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

[Diving Gecko]

You can get chatter with the boring bar if the speed is too high or you take too big or ironically too small a cut. There will be an optimum depth of cut and speed, you just have to find it in terms of chuck rotational speed and lead screw feed speed. Leave as little boring bar unsupported as you can get away with.

Yeah, I tried everything - even very little stick-out on the bar. So, I am putting it down to the expansion arbor not being stiff enough. But it's OK as the reamer did a really nice job in the end.

It would be interesting to be a fly on the wall in the Mares boardroom when they realize that while asleep at the wheel they have missed the opportunity to create a new gun that they should have done themselves.

That's OK. If they just wake up and actually make it afterwards, all is good;-)
They do have to massage the numbers a tad, though. Like going to a smaller pumping barrel and possibly using smaller main o-rings at the front. The latter is something I will be trying out on the next cone.

 

[popgun pete]

I think that as a Mirage is an Apparition and an Apparition is a Spectre then you should call your re-engineered secondary pumping barrel system speargun the DG “Spectre”.

 

[popgun pete]

Any further progress on this project?

 

[Diving Gecko]

Any further progress on this project?

Not much right now - ran into some real work and then also undertook an interesting project for a friend for his underwater camera housing.
But I'll get back on this one in a few days.


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[Diving Gecko]

I've Got The Blues...
Sadly, still no real work on this project - though I did spend a bit of time doing some small upgrades to the lathe.
E.g. some tool holders (yeah, I should have printed them all in blue. I'll def redo the red ones at some point):

The apron on this cheap and merry machine was never really protected from swarf, so I made a cover for it and incorporated angle brackets for the telescopic leadscrew covers to rest against (before, they were just resting right on the half nuts):

Finally, I printed some covers as I was tired of getting chips into places where I would later have to dig them out in order to adjust something:

The cover at the end of the compound is for the leadscrew and I used the same expanding arbor technique from when I made arbors for machining the nose cone:

(The cover plate warped a little in print, but I made a better one later on)

The last thing I did on the lathe is harder to explain. But to set the angle of the compound on these tiny lathes, you have to back out/unscrew the compound slide completely to get to the two allen bolts which will let you adjust the angle - and then screw the compound slide all the way back in. After a while, it becomes tedious. So, I made the simplest mod you can do - drilled two oversized holes straight through the top of the slide so that when the holes are lined up with the bolts, you can simply stick an allen key in there. No more endlessly screwing the slide in and out.
But the two holes needed a cover, too:

(Cheeky, I know, haha)

All in all, these small upgrades have actually made a real impact in user-friendliness - especially the tool holders and the compound angle mod.
Finally, I am thinking of a motor upgrade, too. Actually, scratch that - I just pulled the trigger and the motor is in the mail;-)

 

[Diving Gecko]

Cooking Away
Also, I have been researching a bit more on 3D filaments and while I have really dialled in the printing of the PLA+ material, I always knew that in one respect it was not ideal; it has a fairly low TG point (glass transition temperature) meaning it goes a bit soft around 60C. I thought it would be fine if I always kept the gun out of direct sunlight, but honestly I don't trust myself to do that. I might forget it out in the open on a boat or next to a villa somewhere and while it might not lead to a catastrophic failure it would be nice with a bit more safety margin.
So, I am looking into some materials with better TG like HIPS and nylon (more on the nylon in later posts):

The small dimples on the surface of the prints show that my retraction settings are a bit off and the acid green material kinda collapsed on itself on the lower layers and generally had terrible layer adhesion.
Some of these materials are much harder to print than PLA or PETG which I have been printing so far and I realized I needed an enclosure to keep the prints from warping which can happen when the part cools down too fast. So I whipped this one up in a jiffy from XPS, some alu tape and a few chopsticks...:

When printing these materials, the heat bed/build plate needs to run really high temps but that is actually enough to heat the enclosure up to around 55C which stops the printed parts from warping, helps with bed adhesion and the adhesion between the layers.

