GTA
All Springer/NP/PCP Air Gun Discussion General => Projectiles => Topic started by: Nvreloader on March 16, 2025, 11:30:02 PM
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OK Guys and Gals
This for you smarter/brainier types here, (yes, we have several),
Can you help me figure this information out, KEEP IT SIMPLE, Please,
I am NO MATH Major, just a student from the school of Hard Knocks ..LoL
You only have this information about a pellet, to figure the missing/wanted info out.
.20 caliber,
Weight = 14.10 gr
Head Dia = .199"
O/S skirt Dia= .202"
I/S skirt Depth = .086"
I/S waist Dia = .125"
O/S waist Dia = 0.142
O/S skirt Length = .150"
Bearing Length = .213"
Overall length = .296"
Skirt Thickness .023" to .024" (average)
Inside skirt angle (degree)* = ????
Outside skirt angle (degree)* = ????
Do you need more information, this is what I have been using,
https://www.omnicalculator.com/construction/taper
Skirt Depth = Is from the bottom of the skirt to the top of the inside waist,
that the bolt probe pushes against.
Bearing length = Is from the center of the head diameter band to end of skirt length.
Skirt angle = the degree of the inside and outside skirt cone angles/dimensions.
Thank you, your input is greatly appreciated
Don
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OK Guys
I found an error, the caliber listed should be 20 caliber,
NOT 22 caliber...
I do not have a method to edit the original post, for some reason...
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If your trying to figure out the skirt angle of an existing pellet, you might be able to do it using a protractor and magnifying glass like an optical comparator?
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Answer on AGN.
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OK Guys
I found an error, the caliber listed should be 20 caliber,
NOT 22 caliber...
I do not have a method to edit the original post, for some reason...
I fixed the typo.
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Thanks Bill
This blasted 20 cal angles is driving me crazy.
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You would just be solving for a right triangle, from the edge of the waist down to the base of the skirt. hth
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Google calculator says 75.6 degrees Or it's 14.3 degrees which makes more sense.
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I would think the latter.
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Thanks Guys,
Using the calculator provided, I came up with these figures,
Inside skirt angle (degree)* = 12.14* @ .023" skirt thickness.
Outside skirt angle (degree)* = 11.31*
I subtracted the skirt thickness from the O/S Waist Dia to get the O/S cone diameter ??
The reason for this math is,
I can swing the lathe compound to whatever degree to cut the taper
for the inside skirt cone pin for resizing/uni-forming the pellets skirts etc.
JPSANC
I never had that type of math when I was in school, a long long time ago...lol
It's hands on learning now...
Tia
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Don, you're light years ahead of what I can figure from all of this.
Still interesting to follow though,
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To me, this number is ambiguous:
O/S skirt Length = .150"
Is that the skirt Height (along a vertical line) or measured along the angle of the skirt.
If it's the skirt height, I get 11.31 degrees using your web calculator.
If it's the skirt length, I get ~11.54
If the skirt thickness is uniform, the inside angle should equal the outside angle.
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SB
All I can say it's a school of hard knocks for me, and I am TOO OLD to go back to school
with all those whopper snappers around.
Tia,
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TM
"To me, this number is ambiguous:
O/S skirt Length = .150"
Is that the skirt Height (along a vertical line) or measured along the angle of the skirt.
If it's the skirt height, I get 11.31 degrees using your web calculator.
If it's the skirt length, I get ~11.54
If the skirt thickness is uniform, the inside angle should equal the outside angle."
I am not sure which way to measure the I/S cone values,
I have been using the straight depth measurements 90* from the end of the skirt to Jct of the waist.
I know that the wall thickness of the skirts is NOT UNIFORM in thickness,
as I have sliced several different pellets Brands in half, and you can see the tapering wall thickness.
The H&N have a funny type of tapering inside cone, I had to make a special tool with a .060" diameter rod to reach the total depth length.
My dial calipers/venire even with the smallest end (.065" square end) would not reach all the way, and I have the smallest 4" dial calipers/
venire, could find, even with the minimum .0002" reading, I prefer .1000" scale readings.
I have been measuring the O/S skirt length on the outside slope angle
to where the Jct of the waist and skirt angle meet and the inside straight vertical to
skirt end.
IMHO, I don't think the minor differences are really causing and problems.
I have setup an XL program to keep track of all 4 calibers, as an example,
the 20 cal Slope degrees of the Outside cone angles run from 08.47* min and 18.43* max (degrees) for 90 samples, and the Inside cones angles run from 11.08* min to 24.44* max (degrees).
Those .117 cal pellets are a B(*&%^$%h to hold and measure with my shaking hands, it took me several days to get all the 192 samples done. Yesterday I had a plastic box (Computer) malfunction and lost over half of the info I had finished. >:( >:( >:( and the only caliber I did not have a back up saved for.
Thank you,
Your thoughts and suggestions.
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WHY???? OH Why are you trying to figure this stuff out?? Now I have a headache!!!
Lol, joking. You want some real fun try learning machine math to calculate the tool path for a CNC mill. I've never had trig and that is the bases for the calculation. It was a 2 week course. I don't remember any of it.🤬🤬🤬
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MH
I have a DRO on my mini mill for over 5+ yrs, and I still have read the manual to run it, this new electronic work is getting almost un useable for me, I like the simpler stuff. lol
Tia
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Well it would've helped if I would have had a chance to use it. It was at Boeing and our manager thought it would be useful for the CNC controlled stitching machine op to learn it. I'm not talking about a singer sowing machine but a 8 million dollar 70 feet long 12 feet wide and 25 feet tall 4 head 38 axis stitching machine. We were stitching airliner carbon fiber wing panels. Upper and lower panels that would be joined together like a normal aluminum wing except this one didn't take any shims or moddings. It was a project for NASA to study the possibility of replacing aluminum wings with stitched resin film infusion wings. I'll post some pictures of the monster after I get home.