Choosing spear for dry barrel gun

[Diving Gecko]

Hey Tromic,
Great to hear from you also.
You are absolute right about the differences and similarities between Tomba and STC - I have read as much about it as I could lately. But of course, you would be the one to know best.
I do have one suggestion for your Tomba line of products, if I may (though there may be good reason as to why it is as it is).
Tomba is cheaper than STC for a basic kit for one shaft thickness only and I suspect that's what the vast majority of buyers want. But if you want a kit that has the parts to be able to change between two thicknesses of spears, then the price is the same. The extra parts needed for the second thickness are more with the Tomba system than STC. Marko have sent me some nice pics and it seems that for the extra shaft thickness, you need to change the most outer part of the muzzle, the Delrin (?) bushing and O-ring. I know that of course the bushings have to have different inner diameters to work with different shaft diameters, but I was wondering if it wouldn't be a good idea to make the outer diameter of the bushing the same, if possible? That would mean that only the Delrin bushing and the o-ring would have to be changed to change shafts. That would make it substantially cheaper and you would have that edge over STC again. Also, Marko said it it best if the muzzle parts are machined together for the best possible fit (I guess you don't use o-rings between the aluminum parts of the muzzle?). With the approach of making the bushings the same outer diameter, then Marko wouldn't have to machine a new muzzle head without having the other other part of the muzzle if a customer later on decided to change spear thickness.
(I hope all this makes sense.)
As said, I am still very much considering your great product. It is just that I might buy shafts from STC as they have some already made as freeshafts at a good price and it may be easier to just get it all from them. But then, I can't have a custom color as I can with Marko

Oh, while I have you - about your 1.5mm trigger pin for Seac. What is the benefit? Less force to pull the trigger, is that it? If so, then how much is the difference between a stock pin and your's? And is it only the pin and threaded bushing that needs to be changed or also the sear lever (I think it is called)? Can you tell me the price of that kit? Or perhaps PM me the price.

All best,
David

 

[tromic]

It is possible to have TombaF701 for both 7.00 and 7.14 mm shaft. Or TombaF800 for 7.95 and 8.00 mm. That is all. I prefer Tomba kit to be for one shaft thickness only. In that case one can have the best centering and the optimal sealing with minimal friction - best performance.
There is one kit more you can take in consideration: Evo Air. You can use it with 6.5, 6.75, 7.0, 7.14 mm all with one kit without changing anything!

With 1.6 mm trigger kit you have 3*3/(1.6*1.6) = 3.5 x lower force to pull the trigger (due to pressure in a pneumatic speargun).

 

[zmajmr]

Hi Pete,
....but then I think I saw a lathe on his video so wasn't sure whether a grinder was precise enough - good to hear, I shouldn't be worried about that.

I use lathe because I have it , it is much faster with lathe and more precise, but all that you can do with grinder, you need little more time (you need to check if piston fits little by little, you do not want to take off too much of material) and after grinder you need to use sand paper to make surface smooth. I put some WD 40 on sand paper, fine granulation and I have then smooth surface.

If you have any more doubts just ask

 

[Diving Gecko]

Hi Marko,
I have read pretty much everything I can find on the subject in the past few days - and it is so great to have you, your dad, Fox, Pete and the rest of the gang chime in. It really is amazing how much knowledge is on this forum.
In regards to modifying spears - I am sure, I could do it. But I live in Shanghai (where all spearfishing gear is illegal) and my gun is in Bangkok and my dry barrel kit and spears will most likely be shipped to Denmark. The point is, I am not exactly sure how much time I have to find a workshop with proper tools once I have all the gear together in one place. Also, in the past days, I have found out that STC and Seatec both offer pre-drilled freeshafts and their prices are less (20-30 euros) than what I would pay for an oversized normal shaft. So, it makes better sense to me to get the spear ready-made and right now, I am just waiting for some shipping quotes from a few shops. If I end up getting the spears from STC, I might just get their dry barrel kit also - but only for the convenience of getting everything from the same place. As mentioned above, the price is the same as Tomba if I want it to work with two different shaft diameters. But then again, the vain "design" side of me, actually likes the fact that, I can get it in a different color from you. The fact that STC uses a "dynamic seal" (I think they call it) as opposed to a traditional O-ring doesn't put me off either. I would pick up a spare or two. I might even get them for cheap here in China if I can identify them.
Today, after your dad mentioned it, I have spent a few hours reading about Seatec's Evo-Air system and I am not sure it is the option for me. I think the extra steps of having to screw in the head before loading and then loosening it before firing is something I would simply forget too often - that's how I am... (But I do have to say that the Seatec video showing the shaft glide out without much resistance in the standby mode is quite persuasive). Also, I think Tomislav is unfortunately a bit wrong as it seems it will only work with 7mm shafts - that's what I understand from Google Translate anyways. The freeshafts Seatec offer are all also only in 7mm. (Which is probably a good overall thickness after all).
So, basically I am still undecided, but I hope to get those shipping quotes soon and then finally make my mind up.

