Who wants to build a semi-scale all-wood micro hydro?

[Dr. Jet]

Jeff Ross is Monojeff on here.

Thanks!!

[Dr. Jet]

The availability of decent 1/8” struts has diminished substantially over the past decade. The only suitable one I've found for this application is the Micro Strut sold by OSE (see: https://www.offshoreelectrics.com/pr...prod=ose-80046). This strut is also available from other sources, but Steve’s prices seem to be the best.

The issue with this strut is it needs a nose piece if it’s going to be used with my 1/32” wire drive. I made a prototype nose piece on my trusty mini-lathe, but because of the cheap-a$$ Harbor Fright chuck on the lathe that is incapable of holding a piece in the same position any two consecutive times, the 1/16” hole through the center is not concentric, rendering the piece completely useless.

I broke down and ordered a higher-quality chuck and will make another nose piece when it arrives. But what about the rest of the huddled masses here that want to follow in my footsteps and build their own Micro Blaster, yet don't have a precision lathe at their disposal? I have a solution! It will require a bit of work on the builder’s part, but nothing more than a file, some sandpaper, and a hand-drill will be required to make it work. Just order a package of medium end caps from CST (see the bottom of this page: http://www.cstsales.com/carbon_pushrod.html) and use your hand drill as a lathe. Just chuck one up in your drill and file/sand it to fit. You get 10 in a package, so you can screw a couple up and still make it work.

[Dr. Jet]

The Blue Blaster graphics I ordered from Callie-graphics have arrived. That's what I call fast service; and at 1/3 the cost of the graphics from Mike McKnight. The graphics I ordered from Mike McKnight back in November still haven't shipped. I cancelled my PayPal dispute with him on December 28 so that he could print a shipping label. On December 29, he printed a shipping label. He still hasn't made the effort to put the package in the mailbox though.

I don't care how good this guy's work is. He's a first-class FLAKE in my book. Expensive and unresponsive. I'm too old to put up with FLAKES anymore.

[JimClark]

Pictures of what Callie's did for you?

Sent from my Moto G (4) using Tapatalk

[Dr. Jet]

Pictures of what Callie's did for you?

Sent from my Moto G (4) using Tapatalk

Here you go...

[cjs]

A person wouldn't have to run a nose cone, would they? I am pretty sure others (NativePaul) have exposed wire drives without issue. Either way, what you have looks nice!

[Dr. Jet]

A person wouldn't have to run a nose cone, would they? I am pretty sure others (NativePaul) have exposed wire drives without issue. Either way, what you have looks nice!

Some kind of nose cone would be necessary, otherwise you have a big waterscoop at the front of the strut. This will be a fully exposed wire drive. Stay tuned for additional details as the build progresses.

[Dr. Jet]

The need for a nose cone will become obvious in the photos. The 1/32" wire drive goes like this: Start with a propshaft that is drilled for a 1/16" wire drive. Insert a piece of 1/32" wire into a piece of 1/16" stainless steel tube then insert that assembly into the propshaft. Bingo! You now have a 1/32" wire drive. The length of the 1/16" SS tube can be varied to suit the particular application. Another piece of 1/16" tube goes at the motor end of the shaft where a 1/16" motor coupler joins everything together.

[NativePaul]

I generally run exposed wires in so much as I only use the minimum length of stiffing tube to get the wire through the hull and slip on a piece of silicone tube to seal it, but I always have something in front of the strut, I have tried it wouthout but as well as extra drag, you get some severe handling issues caused by that drag right at the back being intermittent. There are 3 ways I have done this.

Firstly the same as Dr. Jet with a stationary nose piece, I dont have a lathe so I turned mine from 6061 alloy rod with the needle files i use for my props, with the bar chucked up in an electric drill and finished with sanding in the drill, it took a LOT longer than a lathe would so while you could do it cranking a hand drill mounted in a vice, you would have to be pretty damed fit, or do it over several days, electricity makes things easier. I started with a 2.5mm centre hole for a 2mm wire, but as the wire has a gentle curve from coupler to stub, it contacted the nose piece and I went to 3mm which allowed a little clearance static, but in use i found a wear mark on the wire and had to hog it out to 3.2mm for runnig clearance. Ideally it should have a curved hole up the middle, but I lack the patience to carve 2 seperate curved halves for the drag reduction froma smaller hole size, at 3.2mm it isnt causing any handling issues for the fairly big boat.