But since I am also sourcing parts for a curing oven for some composite work I thought I might as well test the heater setup in this little "oven", too:

It's a 200w PTC heater which can heat this small enclosure up to around 75C, though in the following pic, it has not yet made it that high:.

The controller is a set it and forget it type. Supposedly, not a true PID controller but it does a fairly good job at keeping the temp stable within a 2C range.

It looks like November will be quite busy for me with real paid work, but I will get back on this project in anger in December;-)

 

[popgun pete]

You should show those plastic covers and tool holders to the lathe manufacturer and maybe trade the ideas for some other upgrade that you want like a more powerful motor. Excellent work and highly inventive, you see a problem and solve it.

 

[Diving Gecko]

You should show those plastic covers and tool holders to the lathe manufacturer and maybe trade the ideas for some other upgrade that you want like a more powerful motor. Excellent work and highly inventive, you see a problem and solve it.

Thanks Pete,
But honesty I don‘t think they would listen. For all the talk we have about Chinese manufacturing my mini lathe is an example of doing the least, the fastest and just getting stuff sold. Funny example, these lathes used to sell with a brushed motor and a manual low/high speed gear selector but then a few years ago, the main brand making these put in a more powerful brushless motor which didn't need the manual low speed gear. But my lathe doesn't have the better brushless motor but it doesn't have the gear selector either... What it does have is a front plate reminding me not to use that particular gear if the lathe is running... haha

There are a few different factories making these machines and the main one is called Sieg. On top of that, some overseas companies do some cherry picking quality control wise, add a few upgrades and then brand the machines as their own and mark them up a bit. Which is totally fine, as most of the cheaper ones really need some love and adjustment to run well. I didn't mind, I learned a lot.
But had I gotten one of the better ones from a reputable dealer, perhaps I could have shared my little mods with the dealer.

As for the apron cover, I didn't model it completely. Someone else had already designed it and shared it on the main file sharing database for 3D printing. I just downloaded it and then changed the shape ever so slightly, added the angle brackets and the screw holes and "made it mine" that way. But I what I can do is to upload my "mix" of the apron cover plus those other parts to that same data base. I think I will do that, then perhaps one or two guys somewhere will benefit from it.

 

[landshark sa]

I agree with Pete, excellent work and very inspirational post!!

So much so it prompted me to also take the plunge and get a 3D printer. I received it a few weeks ago and although I still have a lot of learning and figuring out to do the possibilities are truly endless!

I've been doing composites and vac infusion stuff for quite a few years now and constantly run into prototyping roadblocks where I'd wish I had the capability to test designs. For example, having a 3D printer would have saved me huge chunks of time when building these carbon fibre speargun handles:

Also for things around the house. I needed non-standard pipe connector for my pool. Even if something like it was available to buy... I had it designed, sliced and printed in less time it would have taken me to drive down to the shops.

So far I've only been printing in PLA but I have some PETG on hand that's going to be tried out soon. Beyond that I'll also like to give Nylon a try and ultimately I'd really like to print in POM / Acetal but from what I understand bed adhesion is super difficult and it may be beyond my printer in it's current form.

 

[Diving Gecko]

I agree with Pete, excellent work and very inspirational post!!

So much so it prompted me to also take the plunge and get a 3D printer. I received it a few weeks ago and although I still have a lot of learning and figuring out to do the possibilities are truly endless!

I've been doing composites and vac infusion stuff for quite a few years now and constantly run into prototyping roadblocks where I'd wish I had the capability to test designs. For example, having a 3D printer would have saved me huge chunks of time when building these carbon fibre speargun handles:

View attachment 52885

Also for things around the house. I needed non-standard pipe connector for my pool. Even if something like it was available to buy... I had it designed, sliced and printed in less time it would have taken me to drive down to the shops.

