: Bumpers etc.
On Tue, Mar 14, 2000 at 02:22:45PM -0500, Cindy Wong wrote:
> > From Cindy:
> > Superglue (is it in the locker?)
I have all of these things in my room.
Joyce, I think the glue is a very bad idea. Please, please, (PLEASE!)
talk to me before trying to glue these things into place so that I can
explain why I am convinced it is a bad idea.
1) The current pulleys don't work. Even after I replaced the heat
shrink on the one and properly melted it, both sides still got
chewed-up too quickly. I'm toying with the hypothesis that PWM
modulation of the motors causes the heat shrink to wear down faster,
but don't hold-out much hope for this hypothesis. It looks pretty
As Joyce saw today, the metal epoxy on the one pulley was chewed-up
almost immediately by the belt. However, right now, I wonder if my
hypothesis about the metal epoxy somehow impregnating the heat shrink
and thus strengthening it was so far off. I replaced both heat
shrinks for testing. Both of them _seemed_ to wear faster than the
one that had the metal epoxy on it. But this is a purely 100%
qualitative judgement, unfortunately.
I tested the cog and belt that I purchased at Active. The cog fits
onto the motor shaft quite nicely, but there's no way the two will
work together. The cog just spins uselessly under the belt, even
with significant tension applied on the belt. Unless we can find
belts that match the cog (or vice-a-versa, perhaps Surayai's
Lexan-based cog suggestion), it simply doesn't have a chance of
working. The belt does adhere to the large pulley on the wheel
very (surprisingly) well, though.
On the positive side, the belt is completely indestructible. If we
can make it work, it will save us many replacement belts.
2) There were no tip120s in stock at Supremetronic.
3) I thought the left opto-encoders was broken. I think maybe it
was: it had gotten mostly pulled out of the solder connections. I
simply did some resoldering. The left wheel also had a lot of play
in it, and I think that this is why the encoder on that side got
mauled twice (once at the lab, and then when I did a test-run today).
I tightened the appropriate nuts on the left wheel.
However, the voltage supply to the left encoder is not working. No
idea why. Maybe a cold or loose solder connection? It seems to be
failing at the source. If I use the power supply from the
rightside encoder, it works.
I'll give you (Joyce) the power supply board tomorrow to figure-out
what's up. It's just a simple broken wire or loose solder
connection somewhere, so it shouldn't take too long to fix.
4) There are only a couple of the small rubber belts left. I didn't
realize this when I went shopping for Joyce today. Next person to go
down to Active gets to buy them. Buy many. Don't let them charge you
more than 25cents per belt. They're labelled at $1.00 but the old man
will give them to you for 25cents. They're not worth $1.00 at the
rate that we chew them up.
> > From locker/Tim:
> > New sensors
22sensors + 8ft*4strands-wire @ $40. Got'em.
> > guys hopefully) before Skule Nite ends. After Skule Nite, Tim should come
> > by and pick up the robot so that he could test the comp program. If I am
TBH, I can give you a simple working comp program without doing any
real testing at all... Bouncing off walls is easy, and we've already
acknowledged that this is going to be mostly a sop to the TA.
Nonetheless, I'd rather run the real Qubit and do some testing.
Signature withheld by request of author.