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Author Topic: Scratch built Babylon 5 Omega Class destroyer (Now with 50cm baby version)  (Read 6829 times)

Offline Kingbob

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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

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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

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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

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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

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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

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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

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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!

Offline Kingbob

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Re: Scratch built Babylon 5 Omega Class destroyer
« Reply #67 on: July 26, 2018, 01:44:08 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!

Have just finished printing and assembling a split ring for the power, and seems to work fine. On this one im using copper tape, not sure how long that will last, might wear down so will have a look for some thin copper sheet to give it a bit more wear.

Also printed the servo mount and gears and that looks like it will work as well, though i need to tweak the small pinion gear to fit the servo better.

I did a count, this ship is up to 418 printed parts! Its a kit!

Offline MSgtUSAFRet

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Re: Scratch built Babylon 5 Omega Class destroyer
« Reply #68 on: July 26, 2018, 07:14:02 am »
Wow! And here I thought my scribbles on paper were going overboard on planning!

Your mockups put mine to total shame!

Looking good, Kingbob!

Keep going!

Steve
"To be honest with you, Picard, a significant number of my crew members have expressed a desire to return even knowing the odds. Some because they can't bear to live without their loved ones, some because they don't like the idea of slipping out in the middle of a fight."

Offline Kingbob

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Re: Scratch built Babylon 5 Omega Class destroyer
« Reply #69 on: August 06, 2018, 05:22:30 am »
Havent done a lot on the big Omega in the last few weeks, been a bit time poor. plus waiting for some LEDs and fibre optic cable to arrive for it. Mostly just sanding and puttying of the rotating sction, but hoping to have that primed and read y in a week or 2.

In the meantime i've also resized and printed a fair part of the main superstructure for a smaller 50cm version.
Its not as simple as just resizing 50% and hitting print, as many parts have screw holes that need to be changed, or screw clearances changed. And some parts have detail thats already at the printable limit of small details, so have had to edit a bunch of parts, either thickening or changing some detail. In some cases i'm able to simplify construction by combining some parts, in other cases i have to go from screw assembly to just glue. The blast shields at the front for example are 3 layered, and at this scale work out at 0.75mm, 0.5mm, and 0.75mm, and dont work being screwed together.
The detail panels for the rotating section had very small fine lines, am having to change those a lot.

But its getting there. This is my prototype, so as i print and assemble i'm seeing things that need changing, so the CAD model has updated parts that i havent re-printed yet.


Offline Kingbob

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Re: Scratch built Babylon 5 Omega Class destroyer
« Reply #70 on: August 09, 2018, 06:10:46 am »
*In best David Attenborough voice*

"And here we have a rare sight, an adult Omega, with its young calf. Not yet ready to fend by itself, it stays close to its parent..." :D

(coke can for scale)

Offline MSgtUSAFRet

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*best anime eyes while gazing at adult Omega with its young calf.*

OOoooooooo! Preeeeettttyyyyyy!

(Coke can for scale? I thought it would be a banana?!) ;)

Steve
"To be honest with you, Picard, a significant number of my crew members have expressed a desire to return even knowing the odds. Some because they can't bear to live without their loved ones, some because they don't like the idea of slipping out in the middle of a fight."

Offline jwood314

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HAha, I didn't even see the baby omega in the picture, took me a second for my brain to get past the awesomeness to see the littler awesomeness!

Offline Kingbob

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HAha, I didn't even see the baby omega in the picture, took me a second for my brain to get past the awesomeness to see the littler awesomeness!

Haha, well it blends in having used some darker filament.
A few people were asking about a smaller one so i did some resizing and re-work to make it. Should hopefully have it fully built and ready for paint this weekend. Going to paint the little one first as a test before doing the big momma!

Offline jwood314

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How about scaling this up to a 2M model?  :)

 




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