View attachment 52886

So far I've only been printing in PLA but I have some PETG on hand that's going to be tried out soon. Beyond that I'll also like to give Nylon a try and ultimately I'd really like to print in POM / Acetal but from what I understand bed adhesion is super difficult and it may be beyound my printer in it's current form.

Super cool. I just got a sample of glass fiber reinforced nylon in;-). Even some carbon fiber reinforced nylon, too. Of course, the fibers are not long and the whole method not as homogenous as a shot in an injection mold, but things are getting better


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[landshark sa]

Nice! I'm keen to hear how you get on with those.

I'm for sure going to try some of the more exotic filaments but I think I should first and get a proper handle on printing with the easier plastics before moving on with those.

Another thing I really want to try is a combination of different types of filaments. My printer has duel extruder's which although more aimed at different colours of the same material does give me the option of printing with different filaments in the same temperature range. I see some guys had some success printing with a combination of PLA and PVA where the PVA is used as support and then later dissolved in water.

So yeah, still lots to try. The learning curve has been steep but very enjoyable, my only issue at the moment is I only have one 3D printer... I have a feeling this one will be getting some friends in the very near future...

 

[zmajmr]

David I am amazed what all you are doing , with printer and how you learn to make parts by yourself, maybe this is beggining of your speargun company

 

[Diving Gecko]

Nice! I'm keen to hear how you get on with those.

I'm for sure going to try some of the more exotic filaments but I think I should first and get a proper handle on printing with the easier plastics before moving on with those.

Another thing I really want to try is a combination of different types of filaments. My printer has duel extruder's which although more aimed at different colours of the same material does give me the option of printing with different filaments in the same temperature range. I see some guys had some success printing with a combination of PLA and PVA where the PVA is used as support and then later dissolved in water.

So yeah, still lots to try. The learning curve has been steep but very enjoyable, my only issue at the moment is I only have one 3D printer... I have a feeling this one will be getting some friends in the very near future...

Yes, I am looking into dissolvable filaments, too. Not to be used as supports but to make whole parts out of and then do the composite layup on top of the part. But I'd ideally want the filament to fulfill three criteria; it should be dissolvable in water or a chemical that is not too harsh and one that does not harm the epoxy, it should be fairly stiff so that can vacuum bag it and finally it would be amazing if it would still hold up nicely at about 70C (then you could do prepreg or post curing laminates). Most PVA is pretty soft and has a low TG but the filaments which are stiffer are difficult to dissolve... Anyways, I will keep looking and I have a feeling that in a year or two, we will have something worthwhile on hobby level.

Now, I did three quick test prints of my nylon samples from eSun. From left to right they are their regular unfilled nylon - eSun call it ePA (I am not sure which type of nylon is it but possibly PA6), in the middle is a glass fiber filled one called ePA-GF and the last one is their ePA-CF which is carbon fiber reinforced:

The "pure" nylon one is a bit ductile, the glass fiber one is a lot stiffer and the CF is possibly even slightly stiffer.
I don't think I will be using the pure version as it doesn't machine well, also it is trickier to print. The fibers in the two others seem to really help both the printability and machinability and I think the surface left from machining is just about smooth enough to obtain a seal on.

Though the fiber filled ones behave better on the printer, they are still not super easy to print. E.g. the darker band on the glass fiber part about 2/3rds up is just from turning the fan off vs. running it at 30% during printing. It is possibly better fused, definitely more smooth but also the diameter of the part in that area is at least 0.2mm different from the rest.
PLA is a lot less fussy to print well. So, if you need dimensionally correct parts, I think you would definitely need to spend quite a bit of time running calibration tests for this particular filament until you got something controllable and repeatable.

I also gave the three parts an hour in the oven at 80C - I think this is an OK test for a part left in the sun (remember, it was the low TG of PLA that led me onto nylon in the first place):

Again, the purer one was quite soft straight out of the oven, the glass fiber one a lot less soft and the CF was the stiffest of the three.

