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All About Guns What's your weapon of choice, and why? Discuss the beloved speargun here!

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Old 05-05-2018, 01:52 AM   #16
doyenofcastle
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Re: Inverted roller

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Originally Posted by popgun pete View Post
link showed up with asterisks not inserted by me, so diagrams posted here from the other web-site.
a small question in case of using mini pulleys for 2 set of rubbers can we replace them by a D shackle ex.M6 ?
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Old 05-05-2018, 02:21 AM   #17
Diving Gecko
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Re: Inverted roller

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Originally Posted by doyenofcastle View Post
a small question in case of using mini pulleys for 2 set of rubbers can we replace them by a D shackle ex.M6 ?
Hey Doyen,
It's a four year old thread and I noticed neither Nanna or Pete has, unfortunately, been active on the forum for some time.
As for your question, I am not sure what you are asking? But if you asking if you can use shackles instead of pulleys then the answer will be no. Just too much friction. But perhaps, that's not what you are asking.
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Old 05-05-2018, 10:04 PM   #18
doyenofcastle
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Re: Inverted roller

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Originally Posted by Diving Gecko View Post
Hey Doyen,
It's a four year old thread and I noticed neither Nanna or Pete has, unfortunately, been active on the forum for some time.
As for your question, I am not sure what you are asking? But if you asking if you can use shackles instead of pulleys then the answer will be no. Just too much friction. But perhaps, that's not what you are asking.
Hi man ,

Yes you r right ,but how is friction will come from ? shackle is very smooth SS bar ,if you just raised the wishbone from the gun body by few mm it won't give any friction ,is it right ?
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Old 05-06-2018, 12:18 AM   #19
Diving Gecko
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Re: Inverted roller

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Originally Posted by doyenofcastle View Post
Hi man ,

Yes you r right ,but how is friction will come from ? shackle is very smooth SS bar ,if you just raised the wishbone from the gun body by few mm it won't give any friction ,is it right ?
Why don't you try it? Personally, I still believe the friction will be much higher. I used to race competition sailboats and in a pinch, if a pulley broke, you could get by with a shackle instead but def at higher friction.
If you want to save money, then make your own pulleys. It seems you have access to a laser cutter, so if you can get to a lathe, too it wont be hard. Get some bearings, cut some small pulley wheels out of Delrin and you are there.

As I said elsewhere, I think you are over thinking things at this stage. It feels like every post of yours is on a new design or idea. Don't get me wrong, it's not bad at all to be hungry for knowledge and eager to try new stuff but I think it is not the best approach to start with.
If you want to make good guns, I suggest you make one based on the best designs out there and your own experience so far and then you can start changing things around on latter versions to compare against your benchmark. If you change too many things at once, you wont know what to blame if it doesn't perform well and almost equally bad, you wont know what worked if it performs well.

In this case, I would choose pulleys for your build. You only need two and they are not that expensive, even less if you make them yourself. Then you do a speed and penetration test, change to your shackles and repeat the test. If you didn't loose speed nor penetration then on every future build you can use shackles knowing that it works. It would have cost you one set of pulleys to gain that knowledge. But as said, I would be surprised if you don't take a performance hit but feel free to prove me wrong:-)
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Old 05-06-2018, 06:06 PM   #20
willstroo
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Re: Inverted roller

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Originally Posted by Diving Gecko View Post
Why don't you try it? Personally, I still believe the friction will be much higher. I used to race competition sailboats and in a pinch, if a pulley broke, you could get by with a shackle instead but def at higher friction.
If you want to save money, then make your own pulleys. It seems you have access to a laser cutter, so if you can get to a lathe, too it wont be hard. Get some bearings, cut some small pulley wheels out of Delrin and you are there.

As I said elsewhere, I think you are over thinking things at this stage. It feels like every post of yours is on a new design or idea. Don't get me wrong, it's not bad at all to be hungry for knowledge and eager to try new stuff but I think it is not the best approach to start with.
If you want to make good guns, I suggest you make one based on the best designs out there and your own experience so far and then you can start changing things around on latter versions to compare against your benchmark. If you change too many things at once, you wont know what to blame if it doesn't perform well and almost equally bad, you wont know what worked if it performs well.

In this case, I would choose pulleys for your build. You only need two and they are not that expensive, even less if you make them yourself. Then you do a speed and penetration test, change to your shackles and repeat the test. If you didn't loose speed nor penetration then on every future build you can use shackles knowing that it works. It would have cost you one set of pulleys to gain that knowledge. But as said, I would be surprised if you don't take a performance hit but feel free to prove me wrong:-)
Completely agree with all of this, i am now using this gun, and would never have anything other than a set of pulleys.

The whole point of these guns is shaft exit speed, so having anything which potentially reduces this contraction speed and shaft speed, makes these guns not worth the time.
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