30 cal can - all you need to make one

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matthewbas
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Re: 30 cal can - all you need to make one

Post by matthewbas » Tue Feb 02, 2016 10:41 pm

what would be the negatives of replacing the chrome/moly tube and end caps with 303. very nice can btw

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CMV
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Re: 30 cal can - all you need to make one

Post by CMV » Thu Feb 04, 2016 7:13 pm

More weight since the end caps are titanium.

I don't know if you can buy 303SS tube - I've never seen it. I'd stay with chrome/moly over 303 for the tube if those were my choices. 303SS isn't very 'stainless'. I have plenty of it corroding in my garage..... It is easy to work with but so is 4130. But if you wanted to do the tube out of 304 or 316 SS you'd get the added corrosion resistance so a benefit there. The 4130 is stronger (yield strength) by a considerable amount, but if you're walls aren't insanely thin no big deal there. If you want to make it for 300 RUM or something it will matter.

If you're a few oz heavier because you want to substitute materials, no big deal. I think you'd break even in weight substituting SS for 4130 for the tube. 4130 is 0.284 lb/in³ density & 316 is 0.289 lb/in³. Conversely, you'd save a decent amount of weight substituting gr9 Ti for the tube.
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Re: 30 cal can - all you need to make one

Post by gunny50 » Fri Mar 25, 2016 5:25 pm

"CMV"

Compliments with your great post, We might want to add the Questions and his answers from the Curtis post to that way most people that want to start have lots of basic info.

Gunny (out hunting easter eggs)

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Re: 30 cal can - all you need to make one

Post by cal50 » Sat Mar 26, 2016 2:38 pm

Well done sir~
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lmpdtroy
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Re: 30 cal can - all you need to make one

Post by lmpdtroy » Sun Mar 27, 2016 10:09 am

So if I didn't want the end caps to be titanium to keep cost lower, would you recommend the 416 SS that you use with the baffle's?

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Re: 30 cal can - all you need to make one

Post by MG_Willy » Mon Jul 11, 2016 3:43 pm

revisiting this again.. while I await my f1 approval... how do teh cones stay ligned up. I re read the thread but if its there I missed it.. sorry if this has been asked before.


Thanks

MG_Willy

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CMV
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Re: 30 cal can - all you need to make one

Post by CMV » Mon Jul 11, 2016 4:50 pm

What do you mean by 'lined up"?

How do all the clipped potions stay facing the same direction? Or how do the cones stay centered in the tube?

If you want the ports/clipped areas all facing a certain direction or pattern, you just build the stack that way on a table or counter - some solid flat surface - and then slide the tube down over the whole thing.

The compression on the baffle stack keeps the cones all perfectly centered & perpendicular to the tube. Once the end caps are torqued, they have no choice but to be 'right'.

OH - I just noticed on my drawing the callout for the chamfer is WRONG!!! Oops... The callout points to the wrong side. That chamfer goes facing to the inside of the spacer, not the outside as the drawing shows. The pictures show it. The idea is the cone recesses into the spacer a little. You can see that in the picture of the whole stack.
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Re: 30 cal can - all you need to make one

Post by MG_Willy » Mon Jul 11, 2016 6:56 pm

The compression on the baffle stack keeps the cones all perfectly centered & perpendicular to the tube. Once the end caps are torqued, they have no choice but to be 'right'.



is exactly what I was asking...

Thanks
CMV wrote:What do you mean by 'lined up"?

How do all the clipped potions stay facing the same direction? Or how do the cones stay centered in the tube?

If you want the ports/clipped areas all facing a certain direction or pattern, you just build the stack that way on a table or counter - some solid flat surface - and then slide the tube down over the whole thing.

The compression on the baffle stack keeps the cones all perfectly centered & perpendicular to the tube. Once the end caps are torqued, they have no choice but to be 'right'.

OH - I just noticed on my drawing the callout for the chamfer is WRONG!!! Oops... The callout points to the wrong side. That chamfer goes facing to the inside of the spacer, not the outside as the drawing shows. The pictures show it. The idea is the cone recesses into the spacer a little. You can see that in the picture of the whole stack.

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Re: 30 cal can - all you need to make one

Post by speed6 » Tue Jul 12, 2016 2:39 pm

A 1.5" tube, 0.058 wall with 20 TPI (assuming a 1.44-20 thread form) leaves you with less than 0.030 wall thickness at the relief or root of the thread. Is this adequate for 308, especially at elevated temperature? My thread calcs may be off, I am just using the sherline thread calculator spreadsheet.

