Team MedBots

All things antweight

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Max
Posts: 105
Joined: Tue Oct 08, 2013 3:14 pm

Re: Team MedBots

Post by Max »

Just had a thought, beetle weight motors!
Looking on eBay it says they weigh 78 grams which is 28 more than I'd like but may be able to get away with it, does anyone know what the reduction is on the built in gearbox? I'm wondering if there is a way of removing some weight from that with aluminium or plastic parts.
Rapidrory
Posts: 1160
Joined: Sun Nov 24, 2013 9:54 pm

Re: Team MedBots

Post by Rapidrory »

I use a single beetle motor in Skutter, and just about get it in weight as a walker... Have you looked at the standard cheap hobby motors? They're very cheap and should have enough torque to spin a robot without gearing.. http://www.ebay.co.uk/itm/DC-1-5V-4-5V- ... 1c50a3cb79
Rory Mangles - Team Nuts

Robots: Nuts 2 and many more...

NanoTwo Motor Controllers: https://nutsandbots.co.uk/product/nanotwodualesc
haz
Posts: 1855
Joined: Thu Apr 15, 2010 11:20 am
Location: Underwater Lair
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Re: Team MedBots

Post by haz »

I got 2 5:1 HP from the lovely Mr McConnell. Sadly my gearmotor powered saw ideas died a death (moar burshless needed) so if they are suitable give me a shout.
Max
Posts: 105
Joined: Tue Oct 08, 2013 3:14 pm

Re: Team MedBots

Post by Max »

Thanks for the offer Haz, I'll be needing 3 so would have to order an extra one.
I think I'll try and get hold of a beetle weight motor of someone and see what I can do to save a bit of weight. Thinking I could remove 1 stage of the gearbox and replace the steel casing of the gearbox with aluminium. The only other parts are a wheel, chassis, battery and some electronics so I might be able to get all that into 80 grams.
If it doesn't work out I'll take you up on your offer though
haz
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Location: Underwater Lair
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Re: Team MedBots

Post by haz »

replacing the steel casing is so much effort. You'd spend more doing that than buying 3 motors unless you have access to a cnc mill.
Max
Posts: 105
Joined: Tue Oct 08, 2013 3:14 pm

Re: Team MedBots

Post by Max »

Probably true! We do have a small cnc milling machine which hopefully they will get going soon so that could be an option. The reason to go for the beetle motor is should have a lot more power so I can get some decent speed and should accelerate quickly. Also they only cost a couple of quid so I think it's worth trying to get one to have a play about with to see what can/can't be done.
Max
Posts: 105
Joined: Tue Oct 08, 2013 3:14 pm

Re: Team MedBots

Post by Max »

From looking on FRA forums apparently there is only a single stage reduction of around 5:1, I was expecting 2 4:1 stages giving 16:1. This means I can just complety remove the gearbox and drive the wheel directly off the motor (hopefully). It will probably draw quite large current for an antweight so may need a large battery but hopefully should be able to get it all in weight.
Rapidrory
Posts: 1160
Joined: Sun Nov 24, 2013 9:54 pm

Re: Team MedBots

Post by Rapidrory »

The motors are 40g each... though make sure you get the ones with the plastic end cap rather than the metal endcap as they have more power... It may be worth having a look round to see if you can find any without gearboxes; they'll likely be a fair bit cheaper...
Rory Mangles - Team Nuts

Robots: Nuts 2 and many more...

NanoTwo Motor Controllers: https://nutsandbots.co.uk/product/nanotwodualesc
Max
Posts: 105
Joined: Tue Oct 08, 2013 3:14 pm

Re: Team MedBots

Post by Max »

40g should definitely be workable even with a 3s battery. Easier said than done finding the bare motor, eBay and AliExpress aren't coming up with much that is suitable, mostly it is smaller motors around 30g and only 6v which I fear will lack enough power.

Can anyone who has bought beetle motors from AliExpress remember which seller they used, if I know which ones sell good motors I can contact them directly to see if they episode be prepared to sell the bare motor.

But as usual I am impatient and would rather get one off a roboteer in the UK so I can get playing.
Max
Posts: 105
Joined: Tue Oct 08, 2013 3:14 pm

Re: Team MedBots

Post by Max »

Here is a test vid using a 9v block battery directly connected to a speed 400 motor:
http://youtu.be/TPPD3i9vUeA

It's fairly disappointing! It may be that the block battery cannot deliver the current but I think the motor just lacks the torque required as it is a high rpm motor (18000rpm no load). The beetle motors should be around 4800rpm so will hopefully have the lower speed and higher grunt needed to move the robot.
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