BTW, your trigger mod must make the trigger buttery smooth. I don't feel my Asso Hunter is hard as it is, but three times smoother would be incredible. Is it only the threaded steel bushing, O-ring and pin which needs to be changed? (That would be a really easy thing to do).

All best and I hope people who will someday be in the same situation as me can benefit from all the info that is coming in on this thread. At some point, I'll compile some links to where I have come across the ready-made freeshaft.

 

[tromic]

This was response to me from one of designers of Evo-Air.

EVO-AIR Volata Sottovuoto ad O'Ring Mobile

"Si Tromic è possibile l'uso della Evo-Air con asta da mm. 6,5 e con mm. 6,75 a boccalino serrato quindi senza spostamento dll'O'ring, il tutto con un minimo attrito che non influisce sulla durata dell'O'ring.

Bisogna pero' ricordare che questa Volata è stata progettata per il suo funzionamento con Asta da mm. 7 ad O'rig Mobile per avere Attrito Zero e Massime Prestazioni, oltre ad alcune prove che si stanno eseguendo con Aste da mm. 7,5 sulle Pompette di oltre cm. 90 di lunghezza"

 

[Diving Gecko]

Wow, indeed you were right. (But then again, how could I have doubted that.)
Thanks for the link to that Italian thread - I had not seen that before.
I guess that is good news, but still not sure I like those extra steps needed to load and fire. But for other folks, who are OK with that, the Evo-Air kit could be quite interesting as it works with shafts from 6.5 to 7.5 mm, so it gives a bit more flexibility.
But now I am just getting more and more confused - I am trying to narrow down options, not be tempted with new ones, haha.

Thanks again,
David

 

[zmajmr]

BTW, your trigger mod must make the trigger buttery smooth. I don't feel my Asso Hunter is hard as it is, but three times smoother would be incredible. Is it only the threaded steel bushing, O-ring and pin which needs to be changed? (That would be a really easy thing to do).

Till now I made 3 trigger kits for other persons, one of them have Cressi SL with 3 mm pin and he told me that now trigger is sweet (person complained me that trigger was hard before), I personally did not feel large difference because I did not put much pressure in my gun so I did not have any problems. So if you do not have problems (you do not use gun on high pressure ) then leave it as it is. And yes, you need to change parts that you mentioned in your post. You can see how parts look in this video:
[ame=http://www.youtube.com/watch?v=4X7IfTILwlA]1.6 mm trigger pin for pneumatic speargun - YouTube[/ame]

Choose your kit to fits your needs and make your life easier, if it easier to buy all from STC then do it , no hard feelings from me, I am glad that I can help you even if you chose other kit.

 

[popgun pete]

Those shafts should be called front tied or front bound shafts. A freeshaft is a shaft without a shooting line. Most spearguns with shooting lines have a rear tied or rear bound shaft. Front tied shafts were originally used with spring guns as the spear did not use a line slide in the earliest spearguns, but line slides were soon adopted. Forward latching spearguns where the sear tooth is located in the muzzle of the gun use front tied shafts as a stop on the shaft tail may catch on the sear tooth, but there have been some exceptions (e.g. Pirelli "Aries").

