If you are a member of AMYA, you have undoubtedly read the article of constructing a drum winch in the 1993 summer issue of the MY Quarterly. To Jim Meister and I, we both have taken a great interest in this topic - making your own winch and save money by doing so. The first point to bring up is the time to build a winch maybe more than what some people would like. Note: the time cost is from 15 min. to 1/2 hour. So to help lower the time need to construct one, listed below are a few tips.
The first item needed is a servo to convert to a winch, one mention is a RCD 20 quarter scale or in other words the Hitec HS-700 1/4 scale servo which can be purchased from Frank's Hobby House, 992-3495. The list price is $49.95 but at Frank's the price is $29.95, a $20.00 dollars savings! The most simplest of winches to make is the lever type, now before you wrinkle your nose at this one, I am now using this type in a One Meter with success. To convert to a lever winch, it needs to have a 90 degree movement one way or in other words 180 degree rotation of the lever.
To do this, purchase two 1.5K 1/4 watt resistors and two 4.7K 1/4 watt resistors, a total cost, a whopping 40 cents. Once the servo is apart and after you have removed the top gears and circuit board, the small potentiometer can be seen in the servo's housing, in it's two brackets. To remove the pot, place your thumb on the pot's brass shaft and push on the shaft. Now, with a small screw driver, reach into the casing and push back each bracket carefully until the pot pops out.
Update Note: For further help, I have included a part from the article on Drum Winches, Number 92 of the Model Yachting Quarterly, Summer of 1993, page 39. "If you want to increase the number of turns, solder resistors on the brown and orange leads. (Orange is the center lead, brown is the bottom lead on the pot). They should be of 1k to 3k values. You can also use a pair of 3/4 turn 3k pots to make the number of turns adjustable, but space may be a problem."
Once that has been done, bend the 4.7K resistors leads at right angles at each end of the resistors. Then solder one lead of both 4.7K resistors to the center connector of the pot. Next, un-solder the two wires off the right and left connecters (make a note of which wire comes off which connector), and solder one 1.5K resistor to each right/left connector. Note - it is best to cut both leads of each 1.5K resistor to the length of 1/4 inch for ease and room. The last task is to re-solder the two wires on the resistors, one wire on each resistor.
You may have to bend the wired resistors to set the pot back into the servo so keep that in mind when you solder on the two 1.5K resistors. To insulate the two wires from each other, I used some clear finger nail polish or what ever you like. At this point note a little metal tab that sits on top of the pot. The tab must go into a square hole in the case, so line it up and snap the pot back into it's brackets.
Now the most important step, when you re-assemble the gears, the gear which goes over the pot must be done right. Turn the pot's shaft all the way to the right or left and place the gear which goes over the shaft. Here is the key, set the gear on the shaft with it's stop pointing in the same direction as the shaft. To test your work, carefully turn the motor's gear and watch the pot's gear turn. If it turns ok, put the top cover back on and screw in the four bolts. If not, think about what needs to be done and try again.
Well it sounds like a lot and it may be but, now you have a winch which works and you have saved some cash.
To finish up the topic of sail winches, part two will cover some points about converting the HiTec HS-700 1/4 scale servo (can be bought from Frank's Hobby House 992-3495 for $29.99), to a drum winch without going over what has been stated in AMYA's Summer MY quarterly.
The first point is the cost and supply of the Spectrol 10 turn 5k #44f1105R pot from Newark Electonics. The cost is $14.00 for each pot and you can only buy in lots of two. If you need just one, call around and see if you can find a replacement for the Spectrol pot.The second point is how do you remove the threaded neck of the pot? The best way is with a jeweler's saw (place to buy a saw is from Stoney's Rocks 985-5594 for around $16 and a bundle of 12 blades is $1.50). You will be cutting brass, so the saw will have no problem doing the job. Cut at the first ledge off the top of the pot. Then, to cut the pot's shaft, hold the shaft and saw off flush with the top of the pot.
Once done, you will have some saw shavings fall into the pot itself and it will need to be cleaned out. On the bottom of the pot you will see two hook clamps, take a small screw driver and pry them back, it is very easy to do. Once this is done the pot comes apart and you can clean the top of shavings. Note, the bottom lid of the pot, in the center there is a small round hole our new shaft will sit in. Once done cleaning, put the pot back together and we will go to the feedback shaft.
I have tried a plastic shaft but I had problems with the shaft twisting. When hand turning the spool and coming to the end of the tenth turn, plastic is soft and breaks. Instead, use 1/8 brass rod. It is strong and just the right diameter. Once everything is together,you can hand turn the spool and when you come the end, it stops. The first step is to round the bottom of the rod, this will go into bottom round center inside to the pot. Next saw off 1 1/4 inches up from the round bottom. At this point you can saw or file a 1/4 inch notch which will fit up into the bottom slot of the gear.
Once done and it is together, now comes gluing. Insert the rod into the pot and take a note where the rod stops at the neck of the pot. Then bring the rod out a 1/4 inch and apply a good amount of CA glue. Then quickly push (with care), the rod back in. Once done, turn the rod so all the glue will make contact.
After the soldering on the leads on the pot, do not glue the pot in the servo's case. This way if the pot fails, it can be taken out for repairs. Since the fit of the pot is so tight, just drop it in and put the servo back together. It may turn a very small amount but that is ok, at the end of 10 turns a little give is less breakage.
Last is the spool, you can make your own but I think a spool from R/C Model Yachts and Accessories, (503)649-7707 may work. The spool I am thinking of is from the Mistral winch, because both the HiTec HS-700 servo and the Mistral have a round fitting for the spool to fit on. Any way, call and see if this idea will work.