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Tomba - All in One barrel sealing
- Thread startertromic
- Start date
Thread Status: Hello
, There was no answer in this thread for more than 60 days.
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Interesting to see the vacuum cuffs are orange. Rubber is reinforced in strength by using carbon black in various grades and particle sizes and structures. That is why most rubber seals and washers, etc. are black in colour.
Thanks Tomi,
I was hoping he had a +8mm version.
Do you, by any chance, know how they are made?
It's quite possible that these cuffs are made from of a colored PU.
I asked him if they were made in PU. He answered me they were made in synthetic rubber..? There are many kinds of synthetic rubber..
Maybe you can ask him for more details. Maybe he could make cuffs for 8.5 - 9 mm? I do not believe he makes them himself.. It is not simple to get the right properties. There are, below the video, in comments, his whatsapp contact number.
@Pete. You are right about the color. I suppose they are maybe too soft compared to Pelengas. Is it better or worst...? I do not know...
They should be tested in spearguns under working conditions.
Duccio made his copy of Tomba700X but I noticed that he had two O-ring on the shaft. I asked him about that. That was wrong, he'd confessed that to me. Maybe he also made some other mistakes in making his Tomba: too heavy slider,.. ? But he still believe that Tomba is one of the best vacuum kits worldwide for the spears using line slide.
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At the small scale items are never truly smooth and that micro texture nibbles at the lip of the cuff tearing tiny pieces away. This can take a long time to accrue any significant damage, especially with lubrication present such as water. The strengthening of carbon black resists wear and that is why vehicle tyres are black. With everything wetted the softer material should be OK for a season which would be enough as vacuum cuffs could then be changed once per year at no great cost. Dry loading wears cuffs out more than loading in the water, so always a good idea when checking your gun on land to add some lubricant to shaft and/or vacuum cuff before pushing the shaft into the gun's muzzle. A glass of water will do if you dunk the gun’s muzzle in it, or a small drop of oil rubbed first on the shaft tail as it will wipe off on the cuff’s lip.
It seems Duccio seal cuffs are not soft and have some imperfections:
"Le ho comprate due di duccio, ma non mi convincono tanto, si la gomma è più dura al tatto ma hanno degli errori di lavorazione, troppo grossolani secondo me, non sono perfette, si vede dalle foto pure l imprecisione nella lavorazione"
Some years ago when STC made his first pistons I bought one for my Cyrano. I was surprised because it had a skirt seal much tougher than original Mares Cyrano piston. I didn't like it! I suppose it was made in polyurethane? It was in blue color.. It had high friction in barrel. I ripped it out and replaced it.
"Le ho comprate due di duccio, ma non mi convincono tanto, si la gomma è più dura al tatto ma hanno degli errori di lavorazione, troppo grossolani secondo me, non sono perfette, si vede dalle foto pure l imprecisione nella lavorazione"
Some years ago when STC made his first pistons I bought one for my Cyrano. I was surprised because it had a skirt seal much tougher than original Mares Cyrano piston. I didn't like it! I suppose it was made in polyurethane? It was in blue color.. It had high friction in barrel. I ripped it out and replaced it.
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Yeah, given their small shaft size range, I was thinking they may not be very flexible. I know this is outragous speculation, haha, but that imperfection almost looks like they could be 3D printed in TPU/TPE. Would need better pics to see if there are any layer lines. But he had such a huge bag of them, that I wouldn't think it made sense for them to be 3D printed...
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It seems to me that this seals are not 3D printed.. I would say they were made using a mold having two halves. It is better seen on the right image.
Yeah, when I saw the big bag, I assumed they were molded, but that's a sloppy mold, then
Maybe Duccio really makes them himself at home...?Yeah, when I saw the big bag, I assumed they were molded, but that's a sloppy mold, then
Rubber parts are molded with heat and pressure, which is why you get complete mold filling and seldom see imperfections in the finished product.
Seeing those artifacts I doubt Duccio is doing it the "proper industrial" way with heat and pressure as why spend the money to do so unless the mold was in better shape? Many ways to skin a cat, especially in the home shop and for tinkerers and "synthetic rubber" could indeed be PU, which as I mentioned elsewhere can be had in pourable solutions and cure at room temp.
It is not going to be strong enough as compared with rubber, but the better the fit then polyurethane should work OK, it just does not have the elasticity and wear resistance of rubber in this application where the seal has to stretch out to pass the shaft tail butt through. That is why Salvimar can use the same seal, as does Pelengas, for their full range of shaft diameters, using rubber vacuum cuffs. Taimen has a rather thin lipped vacuum cuff, but have a different cuff for each shaft diameter (there used to be 3 cuff sizes) and also have polyurethane leading edge shaft tail stops which means they don’t ask so much of the cuff material.
When I buy a pneumovacuum gun I always buy 5 spare vacuum cuffs. If you buy a Tomba muzzle then you don't require any specialist cuffs.
When I buy a pneumovacuum gun I always buy 5 spare vacuum cuffs. If you buy a Tomba muzzle then you don't require any specialist cuffs.
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Yes, that's why I am suspicious about using polyurethane for this purpose: "it just does not have the elasticity and wear resistance of rubber in this application where the seal has to stretch out to pass the shaft tail butt through". There are certainly some elastomers that could be used for this application but I doubt somebody can make it in the kitchen.. There are more than 30 different elastomers..
Pelengas has two cuff sizes for shafts: 6.5-7 mm and 7.5-8 mm. As I recall Salvimar has only one size..?
I've read on Italian forum that Pelengas cuffs are much longer lasting than Salvimar.
Although Tomba uses NBR O-rings a suppose some other elastomer O-rings might be used too. They do not require any lubrication other than water and should not have special properties regarding environment influences.