Special Navy Type IIa

[raalst]

In my stash I still had a Special Navy Type IIA silently waiting.
I like these little boats, and I am looking forward to the puzzle of how to fit everything in.
The objective is a statically diving boat.

I want to try a new idea for the ballast system, and try how far I can go putting components in the water,
i.e. outside the WTC. because there is not much room for a (removable) WTC.

I purchased 3 traxxas waterproof sub-mini servo's. 3, so I can experiment with one.
that one was quickly opened, and while there are miniscule o-rings, there is also a lot of air in the servo's.
I intend to fill them up with mineral oil (lube oil of my lathe..).
One of the sides has enough room in the gearbox to drill a hole (to insert the oil) and
seal it with a M2 bolt afterwards.

The servo misbehaved (also without the oil added), but I think that is maybe caused by a
malfunctioning receiver or ESC.

[raalst]

Re: Special Navy Type IIa

one of the challenges is to make functional rudders and planes.
The kit rudders are small, and do not lead themselves to drilling etc.

I found a quick and easy way to create my own rudders.

I have some plasticine (often used for moldmaking).
I pressed the plastic kit part into the plasticine,
removed the part so it's negative (of one side) remained in the plasticine,
then inserted a brass rod where I wanted it.
Then I just made a bit of epoxy glue and used that to fill the negative.
obviously the other side does not look like anything, but a bit of filing and sanding gave me a decent diveplane.



since then I also made myself a rudder, since I could not think of a way to extend the rudder axle
in a reliable way.

[raalst]

Re: Special Navy Type IIa

another challenge is to obtain decent props.
The smallest I could get was 2cm dia, and I need about 15mm dia.

So I bought the 2 cm in plastic, then used the lathe to cut them to size.
This was surprisingly easy with a sharp modellers scalpel (and a bit of guidance from others)

how good they work will remain a mystery until first trials.

[raalst]

Re: Special Navy Type IIa

I have made a 3-D model of that pesky support strut for the axles.
I'm very curious how this will come out (it needs a few weeks to be printed apparently).

http://www.shapeways.com/model/1183418/uithouder8.html

in the mean time I'm cobbling together the electrical system.
I intend to run the system on either 6 or 8 AAA penlites. I want to know if I can safely run all 2 motors, rx and 2 servo's
without the voltage dropping too low.
I bought a corona rx, two Robbe rokraft 50 esc's and two traxxas water proof servo's.
also a robbe 6v gearpump. the main motor will be sourced out of the scrapbin.
ah, and one of Norberts' splendid lageregeler of course.

[JWLaRue]

Re: Special Navy Type IIa

Ronald,

I did the same thing for my 1/32nd scale Type II several years back. I worked with Jim Butt to create the 3D CAD drawing of that A-frame in Solidworks. Unfortunately, the state of 3D printing was not up to the task back then of producing a part that was usable in that size model. (I ended up hand crafting the part)

Since 3D printing has come a long way since then, I think you'll end up with a very good part. Let us know how it goes!

-Jeff

[thor]

Re: Special Navy Type IIa

Ron,

We have a brand new, super fine resolution 3D printer on the way to the shop. Maybe we can help you out!

Matt

[JWLaRue]

Re: Special Navy Type IIa

Matt,

...make, model, etc.!

-Jeff

[thor]

Re: Special Navy Type IIa

Jeff,

Our old mBot has given up the ghost so we purchased a 3D Stuffmaker Evolution-Mega Prusa with the .2mm head. It is not quite aerospace grade, but so close that with very little clean up the parts will be nice and smooth. It has a 16 liter(11.4"x10.6"x7.87") print volume so it can make a pretty significant part on high resolution. You can select PLA or ABS. We chose the PLA model due to the inherent quick cooling and natural smoothing it provides. The ABS version is a little bit rougher.

Its pretty inexpensive for what you get. If the business continues to grow we plan on buying a full blown stereolithography printer with the resin bath. They have resolution down to .001", but are REALLY pricey.

Here is the link:

http://www.3dstuffmaker.com/

[raalst]

Re: Special Navy Type IIa

Hi Matt,

I doubt if it is worthwhile to send such a tiny part halfway across the world.
But I'm willing to explore the relative qualities.

I have sent this design already to Shapeways (which operates out of holland, I believe) to be produced in their SLS machine.
that is a nylon sintering machine.
more info on their capabilities here : http://www.shapeways.com/materials/mate ... ons?li=nav

what materials do you print in ? and what minimum wall thickness does your shop require ?

I still need to make a watertight comportment with an odd shape. that sintered nylon is a bit porous.
is your material non-porous ?

lastly, what types of design files do you accept ? or maybe you have a link to your 3D shop ?
<edit> be sure mind is operational before engaging mouth, you clog. DOH ! I'll have a look at stuffmaker.</edit>

[bigdave]

Re: Special Navy Type IIa

You always have such cool toys Matt.
You must have been a hit at show & tell. BD.

[thor]

Re: Special Navy Type IIa

Ronald,

I can print in ABS or PLA. A better surface finish is obtained with PLA. I will leave the wall thickness to you. I prefer to start with a .025" minimum wall thickness, but I work with the clients to meet their specifications. PLA printed in .2mm (.007") resolution provides a 100% waterproof component. I can cast these up in metal for you, as well, if you would wish to take the next step. I can accept any of the most common CAD files, but I prefer an .iges file created from nurbs surfaces. Any of the better CAD programs can provide you with this file type. I clean up the files, place them on the XY reference plane at 0,0 and orient the object upward on the Z axis. Then convert the CAD file to a CAM file for G-code process into an STL file for printing.

Here is the link to my shop website with the SLA processes we utilize.

http://www.precisionpattern.biz/processes.htm

Dave-The guy who dies with the most toys wins, right?


Matt

[bigdave]

Re: Special Navy Type IIa

I actually have that bumper sticker on the wall of my shop. BD.

[raalst]

Re: Special Navy Type IIa

@ Matt,
thanks, I will check with you in a few weeks. I might need a WTC being printed.

just now an early version of the support was delivered. good for checking measurements.