GeckoSub Pulley Loader - Another Idea For Assisted Loading of Pneumatic Spearguns

[Diving Gecko]

A while back, I posted this picture as a teaser on my Evo Mirage build thread:

A few folks thought I was about to make a roller gun or a pulley roller gun but while I might do that one day, this roller was actually for something else.

I have been thinking about the Tomba Easyloader from time to time and various other ways to load regular pneumatics at higher pressures than one can normally load at and wanted to give a pulley loader a try. I am sure others have tried this approach before though I don't think I have seen examples of it. But it's just such a simple idea that I am sure I can not have been the first one to mull it over.

Anyways, I am flying to Indonesia tomorrow so wont post a huge lot about this, mostly just some pics.
First, I thought about using a block from Ronstan:

But then felt I could slim down and simplify the design even more if I made the pulley myself - the cam cleat is Ronstan's smallest offering:

I cut a form tool myself to make the groove in the pulley (sounds harder and more fancy than it was):

I have always wanted to play around with ceramic bearings and though there is no real world need for them in this gadget, I did it anyways (the line is 4mm):

The tube which slides over the shaft is some store bought 8x12mm carbon fiber tube but I made two brackets myself; one to mount the cam cleat on and one to keep the line close to the cam cleat.
I designed and 3D printed some plugs, wrapped them in packing tape and laid up the carbon fiber. Like when I did the nose cone repair on the Evo Mirage I didn't bother to vac bag them, I just used electricians tape for a bit of compaction. Not the best result but OK for a proto:

Using packing tape ensures an easy release:

Oh, I forgot to say, though I don't have pics of it, I cut a delrin plug to have the same taper as my regular shafts, inserted it in the CF tube and filled the tube with epoxy and chopped CF and once cured, I pulled the tapered plug out. So, the spear tip mates perfectly with the inside of the tube.
Then I machined the groove for the pulley and drilled the transverse hole for the booking binding screw holding the pulley in place:

 

[Diving Gecko]

I then glued the cam cleat bracket to the tube and assembled the Pulley Loader:

And figured that since the inner diameter and shape of the tube is such a tight fit for my 8mm shafts, it would be a good idea with a small vent hole:

Mounted to a spear, the contraption looks like this:

Obviously, the other end of the line has to attach to the muzzle somehow. On a stock Predathor nose cone this is actually fairly easy as one could make a gooseneck (that's what sailors call it) like this:

I had a quick try at printing a test nose cone with mounting lugs for the Pulley Loader line:

Though the print and design was not really optimized yet, I could pull more than a 100kg on it before it failed:

(I can't recall what I pulled on the Predathor nose cone but it was more than 80kg, too and no signs of failure at all)

Carrying it is one issue, I guess you could tuck it under your belt or in a small neoprene pouch on your belt, like one of these:

It's hard to judge the size but it really is rather small:

Now, the bigger issue is whether I can avoid the shaft going completely pear - or rather banana - shaped on me during the loading process. If I can't control the bending this gadget is dead in the water (to end this sentence on another metaphor).

While I am bringing the Pulley Loader with me to Indonesia, I am not sure I will get a chance to try it out. I didn't have time to finalize a nose cone with lugs for the loader line and I didn't bring a regular Predathor, either.
But since I made the thingey I reckoned I might as well share the pics and thoughts.

 

[tromic]

Interesting idea Davide and nice realization! It lowers the force needed to load the shaft 2 x. But the shaft will "banana", or maybe not if you menage to use two hands to prevent excess bending.

 

[Diving Gecko]

Interesting idea Davide and nice realization! It lowers the force needed to load the shaft 2 x. But the shaft will "banana", or maybe not if you menage to use two hands to prevent excess bending.

Thanks Tomi!
Yep, it's 2:1 purchase or halving the force needed to load but you are absolutely right - it may not work in real life, haha.
I was hoping I could have made a "multi function nose cone" for the Mirage with lugs for the pulley loader line - that way I could have tested it and compared it to the Mirage loading system on the same gun. But I was pressed for time and didn't manage to make such a nose cone.

If the pulley loader does work, if you can keep the shaft from bending, then you can can run your gun at, say, 30-35 bar and not need a Mirage loading system at all. You could get rid of that potentially throttling, power robbing bulkhead and have a very simple but powerful and efficient gun.

 

[tromic]

If it wont work you still can make EasyLoader. I will work.

