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06-23-2008, 05:31 AM
| #1 (permalink) |
| Newbie Join Date: Jun 2008
Posts: 28
| Milling Shocker - minimum thickness? Is there a general rule or anything to go by when milling guns? I want to give my old shocker (shoebox) a serious trim... Anyone know the minimum thickness that the walls have to be? I can get my calipers for measurements if need be... Just a thought of mine - I guess the minimum thickness is dictated by the input pressure, i.e. a gun running @180psi can have thinner walls than a gun running @550psi....so each gun is different, sound right? |
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06-23-2008, 10:04 PM
| #3 (permalink) |
| Active Member Join Date: Sep 2006 Location: Golden CO
Posts: 330
| Yup, let me pull up my formulas Hoop stress (what you'll be concerned with) = Pressure * Inner radius / wall thickness So you'll need to find the allowable stress of the material of the shoebox, then multiply by a factor of safety (4-6? I'd lean toward 6. I don't have a code book handy.. but it's next to your head).. Solve for T, and you're good. Lo edit.. looked up some general pressure vessel codes, I'm going to say F.S. of 4-6. Sorry. Points to Weekend Baller.
__________________   RECON Editor-in-Chief: Click the above RECON icon to subscribe,Click here for subscription questions, or Here to submit content Last edited by Lomarandil; 06-24-2008 at 11:40 AM. |
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06-24-2008, 11:40 AM
| #6 (permalink) |
| Active Member Join Date: Sep 2006 Location: Golden CO
Posts: 330
| Sorry, I don't know the specs on shoeboxes to be able to say yes or no there. Lo doh.. I need a cup of coffee. Misread there. Mayvik is right, that's a definite NO.
__________________ RECON Editor-in-Chief: Click the above RECON icon to subscribe,Click here for subscription questions, or Here to submit content Last edited by Lomarandil; 06-24-2008 at 12:38 PM. |
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06-24-2008, 12:01 PM
| #7 (permalink) | |
| Sausage Lover Join Date: May 2007 Location: Denver
Posts: 2,521
| Holy crap man, unless you are going for ridiculous weight savings I would not go to 50 thou aluminum on a pressure chamber regardless of what the pressure is (especially with the notoriety of SP low-grade aluminum). Without knowing what your milling geometry looks like (i.e. how many ribs and such you're using, their thickness, etc) it's hard to say for sure, but I would be extremely cautious about using material that thin, LP gun or not. Do you realize how thin 50 thou of aluminum is? Go to Home Depot and look at a sheet of .050" sheet stock, and imagine a tube with just that thickness for the wall. Also, don't forget you're going to be getting this anodized, so you shouldn't count anodize thickness in your calculations unless you feel extremely comfy with the math involved for modulus factor decrements due to anodize layers. Can you guarantee you're NEVER going to see more than 180psi in that area, i.e. reg failure, etc? Can you guarantee you're not going to mill below .05 with tolerance on your equipment? Can you guarantee you're never going to sell this gun to someone else who doesn't know how to set the regulator and pumps 400psi in it by mistake? Operating pressure is not burst pressure, and you shouldn't treat it as such. Not to mention you also need to consider handling the gun, i.e. if you slide into a hard bunker you're not going to be inflicting a 180psi distributed load, you're going to be inflicting several hundred pounds in a very localized area. I'd rather my gun be a little bulkier than have it blow up in my hands or punch a hole in it on a tree branch. In summary, unless you're equipped with aircraft grade finite element modeling software to do detailed stress calculations on your milling model, I would not go that thin.
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06-24-2008, 12:39 PM
| #8 (permalink) |
| Active Member Join Date: Sep 2006 Location: Golden CO
Posts: 330
| Gosh.. I need a cup of coffee.. perhaps a few. Lo
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06-24-2008, 06:12 PM
| #10 (permalink) |
| MCB Member  Join Date: Apr 2006 Location: Michigan
Posts: 308
  | My rule of thumb is 3/32th (.093) but no less then 1/16th (.062). I have pushed .040 but with no luck. Blow the side wall right out. Just my .002 worth. Ken W
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seems like MCB is becoming more and more like a 
