GeckoSub Mirage Evo - And Adventures in 3D Printing Speargun Parts

popgun pete said:

How these do printed parts hold up in water, as in do they expand? Some plastics do and in some cases changed tolerances destroyed the reputation of the product with triggers jamming, e.g. the "Pelaj" speargun. Admittedly the tolerances should not be such a problem with a loose fit item like a line release finger. Also although not subjected to much load you don't want an accidental bump snapping the line release finger off if impacted from contact with another object.

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That remains to be seen;-).
But if I do get a resin printer, I will surely test this and perhaps try to leave some parts out in the sun for a long time, too and then break them later. The test hooks shown in some of the previously attached videos would be easy for me to replicate and I have a manual "torture bench" already which I have been using to test breaking strength of dyneema lines and pull force of rubber bands in the past.
I know some nylons are incredible hygroscopic and can absorb a lot of water leading them to swell and go soft, too. From memory, it might be something as crazy as a 7% increase in weight(?) that they can take on this way. I actually did print some nylon parts on my filament printer and when they were dry they seemed strong and stiff, but just a few days later, you could feel that they had gone softer. I didn't weigh or measure how they had grown or how soft but it was very obvious.
My hope, of course, is that the tough resins are impervious to oil and water. And if they don't like prolonged UV exposure, I guess I could coat them with a UV blocking top coat.
All this is stuff we need to figure out along the way.
For now, I like the increased accuracy, the smooth surfaces (for o-ring sealing) and the allure of resins possibly strong to make functional, structural parts.

ECK said:

Is there a rubber filament for printing these linings?

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There are many flexible filaments, yes. I haven't actually tried any yet as you need to learn how to print them. Basically, you need to print much slower and it is best if you have what is called a direct extruder so there is more control of the filament when pushing it into the nozzle and retracting it. That said, I actually have such an extruder, so I should be able to print flexible materials with a bit of practice. Just haven't needed to, yet. But I agree, handle grips are a very good candidate for printed rubber.

As for resins, there are a few flexible resins coming out now, too. And like the tough resins, I would expect more options to hit the market in the future.
Here's a link to a semi-flexible resin (turns out it is from the same company that makes the very strong resin, I mentioned earlier):

ECK said:

Thanks!
This resin is of course flexible.
But it is not clear how it will be in water, in the sun?
This is all you need to try. While I see that he makes just toys.

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Most people with 3D printers seem to be making just toys...
Also, keep in mind, that consumer resin printers are a very new thing. They only really came down in price about half a year ago.
But if I get one of these printers, I will try to make some tests to reflect our use.

ECK said:

I looked around a bit. A lot of people are looking for what can be printed on the printer and find useful. They print simple tools and fixtures. We can also think about it.

There is such a Chinese device to sharpen drills

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It is necessary to change the design to make it convenient to sharpen the harpoon. This device is needed when you have left far from your workshop.

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Yes, while Thingiverse has a lot of models already ready to print shared by other users - like drill sharpeners here - it is a necessity to know how to draw your own parts on the computer. Without that skill, you can only print other people's designs. So far, someone has already shared fish callers and nose clips but if you want something more out of the ordinary, you have to design it yourself.

An update on the resin printed line releases - so far, after two days of use, the One Air release works well.

ECK said:

I developed some things. I know how to do it.

I was disappointed with the result:

Maybe I'll try to do something on another printer.

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Sorry to hear about your bad experience. From the pics, it looks like an FDM printed part that cracked right along a layer line. In general, for most FDM materials, this is a classic failure mode. Some materials are worse than others in this regard. But if the person operating the printer knows their stuff, it should be possible to reduce this risk substantially.
Personally I try to print with as high temps as I can get away with as this helps the layers fuse better. Along that same thinking, I have started using less and less cooling fan on the part. But if your parts have intricate geometry, you might not be able to do that. Also, in general, it's a good idea to oversize parts a little bit compared to injection molded parts as FDM parts just wont be as strong, so better to hedge your bets a little by using e.g. thicker walls when you can.