The main issue with nylon is that it absorbs water and the water changes its characteristics, e.g. making it softer and increase in size. This takes a few days, I guess but I know that sometimes injection molding companies drop brand new parts in boiling water to speed up the process before sending the parts to the customer. That way, the part dimensions don't change between leaving the factory and being checked at the customer.

So, I dropped my three testers in a pot of boiling water, too. And while they did absorb water and become softer to the touch, I think I will let them sit overnight to reach some sort of equilibrium before making any conclusions on that point.

 

[popgun pete]

How do you think this stuff would hold up if say you printed an anvil out of it and maybe even a piston, such as a "Mirage" type pumping piston which has no tail?

 

[Diving Gecko]

How do you think this stuff would hold up if say you printed an anvil out of it and maybe even a piston, such as a "Mirage" type pumping piston which has no tail?

I think the pumping piston would be doable - if you could get a good enough surface on it for the seals to work with. There are one or two filaments that are pretty easy to print which are not too brittle.
Anvil is the shock absorber, right? That one, I am less sure of. Just from banging around on the filaments I have printed so far, machining and sanding them, I feel like I could find one that wouldn't crack, but it might just mushroom a whole lot instead.

Where 3D printing on hobby level is still lagging a bit behind is in the more advanced plastics that can be used for structural parts. I think it will come, from the reading/researching I am doing on it it seems there's a push to make it happen.
Just a few years ago, 3D printing was more of a black art. But I feel that the childhood illnesses period is largely over, the systems shaken down and many printers operate work quite well now and the precision and stability seem to be getting there, too. Don't get me wrong, it's not plug and play, you still need to understand how the printer works to calibrate it, make adjustments for different filaments, etc. to make the most of it but it's not the nearly the maze I think it was not too long ago.

As for the more advanced materials, mostly it's about temperatures; upgrading the system to print at up to 400C instead of 250C on build plates going up to 200C instead of the 100C where most hobby printers max out now. And then adding an enclosure so the prints don't warp or crack under sudden cooling. You don't need much on the electronics side. Perhaps a bigger power supply and some relays but more importantly a lot of diligence when using a printer like this - with these temps and amperages, I reckon the fire hazard goes up quite a bit.
And then, of course, those more high tech filaments need to become wider available and more affordable.

Remember, over on spearboard, there was a guy who designed and built two functional 3d printed bandguns? I think it will be even more viable to do things like that 1-2 years from now. But already now, I think you could very well make a 3D printed shell of a gun and then cover it with carbon fiber to make it structurally sound. A bit more advanced would be to make the handle in the same way but in lieu of that you could buy one. Or you could make a mold on the 3D printer for the handle and then you could print a custom grip to mount on the handle. As for a muzzle, I think that could probably be printed, too.
When it comes to pneumatics, it's a bit more complicated as we have the whole sealing issue to deal with which calls for tighter tolerances and smoother surfaces.

 

[landshark sa]

Yes, I am looking into dissolvable filaments, too. Not to be used as supports but to make whole parts out of and then do the composite layup on top of the part. But I'd ideally want the filament to fulfill three criteria; it should be dissolvable in water or a chemical that is not too harsh and one that does not harm the epoxy, it should be fairly stiff so that can vacuum bag it and finally it would be amazing if it would still hold up nicely at about 70C (then you could do prepreg or post curing laminates). Most PVA is pretty soft and has a low TG but the filaments which are stiffer are difficult to dissolve... Anyways, I will keep looking and I have a feeling that in a year or two, we will have something worthwhile on hobby level.

Now, I did three quick test prints of my nylon samples from eSun. From left to right they are their regular unfilled nylon - eSun call it ePA (I am not sure which type of nylon is it but possibly PA6), in the middle is a glass fiber filled one called ePA-GF and the last one is their ePA-CF which is carbon fiber reinforced:

The "pure" nylon one is a bit ductile, the glass fiber one is a lot stiffer and the CF is possibly even slightly stiffer.
I don't think I will be using the pure version as it doesn't machine well, also it is trickier to print. The fibers in the two others seem to really help both the printability and machinability and I think the surface left from machining is just about smooth enough to obtain a seal on.