I am pretty well into riggers now and usually run a ski on my oval ones, in that case the strut sits over the ski so you can run a slab fronted strut without the water smashing into it at speed. This is my Naviga Mini Hydro class (<450mm) oval race boat, with a 1.2mm wire using the same cheap Chinese 1/8" strut as Dr. Jet is using above but with the nose cut off so there is JUST enough meat to drill the nose and tail out for 1/8x1/4 ballraces. This is a very free running drive system taking aproximately .2A to spin at 38k RPM.
IMG_7840.jpg


Paul Williams a friend of mine that is the UKs equivalent of Jay Turner in so much that he wrote the book on FE, but is unbfortunatly no longer racing made me some wires a few years ago and they are still my favourite dirive for SAWs boats, the nose pieces on them are stainless bored wire size and spin with the stub, the stubs are bored wire size and overbored to have part of the noise piece inside, which effectively doubles the depth that you can drill the stub before the tiny wire size drill and ream wander offline, whilst at the same time ensuring that a broken wire doesnt mean a lost prop. On the downside it does make maintenance a bit of a PITA as like the cheap Chinese 2 piece flexies, the strut has to come off to remove the wire.
IMG_7835.jpg

[Dr. Jet]

I’ll pick up the parts tomorrow afternoon when I make my Costco run. Now I can get down to the serious business at hand and actually build something. I am indeed fortunate to have an admittedly older version of AutoCAD running on my computer and the knowledge to use it. I just love the smell and precision of laser-cut parts. Another cool thing is I can make one kit for just me or hundreds of kits for anybody that wants one. Ummm… Err…. Well, I can make two or three kits for anybody that wants one.

The first thing to do is to block-sand all the 1/16” balsa parts while they’re still in one sheet to get them looking good and even. Then it’s on to cutting the parts out and gluing them together. Stay tuned for a step-by-step process with photo documentation.

This is going to be fun!!

[cjs]

Well, I can make two or three kits for anybody that wants one.

...since you're offering. What would it cost?

[Dr. Jet]

...since you're offering. What would it cost?

I'll see what my Laser Guy would charge for subsequent runs. He charged me $60 to do this one and I have about $45 worth of wood in it (see note above RE: the cost of wood). I'll have a lot of extra materials for the wire drive (1/16" SS tube and 1/32" wire), the CF rods for the wing and fins, and a parts list to finish it. I ordered some of those CF plugs from CST to make nose cones, so I could supply that as well. I also have a couple of those purple struts that are extras at this time.

[Dr. Jet]

It's a good thing to do a prototype build first. I discovered several busts in the dimensions of the sump pieces and some other bits that I will have to revise if I'm going to make this available to others. After all, I seek perfection. I used some of my balsa stock to make proper sized pieces where I could on this prototype build.

Here we go:

1. Lightly block-sand all the 1/16” balsa parts to eliminate any surface fuzz before you remove them from the laser-cut sheets.
2. Dry assemble all the 1/16” ply framing parts and confirm that all parts are fully seated in their respective slots. If necessary, open up the slots with a flat needle file. Tack the transom and bulkheads A to the main stringers with a small drop of CA. Tack all the bulkheads in place.
3. Locate the 1/16” balsa control plate and tack it into place with thin CA. Properly done, this will insure your framework is square. Use a straightedge to insure the control plate sits flat on the bulkheads and beyond.
4. Next, tack the tunnel strips into place against the main stringers and bulkheads and butting up against the control plate.
5. Tack two nose pieces to the front of the tunnel strips and flush with the bottom of the tunnel strips. Add a third nose piece on top of the tunnel strips and against the two nose strips to provide a surface to glue the deck strips (Step 10).
6. Tack the sump standoffs in place.
7. Tack the aft sump bottom in place.
8. Tack the forward sump bottom in place.
9. Tack the turn fin doubler to the INSIDE of the right sponson.
10. Sand a bevel on the front of the ¼” x 1/16” basswood deck strips and tack into place.
11. Trim away the center sections of bulkheads B and C. Much of this has been laser-cut to make it easy to accomplish.
12. Assemble the 1/16” ply motor mount and tack into place.
13. Tack ¼” x 1/16” basswood strips in place between the deck strips for the forward and aft hatch supports.
Place the completed framework on a well-lit table and stand back to see how cool you work looks thus far. Way to go!

[Dr. Jet]

Another Photo

[Dr. Jet]

Well, I've made a WHOLE BUNCH of revisions to the laser plans...... What a project!! It's like having a JOB!

[Dr. Jet]

Here are some more:

[Dr. Jet]

Even more. This is not the motor I will eventually use.

[Dr. Jet]

Yet more. That's a coupler from an Aquacraft GP-1, reamed to 1/16"

[Dr. Jet]

I'm at a bit of an impasse now. I traced Garry Finlay's plans for the sponson bottom, but it came out a bit undersized. I ordered some more 1/32" ply and modified the AutoCAD drawings accordingly. As soon as the sheet arrives, I can re-cut the sponson bottoms and get on with the build.

