Welcome, %1$s. Please login or register. - Did you miss your activation email?

Login with username, password and session length
 

Author Topic: Scratch built Babylon 5 Omega Class destroyer  (Read 5485 times)

Offline Kingbob

  • Lieutenant
  • **
  • Posts: 32
Re: Scratch built Babylon 5 Omega Class destroyer
« Reply #60 on: July 01, 2018, 03:23:44 am »
In terms of designing parts, i think she's done. Did the last parts for the chin, then did a name plate, "A", and Earth Alliance logo. They arent just for show on the CAD model, i've printed them as thin parts that i can either paint by hand and glue on, or, use as a paint mask to airbrush the logo on.

For example, at the top is a layered one, to paint/glue by hand. Middle is a base, and bottom is a mask to paint the base borders.


But this should be the complete head, all parts printed and ready for sanding, priming, puttying, sanding, priming, puttying, sanding, priming, puttying, sanding, priming, painting!
Antenna and styrene bits not added obviously.

Offline Kingbob

  • Lieutenant
  • **
  • Posts: 32
Re: Scratch built Babylon 5 Omega Class destroyer
« Reply #61 on: July 06, 2018, 11:52:28 pm »
God bless the man who invented the Dremel sander!


Offline Kingbob

  • Lieutenant
  • **
  • Posts: 32
Re: Scratch built Babylon 5 Omega Class destroyer
« Reply #62 on: July 19, 2018, 12:34:05 am »
Decided i should design something to make the rotating hab section, actually rotate!

I'm going to attach a large inverted gear (teeth on the inside, opposite to a normal gear) to the center support bulkhead in the rotating section. Then clamp/screw a small platform to the central aluminium tube that runs down the centre of the ship for support.

On that platform will sit an Arduino Nano, and a servo modified for continuous rotation. I do have a small stepper motor i could use but i dont think it will have the torque to rotate the whole section, which weighs about 1kg. Will have a small pinion gear on the servo, which will in turn drive the big gear on the bulkhead.

By going small pinion to large rotating gear, and by controlling the servo speed i should be able to get a nice slow rotation.

Also by mounting the servo/arduino on the support tube, they wont actually rotate, so they can be powered externally.

Only problem is that this will make it difficult to light the rotating section, as any wiring to it will also need to rotate. If its connected to the same power, the wire will wrap around the tube and seize up. Only 12 LEDs in that section, may just have to throw a 9V battery in.

Offline manu

  • Captain
  • ****
  • Posts: 270
Re: Scratch built Babylon 5 Omega Class destroyer
« Reply #63 on: July 19, 2018, 02:05:49 am »
great project.
For the rotating section you could use a rotary feedthrough or multiport swivel. Got to check ebay there should something be available for a few bucks.

Here's an idea:

If you need only + and ground you could use a music jack like this

https://www.ebay.de/itm/3-5mm-Mini-Jack-Socket-to-6-3mm-Jack-Plug-Adapter-GOLD/200306388645?epid=1905297515&hash=item2ea330eea5%3Ag%3AaWsAAOSwNe9aQglg&LH_PrefLoc=2&_sacat=0&_nkw=6%2C3mm+jack&_from=R40&rt=nc

It is rotationally symmetrical, the plug can rotate in the jack, if you use stereo you can feed through 3 cables (e.g. steadylights, flashing lights, gnd) video for 4 cables and it is dirt cheap. Needs to be mounted in the center of rotaion though

Otherwise you can look for Through hole slip ring connector
http://rotaryslipring.wholesale.autoplansearch.com/pz63ac676-small-thickness-flat-pancake-slip-ring-low-contact-pressure-for-robots-control-system.html
http://www.throughboreslipring.com/sale-9342811-through-hole-compact-high-speed-slip-ring-connector-for-cnc-equipment.html

Will this kit be available for others as well?
« Last Edit: July 19, 2018, 02:36:23 am by manu »

Offline Kingbob

  • Lieutenant
  • **
  • Posts: 32
Re: Scratch built Babylon 5 Omega Class destroyer
« Reply #64 on: July 19, 2018, 04:03:52 am »
great project.
For the rotating section you could use a rotary feedthrough or multiport swivel. Got to check ebay there should something be available for a few bucks.

Here's an idea:

If you need only + and ground you could use a music jack like this

https://www.ebay.de/itm/3-5mm-Mini-Jack-Socket-to-6-3mm-Jack-Plug-Adapter-GOLD/200306388645?epid=1905297515&hash=item2ea330eea5%3Ag%3AaWsAAOSwNe9aQglg&LH_PrefLoc=2&_sacat=0&_nkw=6%2C3mm+jack&_from=R40&rt=nc

It is rotationally symmetrical, the plug can rotate in the jack, if you use stereo you can feed through 3 cables (e.g. steadylights, flashing lights, gnd) video for 4 cables and it is dirt cheap. Needs to be mounted in the center of rotaion though

Otherwise you can look for Through hole slip ring connector
http://rotaryslipring.wholesale.autoplansearch.com/pz63ac676-small-thickness-flat-pancake-slip-ring-low-contact-pressure-for-robots-control-system.html
http://www.throughboreslipring.com/sale-9342811-through-hole-compact-high-speed-slip-ring-connector-for-cnc-equipment.html

Will this kit be available for others as well?

Yeah ive been looking at slip rings, and did briefly consider using an audio jack, but they'd have to be around the center of rotation, which means either inside the supporting rod, or would have to cut the supporting rod so the sections can rotate separately.

What i'm thinking, is to basically turn the centre rod into a headphone plug. So drill a small hole for wires to come out, connect them to a couple of rings of adhesive copper tape around the rod. Then 3d print a cover to go over them, with a couple of copper or aluminium sprung contacts (probably salvaged from my parts box), within the cover.

So effectively turn the rod into a headphone plug, with a jack that can rotate around it. Make sense? Might be easier once ive drawn a model of it. Hopefully i can integrate it into the large gear that will attach to the bulkhead, do it all-in-one.

And yes this will be available to others. In fact i'm already printing one for someone.

Offline Kingbob

  • Lieutenant
  • **
  • Posts: 32
Re: Scratch built Babylon 5 Omega Class destroyer
« Reply #65 on: July 19, 2018, 07:40:12 am »
A quick mockup to see if what i'm thinking of will fit.

This is looking inside the rotating section. The servo would be on a mount that is screwed to the central aluminium tube, so its fixed in place. It has a small pinion gear on its spline, which sits inside an inverted gear which is attached to the bulkhead.
So as the pinion turns, the large gear turns around it, and the rotating section will rotate around the aluminium tube.

I dont even have to worry about gear ratios, pinion to large will already slow it down, and can control the speed of the servo easily.
Most complicated part is modifying the servo to do continuous rotation, and thats just a matter of a couple of resistors.


Offline manu

  • Captain
  • ****
  • Posts: 270
Re: Scratch built Babylon 5 Omega Class destroyer
« Reply #66 on: July 20, 2018, 02:07:30 am »
Makes sense I guess. One hole for each cable, a contact ring for each cable. Since you can print parts yourself, this seems to be a vaiable option.
Great idea!

 




Enterprise © Bloc