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Caselman air machinegun

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Re: Caselman air machinegun

Unread postAuthor: hectmarr » Wed Mar 06, 2019 12:39 pm

Nice weapon It has a lot of power for what it looks like, and the sound, for my taste, very nice. :)
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Weapons do not exist, they are built. This hobby is a science - totally procedural art.
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Re: Caselman air machinegun

Unread postAuthor: wyz2285 » Wed Mar 06, 2019 6:29 pm

Will Jack finally fulfill his dream of BANGBANGBANG instead of PURRRRRRR :lol: ?
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CpTn_lAw wrote::D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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Re: Caselman air machinegun

Unread postAuthor: jackssmirkingrevenge » Wed Mar 06, 2019 8:08 pm

wyz2285 wrote:Will Jack finally fulfill his dream of BANGBANGBANG instead of PURRRRRRR :lol: ?


Oh come on, that happened almost 10 years ago, we've moved on now ;P

The bigger question is "Will Jack actually complete a project instead of losing interest after getting it to sort-of work after countless abortive attempts?" ;)
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: Caselman air machinegun

Unread postAuthor: Anatine Duo » Wed Mar 06, 2019 8:44 pm

It's always more work than we think! You get it to shoot... now to get it to cycle... then the feeding...

I have many unfinished projects because I have many projects!

It will be awesome to see this function. It would be even more awesome to see the valve assembly for sale ;)

Now let us stop distracting JSR!
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Re: Caselman air machinegun

Unread postAuthor: jackssmirkingrevenge » Thu Mar 07, 2019 8:13 am

Anatine Duo wrote:It will be awesome to see this function. It would be even more awesome to see the valve assembly for sale ;)


I'm always open to machining commissions for a small fee, time permitting. That being said, commercially available balanced valves are a thing, like the Cothran Powerhouse:

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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: Caselman air machinegun

Unread postAuthor: wyz2285 » Thu Mar 07, 2019 10:09 am

Seems like the balanced valve is the crucial part, also rifled barrel may cause extra pressure build up to help cycle the action.
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CpTn_lAw wrote::D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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Re: Caselman air machinegun

Unread postAuthor: jackssmirkingrevenge » Sat Mar 09, 2019 7:53 am

wyz2285 wrote:Seems like the balanced valve is the crucial part, also rifled barrel may cause extra pressure build up to help cycle the action.


Yes, anything that keeps barrel pressure high is going to help, including a tight fitting and heavy projectile. Unfortunately for your humble scribe, this particular project has none of those things :roll:

Some minor progress in the meantime due to continuing valve sealing issues, it eventually became apparent that delrin for a balanced valve at 850 psi was not going to cut it so I made a new poppet out of aluminum with a UHMWPE sealing face and it was an immediate improvement, sealing consistently and as low as 250 psi. I also finished off the breech attachment:

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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: Caselman air machinegun

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Re: Caselman air machinegun

Unread postAuthor: mrfoo » Sat Mar 09, 2019 2:08 pm

That's purrrrrdy
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Re: Caselman air machinegun

Unread postAuthor: jackssmirkingrevenge » Sun Mar 10, 2019 3:27 pm

Image

Finished it up enough to allow for some testing and the result was quite disappointing, mainly because of a feature I failed to consider. The rather short hammer is free to twist in the tube when asymmetrical force is applied, causing it to lock up. This makes it almost impossible to cock via the bolt, even manually. A bit of a rethink is required...

Still, a very enjoyable Sunday morning's tinkering in the workshop, been a while since I lost track of time making swarf :)
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: Caselman air machinegun

Unread postAuthor: hectmarr » Sun Mar 10, 2019 6:08 pm

It will have some problems that always exist, and that you will solve with security, but what I see is a jewel in terms of design and construction, without any doubt for me. You are yourself!
One of the things that I like personally, talking about the hobby, is just that, forgetting for a while the objective time, to be able to do what I want with him, in psychological time. We can live 1 year in an afternoon, or an afternoon that seems like a year. :shock: One of the most sophisticated and exquisite human sensations (?).
Once solved the problems that you mention in your post, this weapon will be more yours than yours. In summary excellent work! :bounce:
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Re: Caselman air machinegun

Unread postAuthor: jackssmirkingrevenge » Tue Mar 12, 2019 8:08 am

Thank you for your faith in my abilities Hector :)

In order not to disappoint, herewith some minor progress:



I added a shaft to the hammer that runs through the endcap, which now supports it over a much longer axis and reduced the friction considerably, I can now cock it from the side with very little effort.
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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Re: Caselman air machinegun

Unread postAuthor: hectmarr » Tue Mar 12, 2019 8:18 am

It was like silk! :bounce:
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Re: Caselman air machinegun

Unread postAuthor: Anatine Duo » Tue Mar 12, 2019 11:30 am

That's lovely!
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Re: Caselman air machinegun

Unread postAuthor: wyz2285 » Wed Mar 13, 2019 10:50 am

You could use a teflon shell with a steel core as hammer, should furthermore reduce the friction. You will need every bit that helps because the bolt it too high up, further increase the tilt on the hammer.
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CpTn_lAw wrote::D "yay, me wanna make big multishot pnoob with 1000 psi foot pump compressor using diamond as main material. Do you think wet bread make good sealant? " :D
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Re: Caselman air machinegun

Unread postAuthor: jackssmirkingrevenge » Thu Mar 14, 2019 9:13 am

wyz2285 wrote:You could use a teflon shell with a steel core as hammer, should furthermore reduce the friction. You will need every bit that helps because the bolt it too high up, further increase the tilt on the hammer.


I don't think that will be necessary...

After solving the intermittent valve seal problems with a looser balancing "cup" that allowed the poppet to align itself irrespective of the relative position of the endcaps, I made a new more solid breech and coupled with the new hammer arrangement it has done the trick!



Even without a projectile in the barrel to maintain pressure, it's cycling full auto as long as the trigger is pressed, which is very promising.

Lots of tuning to follow but this is very encouraging :D
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hectmarr wrote:You have to make many weapons, because this field is long and short life
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