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Dec 06, 2018, 09:29 AM
Where's Pamela?
patmat2350's Avatar
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There are several details to add to the work deck area under the boat deck.

The watertight doors are paper-thin etchings, and need to have some backing added to give them the right look (arrow). Also, radius the corners some more.

The boat deck piece needs to have fascia glued on; thick ABS strip is provided for this. I'm debating adding additional beams underneath... the area is almost unviewable...

Life rings are nice little orange rubber moldings, held on with delicate PE brackets.
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Dec 07, 2018, 04:43 PM
Where's Pamela?
patmat2350's Avatar
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Tested a drive unit. Dry and unloaded, it ran about 3500rpm on 7.8v, giving an effective kV of about 455.

The vertical stem alone is very quiet... add the lower unit with the bevel gears, and it's a bit noisy. It would help if I loaded in more grease, and secured the lower unit lock screws.

This motor is custom made for KY, and isn't separable from the unit.

Prop diameter is 54mm. Being a 3d print in an "ABS like" material, I wouldn't spin it as fast as a brass prop. In brass, I'd want it to max out at 6200rpm... but I'm sure this will get a tug moving at a reasonable tug speed.

Fairplay 30 Drive Unit Test (1 min 1 sec)
Dec 08, 2018, 09:48 AM
Where's Pamela?
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Steering


There are simpler ways to set up the steering linkage, but I took some time to manufacture adjuster blocks here. Using set screws, it's a quick job to set the rod lengths without need for a turnbuckle arrangement, or popping the rod ends on and off.

The 3d printed steering arm has bosses that can be tapped to accept M3 screws. I used Dubro ball links at both ends- M3xM3 at the steering arm, and #2-56 screw/#4-40 rod at the servo... because I had them, and because they're a good fit.

The servo is a standard size, and I expect any standard servo will work here... though I'm using a fancy Hitec digital (because I had it...). The servo is mounted on a PVC foam board bracket, glued into the hull. Note that the servo output is centered in the hull... this is important for the linkage geometry.
Also important- you want to match the operating radii at servo and steering arm, or you will introduce some geometry issues. The radius at the steering arm is about 1.1" [28mm].
Note that the small travel of the steering arm produces 180 [90] movement of the Schottels.

I still haven't solved the wire control issue... but I'm thinking about a vertical wall just outboard of the push rods, to keep the wires out of the steering, along with spiral wrap on the wire bundles, and some sort of guide a bit farther forward. I can't stop the wires from flopping, just have to control where they go.

Another issue: The steering arm has pins to limit travel (hard stops), and the servo can drive hard against these stops. There's no servo-saver in the linkage, so I'll need to either program the digital servo with end-points, or do it in the radio. If the servo travel isn't limited, the servo will break the steering arm!

Fairplay 30 Steering (0 min 44 sec)
Dec 08, 2018, 12:38 PM
Registered User
Hello,

I'm new to this forum. I'm especially interested in this thread as I'm considering building either the Fairplay 30 or the Fairplay I after a longer hiatus from model ship building. I'm not decided yet.

In the meantime I have written reports about the real tugs for a friend's website, among others Fairplay I (including III, X, XIV). Living in Germany the reports were mostly of German and European tugs. I have photos of both tugs (I and 30) but can currently only use photos of Fairplay I. I got those of the 30 with the advice not to forward them to others. But I'm working on it.

I find this thread great and very informative. I hope it is allowed to support this thread with additional information?

So I try it.
I have a remark regarding the doors. In the closed position the thickness of the etched sheet seems correct. In the open position the doors need an in-fill panel.

The attached photos are of Fairplay I but Fairplay 30 has the same type of doors (I checked)

For the servo Hobby-Lobby Modellbau recommend a throw force of 20 lbs.
Volker
Dec 08, 2018, 05:50 PM
Where's Pamela?
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Welcome Volker, and thanks for the information!
Yes, the water-tight doors are different from what I assumed...
Dec 08, 2018, 06:11 PM
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OK, here's an improvement for the wire control... a wall next to the moving linkage, and slippery spiral wrap on the cable.

.

Fairplay 30 Steering, v2 (0 min 36 sec)
Last edited by patmat2350; Dec 08, 2018 at 06:20 PM.
Dec 14, 2018, 02:43 PM
Where's Pamela?
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I should move faster... but little jobs like installing lights turn into BIG jobs.

