Gearmotors/Servos - Really basic question

Most of the premade wheels are for Futaba-spline servos. So, get a Futaba, GWS, Cirrus (in-house brand of Hobby People mail order), or other servo that has a Futaba-compatible spline. Of the makes, GWS and Cirrus are probably the cheapest.

-- Gordon

I assume you are talking about hobby servos ? If so, it depends on =

I have a feeling these links might help you out:

Good luck ! JCD

Yes, you can gut the electronics, remove the physical stop, and use it as a gearmotor.

I'm partial to the Hitec line, but Futaba is also good. Select your wheels first, and then you should have no trouble finding a compatible cheap servo. Off the top of my head, LynxMotion.com has wheels for Hitec servos (get the HS-311, which should cost you under $10), and BudgetRobotics.com has wheels for Futaba servos.

HTH,

- Joe

That will work, but most people don't do what you suggest. Instead, they modify the servo for continuous rotation. This gives you a motor with a variable speed drive for cheap. Granted, it's not the best VSD. But it works. I think Hitec makes the best low-price hobby servos. Some are more easily modified than others. ServoCity.com has some good guidelines on their web site. They also sell all sorts wheels that will attach to them.

BRW

That will work, but most people don't do what you suggest. Instead, they modify the servo for continuous rotation. This gives you a motor with a variable speed drive for cheap. Granted, it's not the best VSD. But it works. I think Hitec makes the best low-price hobby servos. Some are more easily modified than others. ServoCity.com has some good guidelines on their web site. They also sell all sorts wheels that will attach to them.

BRW

Yes, but you may need to remove the moulded "stop" on the final gear to get

Deep.

Hobby Engineering sells servos without the electronics in them.

-Kit

Excellent, thanks for all the replies.

I'm thinking it would be a lot easier to build robots in the US (I'm in the UK) - all the shops seem to be there!!!

The only place I've foundis Technobots.co.uk who have a good range but seem to be about twice the price of US stores :o(

Oh well....

Gareth

Hobby Engineering says on their website that they will ship international. But they don't give the shipping cost.

There is also Solarbotics

-Kit

Didn't realise Hobby Engineering would ship to the uk, will look into that.

I knew Solarbotics did but unless you pay $40 it takes 4-6 weeks and isn't insured or tracable....

Gareth

That's funny -- I'm in the US, and I've often thought the same thing about the UK. There are a LOT of robotics/electronics resources in the UK, often carrying things we can't easily get here in the states. Unfortunately, I don't collect those links, so I can't point any out to you... but keep looking, they're certainly there.

Best,

- Joe

Other UK stores that you may wish to check out are:

The other place that I have bought things from is ebay. there are loads of component suppliers on ebay, (you can get some really cheap servos shipped from Hong Kong) you can get lots of component packs/materials/tools etc quite cheap on ebay, its now pretty much my main source of components.

hope this helps,

Lee.

That servo is made by GWS (but is a special item). Try

-- Gordon

Thanks Gordon. They don't seem to carry that special server, oh well.

Final question on this subject...I read somewhere that servos aren't very consistent when it comes to speed. I was hoping to create a four wheel drive robot with one servo driving each wheel but if they all run at different speeds it's not going to work very well!!! :o) Is this true??

Thanks

gareth

They aren't any more/less consistent than any open loop motor. You might used encoders to control the motors on opposite sides, and make sure there is sufficient wheel slippage for the motors on the same side. That seems to work well.

-- Gordon

O.K. I lied - another question...

How do you get wheel slippage with a wheel attatched to a servo?

Ta

Gareth

A wheel surface that doesn't "grip" the road too much. A medium to hard plastic might be good. A real soft rubber would probably not be.

This is the kind of thing thing where you know the problem when you see it.

-- Gordon