Revell Gato 1/72 scale build

[bwi]

Seams/weld beads

Decided to tackle creating some seams/weld lines. I have destroyed many as I joined the bow, aft, and installed the prop supports and I needed to see if I could recreate them or decide to remove all of them.
I had seen a build were tape was used and CA applied then baking soda was drizzled in (at the time I forgot where, so let me give Erich another shout out!) and David uses CA and Baking Soda to make fillets. Another option is I could mix glaze and use that to create seams or Nitro-stan. Then I saw a build somewhere that the individual used thread drenched in CA. So many options - not anyone was wrong. I decided to go with fill with baking powder then add CA.
To begin, I lined up a couple of pieces of painters blue tape. Rub the edges down with your fingernail and around cross seams that intersect the line you are building.
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Sprinkled baking powder on and pushed it into the gap between the tape. I even left a little extra on top of the seam.
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Applied thin CA and applied a drop. Then I used a piece of metal (actually a pocket clip from a pen) to move the CA up and down the seam. Then applied another sprinkling of baking powder to set any wet CA.
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Using 120 grit wet/dry sandpaper, began sanding the along the newly created seam. The goal is to knock down any high areas and use the tape as a depth guide.
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Removed the tape and I am left with a wonderful seam. A little bigger than I wanted, but a seam/weld anyways.
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The next one I put the tape pieces closer. I thought it might be too close, but as it turned out it was not. So the gap needed to be smaller than you would think.
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Then I went ahead and put some primer on to see how it looked. I like it.
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A Craftsman @ work
grtz, Bart

[salmon]

Stop it Bart, you’re making me blush. Thank you. You, my friend, are the craftsman!

[scott t]

"Stop it Bart, you’re making me blush."
Rosie cheeks are in this time of year just look at Santa.
Thanks for posting this build Tom.


Scott T

[salmon]

Scott, I owe you a big thank you for the ballast pattern! You are one smart cookie!

[salmon]

Question:

Has anyone used 3.7v Li-ion batteries like the ones listed below?

https://www.ebay.com/itm/5000mAh-Rechargeable-18650-Battery-3-7V-Li-ion-Batteries-Cell-Bat-Dual-Charger/382597143999?hash=item5914911dbf:m:mzwb-d1-jibZ05bd9-xfgKA

[salmon]

The battery compartment.

The components you need/optional are:
Switch (optional) with waterproof boot. The only two parts I am going to use are the switch itself and the boot - this will get sealed up with RTV silicon when it is finally installed.


A wire strain relief. I did not have mine, so I made one with Sculpy clay. In this case I made it a triangular shaped rectangle (looks like a long tent).


Bake it @ 275 degrees Fahrenheit for 10 - 15 minutes (I split the difference and did this one in ~12 minutes).
It comes out like this:


Not much of a difference. Left it to cool, then drilled 4 - 1/8” holes. Not even, but it works.


The only issue I had was a small amount of breaking when I drilled the holes. I used some CA to seal the holes and (my thinking is) strengthen the area.


Fuse - in this case it is a 10A fuse - there so many different types of fuses, I got this one because it was convenient. There are waterproof ones out there, but if water gets into the fuse, I have bigger problems going on. This is a protection for all the stuff in the engine room of the WTC - disconnecting the battery or connecting it, faulty battery can cause a surge.


Connectors - I chose the Deans style connector, your sub your choice.


Battery - I went with the 3s 11.1v LiPo, but there is LiFe, NiCad, etc. same as above, your boat your choice. My choices for types of LiPo was limited because I shortened my battery compartment.


Here is the basic layout (minus strain relief for simplicity). I just placed the Deans connectors in the picture for representation, not accuracy. Mind your polarity!


And here it is all put together.



I will RTV silicon the switch in and seal it around the boot.
I bought the switch separately. I forgot to mention in the post about drilling out the hole in the end cap for the switch - ooops!

My original set did not come with any Kli-Cons, when I bought my WTC from an individual, that set had 3 pairs in it. Not enough, may need to order more or make different connectors.

I advocate a larger switch, but that one will do.

The likelihood of the ESC demanding full current at start-up (there is a several second delay as the ESC goes through a start-up protocol), which is the only condition that would demand high current that would ark across -- and damage -- the switch poles, is almost nil.

[salmon]

I bought the switch separately. I forgot to mention in the post about drilling out the hole in the end cap for the switch - ooops!