The line slide with line loop system used with a front tied shaft to stop the line slide pulling off the bare shaft tail can create problems if the loop unexpectedly catches on the muzzle, I have had it happen. Personally I think rear tied shafts are superior to front tied shafts, especially on longer guns. The only reason front tied shafts are used is if the designer can see no easy way to engineer a line slide system. In my opinion the system created by Tromic is superior to the front tied systems such as the STC-X system; basically front tied lines are a compromise. If they can engineer them then speargun designers have always used rear tied or rear bound shafts. Russian spearguns use front tied shafts for the many forward latching spearguns in their arsenal as forward latching spearguns are easier to make with fewer pressure seals required in the gun, but the annular groove in the shaft for the sear tooth weakens it, as does any tie hole in the shaft located up front. Pneumovacuum spearguns have made the engineering of line slides more difficult, but not impossible, if the design installs the muzzle vacuum seal in the gun as a fixed item. An example is the "Taimen", but the easiest solution is if the seal is installed on the shaft, as Tromic has done, plus the seal can be easily inspected when it is sitting on the shaft and not hidden inside the gun.

 

[tromic]

Pete I agree about all you said! "Free shaft" guns are also more sensitive to damage if water enter the gun. But, they are more simple in design because have less parts.

 

[Diving Gecko]

Hi Pete,
I couldn't agree more on the naming - it is counter intuitive for sure. I think the Italians call these shafts "naked" or "nude" which makes so much more sense. I fear it is too late to do anything about it though I agree that calling them "front tied" would be a good solution.
I understand your view about engineers always doing tail tied speargun designs, but on the other hand, hydrodynamics simply has to be better on a nude shaft. I also see that if there is much drag on the shooting line, then in theory it could easily pull the shaft off course. But I think that the shaft has so much inertia and with a thin mono and a good rigging, in practicality it is less of a concern. (Again, I am a newbie and all my "knowledge" is strictly from reading and theorizing.) But in reality, it seems people who use nude, front-tied spears are mostly having trouble retrieving them from rocks and not with precision. Also, it might be that engineers up to now have opted for rear-tied spears, but Sporasub's One Air which has to be the gun with the most R&D out there in decades have opted for mixed solution. It is almost a completely nude design. It is front-tied and has no stop washer on the tail, but if you want it, it can be fitted with a guidance slider which keeps the shooting line parallel to the spear and guides it so that it "exits" more from the rear.
Maybe that's the best of both worlds?

Marko, thanks for your understanding! It really is admirable that you are so willing to help out. I guess you are just a good guy - as well as knowing you are producing a great product.
Also thanks for clarifying the parts needed for the trigger pin modification. I tried to service my own trigger pin as it was leaking but did not have a replacement O-ring (I did take it apart). It has to be one of the easiest mods one can install. You just need a pair of needle-nosed pliers, a screwdriver and a deflated gun. If anyone needs a smoother trigger, I would not be scared by the work involved at all.

"Unfortunately" I am not ruling out Evo-Air after all... It might be a good compromise. Almost as simple as Tomba (except for the extra screwing in and out steps) with a normal O-ring, it takes 6.5 - 7.5mm spears and I can get the muzzle and spears from the same shop. Also, it is on sale at some places for 75 Euros now (down from 100 Euros).

I hope to be able to make up my mind on all this in the coming week. I just need those shipping quotes as they sometimes can be a bad surprise.

 

[foxfish]

The way I interpret the term, is in a dry barrel aplicacion, the spear is free from the slider arrangement ... a free spear!
I use this arrangement as it simplifies the loading procedure & seem to have little effect on performance or accuracy.
Maybe not ideal but I just prefer the method.

 

[tromic]

Hi Pete,
...
I understand your view about engineers always doing tail tied speargun designs, but on the other hand, hydrodynamics simply has to be better on a nude shaft.

Tomi, thanks for your understanding! It really is admirable that you are so willing to help out. I guess you are just a good guy - as well as knowing you have a great product.

1. Nude shaft is not better in hydrodynamics than Tomba with slider! But it is better than STC, LG ...
2. Thank Marko, not me (Tomi).