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Re: 30 cal can - all you need to make one

Post by CMV » Tue Jul 12, 2016 5:59 pm

speed6 wrote:A 1.5" tube, 0.058 wall with 20 TPI (assuming a 1.44-20 thread form) leaves you with less than 0.030 wall thickness at the relief or root of the thread. Is this adequate for 308, especially at elevated temperature? My thread calcs may be off, I am just using the sherline thread calculator spreadsheet.
You are correct - .058 - .031 = .027 under the root of the threads. I don't know what the bare minimum safe thickness is & am sure it depends on material. Under .030" is probably not good. However, I used 4130 which is considerably stronger in ultimate & yield strength compared to many common tube materials. 97,200/63,100 for 4130. 316SS is 84,100/42,100, 3Al2.5V (Gr9 Ti) is 84,900/72,500, 304SS is 73,200/31,200. So I'm thinking I'm ok with the stronger material. But you can use a finer thread or thicker tube if you want.
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Re: 30 cal can - all you need to make one

Post by vaeevictiss » Wed Jul 13, 2016 3:47 am

damn why didnt i think of that taper on the spacer lol. that looks nice. I think i added a lot of time to my two rifle cans by machining the perfect lip around the edge of the cones for the spacer to sit on. The taper idea would have been much faster and would work well!

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Re: 30 cal can - all you need to make one

Post by speed6 » Wed Jul 13, 2016 11:54 am

I will have to confirm my numbers (just a guesstimate using the ideal gas law) but I get about 36 ksi hoop stress at the thinnest section using 7.62x51 and a 16" barrel. That is about a 2:1 factor of safety at room temp using yield as your allowable stress. I looked up a similar material in ASME Boiler and Pressure Vessel Code and got about 15ksi for yield at 700 degrees...that is a very conservative number, and 4130 doesn't lose strength that much with high temp, but I would use a finer thread (maybe 24 or 28 TPI). For 300 blackout etc. that thickness should be fine I would think.

ETA: random advice from guy on the interwebs, use at your own peril. Also, corrected hoop stress results.

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Re: 30 cal can - all you need to make one

Post by MG_Willy » Wed Mar 22, 2017 3:31 pm

Form 1 has been back a bit now.. I have begun my build based on this design. I have my cones and spacers done in Stainless :) I still need to do a
a little on them getting clipped ... Then the hardest part I still have to get my tube done.

Thanks for this thread.. I will post some pics of my internals as soon as I get a few mins. :)

MG_Willy
MG_Willy wrote:Thanks that is what I was curious about.. it does look great.

Thanks for the info.
CMV wrote:
MG_Willy wrote:Beautiful... I have a couple questions.. 1. can I copy it :) hehehe and 2. what is the length of your baffle stack and spacers combined. trying to understand your spacers are 6.32" total with the cones also providing a little space but I cant determine that. and 3.. how much space is the space between your threads? Im assuming that your baffle stack length and the spacing between your threads be close but might over lap a tiny bit to provide a rock solid fit when tightened down.

Looks beautiful and a GREAT write up.

thanks

MG_Willy
1. Of course. I posted all this just so it could be copied.
2. Roughly 7". 8" tube, each end cap screws in appx .500"
3. Not sure what you mean by 'how much space is the space between your threads?'. I didn't measure precisely, but the tube internal threads are longer than the threads on the endcap. I threaded each end at least .600" into the tube.

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Re: 30 cal can - all you need to make one

Post by Historian » Wed Mar 22, 2017 4:52 pm

CMV, compliments on an outstanding presentation!

Informative, inspiring, and 'eye-candy'.

Another project on the consideration-list when HPA passes.


Best.

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Re: 30 cal can - all you need to make one

Post by MG_Willy » Thu Mar 23, 2017 10:53 am

Here is the promised pic :) its only one and its missing the rest of the cones :) but ...
Image
MG_Willy wrote:Form 1 has been back a bit now.. I have begun my build based on this design. I have my cones and spacers done in Stainless :) I still need to do a
a little on them getting clipped ... Then the hardest part I still have to get my tube done.

Thanks for this thread.. I will post some pics of my internals as soon as I get a few mins. :)

MG_Willy
MG_Willy wrote:Thanks that is what I was curious about.. it does look great.

Thanks for the info.
CMV wrote:
1. Of course. I posted all this just so it could be copied.
2. Roughly 7". 8" tube, each end cap screws in appx .500"
3. Not sure what you mean by 'how much space is the space between your threads?'. I didn't measure precisely, but the tube internal threads are longer than the threads on the endcap. I threaded each end at least .600" into the tube.

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Re: 30 cal can - all you need to make one

Post by CMV » Fri Mar 24, 2017 6:35 pm

Why the 2 long spacers?
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Re: 30 cal can - all you need to make one

Post by MG_Willy » Fri Mar 24, 2017 7:32 pm

CMV wrote:Why the 2 long spacers?
It was a mistake, its not going to be used. but was just there when I took the pic.