My original set did not come with any Kli-Cons, when I bought my WTC from an individual, that set had 3 pairs in it. Not enough, may need to order more or make different connectors.

I advocate a larger switch, but that one will do.

The likelihood of the ESC demanding full current at start-up (there is a several second delay as the ESC goes through a start-up protocol), which is the only condition that would demand high current that would ark across -- and damage -- the switch poles, is almost nil.

Closed, that 2 Amp switch can pass 10 Ampere's easy. Switches are rated for the arcing current the contacts can tolerate at the moment of closing/opening, not what the closed poles can handle once all contacts are engaged.


Using s flame bur, ground out the area that I marked. Test fit again and ground again.


Servo is tested to see how the fit is.


Cut off the screw down tab on the sides that will face another servo. and fastened the servos with a zip tie.


I could put the ESC under the servos....


or I could put in the dual LPB.....


Putting the push rods in, do I need to do anything special? put silicon on first, then thread them through? Polish them first?


Then I was told "The receiver goes atop the servo foundation, between the servos. The ESC mounts against the forward face of the aluminum device bulkhead, the LPB with attached MPC's goes under the aluminum device tray. The ADF and Lipo-Guard attach to the outboard face of the servos with 'servo tape'."

One of my push rods is really tight. I have used silicon on it and it is still extremely snug. I remember in the beginning there was someone else that had that issue and I will see if I can find the posting.

Had trouble with one of the push rods being very hard to move, I went ahead and put a 1/16” rod in and slowly turned it with silicon oil. After several tries it seemed to be moving better. We will see later how water tight this is.
I had started to install my push rods when I thought I wonder how the fit is with these servos mounted......barnacles, it didn’t.


I had choices, I could grind the center divider down, this would move the servos closer to centerline and bring the servo arms in. This sounds good, but I have seen the receiver stored there in between the servos so if I eliminate that space were does the receiver go?? I am learning that space is a premium. So next choice....
I could cut the bottom out and move the servos down allowing the widening curve of the tube give room for the arm. This is a better choice, but I want to have a SNORT system in place it goes below the servo deck.


If I move the servos down enough to allow the arm to swing, there would be NO room for the SNORT pump. So next choice.....
Why not lower the server AND cut the arm back? A combination of cutting out the bottom of the tray to lower the servos and trim the servo arm back. But how far would I need to trim....I needed to find that out.
The servos span ~58mm and that is just to great a distance to accommodate.

[salmon]

So I marked with tape where the arms touched the tube.


Then eyeballed about where the server could be placed and still have room for the SNORT pump below. It looked like I could use the fourth hole from the center for the push rod.
using some calipers I measured the distance and tested that in the tube to see where it met with a little room for the plastic needed around the 4th hole.


Yep I think we have a winner. Peeling the servos out of the RTV was not too tough to do. It looked like most of the support will come from the resin center piece and not the areas below the servos themselves.


Off to the bench to cut and remove the bottom pieces. I used my jewelers saw to cut on each side of the bottom aluminum plate. Then scored between my two cut lines and bent the metal until it snapped off.


Then did a little clean up on the edges with a file.


And the finished tray.


and a test fit with the arms trimmed back and the servos lowered and SNORT pump below...... and the result is.......


a fit!

[salmon]

A tool I used for bending rings for sizing was called a Bow Closing Plier - I used a larger plier all the time, but I had this smaller one with a brass jaw that I never used. However it seemed perfect for this application.


I drew out the layout that I saw David had used. I noticed he had 2 come in over the top of the arm and 2 come in under the arm.


I needed to make a couple of push rods myself and my son gave me a Z bender for the holidays. This plier is so simple it was fun just bending ends with it.



Then using the bow closing plier with brass jaw it was mostly simple getting things bent.



I redid the pushrods because it did not look good and made it symmetrical.

Here is the updated crayon drawing of the WTC with the pushrod designations and the way I ran the pushrods.

[salmon]

Like I mentioned earlier, I re-did the pushrods. I also tested the range of my bow plane, rudder, and stern planes.


The forward most servos have the pushrod coming in from the bottom and the aft two have the pushrod coming in from the top. This creates a clearance if the pushrods should cross. The new pushrod in pushrod bearing (Marked D. or Stern Plane) was tight again. I am sure that the brass rod has a variance to it, a little variance and it gets super tight. I sanded with 1200 grit paper. Chucking up the brass rod into the bit, I turned the rod at a slow speed and moved the sand paper up and down to try to keep it even. Then applied a lot of silicon oil to the rod and worked it through the bearing and moved through its paces seeing if it would get better. It did get better.


