/diy/ - Do It Yourself

This is the fiberglass resin I'm using. I guess what I'm asking is what's the easiest to work with material for the structure of my fish here? Keep in mind that my 3d printout has an opening that I plan on installing a small door in the front segment, so I can put things in and out (like my microcontroller, raspberry pi, wiring, camera, etc).

hold it
that fibreglass resin is -just- the resin
you also need the glass fibres to create the strong composite material you're probably thinking of

also check on a test piece that the resin/hardener mix won't melt your printed plastic

>>787860
no, not really.
if it was something structural then definitely yes. and OP could make a mold and fill it with a premixed loose fibreglass "bog" like you'd find at an auto store.

polyester resin is incredibly strong by itself. it just doesnt take well to shock damage without the composite filler. I water proofed my ebike battery with two coats of polyester resin. I've stacked my bike and smashed it on rocks quite a few times expecting it to be broken when i lift it up but nope, its held up without a scratch.

>>787820
>>as a 3d printout is not really reliable
You aren't using a Z-corp machine are you? If yes, then you should be very concerned about structural stability, because z-corp prints are about as strong as chocolate.

If you are using an FDM machine and you are worried about the parts being strong enough set infill to 100%, it will use a lot of filament, but you will end up with pretty strong parts.

Though honestly, how much force are your parts going to experience in a fish robot? Now if you are worried about surface finish and not structural integrity there's solvent polish:
http://blog.reprap.org/2013/02/vapor-treating-abs-rp-parts.html

You can also just sand it you know?

Oh and don't use PLA, it is prone to rotting when wet.

Video related, a dead fish swimming upstream.

>>787892
> dead fish swimming upstream
how

Seen the fishtail done very simply in the past with 1 servo and 2 cables.

Can't find a pic so have to try and give you a verbal description.

Each of the tail segments had thre horizontal holes. 1 central and one each side near the edge.

The central hole had a cable running through to the tail fin and was anchored at each segment.

each side hole had a flexible cable that ran back to each side of the style of servo horn in the link below. The other end of these cables was anchored to the tail fin.

As the servo rocks back and forth, the cables push and pull the tail fin to and fro.

http://www.modelflight.com.au/e-flite-3d-servo-arm-set-w-screws-4-suit-s75-hs-55.html?gclid=CLnt2-WhvsQCFVeVvQodSAEAEw

Hope you can get a mental picture of this.

If you look on youtube for animatronic tentacle you will get a good idea of what I'm on about.

sorry I meant 3 cables

>>787892
Hi there!

You seem to have made a bit of a mistake in your post. Luckily, the users of 4chan are always willing to help you clear this problem right up! You appear to have used a tripcode when posting, but your identity has nothing at all to do with the conversation! Whoops! You should always remember to stop using your tripcode when the thread it was used for is gone, unless another one is started! Posting with a tripcode when it isn't necessary is poor form. You should always try to post anonymously, unless your identity is absolutely vital to the post that you're making!

Now, there's no need to thank me - I'm just doing my bit to help you get used to the anonymous image-board culture!

>>788123
Oh my god fuck off. The guy posted useful ass info and a crazy webbum.

>>788123
fuck off with that

OP here, thanks for the replies everyone!

>>787860
Like >>787872 said, the glass itself is pretty strong. I don't have any real doubts about its strength. It's a little ugly, but not much some good coating can't fix.
>>787892
The issue in my case is more that my printer is shit and will take forever printing something with more than 50% infill. Badass webm btw.
>>788104
I know there are simpler ways of doing this but considering how much effort I put in the design, and how badass it looks I kinda want to stick with this. I get the mental image of what you're trying to get across though.

>>788249
>>788260
Yes he did. He also posted with a trip, which as the copypasta says, has not a fucking thing to do with the anything. information does not need an identity. To ascribe one is simply trying to put yourself above the pack, which is just some egotistical bullshit on an anonymous image board.

Sage because offtopic.

>>788384
I'm inclined to agree with anon, here. /diy/ is one of the few places that doesn't have a huge host of resident tripfags and I'd like to see it stay that way.

>>788384
as much as I dislike tripnames I think oddly /diy/ is one of the boards where they could be fairly usefull... the idea being that if you give good or trusted advice you would be readily identifiable... however in the long run I think it's better that each post must stand on it's own substance and that the onus is on the reader to use common sense to decide if the advice given is good or not.

also it's weird to see that we have a few nontrip posters that are pretty identifiable by their posting style.

hvac guy would be a great example of this.

>>788091
The semicircular thing in front of the fish is an obstacle that leaves an oscillating vortex wake, this oscillating vortex wake makes the fish swim. There's more about how this happens here: http://www.people.fas.harvard.edu/~glauder/reprints_unzipped/BealEtAl2006.pdf

>>788375
>>The issue in my case is more that my printer is shit and will take forever printing something with more than 50% infill
Even with 50% infill 3d printed parts can be pretty strong. Especially if the forces you apply to them are in the plane they were printed. You should do an estimate of how much force your fish is really going to be under and see if you really need more than 50% infill or fiberglass(start with the torque your servos can apply).

After reading more about this specific fish robot(see: http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6181603)), you could probably get away with really really low infill percent. A large hollow with honey comb on the inside can be pretty strong. And looking back, you really don't want a solid structure, because then you'll have to add a huge amount of ballast to make your fish neutrally buoyant.

Now if you must do fiberglass, one thing you can do is us your 3d print as a core, that is you wrap your 3d print in fiberglass and not bother removing it. Although if you use PLA, you can use the chemicals here to dissolve it: http://ifeelbeta.de/index.php/support/support-full-disclosure

Not sure if any of these things will damage fiberglass resin though. Pic related, a part made by a similar process, wrap dissolvable print in composite, cure, dissolve stuff, done

>>788384
If you're so jealous of tripcodes, just get one.
Or be non autistic and just ignore it. And finally let's not forget that tripcodes make it easier to block retards so you literally have nothing to bitch about.