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[Rob47]

I am build in a Leander frigate and the radar on the forward mast projects well out from center line, I want this to rotate and tried using gears but to no avail, then found those very tiny micro motors, which just happend to fit the radar support frame.  The problem I have is seems almost impossible to reduce the rpm, tried using a voltage reducer and the radar still looks like a helicopter trying to lify off, so any suggestions please.


Bob

[Capt Podge]

What size battery are you using, I'm thinking you could try just a single 1.5v or maybe a 1.2v


Ray.

[Fastelectrics]

I have used this type of motor. They are available in a range of RPM and voltages. https://www.ebay.co.uk/itm/224635776971?hash=item344d55efcb:g:bswAAOSwc05hXEgw

[mudway]

FYI, the 965 rotated at only 10 rpm.

[Rob47]

I have used this type of motor. They are available in a range of RPM and voltages. https://www.ebay.co.uk/itm/224635776971?hash=item344d55efcb:g:bswAAOSwc05hXEgw

Thanks for the link but they are way to big, I am talking about the micro motors used for vibration in gadgets, have posted pics so you can see


Bob

[Rob47]

FYI, the 965 rotated at only 10 rpm.

Ta for that at the monet it is doing 7,000rpm

[Rob47]

to clarify, this is the type of motor and the shot of the HMS Phobe mast shows the  large "Cheese radar at the top of the mast, as you can see it is mounted well forward so dirct drive up the mast not and option unless someoen has a really good plan.  The micto motors are decribed as coreless, does that have an impact?  I have tried running it at 1.2 volt as well


Bob

[JimG]

As a possibility could you slightly deepen the platform and use a rubber band drive to a larger slow motor in the mast? A small o ring might do the job.
Jim

[Rob47]

Jim
I had that as an idea, no need to deepen it plenty of room, only thing that stopped me doing that as elastic bands to fragile and once all sealed up and it snaps, tried to think of something else and yes "O" rings are the answer.


Bob

[John W E]

Hi Bob


Rather than use an 'O' ring for your drivebelt - go on to Ebay and Search for 'Cassette Drive Belts'.   You can purchase some square section ones of various diameters.   The other thing you can also use are Meccano Drive belts - they are very much the same thing.   The problem with 'O' rings is that they aren't designed to be stretched and used as a drive.   Although I do know certain folk use them and are quite happy using them.

Pack of Ten Assorted Rubber Drive Belts for Cassette, CD ROM, DVD Player etc | eBay
John

[BrianB6]

I would not worry too much about elastic bands.  After 40 years one still works on my corvette. 

[Rob47]

I would not worry too much about elastic bands.  After 40 years one still works on my corvette. 

 


Bob

[chas]

Maybe I've missed something, to reduce about 7000revs to about 10 needs 700 to 1 reduction. So a pulley or two isn't going to work. There are some very small motors and gearboxes around, what size do you need?

[Rob47]

Maybe I've missed something, to reduce about 7000revs to about 10 needs 700 to 1 reduction. So a pulley or two isn't going to work. There are some very small motors and gearboxes around, what size do you need?

Pulleys were not for the orginal motor but do work as the motor can be hidden in the mast, the one I riased the question on is as per the image its ideal as it fits the radar mast spot on and looks as if it should be ther, hence the preference for it,


Bob

[T888]

Rob,


Look at my Oliver Hazard Perry build re the radar and the video.

[Rob47]

Rob,


Look at my Oliver Hazard Perry build re the radar and the video.

Nice little motor but to big for the space availabe, 12mm l and 4.5mm w it seems no matter what voltage these motrs get they are fixed revs, managing to get a gear whell system sort of working so may be the way


Bob

[T888]

Hi Rob,


Have you thought about using fine s/s fishing wire. If you put to motor with the gearbox (using 3v rpm is 29rpm) I used in the main mast (if you have space) then run a plastic or brass tube bent to a smooth curve to the base of the radar. Using the s/s as a flex drive running in the tube.?

[John W E]

.... hows about using a defunct servo?   modify it to continuous rotation and disregard some of the electronics inside.   So you basically are wiring up the motor to no more than 6 volt.   Then, just run a shaft up the centre of the mast which has a 6mm pulley on it.   Maybe a 6mm pulley underneath the radar.  and.... hey presto a nice slow, rotating, radar.


You could control the speed of the servo with a cheap speed controller.   


John

[Rob47]

.... hows about using a defunct servo?   modify it to continuous rotation and disregard some of the electronics inside.   So you basically are wiring up the motor to no more than 6 volt.   Then, just run a shaft up the centre of the mast which has a 6mm pulley on it.   Maybe a 6mm pulley underneath the radar.  and.... hey presto a nice slow, rotating, radar.


You could control the speed of the servo with a cheap speed controller.   

No can do John, look at the image in eed to control the cheese radar which sits out on its own platform, two options are find a way to reduce the 7000 rpm motor or a centre drive up the mast then gears or pulley to the edge of the platform


Bob

[Martin (Admin)]

You could probably get a 'flexy drive shaft' in there Rob, seen that done a few times in models.
As there is 'no load' realistically speaking, shaft only needs to a 'hair' if spring steel rod, or even plastic rod!

https://www.ebay.co.uk/itm/165108292820?hash=item2671389cd4:g:v7AAAOSwgg5hW0di

[Rob47]

Solved
Two Pulley wheeels and drive belt, works a treat, now looking for small elsatic band as mallest drive belt has to be doubled, now need to rebuild the housing it all sits in, so it took some time but glad its done.

Bob

[Akira]

I have heard of folks using rubber bands , as drive connectors, used by dentists for people wearing braces.