I was able to do a little work on the hull, completed touch-up on weld seams, sanded, primed, and painted the hull. It is hard not to want to spend a lot of time working on the details and proper painting, but the goal in mind is complete the boat. Maybe this will give you an idea of the amount of seams I had to fix......

[bob the builder]

I just found this thread. Great work on a step-by-step. Valuable stuff in here!

The tight fit of your seal can be addressed with a 1/16" drill bit. The rubber o-ring won't cut if you run the bit through the body, which will take out any resin that may have expanded into the interior passage. Be careful with sanding your linkage shaft, as the tolerance between it and the o-ring is what will keep the wet stuff out of your cylinder.

Keep it coming!

[salmon]

Thank you Bob! you are way ahead of me....I will document that seal soon!

[salmon]

Anyways, I needed some magnetic connectors and I had rare earth magnets (We repair computers and Apple uses magnets in their laptop screen casings). So I tried a variety of ideas.... some I am not proud of, others kinda tickled my fancy (like using a straw, Sculpy clay, threaded coupler, and magnet. I thought the baking process would melt the straw (it did not) and it was really slick). Still most were larger than I wanted. I finally came up with this idea.
Using the good old fashion CA and Sodium Bicarbonate (baking soda) I attached magnet and threaded coupler together.


I threw this out because magnets hold great if you are trying to pull apart, but sideways or sliding magnets apart is relatively easy. That is what was happening here. The magnets would slide and any adjustments I had would get messed up or not repeatable.
So, I made these instead:


The left one shows a regular connection. There is a length in the center that if the pushrod pulls farther than the plane will allow, it will stay connected. On the right is one made with an o-ring and it works with the snort system.







So, if you see any of the red and blue magnets, know that I replaced them.

[salmon]

The torque tube
The kit supplies the brackets to hold the torque tube. This tube goes from the aft end of the tube to the bow dive planes. It is made to rotate causing the gear in the bow to deploy the dive planes and recall the planes. The tube had me stumped because the aluminum tube recommended diameter is the same as the Dumas connector. Then David shared one of his pictures and it showed using 1/8” aluminum tube as a sleeve over the tube and Dumas connector. Brilliant and simple. It is similar to the way the propellor shafts were made using a rod as a pin.



Then I asked David about quick disconnect and he shared about making it snap in. Again brilliant! Taking a round file I filed straight line from the hole to the edge. The file is a smaller diameter than the hole in the torque tube bearings. So once the initial line was ground out, it was a matter of slowly expanding the space wider and wider. Also add a little bump in the slot. Maybe this will help make it clearer:


Using a round file I made the hole large enough to accept the tube and slowly opened above to create the bump.


Place sandpaper (rough side up) on the tube and slide the torque tube bearing back and forth to true up the curve of the bearing to match your tube diameter. Then find the locations of were the bearings go. With the torque tube installed to the plane retract in the bow, I began by placing the bearing closest to the aft end and then slid the other bearing until it made contact with the tube. I taped around the bearing to prepare for roughing up the location for affixing.


Using 240 grit sandpaper rough up the area.


Just to see what it looks like without tape.


Apply a little RTV.


Torque tube installed.


To transfer the in/out motion of the servo into an up/down motion, this elbow is installed and magnets connect the output of the servo and to the ball attached to the torque tube. When I installed this, I CA'd the tube brackets on the hull way too early and needed to undo the bond and readjust. I recommend installing this after you get the torque tube installed. I ended up moving the bar up and closer to the sub-driver.


If you look at the above two photos it may make sense. If not ask and I will try to do a better job of explaining.

[salmon]

Power between battery and engine room

Here is how I strung the main power wire through the WTC. I may re-do this and use a different wire because I may want to run a servo or a secondary mini SNORT from the battery compartment and there is not much room once the wire supplied is installed.
It was Thanksgiving and my wife left the string out for tying up the turkey. I took that opportunity to snag a length of it. I tried to tie the string to the wire and pull it through, but that would not work. So I CA'd the string to the wire to keep the diameter as small as possible.


Since the string is much smaller, it went through with a little shaking, twisting, and jiggling.


Then using the string to pull and some long nose pliers to push the wire came through.