Bruce

All things small and scratchy.

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earthwormjim
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Bruce

Post by earthwormjim » Thu Nov 04, 2010 6:08 pm

Thought I would start a topic on Bruce,as I am going to start again with him.
Hope no one minds. :)

I have stripped off all the bodywork,and had a look at the drive servos,as it has been possibly as much as 10 years sinc the last time they were looked at properly.
The label is long since gone,but they are fairly unique servos,due to the molding where the shaft exits.
I can't honestly remember the exact mod,but the lego output shart is epoxy'd onto one of the gears,and I think that at least 2 reduction gears have been removed,and there is a 3mm nut used as a washer to fill the space where the gears used to be...
Image
I am going to rebuild Bruce in a similar fashion,but with an eye on being a little more robust,(hopefully!) :D
Cheers,James

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Post by alasdair » Thu Nov 04, 2010 9:15 pm

How did you get him to go so fast?! With servo drive I thought he would be super slow! :-?

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earthwormjim
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Post by earthwormjim » Thu Nov 04, 2010 10:15 pm

alasdair wrote:How did you get him to go so fast?! With servo drive I thought he would be super slow! :-?
As far as I can recollect,the three final reduction gears have been removed,so the gearing has changed hugely from when the servo was made,but it has also reduced the torque as a result.

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joey_picus
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Post by joey_picus » Fri Nov 05, 2010 12:55 am

It's still one of the best built fleaweights I've ever seen :) at the risk of sounding a bit noobish, how did you get the lego adaptor to sit centrally on the gear?
Joey McConnell-Farber - Team Picus Telerobotics - http://picus.org.uk/ - @joey_picus
"These dreams go on when I close my eyes...every second of the night, I live another life"

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earthwormjim
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Post by earthwormjim » Fri Nov 05, 2010 8:02 am

Joey wrote:It's still one of the best built fleaweights I've ever seen :) at the risk of sounding a bit noobish, how did you get the lego adaptor to sit centrally on the gear?
Pure coincidence! The shaft fits perfectly through the hole in the casing,and the shoulder on the shaft fits snuglt against the inside of the casing too.So I put a small dab of epoxy on the gear,attached the shaft,then put the casing on.When the epoxy had dried,I opened the casing,and added a load more epoxy to make the joint a bit more permanent!

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earthwormjim
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Post by earthwormjim » Fri Nov 05, 2010 10:25 am

I have been searching servo pics and stats this morning,and have found Bruces drive servo...
Image
It is available here...
http://www.robotshop.com/eu/gws-pico-st ... n=GoogleUK
For about ?8,(non UK site.)
Or here...
http://www.shop-uk.high-torque.com/inde ... s-GWS.html
For ?18.66,(UK site!)
They are also listed on Pololu's website...
http://www.pololu.com/catalog/product/501
Enjoy! :D

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Post by peterwaller » Fri Nov 05, 2010 11:30 am

I remember them my first ever antweight reobot Combatant started with those for drive. I seem to remember the output shaft was a bit floppy so I put a bearing out side of the wheel to give more support.
http://i109.photobucket.com/albums/n66/ ... 160097.jpg
They were only held together with a piece of heatshrink and the label.

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earthwormjim
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Post by earthwormjim » Fri Nov 05, 2010 11:40 am

peterwaller wrote:I remember them my first ever antweight reobot Combatant started with those for drive. I seem to remember the output shaft was a bit floppy so I put a bearing out side of the wheel to give more support.
http://i109.photobucket.com/albums/n66/ ... 160097.jpg
They were only held together with a piece of heatshrink and the label.
Thats right,Mine are held together with masking tape! :)

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earthwormjim
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Post by earthwormjim » Fri Nov 05, 2010 11:47 am

I dont suppose anyone has a spare servo arm for an SD 200 servo in their collection of old parts?
Bruces was ripped in half! :(
I would be very grateful.
:)

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peterwaller
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Post by peterwaller » Fri Nov 05, 2010 2:09 pm

I have never used that servo but Galaxy Models sell the arms.
http://www.galaxymodels.co.uk/detail.as ... 9&rootid=2
Strangely they have the pico servo's on offer for ?4.99 at the moment

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earthwormjim
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Post by earthwormjim » Fri Nov 05, 2010 2:35 pm

Thanks Peter. :)

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Post by earthwormjim » Fri Nov 05, 2010 4:21 pm

At AWS33 I saw a few people using the throttle cut switch to operate flipper servos,on dx6i Tx's.Which I thought was a great idea,although the location of the button,(over the RHS stick),wasnt ideal.So I have run some cable from the switch terminals inside the case,over to the side of the LHS stick,and mounted a push button on a small piece of carbon...
Image
It seems to work very well,and is comfortable to use. :)

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Post by earthwormjim » Fri Nov 05, 2010 5:07 pm

I thought I would make a chassis for bruce out of some 1mm carbon I got to play around with. I have made cut outs for the flipper servo shaft,the drive servos,and the battery.I put masking tape over the shiny surface of the carbon,as its easier to mark out,and will hopefully protect the nice shiny surface! :)
Image

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Post by earthwormjim » Sat Nov 06, 2010 9:58 am

I have decided that 1mm carbon is too brittle to make such small pieces with.(In other words,my fingers are too fat!:D )The layers separate under stress.Probably something to do with using a wood blade in the Jigsaw to cut it with!! :o
Anyway,I have decided to build using the 1.5mm glass fibre board that Peter gave me,and this is going to be a new flea,to partner "Bruce".Code name...
"The blue ringed Octopus" :roll:
Looking at Bruce,all the chassis parts are intact,they all only broke at the glue points,so in theory,I should be able to clean her up,and reassemble! :)

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Post by joey_picus » Sat Nov 06, 2010 10:38 am

I find it rather odd that 'Bruce' is referred to with feminine pronouns :P a bit Blackadder in nature perhaps...

Do you have the weight for a mechanical connection between all the chassis/armour parts, or is it right on the weight limit?
Joey McConnell-Farber - Team Picus Telerobotics - http://picus.org.uk/ - @joey_picus
"These dreams go on when I close my eyes...every second of the night, I live another life"

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