Alt-BEAM Archive
Message #10256
To: beam@sgiblab.sgi.com
From: Ben Hitchcock beh01@uow.edu.au
Date: Wed, 16 Feb 2000 08:43:52 +1100 (EST)
Subject: [alt-beam] Re: My pvore wont grip!
Hi,
I find that the most difficult part of any robot is the mechanics.
So you are not alone!
> Arg. I got my modified photovore working, but it wont move. The motors turn,
> but wont grip. I've tried putting wire insulation on then. Didn't help. I've
> put sticky tack. Won't turn. I've tried putting LEGO wheels on them! Still
> would turn. Arg.
Try some heatshrink. i got a couple of tubes from my local electronics
store for about $2 I think. I put two layers on my motor shafts, and
bingo! No slip, and the
robot moves very well, even on a polished steel oven tray (Don't tell my
housemates this!)
> Also, is it alright for the motors to have some play in
> them. I mean like the shaft will slide in and out? I find that when the
> shaft on one of my motors is pushed in it wont turn very well. How do you
> fix this play? Thanks
I know what you're talking about, and it is a problem. If you are using
pager motors, some types have a couple of little white nylon washers that
live on the shaft, external to the motor itself. These get pushed down
the shaft if you punch the weight out, or if you push too hard on the
shaft itself. It's pretty simple to fix - just grab the shaft, and push
the washers back down so they're flush with the motor bearing. Now gently
wiggle the shaft. You should have a tiny bit of in/out movement. I
estimate that I get about 0.1 mm movement when it's all adjusted right.
If you push the washers too far then the shaft gets jammed from the
washers rubbing against the bearing. Just pull the shaft out and try
again if this happens.
hth,
Ben
10257 Tue, 15 Feb 2000 17:06:12 EST [alt-beam] Re: My pvore wont grip! beam@sgiblab.sgi.com JVernonM@aol.com In a message dated 2/15/00 3:03:42 PM Eastern Standard Time,
william@characterlink.net writes:
> Also, is it alright for the motors to have some play in
> them. I mean like the shaft will slide in and out?
Nope, you have just discovered the major flaw in removing the weights from
pager motors. That is, the weight is part of the centering mechanics of the
motor shaft. When the weight is removed, the shaft can move in and out
slightly, dramatically hindering performance. The only solution is to add a
very small tube to the shaft to take the place of the removed weight. If you
notice, there is a small nylon washer (sometimes more than one) that is left
on the bottom of the shaft after the weight is removed. This is the spacer
for the weight, but it doesn't hold the shaft in place. Snug the tube (metal,
plastic, it doesn't matter as long as it grips the shaft tightly and holds it
in the proper place) down to this washer(s) but don't go to far. This works
well if the tube is also very thin or you will end up with the previously
posted torque problem. This tube, as far as I can gather, is the only reason
Dave's motors are priced at 10 and 15 dollars each. They come from the
manufacturer with the weight removed and a tube already installed (actually,
the tube is installed instead of the weight). If, like me, you would rather
pay a more reasonable 2-3 dollars each, I'd suggest using the tap or
crush/cut method of removing the weight, being VERY careful not to move the
shaft at all. Once removed, carefully add the tube. Be aware of pushing the
shaft in as well. One method is to use shrink tube only a few millimeters
long. Slide it down to the spacer, shrink it down, make sure it's in the
right spot and add a drop of superglue to the outside edge of the shrink
tubing. This will creep down into the space between the tubing and the shaft
and lock it in place. Not to much, or you know what will happen. This method
avoids damaging the motor by pushing the shaft down while trying to add a
stiffer tube. Those pager motors are a tender lot. In truth, the only way to
insure (at this time) that your photovore won't stop working because of motor
shaft problems in the future is to bite the bullet and buy them from Dave.
You just can't match the quality of a factory manufacturing process in
keeping a weight free motor reliable. It is a shame that a quality built
popper can't be freeformed without quadrupling the parts cost in order to
install reliable motors. And lets not go into shipping and "handling".
