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Old Aug 20, 2013, 08:30 AM
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Scotch yokes

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Originally Posted by Sub culture View Post

I like the miniature scotch yokes for the servo links.
So do I. Where did you obtain them?

Dan
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Old Aug 20, 2013, 08:43 AM
Man from Atlantis
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If you read the desription it says they're made up by a friend of his.

Shouldn't be difficult to fashion your own if you have a bench drill and can chain drill and file a slot. Ken's ones look like they've been machined out of solid, but you could make ones that work just as well from sheet stock, and solder them onto the rods.
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Old Aug 20, 2013, 11:47 AM
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That is correct, my friend is a machinist and he made them for me. They are made from a solid block of brass. You could solder some sheet brass to brass tubing, drill and file the slots to duplicate it. It would take some fine workmanship, but it could be done.

I'll post some more detailed photos when I can so you can see the entire part.

The servo arm was drilled out with a 1/16" bit and a stainless pin was inserted. You could use brass rod as well.
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Old Aug 20, 2013, 12:03 PM
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Quote:
Originally Posted by Sub culture View Post
Perhaps you could reuse the insides of the original equipment in a sub of your own design.
I don't think so! Although I would not mind trying.

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I think the combination of a vacformed plastic flange and large equatorial separation was the achillies heel with these designs. I'm sure with some reinforcement around the edge, plus maybe two or three radial braces mounted along the length would have cured any issues
I don't think I had a problem with the seal between the two halves. I suspect one of the many openings that I had in the WTC. When I took it apart, the push rod seals seemed suspect, more on how they were fixed to the WTC, not the seal themselves.

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but Dave's WTC should give you hassle free sailing.
I'm sure it will be hassle free. Seems like the way to go, like Sir DM was telling me all along.

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I like the miniature scotch yokes for the servo links.
Thanks! It looks to be a better way to go than putting unnecessary forces where they should not be.
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Old Aug 21, 2013, 09:53 PM
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Here are a few close up shots.
First the posts are needed to keep each one of the push rods moving in a linear motion, no sideways movement at all. This allows the push rod to exit through the seal in the aft bulkhead without any lateral movement.
The yoke is one solid piece. You can probably fashion something like it from sheet brass and tubing. I had to file one side of the round part so that it did not bind against the servo arm when the arm moved forward. Also had to slightly file some of the servo arm. As the servo arm moves forward, there was a slight tendency for the yoke to move toward the servo shaft and not slide correctly on the pin, even though the post should have kept it move in a straight line. As the arm moves forward, the combination of the filed part of the yoke moving against the filed part of the servo arm guides the push rod in a straight movement.

Check out the video. Somehow the video got elongated in the conversion. But you can see the movement anyway. The center servo operates the stern planes, the rightmost servo operates the rudder. Where the push rod goes through the post, needs a drop of oil there also.

Video: http://s11.photobucket.com/user/ken_...tml?sort=9&o=3
.
.
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Old Aug 21, 2013, 10:49 PM
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Ken,
You really do amazing work. It might be overkill, but then it looks like it works smoothly....and I might use this in a future build!
Anyways, thank you for your creativity and look forward to seeing her dive.
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Old Aug 31, 2013, 03:20 PM
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Thanks Tom. I know some of the things I do are overkill, but I just can't seem to just do something like throwing it together. When I do something, each item seems to be a project in itself.

In order to get the SD to fit I had to cut away the forward and aft mount from the old original WTC. The forward one was cut down with a curve the same diameter as the Lexan tube and this one will be used more or less to hold the forward part in position on the centerline. The aft one was just cut down so it clears the SD and mechanical parts.