 

[popgun pete]

The pulley idea has been around for some time as you only need to anchor one end of the cable system on the gun and then you and the gun share half the muzzle loading effort each. The main problem is the cable travel movement is doubled. Possibly a combination could be more effective with a stepped series of loading bars such as is used in the Mares Extended Clever loader. You use the pulley system to get the shaft say half way into the gun, then lock the system off and change your gun gripping position to grab onto the tip mounted loading bar and finish the last muzzle loading push directly.

Of course this is just a variation on using a stepped loader which is what an extension loader does, but a locking of the system at half way means you trust the cables to hold while you change position on the gun. It may be that a combination of pulling upwards with pulleys mounted at the rear of the gun until you change over to pulling as usual directly on the loading bar.

 

[Diving Gecko]

The pulley idea has been around for some time as you only need to anchor one end of the cable system on the gun and then you and the gun share half the muzzle loading effort each. The main problem is the cable travel movement is doubled. Possibly a combination could be more effective with a stepped series of loading bars such as is used in the Mares Extended Clever loader. You use the pulley system to get the shaft say half way into the gun, then lock the system off and change your gun gripping position to grab onto the tip mounted loading bar and finish the last muzzle loading push directly.

Of course this is just a variation on using a stepped loader which is what an extension loader does, but a locking of the system at half way means you trust the cables to hold while you change position on the gun. It may be that a combination of pulling upwards with pulleys mounted at the rear of the gun until you change over to pulling as usual directly on the loading bar.

I am not sure a combination loader would work for me, personally. I don't think I have the strength to load a +30 bar gun without some "cheating" - even if the pulley allowed me to hold the shaft momentarily until I got both hands on a handle, I don't think I could manage the final effort.
Pulling twice the length I think would be fine, I think any issue would be with "storage" and possible tangling.

Now, talking about all this makes me want to really try it. But it may have to wait until I make a new nose cone. Alternatively have a line anchor laser cut in stainless steel plate that can sit under the muzzle or test the gadget on a Predathor gun as I can easily anchor the pulley loader to that gun's nose cone without any mods.

 

[tromic]

Davide, attaching spetra to the muzzle as you shown on images above does not seem to be quite secure to me. The plastic maght brake at same moment..?

 

[popgun pete]

Impulse loading is what breaks things. If you test to double the expected maximum and apply it as a sudden jerk that adds load instantly, which is what you get if something slips then suddenly grabs again, then the device should be OK. High strength cables that whip and catch onto something suddenly that halts their progress have been known to just blow apart when a couple of strands then bust, the load shifts onto the remaining strands and then they all fail rapidly if not instantly.

 

[Diving Gecko]

Yeah, I'm fairly sure the predathor lugs can hold 100kg (50kg each) which is a safety factor of at least three. But I agree, a sudden jerk can snap plastic so it would have to be tested better.

The safest solution would be a sort of anchor which could go around the barrel and be held in place by the muzzle. Laser cutting it out of 2mm stainless and then bending it is what I had thought of so far.


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[popgun pete]

Yes, that sounds better as plastic can develop stress fractures which you cannot see until one day the object just breaks unexpectedly. Some years ago there was an iron hand/grip gadget that gripped on the shaft and an anchor point working somewhere on the gun muzzle, I cannot remember the details, but some jaws worked on the shaft. It was a release and alternate hold device working in a step sequence which now has sunk without trace, however the anchor part was OK, but the shaft puller would have chewed up the shaft surface.

Now I remember it was a "Giga Press" and it was discussed here: https://forums.deeperblue.com/threads/cocking-device-for-pneumatics.82513/

 

[Diving Gecko]

Yeah. As soon as you mentioned "jaws" I remembered the STC gadget. But again, I don't think there's any "purchase" in that like there is in Tomi's easyloader or a pulley loader.

I guess the jaws are not much different than one of those front locking Russian guns you analyzed a while back.

Or wait maybe it does have some leverage or purchase - I'll have to read up on it. With the handle only I guess it's just a handle letting you load in the sweet spot of your body position but with the muzzle gadget attached perhaps there's something else going on.


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[popgun pete]

The muzzle part is like the hand part and engages by pushing on one side of the muzzle, so it is in a sense hooked onto a flange. Both gadgets approach the item that they want to engage from the side, so to pull them free you tilt the hand part outwards away from the shaft. It seemed rather dangerous to me and a field day for lawyers if any nasty accidents happened. The muzzle part holds onto the shaft while you change position by moving .the hand part further up the shaft and away from the muzzle before you lock onto the shaft again and have another push into the muzzle, so the muzzle part operates like a one -way valve, it lets the shaft move in, but not out of the muzzle.

