Working radar construction question.

[yngwie]

I wonder if someone have any suggestions for an working radar application for my Smit Rotterdam tug? Motor/gearbox assembly is allready solved. My problem is to connect the two radars without visible shafts. The space is limited because it´s scale. I´m sure someone have built this tug before and maybe has some ideas about how to do.

/Yngwie.

[Tony Oliver]

Fine gauge piano (22g) wire running in a curve? Through a few plastic guide tube bearings?

[Umi_Ryuzuki]

Small pulleys and a belt leading to a motor in the mast.
All set under, or inside the platform.

[yngwie]

The pulley/belt idea will be the best for now. But what do I use as a belt? Rubberband? Must be very small.

[Umi_Ryuzuki]

Look for some o rings at the Hardware store.
An old cassette, or micro cassette recorder may have what you're looking for also.

[Tachikaze]

I like Umi's idea. A single shaft up the mast with pulls extending out to the radar units. These units will rotate at different rates. I believe that the smaller one will rotate at 1.5 times faster than the larger one.
A dissassembled cassette player or old answering machine may have the geared rubber band. Also All Electronics cares gears and cables at time.

[Al Stein]

I think you'll find O-rings too stiff for this application, but the belt-and-pulley idea should serve well with the right kind of belt.

I don't suppose you can buy radio "dial chord" anymore? If not, a heavy braided nylon chord (like squidding line) should be effective. On radio dials, they used to put several turns on to avoid slipping... with the radars constantly turning in one direction, multiple turns would cause a tangling problem. A single loop around the pulley should give you enough purchase and you could add guides to keep the line from tangling.

Rubber bands would work really well, but they wouldn't hold up real long and it would be a real pain to replace them.

[yngwie]

Thank you guys! I had made an antenna mast of EverGreen plasticard instead of that grainy wood and added some scale touch to the radars and I even succeded to made the pullys of plastic. I can now decide the size of the pulleys and in that way made them to rotate in different speeds.

The parts in the picture may seems a bit roughly and blocky, but I will trim them of after the construction is set. The radarantennas next to my plastic antenna mast, is the brass ones from kit. Just for show how bad they look.

I did some overkill to the "radarmotor" (Candy lollipopmotor). I put some small ballbearings to every bearing points for super smooth running, and it sure runs smooth now.

/Yngwie.

[AustinTatious]

I wanted to suggest that you could ues small servos, and disable the POT, easy to do and you could adjsut speed and direction of rotation easily, plus you could stop and start them remotley

[Darrin H]

I have been using the old camcorder zoom/focus motors. There are tons of old ones at swap meets and garage sales. Usually get 2 per camera. Very nice with quiet o ring belt drive or sometimes gears. Run mine on 2 to 6 volts depending on desired radar speed. The motors usually have different ratios. Also used one for an anchor winch on a small tug.

DH

[JohnR]

I've used an old servo with the pot removed on my Perkasa, speed of rotation is fine and I can control it remotely