 

[Diving Gecko]

Hi Tomi,
1. I hate to disagree with you, but I think I really have in this case. I simply can not see how a piece of plastic attached to the end of a spear has less drag than no piece of plastic at all. I also do not believe that a slider can help induce or prolong laminar flow or can create any kind of lift that we can control or which can make up for the increase in drag.
As long as I don't hear people complain about accuracy being jeopardized I am willing to give it a go for its simplicity. But we are splitting hairs here. I would not be surprised if your Tomba with cut down sliders are better than the rest out there and if I indeed wanted a slider, I would most likely want yours. And actually, I am pretty sure, I would not be able to tell much, if any, difference in practical use being I am new to this and also, I wont have both options to compare.

2. Ooops, you are absolutely right, I'll try to edit that post and give credit where credit is due.

Best,
David

 

[zmajmr]

Look this 2 videos, you will see how path of shaft changes because of attaching nylon behind of barbs. In second video you will see that there is little loop made from nylon (it imitates tiny slider, as I know sir Ramon from Spain has invented that, he makes Tovarich kit). So with free shaft you need to correct aiming in your head because shaft have tendency to fly down (that is no problem for me). With kit with sliders shaft fly straight (much more straight then compared to free shaft). As my father say, kit with plastic slider have better performances (which you will not be aware looking with you eyes in water, I can not tell the difference) then free shaft kit, because line from free shaft configuration is longer for aproximately one lenght of spear, so if you want to shoot on let say 4 m with 1 m long gun you will have 4.8 m of nylon at free shaft configuration and 4 m of nylon for configuration of spear with sliders, but as I told you you can not tell difference looking with your eyes, you need instruments for measuring speed to see which one configuration is better.
So, same distance, in one case more nylon (larger drag) and shorter nylon less drag, in both cases spears fly fast, but little faster at version with sliders.

https://www.youtube.com/watch?v=_vE7v2j6jQs

https://www.youtube.com/watch?v=OOLDI9PZgLs

Now you will be probably more confused, I personaly like more free shaft because when I load spear in gun, spear slides only on plastic and O-rings (at kit with plastic sliders, there is O-ring and stainless steel cone ring, so friction between steel and steel), so it is relatively easy to load spear in gun, because of that I made for my asso 135 free shaft kit for 6.5 mm shaft and I realized that that was not so good idea, because long shaft whith small diameter wants to bend on side where is more drag, I passed my nylon on left side of reel so shaft flew always on left, after that I made kit with sliders for same 6.5 mm shaft and that was much better combination, because drag was on the end of shaft and spear flew straight.
I do not know did you watched this video, that was bad combination, I did not recorded good version (did not have more nerves, I wanted to catch some fish).
https://www.youtube.com/watch?v=SuQ6LEAGaTs

 

[Diving Gecko]

Ah, I see that I will soon be proven wrong (again). haha.
Now, I am not sure I wanna watch those vids. Nah, I will. Tomorrow, since it is getting late here.
I did think about a nude shaft having more nylon but didn't think about it in terms of more drag but only "losing" half a wrap of shooting line. So, the added line creates as much drag or more as a slider. I get it...

Thanks, I guess
D.

 

[zmajmr]

Ah, I see that I will soon be proven wrong (again). haha.
Now, I am not sure I wanna watch those vids. Nah, I will. Tomorrow, since it is getting late here.
I did think about a nude shaft having more nylon but didn't think about it in terms of more drag but only "losing" half a wrap of shooting line. So, the added line creates as much drag or more as a slider. I get it...

Thanks, I guess
D.

Yes, little more drag, that is my fathers conslusion , you have topic about measuring speed of shaft on forum.