 

[Diving Gecko]

Pulley Loader in Real Life Use
Wont bother with another write-up right now, but this post has some thoughts on using the pulley loader in real life:

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

They work OK as I have the tri-cut and the pencil point of these three tips, but I don't have the arrowhead. As for streamlining they fold up into a small package, although they have more frontal area than just a round shaft with a tip ground into it.Bear in mind that these breakaway tips have...

forums.deeperblue.com

[EDIT] No need to click this link, I came to my senses and added the same info plus a bit more two posts down;-)

 

[popgun pete]

The thing with muzzle loading is that for shorter guns, which are easy to load, and longer guns with not much pressure in them you tend to steer the shaft into the gun by slightly altering your direction of push on the hand loader. With a lot more pressure in the gun that directional control becomes much harder as your effort becomes more focused on pushing rather than how you are pushing. I found that I could only load against high pressure with my double handed loader and that meant I had to brace against something by standing on a waist deep reef section with calm conditions, or a trip to the shallows when shore diving. Any surface action and you can get tipped over while struggling to load the gun and that becomes very dangerous. The Seabear MAK 103 was very hard to load at 40 bar, and even harder to pull the trigger, so that gun has gone into store even though it looked rather cool and sort of military, although the "military connection" was bullshit from the distributor.

In order to maintain directional control a double cable pull may be able to overcome shaft bending, or even a triple, however the loading device then begins to look rather bulky. Another problem is some new long shafts already have a slight bow in them and you can be pushing off axis right from the start. Once about half the shaft has gone into the gun then bending is less likely as the shaft centralizing washer in the muzzle is supporting it. The Gigapress muzzle attachment gadget effectively lengthened the muzzle support structure by adding to the length of the muzzle by a few centimeters, but the gripping teeth chewed on the shaft which is a no-no for vacuum barrel guns as any tear marks will rip up the vacuum cuff sealing lip.

 

[Diving Gecko]

Pulley Loader in Real Life Use
Wont bother with another write-up right now, but this post has some thoughts on using the pulley loader in real life:

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

They work OK as I have the tri-cut and the pencil point of these three tips, but I don't have the arrowhead. As for streamlining they fold up into a small package, although they have more frontal area than just a round shaft with a tip ground into it.Bear in mind that these breakaway tips have...

forums.deeperblue.com

I realized the above post was a bit lazy, but I had just spent a long time writing two big posts on the Evo Mirage thread and didn't feel like repeating myself.
But it does make sense to put the info here, too for future reference so please allow me a little bit of copy pasting;-)

I ended up using the pulley loader on my DIY Evo Mirage as its bulkhead was giving me a bit of trouble. Without a functional bulkhead I can't load that gun at the pressures needed for the heavier 8mm shafts I am using on this trip.

Previously, I mentioned how it would be smart to have some lugs on the nose cone for the pulley line to attach to but this nose cone doesn't have any so I made a dyneema "gooseneck" AKA a bridle instead:

The bridle has an eye splice on each end that goes around the shooting barrel and is held in place by the muzzle. I drilled holes on each side of the nose cone for the bridle to exit through. The idea is that the nose cone holes will keep the ends of the bridle from ending up on the same side (the whole idea of a bridle is to center and/or divide the force acting on it).

But as I tightened down the muzzle, the force on the dyneema made it expand and squeeze the nose cone so much so that the nose cracked a little. It's not a problem as there's no structural need for the plastic where it cracked, really. It's just not pretty.

I am attaching the pulley line to the nose cone bridle with a slip knot which has worked fine but a lug system would certainly be faster:

The pulley loader is not yet perfect. I actually had the line slide through the cam cleat which really surprised me as I have used these on sailboats for years and never once had a line slide. Not sure what the issue is but I changed to some slightly thicker line and it seems to have become a little better. I am using Ronstan's smallest composite cleat but I now think Harken's aluminum one in the same size would possibly have better bite.

Here's a pic with the newer line which is 4mm instead of the colorful 3mm I originally rigged it with (earlier, I described that line as 4mm but it was only 3mm):

And here one that shows how the sliding of the line ate into the teeth of the cleat!:-(

Luckily, the cams are reversible, so you can swap them around and use "fresh" teeth but as mentioned, a metal Harken cleat would possibly be better.

