Posts by popgun pete

Quote from Wishihadgills

I wasn't saying that squeeze films don't exist only that they arent really present in a speargun. Many aspects of modern life wouldnt be possible without squeeze films and their application in hydrodynamic bearings and lubrication.

The experimentation I was referring two was more the trial and error of different builders trying different materials and techniques for building tracks and arriving at the current solutions. I guess it would be more of an evolution in that regard.

I didnt say that water cant work as a lubricant or form a film but Im sure you can agree that oil is a better lubricant. Your right about the ice skates but the shape of the blade plays an important role. If the bottom of the blade was rounded or sharp like some people think they wouldn't work. As Im sure you know for the squeeze film to form the shapes need to be very close and the gap between the surfaces has to be very small. Also having a higher viscosity liquid helps. I wasnt suggesting that a squeeze film cant or doesnt form only that because of how wide the gap is relative to the spear diameter makes it easier for the water to flow around the shaft and makes the effects of the the squeeze film minimal compared to other forces. Squeeze films and hydrodynamic bearings require much tighter tolerances than are found in speargun tracks.

This is further reinforced by the trend to use low friction materials . A squeeze film would reduce the friction to the point that material choice would have minimal effect and the extra work to make a the track out of a different material wouldnt be worth it. It would be easier to just make it out of wood.

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There is a squeeze film even on the bottom of an open track, just slide two wetted glass plates over each other. In tire tread pattern design I did a lot of work on squeeze films and how to disrupt them for better braking with fully locked wheels, so I know something about it.

Here is the Undersee mech in the "Reefmaster". The gun behind it is a gun based on the "Reefmaster" which shares the same layout and also fires a 3/8" diameter stainless steel (316) shaft powered by a 3/4" band. Both guns are from the late sixties.

Quote from Wishihadgills

Im not sure a squeeze film is forming in this scenario. Most enclosed tracks that I know of are intentionally made larger than the shaft so that they can function with slightly bent shafts or sand/debris in them. A good quote I read once was that you want your enclosed like an ak-47. It needs to be able to shoot every time even if there is a slight flaw in the shaft or barrel etc. Under ideal conditions a squeeze film might form and in the field you may see a partial squeeze film but I dont think this happens in most if any guns. Another problem with the squeeze film model is that it requires the shaft to move parallel to the track but it is known that on overpowered guns (one of the big reasons people choose enclosed track) and even normally powered guns the shaft flexes and does contact the track walls. If you watch slow mo videos of open track guns you can see how much the shaft flexes. The ability of the track to contain that flex and direct the forces into moving the shaft instead of flexing it. Additionally the oil used in engine lubricants is significantly more viscus and is chosen for its cohesion and ability to form a film. Water is not nearly as good as a lubricant.

Like you mentioned Dustyyoungblood track material wouldnt matter if that was the case but experimentation has shown that the UHMW and epoxy are the best.

I studied Applied Physics at university for my degree and the squeeze films are not some figment of my imagination, however I have not seen the topic of spearguns subjected to any experiment on this matter. As for water, well that is what an ice skater slides around on under the blades of their ice skates, the squeeze film supports their weight to reduce friction on the ice.

Quote from dustyyoungblood

So, in an enclosed track with a circular cross section, and in very close tolerance to a shaft with a circular cross section, then we have a squeeze film of water between them. During acceleration then, is the shaft perhaps not contacting the track at all? But just gliding in perfect equilibrium inside the enclosed track? If that is the case, then using a low friction plastic is not relevant. The only important feature of the enclosed track will be it's shape/size/accuracy of fabrication.

Not at the start as the shaft initially goes from zero, but the squeeze film will form very fast. Then there is the loading of the gun, the plastic tracks make it easier to push the shaft in, plus no shaft is ever truly dead straight. Some enclosed tracks are loose, like the optional one on the Riffe "Metaltech", so that it can take a couple of different diameter shafts. However a light section track will be less effective on shaft whip as the shaft will distort the track temporarily. The Riffe enclosed track is mainly intended to keep the shaft on the gun in the absence of a shooting line holding the shaft at the muzzle.