 

[Diving Gecko]

(I just posted most of the following in response to another thread. A member asked about what kind of dry barrel kits are available and since that's what this thread has been about lately, I thought it would make sense to try to compile as much info as possible here for future converters. Here, slightly edited, it goes):

Basically, from what I have been able to gather so far, all the manufacturers make kits for most brands of guns and in my opinion the biggest decision you have to make is whether you want the shooting line tied to a slider or to the tip of the spear. If you don't want a slider then you have at least three options (Tomba, STC and Seatec Evo-Air). If you do want a slider, then afaik, the Seatec Evo-Air is out of the picture. BTW, Tomba is the cheapest (Euros 60-65), STC quite a bit more (85-100) and Evo-Air is in between (75, with discount). Both Evo-Air and Tomba runs regular, cheap O-rings whereas STC uses more specialized seals (Euros 3.50/Ea). I really don't see this as much of an issue though. I believe they will all last a long time and one should always keep spares around.

In regards to shaft thicknesses, Tomba is custom made to one size (or two that are very, very close to each other) and you have to change app. half of the parts to go with another size. STC is more modular and you'll have to change fewer, cheaper parts whereas Evo-Air can run shafts from 6.5mm to 7.5mm without changing anything (perhaps just the O-ring). This is not an issue at all if you know you are going with one shaft thickness, which I think the vast majority of people do anyways. I am just undecided and may want to keep more options open. So, if you want a kit that can run eg. two different shaft sizes then the price difference between STC and Tomba is neglible (both becomes between 100-110) and Evo-Air becomes the cheaper option (if you can find the 75 discount option, normally 100).
One last difference between the kits worth mentioning is that with Evo-Air, you have to screw in the head of the muzzle before loading and loosen it before shooting each time. If you forget to loosen it, you should be fine, you'll just have a bit more friction and a less powerful shot. With the others, you just load and fire.

Without having tried any of these options, I really like that Marko and Tomi (Tomba) are on this forum as much as they are and I have never come across a single post from anyone having any issues with their products. I have spent a long time reading about it all and I have only seen positive feedback. I think as a rule, people are more driven to post when they have bad experiences so I take this as a very strong indicator that Tomba just plain works!
Also, I am not sure about those extra steps needed for the Evo-Air to function at its fullest, but maybe that's a non-issue and just becomes routine very fast.

I think this is the link which has the most info on Tomba kits - it is mostly by Tomislav (Tromic) who designs the Tomba kits and it basically chronicles the development of the different models and as such also what is available and how they work. It is quite long and you might be able to start halfway through(?). A lot of it is intermediary design drafts and thoughts from Tomi with long-time Darksiders giving feedback and as such it also serves a great educational purpose.
(BTW, you can PM Marko (zmajmr) and he will tell you exactly what is available and the pricing.)

BTW, the prices mentioned are as I have obtained them around Nov. 2012 - they may very well change.

Best,
David

 

[tromic]

I would add to your list Ramons (spanish) Tovarich kit, for "free shaft". It is for one shaft thickness too, but is very good, easy to use and reliable.
For shaft with line slide there is also LG system kit and Mizalo (france). LG is probably better in performance than STC. Mizalo is maybe the most silent kit. A think that Tomba is the best in performance among all other kits with line slide. "Free shaft" kits might be, all about the same, in performace. However, it seems to me that the STC could have highest friction to the shaft, especially at greater depths, because of skirt like seal. But this is only theoretical.
Some users have noted that such a seal on the piston has a much higher friction than the O-ring. They prefer only one O-ring on a piston. I'm not sure how the Evo-Air behaves in greater depth, in terms of friction between the O-ring and shaft. I'm not sure that friction is negligible - because of the water pressure and the cone in which the movable O-ring is positioned?

 

[Diving Gecko]

Great, even more. Thanks Tomi.
Though for me personally, my head will explode if I look into too many more options, haha.
That said, does Ramon still produce kits? (Is it the Karayo?) I sent an email a while back, never heard back.
So, Ramon is in Spain and Mizalo might be French(?) so of course where one is based might also influence one's choice of kit. I don't know anything about LG System.

 

[tromic]

Great, even more. Thanks Tomi.
Though for me personally, my head will explode if I look into too many more options, haha.
That said, does Ramon still produce kits? (Is it the Karayo?) I sent an email a while back, never heard back.
So, Ramon is in Spain and Mizalo might be French(?) so of course where one is based might also influence one's choice of kit. I don't know anything about LG System.

Ramon (karayo) is very ill, for a while.
This is LG web: http://www.lgsub.com/