Need Sshroud/Launch Lug help

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Well-Known Member
I am in the design stages of building a scale model that needs to have the launch lug installed behind, then come through, a paper shroud transition. My question is, on the shroud, how do you accurately make an elliptical hole so that when it's cut out, it allows for a perfect fit of the round lug?

The launch lug comes through the shroud where it angles and I need make it so that it's accurate for a builder.

DJ Delorie

Well-Known Member
Use the angle of the shroud to "stretch" the hole. Calculate, um, 1/sin(x) and scale the hole by that much along one axis. Me, I write in Postscript directly so this is easy to do, but you can do the math separately and just print an ellipse.

jflis

Well-Known Member
flying_silverad, If you send me the dimensions of the shroud and the size launch lug you are trying to get through it I can draw you the oval.

jim

BobH48

Well-Known Member
When I need to do that, I just cut a piece of launch lug at the angle of the shroud and just trace around it.

Not very scientific, but then I'm only doing it for myself and it's close enough.

DynaSoar

Well-Known Member
Originally posted by BobH48
When I need to do that, I just cut a piece of launch lug at the angle of the shroud and just trace around it.

Not very scientific, but then I'm only doing it for myself and it's close enough.

Yup yup yup. Apply a mini-miter saw arrangement to the lug at the angle of shroud-to-body.

Even though the calculations will be exact, the cutting will still come down to handling the material & the same error range introduced. Even if I calculated it, I'd test it first in just this way.

Try: wrap the shroud. Cut a scrap lug at the angle. Color the cut end of the lug with ink. Push the lug along a line on the body parallel to the axis of the tube, until it touches, and marks, the shroud.

Well-Known Member
Originally posted by jflis
flying_silverad, If you send me the dimensions of the shroud and the size launch lug you are trying to get through it I can draw you the oval.

jim

Thanks! E-mail on the way, but just for ha ha's, here are the numbers

2.6" (front)
3.18" (rear)

1.4" (long)

Thanks Again!

Stymye

Well-Known Member
on my aries I held the shroud up to a light ,positioned the lug behind it and drew the shadowed oval.

Well-Known Member
Originally posted by stymye
on my aries I held the shroud up to a light ,positioned the lug behind it and drew the shadowed oval.

(In my best Col. Klink voice) "De Aries ehh? Zen zee un shroud should un be familier ya?"

Stymye

Well-Known Member
ya das ist richtig,ich bin eine kleine teufel mit dem schroud maching !

was ist das?

DynaSoar

Well-Known Member
Originally posted by Tarc3
was ist das?

Der flippin rocket luger fitting ist givink fitz.

now i got it

powderburner

Well-Known Member
I sent a couple of emails (via the TRF system) but they keep disappearing off my "sent" list . . . did you receive them? Maybe the TRF email is not working?
home--ditto

Dave

Well-Known Member
Powder-
Just sent you a new Email

John

jflis

Well-Known Member
John,

I just sent you a shroud with a cutout for the launch lug. Let me know if this is what you were looking for.

jim

powderburner

Well-Known Member
Be careful to use the second file I sent today ---- the first one I emailed had a mistake that I found right after I sent it to you.

Well-Known Member
Originally posted by powderburner
Be careful to use the second file I sent today ---- the first one I emailed had a mistake that I found right after I sent it to you.

Yep...got the second one and am looking at it now. Very cool pic's by the way...you should consider loading this on TRF (maybe here, maybe a new thread) for other folks to use. It's awesome!!

powderburner

Well-Known Member
You are perfectly welcome to use that stuff as you like.
I did not post it for a couple reasons, including: I don't know if my explanation was really that good or went over/under anyone's head.
The notes would have to be broken up into separate posts, and I am ignorant as to how to turn those illustrations into JPGs (I already tried).
But if you think there is a place to use it, be my guest.

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