Tough Resin Materials - A Bit of Data
I did a bit more research and the folks at Formlabs have some OK datasheets on their materials. A bit of background: Formlabs were one of the first companies to make resin printers "affordable". Not exactly affordable to the masses as their Gen 3 SLA printer starts at USD 3500 but still, for inhouse prototyping that's affordable to many companies and still many times cheaper than what resin printers cost before Formlabs entered the market.
Anyhow, I guess since Formlabs targets higher end customers, they put more effort into their testing and datasheets.
I should also mention, that the Formlabs printers use a laser and moving mirrors to expose the resin whereas the cheap Chinese printers use UV light beamed from LEDs that pass through an LED screen (think smartphone screen) which masks off areas not to be exposed. I am not sure how much real life resolution/quality difference there is between these two types of technologies but from my understanding, the resins are pretty much the same and cure at the same wavelength (the laser and the UV leds both emit 405nm).

Looking at Formlabs' Tough resin (which btw come in proprietary cartridges and cost USD175 for 1L), they say it was formulated to be an ABS-like plastic and can be machined and sands easily. As for "solvent compatibility" over 24H, it absorbs 1.5% salt water and less than 1% diesel, isooctane and hydraulic oil. I think this is considered low, so should be alright for parts in airguns that might also see some exposure to spilled fuel in the bilge of a boat.
UTS is around 55MPa and a Young's Modulus of 2.7GPa, which doesn't look too bad when compared to ABS and Nylon. Also, Elongation at Break is at 24%, pointing to it being elastic enough not to be brittle (hence, the 'Tough' name).
But on the flip side is a Heat Deflect Temp (HDT) at a lowly 46C.
I am making the possibly flawed assumption that the other, cheaper tough resins are somewhat comparable to the Formlabs one and I don't know how bad the low HDT will affect a speargun part in real life. But that should be fairly easy to test once I get my hands on a printer like this (NOT the Formlabs, but a Chinese cheapo one).
Oh, just found a bit of info on the Siraya Blu resin, which I have mentioned before as a popular and affordable tough resin (USD50 for 1kg) and it supposedly has an HDT of 80C, though the UTS is about 20% lower than Formlabs Tough. But 80C sounds a whole lot better than 46C and sounds more like safe territory for gun parts to me.
Also of interest is that some users have begun mixing resins to enhance certain attributes. E.g. mixing in a little elastic resin, to make an otherwise brittle resin a bit more ductile.

Here are some screenshots of the tech sheet for Formlabs' Tough Resin:




P.S.
I do hope that none of you run out and buy a resin printer just based on my ramblings. Living alone, my threshold to what is "tolerably messy" might be a whole lot higher than yours. So, please do your own research on whether you feel you can live with the hassles of a resin printer. Lots of good videos on Youtube about the messy aspect of resin printing.

ECK said:

Hi

Thanks for the research.

The 21st century has offered many interesting tools and technologies.

3D printers , CNC router, CNC laser cutter, CNC laser engraver.

All this is impossible to buy. I think what else can be ordered from those who work on this.

We just need to choose which is best.

I wanted to ask, did you come up with this?

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The loader in the pic is indeed made by me but I would never say I invented it. Honestly, I can't recall seeing it elsewhere before I made mine but as Pete often points out, the history of spearfishing is long enough that ideas pop up, become forgotten and then pop up again later. I think he had a recollection of other pulley loaders but since I used to sail dinghies and sailboats that was my inspiration and with that background it was just a simple, potential solution to a problem

We are living in interesting times in terms of being able to home manufacture. As for the price, I actually think that high end, accurate production technologies like CNC routers are rapidly becoming affordable enough that many hobbyists can afford them.

Vlanik said:

Another dance with a tambourine ...

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Do you have something meaningful to say Vlanik?
I suspect you took a Russian proverb and ran it through google translate but it doesn’t make sense.


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