I first tried the pulley loader on the porch of the bungalow I was staying in the night before going spearing and managed to banana the shaft like crazy. Luckily, no permanent bend but it made me nervous about using it the next day. But often loading is easier in the water and it's the same with the pulley loader.
It's still early days with this gadget, but what works for me is twisting the line a few times around the shaft to keep it aligned with the shaft (same ideas as twisting the rubber on a polespear). That, and a hand on the middle of the shaft, have kept it from banana'ing so far.

I am doing three twists so far, but will try to see if one or two is enough. As I load, the shaft tends to untwist itself but it happens towards the end of the loading where most of the shaft is supported inside the barrel, so it's OK. But it does make a bit of a mess with the slip tip line and shooting line being wrapped around the shaft:

The pulley loader is not half bad but it takes a while to load a gun like this. I have used it for two full days by now and have taken the gun from 24bar initially to 27bar on the second day. Both are more than I can load a regular gun at, so I am certainly getting some bonus oomph which, as mentioned, is truly needed once you use the chunkier 8mm shafts. I haven't tried it with a regular flopper shaft yet, only a slip tip shaft which is shorter so I guess less risky loading that one.

I store the loader by wrapping the line around the tube of the loader and just tugging the whole thing under the top of my wetsuit. It's a whole lot easier to store and get to than I feared it would be.

Here's a pic of the loader next to some 1kg weights for a sense of scale. It also shows the loader in the "storable state":

 

[Diving Gecko]

Small Upgrade
We are having an out of the water day, so I made a small hook for the pulley line (actually, my local friend and gun builder made most of it as he has can pretty much make snap swivels and pig tails in his sleep):

Originally, I didn't want a hook on the line since if the bridle breaks the hook could come at my hand fast and possibly try to take a bite out of me. But we made it with the "hook" covered by the top where the line attaches and with rounded, polished edges so I think it is safe.

Using the hook should shave off 10-20 secs of the loading time versus tying and untying the slip knot. It doesn't sound like much at all but when doing drift dives - or being near schools of fish - I am of the belief that every second counts.

 

[Diving Gecko]

With A Regular Shaft
Yesterday, I shot a small dogtooth with the 8mm slip tip shaft and the gun at 28bar.


Despite being only 10kg, the doggie managed to bend my slip tip shaft. The strength of these fish is just crazy. The small ones can pull down twice the volume in floats as they weigh. E.g. this one pulled down about 20l of floats for a little while.

But back to the Pulley Loader;-)
Being out a slip tip shaft, I swapped to the 145cm, 8mm regular barb shaft and had no issue loading that despite it being longer than the slip tip shaft.

The new hook works well as does doing just two twists of the line around the shaft. I'll try to do only one twist next.
I'm also getting faster with the loader though it's still not a very speedy process.

When I made this, I didn't even know whether it would work but now, I'm beginning to think it is a viable option if you want to run higher pressures and shoot heavier shafts.

We have had a bit of bad weather lately so I'm not sure I'll get more diving in. If I do, I'll raise the pressure to 30 bar and report back.

 

[popgun pete]

10 kg is an OK size to eat, not that Dogtooth are great eating, but too big and you have the problem of what to do with it. There are some recipes on Spearboard (http://www.spearboard.com/showthread.php?p=2183443) for these fish. Good shot as he was turning away, so no problems with accuracy. The loader looks like it is working OK, the real test will be if it can load against 40 bar. Another feature that may be worth adding is a floating section so that if you drop it a mooring line ascends towards the surface and you can dive down and grab it and haul it back up.

 

[Diving Gecko]

Actually, I think small DT are very underrated as an eating fish. I think some of the best sashimi I've had have came from 5kg doggies.

As for the shot, there was a deeper, slightly bigger friend of his that I was first looking at on the same dive. But he wasn't interested and kept swimming away from me. Then I looked up and saw this guy. I tracked him, waiting to give me a bit of a broadside which they often do but just having seen his friend not do it, I was ready for this guy not doing it either. That's why I took the shot as soon as he turned away from me.

I've been thinking about making the loader float as it's a bit nerve wrecking when you pull it from under your suit. But it would probably become quite bulky if it was to float so I'm a bit on the fence about it.
Especially since I'm thinking of beefing up V2 a tad. Not that anything has cracked or broken but just for a little more peace of mind. Also, switching to a metal cam cleat will not be helping in that regard.

Yes, 35-40 bar would be a dream and well inside Mirage territory. If I could get the loader to work at those pressures I think I might give up on the Mirages altogether...;-)


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