Comparison of Sliders for Spears

[tromic]

Order of the testing may also have a bearing on the results as the rubber being stretched may not completely recover after each shot as the test series progresses. So shots made at the start may be different from those made at the end due to this rubber elongation effect. To determine if that is happening a reference set-up needs to be tested throughout a test series, intermingling it with the other tests.

I was also worried about the possibility the spear gun would lose some air. But the test with small stainless steel slider was just after the free shaft test, and the difference in results was huge. I just removed the piece of line for the"free shaft". There are some more factors that can influence the measurement, like the sliding knot tension, and the waves in sea during the test, temperature of the water (influence on rubber and the air in the spear gun), moving of the water because of the wind...
Rubber (surgical tubing) was under tension very short time and could recover between two tests. I did one test ( one setup) usually in the morning and the other in the evening, so measurement last for a few days. I suppose the results are quite reliable.

 

[tromic]

There is 3,5 x more energy if using 1 mm mono instead of 2 mm spectra!
It is incredible how high is the influence of this short 1 mm mono!
Energy of the shaft is 90% higher without that piece of line (on 5.5 m distance!).

Close look up of lines used:

 

[tromic]

Here is my previous attempt to compare performance.
http://forums.deeperblue.com/threads/different-setups-performance.91753/#post-858485
http://forums.deeperblue.com/attachments/performance-jpg.32110/
Setup 1. was Tomba10_7 slider; setup 11. was Devoto slider.
Tomba to Devoto ratio was 1.53 in energy. Maybe same as the newest result, because the distance was than 4.13 m instead of 5.5 m. The lower the distance the lower the difference in energy!
Free shaft with 1 mm mono was next to Tomba10 in performance, setup 2.

 

[tromic]

The newest results are quite different from attempt made here!?
Here the mares slider seemed to be acceptable.
It seems that sliders behavior is different on low and high speed.
http://forums.deeperblue.com/threads/comparison-of-sliders-for-spears.100956/#post-930515

Pete, I did 6 to 8 shooting with each slider and calculated the average of 6 shoots. I suppose results are pretty reliable. I had some problems with the new STC piston that I put in my Cyrano instead of original mares piston.
I suppose the separating force: piston-shaft was not same all the time. I noticed some strange behavior during loading the gun. Spear gun was at 23 bar. I used only the shaft for Cyrano 850, without the harpoon. I wrapped some insulating tape around the shaft tip not to lose the shaft.

I find out what was the problem with STC piston:

This made my results in some cases unreliable! Just in may last testing I noticed four shoots with stretching the rubber 24 cm and then three shoots stretching the rubber 21?! The problem happened when the thicker front section of the piston exit the barrel before slamming into the shock absorber. Sometimes, depending on the position in barrel there was some higher friction then in other position, because piston rotates inside the barrel.

But I believe the results on the first image are OK.

 

[popgun pete]

The STC piston nose appears to have been worked to a new belled-out shape through contact with the shock absorber anvil's face. So rather than crack it is being reshaped. But is the change in shape down to the repeated impacts or just gun pressure over time with the piston leaning hard on the anvil? I think I would be looking for a tougher body piston, or you could turn the nose end down on your lathe to correct it, but if the spreading action continues then the piston may eventually split or break.

 

[tromic]

The STC piston nose appears to have been worked to a new belled-out shape through contact with the shock absorber anvil's face. So rather than crack it is being reshaped. But is the change in shape down to the repeated impacts or just gun pressure over time with the piston leaning hard on the anvil? I think I would be looking for a tougher body piston, or you could turn the nose end down on your lathe to correct it, but if the spreading action continues then the piston may eventually split or break.

There is also an another moment. Shaft tail is a cone of about 2 deg, but in the pistons body there is only a boring, not a cone like mares has in his pistons. As the shaft under force being pushed inside the piston it also makes a cone in pistons body. Because the OD of the pistons front end is very close to the ID of the barrel some friction is introduced. I also noticed that the exit of Cyrano barrel, the edge of the barrel is also belled-in, unevenly. This belled-in and belled-out combination makes uneven shooting condition. In some positions friction is higher, in other there is almost no obstruction. I have another, new mares piston, but as I depressurized the gun I have no intention to pump it again 500 times to make new measurements. Maybe... next year. I also received the STC x-shot slider in Zagreb, from an Italian, but I was than already on sea. I had intention to test it too.

 

[popgun pete]

I just took a "Cyrano" spear and pushed it into an old Mares "Sten" metal piston and then pulled the piston off the spear. That left an oily and rusty residue (from the piston) in a ring around the stainless steel spear tail where it had been jammed in. I then pushed the same spear into a "Cyrano" piston and looked with a magnifying glass inside that piston's bore after pulling the spear out again. A few millimetres back from the entrance of the hole there was a narrow, incomplete rusty band left inside the plastic piston bore, but it was more distinct at the front of this discolouration than towards the rear as it gradually faded out to a few specks of rust. The "band" itself also appears to be only a few millimetres wide. Some rust particles have now embedded in the plastic.