Quote from Don Paul

Pete, are the UnderSee still for sale downunder?

Cheers, Don

Maybe this one has been named after you Don. The Don Spearguns I Speargun

It has all metal parts where they count, unlike many other euroguns with load-bearing plastic triggers! Some of the plastic parts are/were sourced from o/s suppliers who do similar guns, but the superior works of the "Don" are worth the price of buying this Aussie version.

The late Don Linklater founded Undersee as "Undersee Novelties" back in 1947.

By enclosing the spear in a cylinder you get the generation of a squeeze film between the shaft and track, like someone slipping over with smooth leather sole shoes on a wet tile floor (which is tantamount to moving across a smooth sheet of ice wearing just ordinary shoes), and this squeeze film limits the frictional effects of the track. When an automobile engine first turns over squeeze films in the residual oil in the bearings create reduced friction before the oil pressure builds up from the oil pump to the running pressure and the plugs begin to ignite the fuel-air mixture. The squeeze film is the result of the velocity differential across the thin fluid film, say the enclosed track being stationary and the shaft accelerating inside it. Point or linear contacts at three points on the shaft will have more friction, not less. For the record the first enclosed track band guns had metal tube tracks, slotted at the sides. The modern enclosed track band gun started with top slotted metal tubes. Consideration had even been given to non-cylindrical shafts and tracks, such as hexagons and octagons, but of course a round shaft is the easiest to make as metal rod is available in many diameters, lengths and materials. Also cylindrical bores are easy to generate compared to barrel tube cross-sections shaped like polygons.

Quote from Jono

Undersee is still alive and well, most of there market comes from newbie i think.

Unfortunately many newcomers are brainwashed into thinking that euroguns are the "be all and end all", such that both Undersee and Sea Hornet are struggling these days. Fashion and product placement has euroguns in all the magazines, yet huge fish were taken with the cocking stock guns of the past. Shaun Adlam owns Undersee these days and even has some euroguns in his product range. The "Don" and the "Godfather" being two of them.

Prodive are now out of business, one model had a moulded plastic barrel and their handle looked rather like a Sea Hornet, only with a different lower grip shape. The innards are similar to the Undersee as Don Paul says. It will do what they will do. Generally 1 x 3/4" or 2 x 5/8" bands.

Quote from Sadot

Well, thanks very much:) I always wonder, how these spearguns wok/performe, here in the main Acapulco Avenue the "costera" in more or less in the center of the bay is a statue of a local "hero" he was a national swiming champion an he command the navy dive guys "comando submarino" in the early days of Acapulco.

The statue has a speargun like the one posted by MARCO the cressi, in one hand, a pait of fins open heals in the other and a mask in the forehead, he die in the rescue atempt of the bodies of a couple that were kidnaped, that in theory were in a place that has 50 to 60 mts. like 164 / 196 ft. of depht.:(

The spring guns must have been reasonably effective weapons as Cressi-sub built a range of different models for different jobs. There were varying lengths and diameters of barrels and the power of the propulsion springs also varied. Some shot tubular steel shafts and others had aluminium shafts for higher velocity shots at more rapidly moving fish. The "Saetta" was for hunting around reefs and had a slightly pre-compressed spring even before you loaded the gun. Most guns had springs that were "loose" in the barrel as they just sat with their front ends at the entrance to the muzzle after the shot.

Quote from Dan

Pete, you are an encyclopaedia of spearguns. Thanks for your contributions.

Well thank you Dan for the forum to put it up in! This knowledge is going "over the horizon" fast, so unless it gets written down it will be forgotten as old-timers head for that "big reef in the sky", or somewhere slightly warmer depending if they have been good or not!

I still hope to locate the "D&F" (not its real name) 1943 gun as some parts of the design would have to come from experience, not theory, as that front curved line wrap hook is to avoid line snags as shooting line pulls off the line release lever behind it. Also the small spur on the trigger finger guard is to allow a reverse hand hold on the handle when cranking the line release lever to latch up the trigger, they don't actually tell you that in the patent, but that is what the spur is there for, to rest your thumb on it.