Though the fiber filled ones behave better on the printer, they are still not super easy to print. E.g. the darker band on the glass fiber part about 2/3rds up is just from turning the fan off vs. running it at 30% during printing. It is possibly better fused, definitely more smooth but also the diameter of the part in that area is at least 0.2mm different from the rest.
PLA is a lot less fussy to print well. So, if you need dimensionally correct parts, I think you would definitely need to spend quite a bit of time running calibration tests for this particular filament until you got something controllable and repeatable.

I also gave the three parts an hour in the oven at 80C - I think this is an OK test for a part left in the sun (remember, it was the low TG of PLA that led me onto nylon in the first place):

Again, the purer one was quite soft straight out of the oven, the glass fiber one a lot less soft and the CF was the stiffest of the three.

The main issue with nylon is that it absorbs water and the water changes its characteristics, e.g. making it softer and increase in size. This takes a few days, I guess but I know that sometimes injection molding companies drop brand new parts in boiling water to speed up the process before sending the parts to the customer. That way, the part dimensions don't change between leaving the factory and being checked at the customer.

So, I dropped my three testers in a pot of boiling water, too. And while they did absorb water and become softer to the touch, I think I will let them sit overnight to reach some sort of equilibrium before making any conclusions on that point.

Must say that your tests look the business, especially the fibre infused ones.

One of the very first items I knocked up in Fusion 360 was a underwater hockey stick. PLA is just too hard to give good feel of the stick to puck so the idea is to use nylon as I think it will give the right combination of feel and durability. I was thinking of using pure nylon but looking at your tests I very well may try fibre infused nylon instead - so thanks for showing your results.

It seems to me not all filaments are created equal as, on my printer at least, I've found differences even when printing "mainstream" brand PLA's. eSUN just seems to print better than CCTREE. It may be that I've not played around or tweaked the settings enough for CCTREE but I consistently get better overall quality prints with eSUN.

While researching different types of Nylon Taulman 3D seemed to stand out as the brand that a lot of guys get good results with. Unfortunately not as readily available in my neck of the woods as other brands but I made up my mind to import some once I get my ducks in a row.

"Less material" moulding for composites is a handy way of getting around the heavy cost of having bladders made and moulds machined so for sure another area I've been looking into. ABS / Acetone will most probably not work but HIPS / Limonene holds some promise as from what I've read there are some resin systems that once fully cured are not affected by Limonene. I also notice Taulman recently released a Universal Support Material, called EVOLV3D USM which can be used as support with a quite a few different filaments - they mention Nylons, ABS, PLA, PETG, TPU, TPE, LSR and is dissolved with normal water. Although they don't specify specific tensile strength or TG it very well may also be useful on its own.

 

[popgun pete]

Remember, over on spearboard, there was a guy who designed and built two functional 3d printed bandguns? I think it will be even more viable to do things like that 1-2 years from now. But already now, I think you could very well make a 3D printed shell of a gun and then cover it with carbon fiber to make it structurally sound. A bit more advanced would be to make the handle in the same way but in lieu of that you could buy one. Or you could make a mold on the 3D printer for the handle and then you could print a custom grip to mount on the handle. As for a muzzle, I think that could probably be printed, too.
When it comes to pneumatics, it's a bit more complicated as we have the whole sealing issue to deal with which calls for tighter tolerances and smoother surfaces.

Yes, that was on this thread http://www.spearboard.com/showthread.php?t=188730
The guns he created had quite thick parts to give the necessary strength I guess. Plus there was the thread on making mounts for speargun flashlights..
http://www.spearboard.com/showthread.php?t=155408 and another thread here as well, https://forums.deeperblue.com/threa...ed-speargun-concept.102131/page-2#post-938597

 

[Diving Gecko]

Must say that your tests look the business, especially the fibre infused ones.

