Motor Help

Hi,

I am building a custom guitar and i have a pickup mounted on two sliders (aluminium poles with linear bullbearing bushing). I then have a small pulley mounted one end and the servo mounted at the other with a belt attached to the underneath of the pickup mount. I have attached a quick google sketchup of what i mean.

My question is, the servo is generally quite noisy and i am using is as it has all of the gears built in for the motor to be able to pull the pickup. Is there any alternatives that anyone can think of with less noise?

Thanks

You could do it with a stepper motor which would be quieter but loads more electronics to run it perhaps

Is it part of the design that it has to be motorized? rout a slot in the rear and put a knob on the belt to move it back and forth manually or bring the shaft out to one side and a big knob on there

Hi,

Yes it is a big part of the design. I am running the servo using an Arduino so not sure it would be able to run a stepper motor?

Thanks

Is it noisy electrically or mechanically?

If the linear bearings are correctly aligned I would have expected the pickup to move with almost no force. If you need a motor with a gearbox then I supect that there are issues with the mechanics of the pickup arrangement. It would be best to sort those out before moving onto the motor arrangements.

Andrew

Hi Andrew,

It sounds mechanical, it has lots of grease and runs fine but just cant get rid of the noise plus when it is inside a guitar body the wood amplifies the sound.

The pickup slides perfectly fine with little effort but when i try and use a normal dc motor with no gears to slow it down it simply doesnt move.

Is it the servo gears that make the noise? On my rc helis some brands of digital sound like gerbils eating bubblewrap when rotated. From my heli experience a non digital may be quieter as would one with plastic rather than metal gears and a high end brand like futaba.

Well if you are running under arduino then a stepper motor is easy

Hi Jake,

You might look into DC gearhead motors. These are available in many levels of quality and sizes vary for ones with practical torque levels from about 6 mm OD to enormous ones 100 mm OD and larger. Good quality very quiet ones are available from Maxon motor but these are pricey. Less costly but slightly noisier ones are available from Jameco Electronics or Solarbotics. Have a google to find them online. I have no connection to any of these firms except as a satisfied customer.

Good luck with your project. JD

Arduinos are born to run stepper motors!

Just google "arduino stepper"

For an even easier solution use a Polulu board as used to drive the steppers in repraps. I have one running my telescope* drive

Neil

*redacted to protect the sensitivities of the innocent.

I would expect the pickup be to very easy to move just using ones little finger. Lots of grease is not needed, and may well be a hinderance. Ideal would be a little light machine oil, say sewing machine oil.

Is it safe to assume that the pickup doesn't move anything except itself? How fast do you need it to move, and how accurate does placement have to be? Without knowing full details I would have thought that a stepper motor driving through a leadscrew should be fine. Stepper motors generate most torque at low speeds. While the stepper motor drive would be open loop I not sure if there is any need for a closed loop servo system?

The axes on my CNC mill are open loop stepper motor driven and they repeat to better than 0.01mm.

Andrew

The servos I have come across rely on a lot of very free running gears, you might be better off with a worm wheel drive. each worm drive wheel should be worth at least two sets of gear wheels.

Frank

Or depending on how fast you want it to move and over what distance, you could try a small synchronous geared motor. Runs from mains, generates quite a lot of torque at a slow speed at the output shaft. Explore eBay, just type synchronous motor into the search bar.

You might find these of interest www.firgelli.com/products.php they are really quite good, very small and economical as well.

Mark

I would use a stepper motor and a toothed belt out of a printer to get speed and reliability. A modest stepper won't need additional gears. You could just transplant the head movement mechanism from an old inkjet printer wholesale.

Out of curiosity, wouldn't you be better having the drive motor at the side, so as to maximise the room for pickup movement without interfering with the neck or bridge?

That seems to be the way other people have done it, although there are some interesting variations on the theme - I like this one:

Neil

Running mains into a guitar - interesting concept on several levels.

Brian

Hi Guys,

Yea running from the mains isn't really what im looking for but thanks. I have found this **LINK** which im going to use. Im going to mount the small joystick at the top of the neck so this can be accessed easily and be used easily. Thanks for all your ideas and suggestions. I will post pictures of how i get on.

Thanks again.

Hi guys,

the guitar is built, thought id share the final product.

http://www.instructables.com/id/Custom-Arduino-guitar/

Thanks

Have you considered using a threaded rod instead of the belt ?. What sort of linear speed do you need and how many positions does it need to stop in ? A threaded rod may allow the use of a motor without a gearbox.

Les.