See ya,
Jim
http://www.geocities.com/SoHo/Exhibit/8281/beamart.html
ICQ# 55657870
10258 Tue, 15 Feb 2000 17:06:43 EST [alt-beam] Re: My pvore wont grip! beam@sgiblab.sgi.com BUDSCOTT@aol.com WOW! no wonder one of my pvores wasn't workin as well as the other. I had
some MPJA p-motors on it and i must have pulled that s.o.b. out really far, i
pushed it in a good 3 mm, now it works a ton better, thats awsome. thx for
the indirect help. Keep on BEAMin
-Spencer
10259 Tue, 15 Feb 2000 14:28:48 -0800 [alt-beam] Re: ....still more questions, thanks..... beam@sgiblab.sgi.com Bruce Robinson "Scolman,Jim" wrote:
>
> Hi Bruce......but the first kit I just finished had a tiny wheel
> glued to the motor shaft.......how is this any different that
> gluing a tiny wheel and tire to EACH motor shaft?
The wheel is not glued or attached to the motor shaft in any way. The
wheel is mounted on a separate shaft and can spin freely. The motor
shaft is parallel to the ground and RESTS on the outside surface of the
wheel.
Kinda like (seen from the end of your robot) ...
+-------
|
======| MOTOR
/ \ |
| | +-------
| |
| |
| |
====== WHEEL
| |
| |
| |
| |
\__/
This is also a useful way to solve the problem of the "floating" shaft
on pager motors. Take a look at Steve Bolt's site. He has a few robots
that use this configuration, with good closeup photos and some
tutorials.
Bruce
10260 Tue, 15 Feb 2000 17:45:24 EST [alt-beam] Re: complete walker beam@corp.sgi.com Bumper314@aol.com Well I got the thing working. I had to run the enable pin to ground and not
+, so it was a stupid mistake. But, my other walkers, he eventually gets his
legs all off center and starts just turning in circles. he also takes very
small steps, I doubt if he can even go over my hand. I hope this new chip
with more current will do the trick. thanks to all who helped
Steve
p.s. that chip that has 65mA ouput is the BCT, sorry for the mistake
10261 Tue, 15 Feb 2000 15:54:50 -0700 [alt-beam] Re: Mark Tilden's BOOK beam@sgiblab.sgi.com Dave Hrynkiw At 09:07 AM 2/15/00 , AprLBrooke@aol.com wrote:
>FWIW, I saw something recently that said that MIT press will have some BEAM
>books out next year, incl. one by MT.
DId you see the postscript at the end of the Smithsonian article? The guy
who shot the pics will be publishing a book thru MIT press of the robots,
with a large number of images of Mark's bots.
-Dave
---------------------------------------------------------------
"Um, no - that's H,R,Y,N,K,I,W. No, not K,I,U,U, K,I,_W_. Yes,
that's right. Yes, I know it looks like "HOCKYRINK." Yup, only
2 vowels. Pronounciation? _SMITH_".
http://www.solarbotics.com
10262 Tue, 15 Feb 2000 17:10:04 -0600 [alt-beam] Re: ....still more questions, thanks..... alt-beam@egroups.com Ben A Micklin Does anybody know how to solder several calculator cells in a series to
obtain w workable voltage? And what is the average voltage/mA for a calc
cell?
Anyhelp from experianced BEAMers would be appreaciated.
~ben~
On Mon, 14 Feb 2000 16:04:58 -0500 "Scolman,Jim"
writes:
> Hi, my first solar robot project, kit, is a success. Thanks for all
> the
> answers to my questions. Here's another.....the solarpopper style
> robots....the two motor ones, why do they run on just the tubing
> covered
> motor shafts?.......why not wheels of some sort?.......is it because
> of the
> mechinical leverage envolved, a large wheel has a long lever arm,
> etc.
> Thanks......JWS.
>
> Jim Scolman
> AMS Services, Inc.
> Bothell, WA
> 425-402-1000 x353
> 206-910-6095
> scolmaji@amsworld.com
> Network Administrator
>
>
>
------------------------------------------------------------------------
> eLerts!
> It’s easy. It’s fun. Best of all, it’s free.
> http://click.egroups.com/1/1234/5/_/5594/_/950634661/
>
> -- 20 megs of disk space in your group's Document Vault
> -- http://www.egroups.com/docvault/alt-beam/?m=1
>
>
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10263 Tue, 15 Feb 2000 19:09:06 -0400 [alt-beam] miller tutorial "alt-beam@egroups.com" michael.hirtle@ns.sympatico.ca (Michael Hirtle) I know You told everyone about where miller tutorial site was moving to
and everything but I didn't catch the address, so does anyone know where
millers walker tutorial site is, I want to try and freeform a microcore
to night.
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