The significance of Yves Le Prieur's gun is that it is one of the first band guns, "demande le 9 decembre 1938", but only published in 1940. The priority date is the 1938 date, but Alexandre Kramarenko got to the patent office first with his spring gun in 1937, so his gun is usually acknowledged as the first speargun. If you take power operated fishing gigs as a starting point then they pre-date spearguns, but the spear never fully leaves the gig. It was a small leap to putting a grip handle on the gig, installing a trigger and letting the shaft fly free of the muzzle. Goggles gave you underwater vision, they have been around for centuries and now you had a weapon that could strike faster and harder than a hand propelled spear or harpoon. Guy Gilpatric was concerned that people could now spear fish without getting the back of their head wet and Yves Le Prieur in a sense obliged him. You would be a brave man to attempt a surface dive with his "antler snorkeled" dive mask as your continued ability to breathe on surfacing was dependent on eliminating water from the mask, one-way valves on three intake tubes on one side let air in (and water too if the snorkel tips were submerged) and three one-way valves let air out of the three exhaust tubes on the other side. So not really a "dive" mask at all, more a personal underwater viewing window. Le Prieur was an accomplished engineer and inventor, he saw this as a surface activity rather than submerged underwater hunting with his free-flow breathing set using compressed air and his "Nautilus" gun, a cartridge powered underwater rifle. You can read all about this in the "Compleat Goggler", Gilpatric's book, if you can still find a copy not snapped up by old book collectors! Jules Verne would have been pleased as his underwater hunters had been blazing away underwater for years with their compressed air guns under the looming bulk of the Nautilus hovering about the bottom, while illuminating the benthic scene with "electric lamps of the latest pattern".

Kramarenko's spring gun used a single-piece trigger, hence the large horizontal biasing spring behind the trigger has to balance the torque on the trigger or it will shoot without you pulling the trigger! This was fixed in the next model and Charles Wilen, his American associate, patented that new gun in the USA. Of course everyone then copied it!

The grip handle is made from aluminium and wood as an internal spacer. Wilen said movement in the grip made the gun unreliable, but it was better than nothing and opened up the sport of spearfishing with mechanical weapons.

The trigger mechanism in compression spring guns is usually of the "pull down sear" type, show here. The push from the propulsion spring tries to revolve the sear lever up, like a locking pawl, and restrains the shaft. The harder the propulsion spring pushes, the better it locks. When the user pulls the trigger the short forward mounted lobe inserted into the back end of the sear lever serves to pull the sear tooth down, aided by the leverage built into the trigger arm with respect to the short length lobe engaged into the sear lever. This force from the finger's trigger pull acts at a long distance out from the sear pivot pin due to the long horizontal length of the sear lever arm giving a considerable mechanical advantage over the vertical offset of the sear tooth from the sear pivot pin. The only problem with this trigger mechanism is that when swinging down the sear tooth ever so slightly pushes the spear backwards against the action of the main propulsion spring, but the longer the sear lever arm then the flatter the arc travelled by the top of the sear tooth as it depresses to release the shaft.

This trigger mechanism was originally completely caked in dark reddish colored grease, the trigger biasing coil spring looked like a short piece of pencil it was completely filled with grease. If spring gun spearfishermen ever sought an heraldic emblem then it would surely have to be a jar of grease surrounded by tattered rags rampant and sitting on a stained field of old newspapers.

A side slotted barrel gun using loop bands designed by Le Prieur, it is designed for shooting from the surface, hence the bulky wooden stock. Le Prieur designed a full face mask with snorkels built into either side, you used it to look down and shoot the fish swimming below. The snorkels had multiple bore tubes and looked like antlers grouped together at the top where they were all fixed together. Air went in on one side and exhausted from the other. A very early gun and it has a patent, as does the dive mask.

The spring gun handle shows that this is someone else's realization of this weapon, but the idea is from Le Prieur.

The diagram is attached showing the original handle and optional shoulder stock.

