Modify a normal servo to wench servo on RC sail boat.

 A RC wench servo required several turns, since GWS died, it's not easy to get one. Thunder tiger also have such servo before, but not any more.

My first idea is to use step motor, with limit switch on belt(served to get first ), like the rail system in 3D printer. These ULN2003 + 28BYJ-48 5V is  very cheap, but after testing, the torque does not seems promising. 

The motor is geared, so the holding torque is quite good, but the motor current is quite low, so the turning torque is low, and can be stopped by hand. with SW control with 2 phases engage, is still the same.

The multi turn servo has a set of reduction gear on the VR, I came across on web with these toy gear, with 0.5M, I decided to make a reduction gear from out side.

I took a metal gear servo, the gear to attached servo horn has a internal M3 threat, I put a very long M3 screw from inside, the the first 15T toy gear is fixed on it.

2nd gear is a 50-10 gear, the the last one(50T) is attached on VR.

this give me a 7 turns servo. it works! The torque is good, the down side is that, if you turn the servo, the dead band is about 5 degree. But it should work  on a sail boat wench.

I made it as a linear servo, but the death band is large, also, it's difficult to keep the tesnsion.

2024/4/27

This is an example of making a multi turns servo for genoa:

https://rctw.net/thread-354800-3-1.html

The idea is to use a 10 turns VR, which is quite large.

Here comes an idea of using small multi turn VR:

First idea is to link this to final gear of servo, But, the turn knob is too small, not easy to do it.

But, there is another version of this:

The shaft is about 4mm, which seems possible to attached to some thing.

By using GT2 belt and pully(easy to find with 3D printer shop) it seems possible to make a linear servo system.