Cheap components for an antweight class

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Shakey
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Re: Cheap components for an antweight class

Post by Shakey »

ozcoder wrote:Has anybody tried using a flight control board as an ESC?
This one has a DSM2 receiver and 4 x ESC, but I don't know if it would work in a robot.
http://www.hobbyking.com/hobbyking/stor ... ouse_.html
Those ESC's look like simple single FET channels so would have no reversing. Plus it'd probably need a firmware reflash.
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AWS 44, 45, 49, 51 & 55 Winner - Far too many robots!

EpicentrE
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Re: Cheap components for an antweight class

Post by EpicentrE »

Thanks for all the help everyone. I'm putting together a price list for this at the moment to be shown to the Fablab this week. I'm currently coming in at about ~£40 per robot including transmitter, excluding the bits we'll be making (wheels. chassis, etc). The only component I haven't decided on yet is a weapons servo. Does anyone have any suggestions of anything around the ~20g range which would be good for a variety of weapons, and can be got nice and cheap on eBay?
Scott Fyfe-Jamieson, Captain of Epic Robotics. Champion of AWS38/41/42.
http://www.epicrobotics.co.uk

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Shakey
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Re: Cheap components for an antweight class

Post by Shakey »

That servo sounds like a job for the MG90. A bit lucky dip in the exact specs of what you get but cheap and metal geared. (I wouldn't quite stoop down to SG90 levels as they strip a lot and as soon as one does it becomes more expensive than a mg90).
Nuts And Bots - For all your components and ready built antweights!

Alex Shakespeare - Team Shakey / Nuts And Bots / Team Nuts:
AWS 44, 45, 49, 51 & 55 Winner - Far too many robots!

EpicentrE
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Re: Cheap components for an antweight class

Post by EpicentrE »

Thanks Alex, that's great. I'll take this list to them later in the week and see what they think :).
Scott Fyfe-Jamieson, Captain of Epic Robotics. Champion of AWS38/41/42.
http://www.epicrobotics.co.uk

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UserFriendly
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Re: Cheap components for an antweight class

Post by UserFriendly »

ozcoder wrote:Has anybody tried using a flight control board as an ESC?
This one has a DSM2 receiver and 4 x ESC, but I don't know if it would work in a robot.
http://www.hobbyking.com/hobbyking/stor ... ouse_.html
Yeah, I have, used a heli board before. Pretty useless as I had it. As Alex says, no reverse. I would try something else first.
Andy B - Team UserFriendly
Reading Cybernetics Graduate 1996
Trying not to take Antweights too seriously. I think I'm failing.
First AWS was 46.

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peterwaller
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Re: Cheap components for an antweight class

Post by peterwaller »

Just bought 5 of the MG90S servo's for £9.55 with free delivery.
Ordered them Thursday afternoon and they arrived this morning and all work fine.
http://www.ebay.co.uk/itm/261214133155? ... EBIDX%3AIT

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peterwaller
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Re: Cheap components for an antweight class

Post by peterwaller »

They are surprisingly easy to modify to full rotation.
Remove the four screws.
Take off the gearbox cover.
Pull the output gear off the shaft this is quite a tight fit so needs a bit of pulling.
Image
The output gear has a plastic insert that runs on the shaft and acts as an end stop so you need to cut off the end stop part while leaving the centre as below.
Image
Drill out the plastic insert to 1.4 mm so it runs freely on the brass coloured shaft which is the feedback pot shaft.
Remove all the gears and plug the servo in to a receiver on the aileron channel and make sure it runs.
Then with the stick and trims centered adjust the pot shaft until the motor is stopped.
Put a enough hot melt glue into the pot mechanism as above to ensure it can't move but careful to clean any off the shaft.
Replace the gears and gearbox cover and ensure it all runs when connected to the receiver.
Replace the four screws.
You will find there is quite a lot of end float on the output shaft so I printed some small washers 7.3mm OD, 5.6mm ID and 0.7mm thick and placed it over the output shaft between the final gear and the plain metal bearing to reduce this.

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UserFriendly
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Re: Cheap components for an antweight class

Post by UserFriendly »

Looks good Pete, however, the teeth in your image seem to stick out, is that a problem?:

Image
Andy B - Team UserFriendly
Reading Cybernetics Graduate 1996
Trying not to take Antweights too seriously. I think I'm failing.
First AWS was 46.

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UserFriendly
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Re: Cheap components for an antweight class

Post by UserFriendly »

...actually, I think I see it. Those teeth are shorter aren't they?
Andy B - Team UserFriendly
Reading Cybernetics Graduate 1996
Trying not to take Antweights too seriously. I think I'm failing.
First AWS was 46.

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peterwaller
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Re: Cheap components for an antweight class

Post by peterwaller »

Yes they are shorter that is where the plastic end stop was.

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