My KBB45 build, suggestions welcome.

[kevinpratt823]

One thing I noticed is that when I soldered the male bullets in that brass tube, which was a tight fit, because I let them cool in there, they are now a loose fit, so I will have to spread the prongs again, maybe even under some heat.

I did my water inlets, and I learned a bit through trial and error. What I did was epoxy some plates to the area, then drill the holes. I then began shaping them from the underside. In hindsight, next time I think I will be better off epoxying the brass tubes in, allowing them to protrude a bit, then grinding them down, sanding flush, then shaping the inlet chutes. Ultimately I kind of ended up going back and doing it that way pretty much.

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[kevinpratt823]

One thing I have learned to consider in a build is making sure I will be able to disassemble things after the fact. Because the lower motor mount screws will be relatively inaccessible once the collet is on, I needed to make sure I would be able to remove the collet. I don't want to have to remove the drive tubes to get the collet off, so I shortened the shafts on the motors, and shaved the drive tubes down just to the point that when I remove the collet nut the collet itself will slide right up to the drive tube and clear the shaft for removal. Here is the back end as it will likely be when complete.
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Now, I am seeking input on a couple things:

Because my drive tubes are so short, and that area is kind of crowded, I am considering just a dab of CA or epoxy where the tube enters the drive instead of actually adding CF supports. Any input on that?

Also, I will be needing to do something with the rear support rings for the motor, they don't mate even to any surface, so I was considering just pooling some epoxy around one of the mount holes. I don't think the rings will actually take much load, but I was wondering what some of you guys do for these. Thanks.

[kevinpratt823]

I made up a quick set of stuffing tube supports just to be safe.SAM_0623.jpg

[TheShaddix]

Looking good! For the watercooling tubes, I found it actually much easier to file down the brass tubes first and create a slanted angle on them to match the sponsons, then epoxy them in instead of grinding them down later as you can easily damage the hull in the process. I figure using a dremel it's too easy to make a mistake and scratch the bottom if it slips. Plus it looks much cleaner if done prior. one question, what are those CF plates for near the water inlets if the tubing misses them completely anyway? Were those meant initially as support but you just missed the positioning due to sponson edge being further out?

Also, you always want to have supports for your flex cable tubes just like you did as that will keep the vibration down, support the cable, and avoid any wobble. I learned this the hard way. Your setup looks right.

[kevinpratt823]

Thanks Shaddix
Maybe it's just the pics, or the way you're looking at them, but the water inlet tubes actually are drilled through the cf plates. I actually drilled the first one from the top side to make sure it did, then matched the measurement on the other side. They extend forward just to give some extra meat where I shaped the inlets, and when I epoxied the tubes in a ran a bit of an extra bead along the top side of the inner edge, which was rounded on the underside to fit tight to the inner edge of sponson. Maybe the be as d of epoxy makes it looks like th he tubes don't h o through the plate in the pics, but they do.
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[TheShaddix]

Oh, now i see it. The epoxy on the side threw me off. Have you tried using some black dye in your epoxy? Matches CF much better. I only use clear resin for cf inlays, the rest is always done with black epoxy plus some strengthening additive.

[kevinpratt823]

Oh, now i see it. The epoxy on the side threw me off. Have you tried using some black dye in your epoxy? Matches CF much better. I only use clear resin for cf inlays, the rest is always done with black epoxy plus some strengthening additive.

I haven't yet, maybe on my next build I'll start concerning myself a bit more with some of those details.

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[kevinpratt823]

For some reason my craftsmanship is much better when ther is 4' of snow on the ground, but now that it's starting to thaw I just want to get this thing done! Here are some pics of the motor supports I hacked together, I also did some strategic beveling to the slots/holes in the lipo sleds to hopefully make it easier to get the tray seated in the slots. Sleds are sloppily siliconed in as well.

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[kevinpratt823]

I started looking at the steering linkage, and I ordered some teflon tubing from ebay. I ordered 1.5mm ID/3mm OD. The cable is 1.3mm, and the inside of the hydraulic arm is just over 3mm, so the tubing should make it all the way in there from the transome for a nice seal. Otherwise they do make the tubing in 1.34mm ID, which would be a real tight fit around the cable.

Now, when I mock up these hydraulics, because of the length of the hydraulic arm when fully compressed, and because this rudder is so close to the transome, I would have to move the mounts out to at least 2-1/2" from the center just to get a bit of throw in the rudder. That would put the cables about 5" apart, with very little throw to the rudder as it is pulling from pretty far to the side. Am I missing something here? Seems I would need much shorter units to get straight pulls.

Upon some research, I see I'm not the only one who ran into this slight dilemma, as Fidelity101 posted about something similar, but his custom rudder mount gave him a solution. I am debating a few other options currently, one of those is cutting the hydraulic arm down, and maybe making an adapter piece for the rudder arms to bring them out and back as suggested on another forum(much of this thread has just been copied/pasted from that one), and it seems Fidelity101 did something similar. There's also the option of ditching the hydraulics altogether and going with something simpler. This hardware was rather expensive for me to start chopping it up............ As we say in my circle, "More will be revealed".

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[kevinpratt823]

After checking and double checking, I opted to shorten the hydraulics by a few mm, I cut them right at the knuckle and trimmed the same amount off the inner rod. This allowed me to move both mounts inward more than 1/2", and I gained a more than a few degrees of throw on the rudder as a result. Because of the angle of pull, the rudder won't even make it close to full lock, but I did check and even with the rudder maxed out the hydraulics can't over extend. A black sharpee marker took care of the cut end lol. I'm pretty pleased with the result so far, I haven't gotten the screws to mount the feet, and I'm waiting on the teflon liner I ordered, but it looks like it will work out well. The rudder arms were drilled/tapped to accept M3 screws, used a small spacer from my car stuff to drop the ball down, then put a nut on the underside.


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[kevinpratt823]

I got some nylon sleeves at the hardware store that were just the right size to run an M4 tap inside to use as servo mount standoffs. Then I went to town on a piece of CF plate for the mount. In all my cars the first thing I do is cut off the switch, but I like having it in the boats, so I extended the wires from the ESC and gave my servo mount a spot on each side for the switch. The rear piece that will hold the teflons for the cables is just a hunk of black acrylic, I have a bunch of acrylic left over from building various reactors/filters for my aquarium system. It may not be on the super sleek level of what some guys can do, but for a guy with limited resources (a dremel, cordless drill, and a belt sander), I'm happy with my first attempt. Still need to get a good servo....
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[kevinpratt823]

I've been wishing I did some extra reinforcement before, so before it's too late I hung her up to get a couple layers across the bridge in front of the hatch as far in as I could reach, and hit some small patches in the corners where I'll be drilling for hatch bolts. In the meantime I layed the velcro onto the sleds and strapped the lipos on the way I'm going to try to run them.
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[Local Boy]

Thanks for posting, my friend...

I like the way you over came the steering issue with the "hydraulics"..

You are blazing the trail for me to follow!

Looking forward to the maiden...

Aloha

[kevinpratt823]

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Hydraulic feet mounted w/#2 stainless sheet metal screws, (had to drill the plates out just a hair), and a little wiring done. Cap banks are velcro'd down there as they have to come up and swing out of the way to get the sleds in.

[Luck as a Constant]

Looking good Kevin.
Glad to see you back on it bro


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