Quote from LunkerBuster

whoa. that is really cool..I cannot imagine how annoying chaning the band would be

You would have been so engrossed with the novelty of using an underwater weapon of completely novel construction that you would have hardly worried about changing the bands. There is no Rene Cavelero "Arbalete" available yet (that design was only registered in 1943) and the only spearguns being used are the many spring guns produced pre-war (e.g. United Service Agency: Kramarenko and Wilen's compression spring gun) and the various home-made efforts built around side slotted tube barrels with wooden rifle-like stocks. Bands are made from rubber items manufactured for other purposes, such as automotive belts and straps, hence early spearguns often use square or rectangular cross section bands. It is the dawn of spearfishing as a sport which will flourish once the war ends. That said, bands don't last long and are not very powerful due to the type of rubber used back then. Sometimes bands would stretch and not return to their original size or would break.

This French band gun is the subject of a patent in 1943 (diagram shown), when France was under occupation by German forces during World War II, but not necessarily in the Sud (South) of France. I have never seen one, but I am sure that it existed, even if only as a prototype. The overall proportions of the gun are similar to a spring gun, but it has a rectangular section metal barrel tube, being a "semi-enclosed track" band gun with a spear tail driving device instead of a wishbone. The unique trigger mechanism features a "double demultiplier" action, which means that the sear lever and trigger both confer mechanical advantage, thereby improving the trigger mechanism's leverage to reduce trigger pull. We take such things for granted today, but that was not the case back in 1943. I wonder if Cyril has ever seen one, or if any of the other French speargun collectors contributing to the "guns of the legends" thread have any knowledge of it. I have produced a second diagram showing the trigger mechanism's action and that of the unusual internal lever arm link to the line release lever. Note that the line release lever is also used to reset the position of the twin sear teeth and latches the trigger mechanism for the next shot, after first inserting the spear into the gun.

Quote from popgun pete

The details are locked up in my old computer, but the guy listed it at a starting price of $14,000! I sent him a message about what it was (he never had a clue how it worked) and told him that he was out by a factor of seven, even at the most optimistic price. He relisted around ten grand, then gave up and we never saw it again. I wondered how he came by it, where were the receipts and instructions? Had it been acquired by honest means or was it liberated from some old-timer without permission? I guess that we will never know. Pay that sort of price and you want provenance, not something from "Midnight Supplies".

Out of curiosity I searched on "Siama Roma" and found another one here COOL OLD GUNS - Page 2 - Spearfishing Planet

This gun is assembled, so you can more easily see how the parts in the timber box go together. "Brevette" means patent, not brand, as the poster has suggested there.

Quote from sdeisen

interesting, I never think of springs working in an opposite fashion

Maxime Forjot had the patent for tension spring guns and produced his "Douglas" line of mid-handle spring guns. Unfortunately he was ripped off at every turn as many copied his design. His story was told in a British "Diver" article which was put up on the Web. The tension spring gun drives the shaft nearly the full length of the barrel, unlike the compression spring gun which only uses half. Tension spring guns can snap their springs at the anchor ends, whereas compression spring guns just lose power as the spring gradually collapses and becomes shorter. In them you can move the rear spring fixing pin forwards to compensate, for the tension spring guns you need a new spring.

Quote from Don Paul

I lost track of this gun, it was out of my price range at the time, I like the box as well.

Cheers, Don

The details are locked up in my old computer, but the guy listed it at a starting price of $14,000! I sent him a message about what it was (he never had a clue how it worked) and told him that he was out by a factor of seven, even at the most optimistic price. He relisted around ten grand, then gave up and we never saw it again. I wondered how he came by it, where were the receipts and instructions? Had it been acquired by honest means or was it liberated from some old-timer without permission? I guess that we will never know. Pay that sort of price and you want provenance, not something from "Midnight Supplies".

Quote from Don Paul

Yes, of course, I'll get it from my kids house this Sun Peter.

Cheers, Don

Thanks Don. I just found one here on a subsequent search, but the images are too small to fathom the workings.