I will use LED surface mount "chips" wherever possible. I can run 2 of them on one circuit using 7.2V, or one... just choose the right resistor. I'm limiting them to about 15 mA each... 20 would be the max.

For exposed areas, I use 30 gage Kynar wrapping wire, and then transition to a larger gage once inside the hull. Each circuit will come back to a common board where all the resistors are mounted. For convenience, I'll plug each circuit onto the board, even though I don't plan to have to service them in the future.

.
Last edited by patmat2350; Dec 14, 2018 at 02:51 PM.
Dec 14, 2018, 03:51 PM
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Gravman's Avatar
Cool. Nicely done.
Latest blog entry: Myrtle Corey
Dec 14, 2018, 04:01 PM
Where's Pamela?
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Thx!

Got my pin crimper today, yay.

The stacked terminal block has one draw-back... the upper layer blocks the lower. Don't think it will be a real problem.
.
Last edited by patmat2350; Dec 14, 2018 at 04:37 PM.
Dec 14, 2018, 09:31 PM
Where's Pamela?
patmat2350's Avatar
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Wow, I will definitely sleep better now.

The steering arm/sector gear part is 3d printed plastic, and it has some hard stop pins to limit motion. I am sure that hitting these stops with full servo force will break something (so don't do that!).

I am using a digital servo, and I just received the programmer for it. Sweet- several parameters can be set, including end points and speed. I set the limits just short of the hard stops, and set the speed to as slow as she goes. So now, no matter what I do at the radio end, I won't overdrive the hard stops, and the Schottels will turn at a more realistic speed.


.
Dec 14, 2018, 09:40 PM
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Gravman's Avatar
Amazing the way things work these days. I remember when you had to have a different servo for a reverse movement. Course that was 45 years ago.
Latest blog entry: Myrtle Corey
Dec 15, 2018, 11:11 AM
Registered User
The motor wire management is greatly improved, but I worry about the wires entering the motor as the assembly turns back and forth through 90 degrees. The bends are not severe, and can probably handle several 1000 full turns, and many more partial turns. I wish there was a way to prevent localizing the bends at the motors. Is it possible to rotate the motor housing 180 degrees so that the wires enter the motor housing on toward the rear? The idea is to get the wires to wrap around the motor a half turn to limit the number of times the wires bend through 90 degrees close to the housing. Chances are, the wires will not break during the life of the boat, but the wires could fatigue after enough use. Distributing the bending motion along the longest possible length of wires will help extend the service life. The better approach is to twist the wires instead of bending, but that does not seem practical here. The larger the radius of the bend the better.
Dec 15, 2018, 11:14 AM
Where's Pamela?
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Possibly... but for the amount I run my boats, likely no prob!
Dec 15, 2018, 09:20 PM
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I may regret this.

The electronics box is removable for service... but in making it so, it's smaller than the volume available under deck... it has to fit through the deck opening. That means that four ESCs, the Rx, junction block, and all those wires have to be crammed in there. It fits... but can I get my hands in to make the battery connections? We'll see...

p.s.: I HATE rats' nests... but it's hard to avoid with prewired components like these. It helps to secure the items... these are all mounted in little boxes... but those wires just stick out everywhere. There must be a better way... send me a note if you know of one!

.
Dec 16, 2018, 05:44 PM
Where's Pamela?
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Quote:
Originally Posted by dbpage View Post
The motor wire management is greatly improved, but I worry about the wires entering the motor as the assembly turns back and forth through 90 degrees. The bends are not severe, and can probably handle several 1000 full turns, and many more partial turns. I wish there was a way to prevent localizing the bends at the motors. Is it possible to rotate the motor housing 180 degrees so that the wires enter the motor housing on toward the rear? The idea is to get the wires to wrap around the motor a half turn to limit the number of times the wires bend through 90 degrees close to the housing. Chances are, the wires will not break during the life of the boat, but the wires could fatigue after enough use. Distributing the bending motion along the longest possible length of wires will help extend the service life. The better approach is to twist the wires instead of bending, but that does not seem practical here. The larger the radius of the bend the better.

Hmm, this is less good than I first thought... the motor pigtail is not secured to anything... so when the flopping action occurs, I'll be putting strain directly on the winding leads! Not acceptable.

I'll need to concoct some kind of strain relief that attaches to the aluminum base. Or maybe just a glob of glue to "pot" the wires.

.
Last edited by patmat2350; Dec 16, 2018 at 05:50 PM.


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