Old metal pistons seem to have a diameter change where a close fitting rod will only insert so far into them and before striking the rear wall, but I think that this is partly due to piston wear after hundreds of shots that have gradually worn away the piston bore. Old shafts that had to be replaced due to them falling out of a gun were found to have a step worn in the piston tail taper as the metal piston eventually wore the spear tail down by removing a short section of the taper. Bear in mind these guns had usually operated at high pressure, so the spear tails had received a workout over their lifetime. Most shafts never got to that condition as they were either lost or bent. If I ever muzzle loaded a gun and did not latch it during a test (on land) of the loading effort then I either had to use a sliding hammer to knock the shaft out or use a block of wood with a hole in it that caught behind the floppers and while standing on the wooden block pull the gun up and off the shaft. Plastic pistons seem to let go easier by wiggling the shaft until it pulls free. It would be interesting to take a casting or mould of a new piston's bore and actually check the shape as it is difficult to measure with any instruments.

The STC piston may be designed for striking the soft faced anvil used in their own muzzle. Also a mismatch between the profile of the face of the anvil and the nose of the piston may be responsible for reshaping of the piston nose in your modified "Cyrano" as actual contact between them may be over a smaller area than the piston had been originally designed for.

 

[tromic]

Cyrano piston has cone shape boring. You can see it if you put in sticks of different OD. I checked it long time ago. Inner ID is about 5 mm (at 11 mm depth) The outer ID is about 5,5 mm, as I recall. Boring depth is more than 11 mm, maybe 21?

http://forums.deeperblue.com/threads/cyrano-piston-modification.82834/

 

[napoleon]

Hi all, my name is Panos (codename: napoleon ) and i live in Greece.
This is my first post here and i have just signed up only to thank you guys for all this usefull information posted here (especially in this particular thread). I guess i'll find a lot more helpful info in the different forum sections.
I have recently owned a Mares Cyrano Evo HF 110 and after losing the shaft (travelling with a great leccia in greek Corinthian gulf), all this info and especially testing results (many thanks Tromic) would be very helpful.

 

[tromic]

Hi Panos!

 

[napoleon]

Hey tromic!

 

[tromic]

Here is my previous attempt to compare performance.
http://forums.deeperblue.com/threads/different-setups-performance.91753/#post-858485
http://forums.deeperblue.com/attachments/performance-jpg.32110/
Setup 1. was Tomba10_7 slider; setup 11. was Devoto slider.
Tomba to Devoto ratio was 1.53 in energy. Maybe same as the newest result, because the distance was than 4.13 m instead of 5.5 m. The lower the distance the lower the difference in energy!
Free shaft with 1 mm mono was next to Tomba10 in performance, setup 2.

Previously mesured results. Numbers in images are column 2. (fig.) in table.
For "free shaft":
Mono on image 5., 6., 7., 8., 9. is 1.5 mm;
Mono on image 11. is 1 mm.

 

[napoleon]

Great testing tromic .
What would be very usefull though is some kind of a ratio of energy tranfered (like your test) to strength (break point) of the joint.
By the way, i tried today the Mares slider with a two barbs shaft (i had it spare for my wooden sling speargun and converted it for my Cyrano). It performed very good, nice accurate shots on small fishes ( ~ 1 kilo sea bream, sargos in greek, sarago in italian i guess) , the only thing i'm worried about is its durability on larger fish, i had it connected with a mono only (1.6 mm), not dyneema then mono.
CU, keep on making great tests.

 

[Ubykh]

can i use omer mini slider or any other metal sliders with Salvimar VUOTO ? if not why?

 

[tromic]

can i use omer mini slider or any other metal sliders with Salvimar VUOTO ? if not why?

Any heavy slider will cause premature damage of the shaft tail end step, that would damage the sealing lips of the gasket cuff.

 

[Ubykh]

Thank you Tromic

 

[Vov]

Great job, Tromic! On heavy shafts like 8 to 9+ mm I would be afraid to use 1 mm mono... There's always a chance for me to miss a "slightly" damaged mono which may tear away with my personal best catch...

 

[tromic]

Thanks Vov! You are right for 8 and 9 mm shaft. 1 mm mono would not be the best choice.
Regarding friction in water of mono 1 mm and 2 mm here is an interesting comparison based on expression (3) from: http://apox.ru/blog/Podvodnaya-ohota/7-Oryjeinii-opit/924-Dvijenie-garpyna-v-vodnoi-srede
This expression is maybe not very accurate at all, but is not so bad either.
The same friction as has an shaft of 7 mm length 100 cm, according to the formula would have mono of thickness of 2 mm, length 3.8 m or mono of thickness of 1 mm, 7.6 m long.
So 2 mm mono has about 2 x more friction than 1 mm mono. This is very close to what I actually had measured!

 

[tromic]

Here are results for year 2017. testing:

 

[tromic]

This was one of the "free shaft" tying of the shaft used wide, but with very poor performance...
I was also surprised and disappointed because the mono was only 1 mm. With thicker mono the result would be even worse, less then 60 % energy performance compared to the shaft using devoto slider.