So it was mentioned using a pin to locate the SD then holding it down with Velcro. How and where to put this pin? Well here is my version. I used some 0.10 ABS and created a new support bracket bulkhead for the SD. The bottom of it is contoured to fit the bottom of the hull and the top semi-circular cutout is contour for the SD to fit. I used sandpaper wrapped around the Lexan tube and ran the semi-circular side back and forth to get the exact same contour. Then I doubled up 2 sections of ABS into a 3/4" square and contoured one side the same curve as the Lexan tube using the same sandpaper method. I then cut this into an H shape with the cutout section 1/10 of an inch thick, the same thickness as the support bulkhead. I cut a notch in the support bulkhead for the H shaped piece. Now this H piece slips on and locks in place on the support bulkhead. After the bulkhead was glued in place, carefully added CA on the square piece, placed it on the bulkhead and press the SD in place with the dog bone in.

I now have my pin, for lack of a better word, that prevents the Lexan tube from moving in any horizontal direction. Next step is to hold the tube in place vertically. Think about using 2 mini size bungee cords from Harbor Freight.
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Old Aug 31, 2013, 03:28 PM
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BTW, Happy Labor Day everyone!

If you look at the picture, there are these two other bulkheads that help keep the hull shape. I was thinking of adding a hole on one side and a notch on the other side and use a mini bungee cord cut to the proper length with knots in each end. One end would go in the hole and the other end I could slip into the notch. And that is what would hold the SD down. I'll have sufficient tension so it does not float out of position.

Thoughts?

There is enough friction between the H pin and the bulkhead that I can lift the entire lower hull. If I added one of these forward, I might not even need Velcro or bungee cords to hold it down, but maybe as a precaution.
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Old Aug 31, 2013, 10:50 PM
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Don't risk not having a strap or in your case some mechanical awe inspiring arm (ok, bungee cord might be sufficient) that holds it down.
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Old Sep 02, 2013, 03:55 PM
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I'll have something that holds it down, just not sure what yet. Moving on.
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Old Sep 02, 2013, 04:14 PM
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Cut out another support for the front of the tube. Made another block of ABS and once I had the contour of the tube on it I glued another piece onto it creating a tongue. Figured out where the tongue touches the bulkhead and made a slot. Glued the support in the hull and put the block in place. Put CA on the block and put the tube in place gluing the block to the tube.

With this setup there is enough friction to lift the lower hull. I'll see how this works out in the water. Will probably add that tie down like Tom mentioned as a precaution.
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Last edited by ken_nj; Sep 03, 2013 at 01:13 AM.
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Old Oct 05, 2013, 11:54 AM
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Been a while, some updates. Figuring the angles on the push rods was tedious. The bends are compound angles, had to get the joints to meet properly. Eventually got it as you can see.

For the bow planes I glued two standoffs to the Lexan tube to use as guides for the brass rod. Two sections of 1/6" rod are soldered together and the guides are positioned so that I can slide the rod out for service so I don't bend the crap out of it.
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Old Oct 05, 2013, 12:03 PM
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For battery connections I used a PCB connector and plug from Jameco. I did not use the protective cover for the plug. Used heat shrink tubing to protect the soldered connections. Seem to work OK. The battery pack is held in place with foam like I've seen on pictures that Dave sent me.

At the other end I tried an XT connector a friend gave me. Not quite happy with it. It's a bit big and your hands jerk when you separate the connectors. I might switch it with one that I used on the battery end.

The end cap had a place for a switch so I drilled it out, added the toggle and used a waterproof cover. Added some RTV to complete the seal just in case.

To charge the batteries, remove them, and my charger has the same jack as the plug.
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Old Oct 05, 2013, 03:00 PM
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I've kinda been working on trimming the boat out. I have it trimmed so 1-2 inches of the sail is out of the water and the boat was level. Having trouble getting it to come to the designed waterline. It should get it there sooner or later.

But right now I have to move the SD forward by a 1/2 inch to fix a clearance problem with one of my extras! Specifically the pop-up stern light. Once that is done back to trimming.
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Old Jan 23, 2014, 04:29 PM
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Ken,
What is happening with your sub? I miss your postings.
Peace,
Tom
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