Stay tuned.....

[Dr. Jet]

Photos. Aft non-trips installed, cowl refined.

[Dr. Jet]

Remember when I said there was a bust in the sump dimensions? Well, that bust carried through to other items. I originally had the stuffing tube exit hole laser cut, but because of the dimension bust, I had to move the hole. It's no big deal, but it just goes to show how one little glitch can cascade down the pipeline. I'm going to omit this hole in future kits and let the installed motor/coupler determine the exact location of the exit hole.

So I pulled a motor similar to the one that will eventually go in here from another hull and used it to establish the stuffing tube location. Some cutting and filling on the bottom and everything is cool.

Here's more photos.

[Dr. Jet]

I did a parts layout, then did a bit of Dremel Tool action on the project, then revised the AutoCAD drawings again. I've revised the plans so many times, I think I'll need to build another prototype, just to make certain it finally meets my standards.

[Dr. Jet]

Here are photos of the drive:

[Dr. Jet]

So I've closed up the shop for the evening and opened a bottle of wine. As I'm sippin', I got to thinkin'..... (uh oh..... ) This boat is going to be 17.4" or 442mm long. Some time ago, that was considered a micro. In the past decade that I was doing other things, several manufacturers came out with similar-sized and even smaller models. Smaller motors are available now as are smaller servos, ESCs, Rxs. and what-not. A few scratch builders have made outriggers that were considerably smaller than 400mm. Some clown on this site is actually trying to build a 7-1/2" semi-scale hydro! Now that's micro! I have my doubts as to whether or not it will work.

I think I mis-named this thread. It really should read "Who wants to build a semi-scale all-wood MINI hydro?" For the sake of argument, I'd call 1/20 scale (18" or 460) a mini and anything smaller than 1/24 scale (15" or 380mm) a micro.

From here on, I will refer to this as a MINI and not a MICRO.

Your thoughts are welcome.....

[NativePaul]

For what it is worth the Naviga Mini Mono and Mini Hydro classes are for hulls under 450mm long, which is about 17.5".

I love small boats, I have built 5x cats, 3x riggers, and one Eco that are 450mm for the mini racing or SAWs classes. My only scale boat is an 11" MTB, and I am just about to start building a 7" Hydro for ships and giggles.

[Dr. Jet]

...... I am just about to start building a 7" Hydro for ships and giggles.

Chris Casper still has a few of those little hulls available. They're small enough and light enough to fit into a padded envelope so shipping to the UK would be reasonable enough. He's a great guy and really helpful. chriscasper@earthlink.net

[NativePaul]

Nah, I saw Jim's gift before you claimed it, but didn't jump on it for a reason. The bottom looks bad enough that I think it would be quicker to scratch build one than to mod it to my specs. I would have felt bad taking Jim's just for the deck, and am glad you got it as your build has given me the kick I needed to go for it. Pickleforks are more to my tastes than shovels as I only got into boats in the '90s, so making my own deck too seems like an easy choice for the savings, I think I have all the materials to make one on hand, so it shouldnt cost me anything apart from the gear inside. While I have the foam out for the bottom I may as well make a deck, I cant see the hull build taking more than a day. We are going for slightly different angles, I am hoping for about half the weight of yours and with similarly less power.

Your rudder rocks, I doubt I will do anything nearly that good.

[Dr. Jet]

Depending on how the Casper project goes, I may do a 1/32 scale (10-7/8") version of the Atlas hull that is the subject of this thread, just for "ships and giggles". That's a long ways away though. I have this project to complete, the little Casper to complete, and a paint job on the MHZ Miss Madison to complete. Then there's a couple of half-finished projects in my inventory as well.

[Dr. Jet]

I haven't posted much here lately for a number of reasons. I discovered a bust in the 1/32 ply, so I had to order more material and get it cut. As of this writing, that has been accomplished and the bottom of the hull is now complete, and I have added a layer of epoxy to the inside. I need to get more expanding foam (mine has all petrified) to fill the sponsons and I can add the deck.

Once this hull is complete structurally, I plan to donate it to a building-challenged friend to finish and I will build prototype #2 from my revised drawings. I easily have 5 times the amount of hours invested in the drawings than I do in building the hull, but I am a stickler for details and want it perfect. Building a first prototype allows me to say: "Jeeze, I should have done it THAT way..." Building the second will confirm all the changes are correct and work as planned.

Stay tuned for photos and discussion.

[Dr. Jet]

Yes boys and girls, the good doctor has been busy and has not neglected this project. It is now sheeted, painted with a light coat of sanding sealer (not enough to completely fill the grain), and shot with a light coat of primer to look for imperfections and gaps. I'll give it a day or two to completely cure and start sanding and filling.