But its stainless steel so it will go in the bin for possible use later.


Thanks

MG_Willy

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Re: 30 cal can - all you need to make one

Post by MG_Willy » Wed Apr 12, 2017 4:21 pm

getting there. I need to clip the cones and a measurement is off somewhere so i will be adding a small spacer (about 1/4 inch) to compress the stack solid together..

Image

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Re: 30 cal can - all you need to make one

Post by CMV » Wed Apr 12, 2017 8:03 pm

What did you knurl the endcaps with? That pattern looks interesting. I have tools that do straight ridges or diamond pattern but haven't seen the dots.

Hold off clipping the cones. You might find that you're perfectly pleased with its performance w/o clipping. You can always go back and do that later if you want.

What is your current baffle spacing? If you have .250" of leftover space you might be able to cheat another ~300" (.035" off every one pictured for example) and put in another baffle? Shame to let it go to waste. Either way, I wouldn't want a spacer that short. Too easy to lose, have difficulty removing when crudded up, etc. If it were my build, I'd scrap the part with the measuring error and remake to the correct length to close that gap vs an additional short spacer if squeezing in #9 wouldn't work.

Don't know what style tool you are using to cut your threads, but if it requires you to leave a runoff groove that fat you might want to consider something that lets you thread closer to a shoulder. I use this: http://www.mesatool.com/products/threading-tools/ very inexpensive and works great. That endcap could be shorter overall. Doesn't much matter - just something to note to make your next build even better.

Looks very, very nice! Can't wait to see the video of it in action.
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Re: 30 cal can - all you need to make one

Post by MG_Willy » Wed Apr 12, 2017 8:41 pm

Actually bought the caps that way. so im not real sure..

CMV wrote:What did you knurl the endcaps with? That pattern looks interesting. I have tools that do straight ridges or diamond pattern but haven't seen the dots.

Hold off clipping the cones. You might find that you're perfectly pleased with its performance w/o clipping. You can always go back and do that later if you want.

Great idea will do...

What is your current baffle spacing? If you have .250" of leftover space you might be able to cheat another ~300" (.035" off every one pictured for example) and put in another baffle? Shame to let it go to waste. Either way, I wouldn't want a spacer that short. Too easy to lose, have difficulty removing when crudded up, etc. If it were my build, I'd scrap the part with the measuring error and remake to the correct length to close that gap vs an additional short spacer if squeezing in #9 wouldn't work.

I need to re-measure them all and verify and see where I went wrong lol maybe they are all just a bit short...

Don't know what style tool you are using to cut your threads, but if it requires you to leave a runoff groove that fat you might want to consider something that lets you thread closer to a shoulder. I use this: http://www.mesatool.com/products/threading-tools/ very inexpensive and works great. That endcap could be shorter overall. Doesn't much matter - just something to note to make your next build even better.

Looks very, very nice! Can't wait to see the video of it in action.
Thanks... this is my very first build any comments are more than welcome... :)

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Re: 30 cal can - all you need to make one

Post by sddds13 » Mon May 15, 2017 8:33 pm

I plan on following this design when my F1 comes back approved however I need some guidance/opinion altering the design for my applications.

I would like to use this primarily (75% of its use) as a 9mm can on my 5" AR pistol and the other 25% on my AAC Handi-Rifle shooting Subs. I plan on the endcaps and tube to be made from Grade 9 Ti, 8" tube with nominal .070 thickness.

The questions I am confused about are: blast baffle size (strictly subsonic), geometry of baffles (K, cone, or combination), and material for baffles/spacers, lastly, would a inner diameter .415 be good or too large/small?

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Re: 30 cal can - all you need to make one

Post by fishman » Mon May 15, 2017 10:48 pm

sddds13 wrote:I plan on following this design when my F1 comes back approved however I need some guidance/opinion altering the design for my applications.

I would like to use this primarily (75% of its use) as a 9mm can on my 5" AR pistol and the other 25% on my AAC Handi-Rifle shooting Subs. I plan on the endcaps and tube to be made from Grade 9 Ti, 8" tube with nominal .070 thickness.

The questions I am confused about are: blast baffle size (strictly subsonic), geometry of baffles (K, cone, or combination), and material for baffles/spacers, lastly, would a inner diameter .415 be good or too large/small?
Imo Ks are king for low pressure subsonics, they're harder to machine and harder to disassemble though. 0.415" is fine. I recommend starting your own thread or this one will likely be derailed.
300 blackout form 1: http://www.silencertalk.com/forum/viewtopic.php?f=10&t=137293

5.56 form 1:
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=141800&p=955647#p955647

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