Earmuff Rim's costruction process...

Look at the nozzle pads.

This page will show the progresses I did on completing the pads (see previous point on the menu) and start the MY SECOND NIGHTMARE: the RIMS!

 

Ok let's start: Finishing the Pads

 

The first pad's mould after building the 2:1 shape (see the previous page), have been poured & also coloured black.

This to build the the lower 3 pads of each Earmuff (click on each thumbnail to have an enlarged view).

 

      

The top pad is a bit different, and also apparently simpler.

It sports a square groove in the middle with a teeth detail inside:

 

Anyway all this should always to be considered provisional: anything I realize that could be done to better the appearance of the "thing" will be promply used.

In this point-of-view, we now start to consider the building of the rest of the earmuff itself: the coned shape. Using a Cone Calculator program, available elsewere on this website, I calculated a cone shape suitable for my sphere scale:

The idea is: once the cone is built, I could glue the rims all around, using some stiffy triangular shaped styrene. But this would led to a problem: How to build the 45 and 90 angles? It may seem absurd, but there is nothing available in these angles. So I have to build them on my own. How shall I start? Ill' count how many different sizes are needed, starting from the smallest.

So, I drawn them using a rather simple CAD program, printed it and cut the styrene (left to right, top to bottom):

 The last "round" thing is a scrachbuilt millstone to refine each mould. Even if it took lot of time, the final appearance wasn't so satisfying. The "teeth" was not deep enough. What a work! What a mess!

Question: How to obtain Evenly spaced, EQUAL rims, in that AWFUL shape? ... I went on a lack of imagination... Maybe a plastic tie-wrap pieces could be the response: let's try it:

The spacing was good, but the shape NOT! I abandoned this way, because it was rather difficult to build this thing using this idea.

SO???

After LOOOONG searching, I found somewhere o the net, a modeller's supplier, with 90 styrene strips. I have an idea. Keeping in mind that I've to build TWO Earmuff's. I WANNA MAKE A MOULD. Equal items, mounted in different angles on the POD's sides. Could it be possible to use pieces of this styrene to "mould" some milliput-like paste?

Let's try (left to right, top to bottom):

The smarter of you, already noticed that I've utilized even a smaller strip cut from an "electrical styrene duct", identifying in it a possible triangled line. The strip was too small to built it by hand, so I decided to use it as it is.

Finally we've a mould. No, to be precise we've it's NEGATIVE! In fact, pouring RTV inside, would give me a shape like the desired earmuff. It's not what I'm looking for. But I've to start from somewhere. First I put some water inside, to identify the RTV volume needed, then I poured the RTV (left to right, top to bottom):

The last two shots are for checking "the gum" against the model. It seems good enough, lot of flash, but I get it right, I've to make it "negative" as  said before. EASY, one could say! NO! In fact it's impossible to pour directly RTV over other RTV, to get it negative: The RTV will glue together in a single piece! There are several methods to avoid this.

But since every step is new to me, I'll ask a suggestion to a friend,  1st class-modeller: Eliot Brown.  Very Happy

The solution is to "paint" nivea hand creme inside. But I worry if this could ruin the smooth shape created (left to right, top to bottom):

In the last shot I poured a thin layer of resin. Unfortunately the smoothness has been lost!!! But I think is not too much  problem: using elbow oil (Eliot teaches!!), and the right sanding paper, should be no problem!

Oh now what a luxury! I can pour as many Earmuffs I want!!! ALL equal each other!!!!

Now, utilizing the very precious ingredient mentioned above, the Elbow Oil; I can start refining the earmuffs this way obtained. I did a "production" trial of three items. As you can see in the next shots, some hidden bubbles can be seen here and there: really not too much to worry about, since it can be refined anytime!

I'm proud of it! he he!