NASA Gemini Helmet and Spacesuit build

[dogstar]

So, here's the start of my thread to build an early Gemini helmet and eventually a suit...been doing a bunch of online research and wish I could find
more specific measurements of stuff, but I did find some images of what appears to be an early Gemini helmet with an over head plan view
that had a scale in the photo (score!)...I then cobbled together a kind of "blueprint" views photo to use as a guide to make my model...it's about 30 some inches square and
I had it printed out at a local Fedex-Kinkos for $4. bucks and change...(see attached)..
also, have been researching how to create the casting model and am liking this guys process to create it...this is a link to an instructable for a Daft Punk helmet...his technique for making an mdf frame to guide his styrofoam and bondo sculpt is interesting and helps with getting the right forms/shape pretty easily...any advice or suggestions would be greatly appreciated!
https://www.instructables.com/id/Building-a-Daft-Punk-helmet-with-programmable-LED-/

 

[N3rdyboy]

Thanks this method will help me out with my helmet!

 

[lmgill]

I have not seen it mentioned here, but one way to make this type of shape, is a pattern sweep. This is done by cutting half the silhouette of the desired profile from a piece of aluminum, attaching a set of pivot points at the center line and the aluminum is used to "sweep" the material, generally plaster or clay, into the 3 dimensional version of the profile.
You folks with 3d rendering experience will recognize this, your virtual tool does the same thing. This is a very old, tried and true technique.

When I built Orbital Outfitter's very first prototype helmet (Real functioning pressure helmet) I deliberately chose this sweep method, because this is how some of these early first space helmets where prototyped. I thought this technique would be appropriate for the first commercial space helmet.
Here are some pictures, First: the sweep frame and aluminum sweep, Second; a piece of rigid urethane foam set over the sweep frame to "take up space" so less clay is required.
Third: the nearly finished clay part, with the sweep in place, Forth: The the raw swept piece (without the sweep) before I blended (By hand) the transition into the neck ring flange. Fifth: The final FRP part out of the mold. Last picture is a partial nose cone pattern for a spaceship mock up, swept in WED clay over a wooden frame. This is one third of a 12 foot dome.


The big advantage here is you get a nearly finished part ready for a mold and in the case of the helmet, you also have the exact center of the visor pivot point, in regards to the helmet.
The technique can be done with two pivot points, like the helmet, one pivot point like the ship nose, or with no "pivot" point, as in a straight drag along two parallel rails.
Some key things: You want to have a way to easily remove the sweep, so you can clean it, as excess material can build up on it. The pivot to sweep needs to precise, the sweep can not wiggle or flop around, otherwise the finished part will not be smooth or accurate. The cut edge of the aluminum is left square and with crisp, sharp edges. This help make the swept part clean and blemish free. With some experience, very fine details, less than a 1/16" in size, can be reproduced cleanly. Your sweep wants to be very accurate, take the time to make it right, because you final product will only be as good as this profile you cut.
If you do this with plaster, you will want to sweeps, one slightly smaller (about 1/8") than you finished part, which has a serrated edge (Like pinking shears). This leave a grooved surface for your final finish coat of plaster to grab. You put the second larger sweep in and do your final sweep. This is almost essential, since as the batches of plaster harden with each application to get to your final shape, it is too difficult to get the final surface even. So adding the last 1/8 to 1/4" over this grooved surface is more controllable and you can get a part that is flawless.

 

[N3rdyboy]

Interesting

 

[dogstar]

thanks for the great info Imgill...its going to come in very handy....much appreciated

 

[Mr. Nagata]

@lmgill Beautiful!!!

 

[dogstar]

speaking of visor pivot point...@Mr.Nagata, where did you get the parts for your Mercury helmet visor pivot hardware? are they seperate washers and a giant circlip under them or a solid conical "pyramid"? and how would one specify that large of a circlip...is there a real world use for those that i could track down? did you find some info on what the actual contruction was or is yours fabricated by your own imagination to resemble the real thing?