Cheetah 6S: My first cat!

[larryrose11]

ls1fst98
That is the middle step right? That may have other effects, both positive and negative. I have never owned that hull.

There are a lot of knowledgeable folks on here. and a lot of industry hawks too. Tiquman was able to contact the designer of the hull to confirm his observation about the last step. You may be able to do the same.

[larryrose11]

Srut bushing.
The strut I have is froom TFL. I like it. Its beefy, and it has a grease port on it (grease port removed in this pic) I cant find a TFL bushing, so Ill use a speedmaster. The issue is that the sppedmaster unit is just a smidge too big for a proper interference press fit, typically 1/1000 of an inch, or 0.025 mm.
The strut ID was 0.2480 inch (6.30 mm)
The original bushing was 0.2496 inch, 6.339 mm. ( I had to use the expensive, more accurate calipers at work to feel good about the measurment.)
So, it needed to come down.
I gently sanded the outside ring of the bushing with 300 grit, till I took of enough.
I got it down to 0.24881 inch. (6.32mm)



Time for the pres fit.
To make the alignment easy, I wrapped the thinner part of the bushing in a layer of paper, to hold it off the wall of the strut


Here is the press fit assembly.

[larryrose11]

ESC Cooling MOD
I'm paranoid about cooling, because I have had parts burn up.
So, Im paying extra attention to the cooling system. Im running dual cooling lines, large diameter. the smallest diameter (except the cooling inlet, which is high pressure) is 3.9 mm or so. much larger than the stock, 2mm. I also wanted a particular layout. I will be using polished aluminum tubes for most of the cooling lines. It will look sweet against the CF I think.

The plan is to mill out most of the interior of the block, and putting a 6mm threaded end cap on both sides to accept the high flow fittings I got from Kenetic, which have a 4 mm ID.
Here is the stock T180 cooling block, with a broken brass water fitting from me trying to get it out.


MILL TIME!! here is a shot from the mill, widening out the center channel.


After the mil. Sorry for th bad pic, but you get the idea.


I made the end plates, and went to the LHS for the rest of the goodies, threaded rod, and some acorn caps nuts.


Here is the final product!!

[ls1fst98]

ill do some digging. great work! ive been looking at one of these hulls after i finish the 3 im working on at the moment...wife hates having soooo many projects at once.

[Basstronics]

FYI That brass bushing is meant to be a slip fit into the strut- not a press. So you have one brass tube that is pressed into the strut. Then the secondary brass tube with holes is meant to rotate in the other. Holes are there to help hold the grease.

Cant remember if this strut was setup for brass as described above or if it had lead teflon bushings?

[larryrose11]

Basstronics,
The origional strut had lead-Teflon bushings.

Not a press fit? Huh. Some other sites said it was just a press fit. Clearly, the holes are for the grease. Never heard of a setup like that. Most rotating bushings like that are bronze, not brass. What I have will work. and there is plenty of room for grease to get into.
Can someone else comment on this? IM not discounting you Basstronics, just would like another opinion.

[Basstronics]

JAE Struts are setup like I described...

Im not sure I would want bronze @ 20K+ RPM... lol

[larryrose11]

Bastronics, you totally right.
So, To that end, I redoing it right.
I took out the bushing I put in, drilled the strut, and press fit a appropriate sized tube, as recommended.

First, I needed to drill out th strut slightly. So, here it is in the mill.
I use the mill to be ablr to get great allignment.
Furst I use a drill the fits snuggly down the existing hole. and I use the to align the part in the mill. ONce that drill is in the chuck, and the part in the mount, I can then just replace the bit with the right sized one, and re-drill the part.



The pics of the rest of the process didnt turn out, sorry.

[larryrose11]

Strut install
I drilled the hull, and installed the strut. I use a machienst layout right angle to make it is all square.


Up next it the stuffing tube holder

[larryrose11]

Installing the stuffing tube holder.
I got the idea from this forrum that a removable stuffing tube is a good idea.
So, I cut a small section of tube 1 size larger than the stuffing tube. I set the motor in the mount, and put the whole stuffing tube / flrex shaft in place to serve as a guide, carefully lined it up as the epoxy set up.


I need to reinforce the penetration in the hull, so I laid up carbon fiber over i.

once it cures, Ill sand it smooth for a finish coat of West.

[larryrose11]

Motor mount
Time to mount the motor!!
I made my own mount, and I designed it with a big foot for attaching ti the hull. Lots of glue contact area.
Here is the mount area, all masked off.
IM using West epoxy, and short cut carbon fiber. I cut the fibers right into the epoxy, and mixed it in.

I placed the motor, mount, and collet all attached with the flex shaft all together for final alignment while the glue is wet.
Sorry, no pic.
Once it is set up, I took the motor out for finishing

In order to maintain a good finish,I needed to fill in the corners where the mount meets the hull.
Fir this, I found that hatch tape does not stick permanently to epoxy when it cures.
So, I tipped the hull on its side, and mixed up a small amount of West.
Pour it in the crevis, smooth it out, and cover with Hatch Tape to make a great chamfer.

[larryrose11]

Cooling exits.
IN the above photo, at the top, you can see some blue tape, and some glue dripping off of it. That is the through hull colling tubre exits I made. Just two short pieces of aluminum tubes to holed a cooling tube, in a similar idea to the stuffing tube holders. Once they were mounted, I layed some CF cloth over it. Once cured, I sanded it smooth
Here ys see the 2 exits and the right motor mount covered in painters tape.

[larryrose11]

Cooling tube holders
I had the idea of uing lont aluminum tube as cooling lines. It has a large ID, straight, and I could pollish it. So, I cae up with the idea of mounting them by putting wire grommets over then, and holding them in place with CF plate


Here they are, installed in the boat. I just used a bit of West to hpld in place, and make a fillet to blen the attachment into the hull.

[larryrose11]

Dang!! I forgot the battery tray I made.

I have read on here a few times about people lamenting that the battery tray cant be remooved to repair a crack in the hull,
So, I decided to do something different. So, I made some batter trays.

I started out making a good sized angle out of CF.


I cut it in half, and sanded it to fit. I attached blocks to the edges to make a pass through for the Velcro straps, and to serve as attachments for the battery tray to the hull


I decided to attach these trays with RTV silicone, so it could be removable if you need to.


Here is what it looks like with the Velcro installed.

[larryrose11]

I did some experiments, and found that you can clear coat CF, and it looks really good. So, I wet sanded the interior with 400 grit, and cleaned

it throughout .
Interior is ready for clear coat.


and here is what it looks like after the clear coat. You can also see the polished aluminum transom plate I made, just for some extra bling


Here is a detail shot of the interior right side: motor mount, cooling exits, and battery tray