One of the very first items I knocked up in Fusion 360 was a underwater hockey stick. PLA is just too hard to give good feel of the stick to puck so the idea is to use nylon as I think it will give the right combination of feel and durability. I was thinking of using pure nylon but looking at your tests I very well may try fibre infused nylon instead - so thanks for showing your results.

View attachment 52939

It seems to me not all filaments are created equal as, on my printer at least, I've found differences even when printing "mainstream" brand PLA's. eSUN just seems to print better than CCTREE. It may be that I've not played around or tweaked the settings enough for CCTREE but I consistently get better overall quality prints with eSUN.

While researching different types of Nylon Taulman 3D seemed to stand out as the brand that a lot of guys get good results with. Unfortunately not as readily available in my neck of the woods as other brands but I made up my mind to import some once I get my ducks in a row.

"Less material" moulding for composites is a handy way of getting around the heavy cost of having bladders made and moulds machined so for sure another area I've been looking into. ABS / Acetone will most probably not work but HIPS / Limonene holds some promise as from what I've read there are some resin systems that once fully cured are not affected by Limonene. I also notice Taulman recently released a Universal Support Material, called EVOLV3D USM which can be used as support with a quite a few different filaments - they mention Nylons, ABS, PLA, PETG, TPU, TPE, LSR and is dissolved with normal water. Although they don't specify specific tensile strength or TG it very well may also be useful on its own.

I am doing some experiments on these things these days. Let me shoot you a PM.

 

[Diving Gecko]

David I am amazed what all you are doing , with printer and how you learn to make parts by yourself, maybe this is beggining of your speargun company

Oh, thanks so much! Means a lot coming from such a talented guy as you.
BTW, did you find time to finish CNC your lathe? I kinda lost track of that project.

 

[Diving Gecko]

Water Absorbing Test Results
OK, so an update on the nylon filaments absorbing water.
As I mentioned, I boiled them and then let them sit overnight. But actually, after boiling them and drying them with a towel, I weighed them and today, I weighed them again and there was no difference - so, while my little jewellers' scale might not be the most accurate, it seems you don't really force more water into the nylon by boiling than you would by letting it sit - you just speed up the process. This would make sense as I know that some plastic part manufacturers actually do this.

After having weighed the "water saturated" parts twice, I dried them in the oven again and they ended up weighing the exact same as they did before I boiled them.
By weight, the "pure" nylon absorbed 2.9% water, the glass filled nylon 3.9% and the carbon fiber version a surprising 7.2%. I have no explanation for this as what I read on the subject suggest that the fiber filled plastics should absorb less than a purer grade.
Either something is wrong with the measurements or perhaps, the nylon used in the fiber filled filaments is a different grade (Some nylons absorb more water than others). I don't know if the manufacturer will tell me but I will ask what type they use.

What I can say is that just to the touch the parts become quite a bit softer after having been "water saturated" and this corresponds well with what I have read, too. They didn't swell enough that I could measure much of a difference though which is a positive.

Now, are they too soft in this state? I actually don't feel so and I am judging this on how soft the original parts on the old Mirages are. I speculate that those are made from unfilled nylon (I have been cutting two of those handles up) and they are quite pliable. Still, that gun was rated to work with pressures of 40 bar.

I have described the epoxy vacuum impregnation method earlier in this thread and while I don't like the vast amounts of wasted epoxy that comes with it, perhaps this filament would be a good candidate for it. I don't know if the epoxy would take the space that the water does in the nylon but if that's the case, the parts should come more stable and stronger.

Honestly, the better way to go about this would be to test this with a sort of strength/stiffness test. E.g. printing a schackle of sorts and pulling it apart on my test bench or printing a plate and measuring deflection when subjected to a load. While it wouldn't exactly being a detour doing that, I feel like it would be smarter to keep it simple and just try to make some functional parts before I start overthinking it way more than I already am;-)