Giger Alien '79 head refurb

some updates:
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Update: I will be redoing the left side of the head, i'm not happy with the tubes not being uniform, left side is about 1/4" lower. so will be cutting it all back out tonight.
 
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Thanks for the comments guys :)

Small Updates:

i decided to cut the piping off the left side behind the cheeks and also where the dome sits, it didn't match the right side. i sculpted in new piping, and happy with the outcome now.
i also mounted the piping behind the teeth, i will be sculpting these in soon.

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Hi Leigh, I have been working on it here and there as i have time, I'm currently in the middle of buying a home so that isn't helping :p
I have mounted the piping along the spine as best as i think i can get it. it wasn't very uniform before. I'v also built out the right cheek area to match the left side.
I should be starting the spine soon, little nervous with that but we will see how it goes :)

I'll try and post some pics this weekend.
 
Good Stuff :)
If I were you I wouldn't worry too much about symmetry, the original was quite different side to side :)
 
haha i know leigh, but i'm bit of a perfectionist and the fact that it isn't bothers me some :p
I'm trying to get it close without going overboard with it.
thx for the fb add btw
 
i am :p but i have access to an industrial grade pump so i think it should go some what well i hope.

Might I suggest a negative vacuum form then?

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This is a 3mm (1/8") Perspex dome using reverse vacuum forming. Basically I placed the sheet on the top of my vacuum chamber, got a seal and began heating the plastic to 200 degrees C. I had created a suction in the chamber to about -15" and as soon as the plastic became ply-able, it began to sag in. I watched the guage and as it dipped to -10", turned the pump back on to take it back to -15" and then shut it off again.

I will be running more tests on this method soon where I belive the molds can be made from a hard silicone with a shore of A40+. There is also an A65 available as well. The silicone is supposed to take temps up to 350 degrees C and because it is rubber, it will A, make a perfect copy of the master part and B, always give a good seal.

Having used both positive and negative, I see more advantages using negative vacuum forming over positive.

Some of those are -

1. time where you have just seconds to evacuate all the air with a positive pull. Neg pulls can be progressively increased as needed.

2. heat where you have just seconds to get the plastic down before the plastic begins to cool. Neg pulls can be heated during the process or re-heated if required.

3. part size where the temp and the plastic types/thickness affects the final part size normally resulting in parts that are slightly over-sized. When making a buck for positive vacuum forming, you much take this size increase into consideration. With Negative vacuum forming, the part is the exact size of the mold very time.

4. Details are often lost in postive vacuum forming unless you are making paper thin pulls. With negative vacuum forming, it is possible to have sharper lines or use thicker plastic on deeper pulls. Even though this part of the Alien is a long dome, it is a tall part due to the length.

5. Material wastage is one negative about positive vacuum forming. You need a massive sheet of of plastic that is at least 40% larger that the footprint of the part you are making a pull from. So you also need a massive platen and heater plus suction to make this work. I believe it is possible to make parts like this from way smaller gear using reverse or negative vacuum forming. The dome in my photo was just 450mm x 450mm x 3mm. If this could be done in a positive vacuum form, I would suggest that the sheet of plastic would need to be at least 1200mm x 1200mm.

6. Ease of use. At that size (1200mm x 1200mm), it is now a 2 man job just to set it up, not to mention the energy needed to push the plastic down in the first place (unless you have access to a motorized pro version of that size). With negative forming, once you get a seal, you can start the heating slowly.

7. Fails due to plastic burning is common with DIY positive vacuum forming because you are on a time line. You need to get as much heat into the plastic as you can to allow the plastic to form properly. Sometimes you won't get enough at the edges and as a result, have sloping sides. Look how tight my negative vacuum form is. The only thing I did wrong with that dome was I did not use a frame and as the plastic heated and stretched and was pulled down, it also warped and eventually broke the seal. If I had used a good frame and clamping system, I would have been able to have a nice flat surround.

8 Positive vacuum forming is noisy. The vacuum must be on the whole time. With negative forming, once the vacuum is started (and assuming a good seal is made), you can shut the pump off only turning it on to increase vacuum when needed.

Some things to think about anyway.
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hi cavx
Thanks for the info from what you are describing the negative forming does seem a lot better. one thing i'm a little confused about is where would the holes be for the vacuum, i would think they would need to be at the bottom of the mould and if they are wouldn't they leave marks. can you post a picture of the mould you used to create the bubble you have shown.

thanks again for the info
josh
 
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update, i finally have all the piping sculpted in and i also roughed in the first row of the spine. after it is done hardening i can start sand and carve them into a nicer shape. then it will be on to the side rows.

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I love how the text on the original pipes is still visible, the lower ones look to just be petrol syphons.
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Are you gonna keep the letters or sand them off?
 
hi cavx
Thanks for the info from what you are describing the negative forming does seem a lot better. one thing i'm a little confused about is where would the holes be for the vacuum, i would think they would need to be at the bottom of the mould and if they are wouldn't they leave marks. can you post a picture of the mould you used to create the bubble you have shown.

thanks again for the info
josh

Your welcome. I hope to make a start on some molds soon and will start a thread on the technique as I go.

From what I can tell, you only need one very small hole in the lowest part of the mold and I intend to start with the needle of a (0.5mm?) syringe which will be removed after the silicone cures. With a hole that small, you won't even get a pimple on the surface of the plastic but you should be able to suck all the air out and therefore get a perfect fit of the thermo-formed plastic to the inside of the mold. The challenge with doing a part like your ALIEN dome is the cost for a one off is high. If you are able to do a run, then not so bad.
So once your molds are made and tested for air leaks, you would start the process by pulling enough vacuum just to flex the plastic. If using thick plastic, I'd suggest the vacuum is strong enough that you can not break the seal by hand.

As you heat the plastic, it will sag as it is pulled down by the vacuum. I would suggest you would want to work the heat from the edges into the centre so that you don't block the hole until right at the end. I look forward to making a few molds soon when I buy more silicone. Mine will be various parts including some TK armour bits and some BTTF stuff and maybe even my long awaited Pred Bio. In theory, you could reverse vacuum form a small boat. From watching the degass process, things heat up under vacuum and get cold under increased pressure, so maybe the vacuum is actually aiding the heating process. Water boils at room temp at -30". As I pressurize the chamber, the water is turned ice cold.

I first saw negative vacuum forming on YouTube where the guy was making detailed masks and had even made a Darth Vader dome.

There are a heap of ply wood forming videos where they bend ply under vacuum (huge rubber mat on the platen) and it stays that way. Normally you need hydraulic presses and steam to make these bends. Also check out vacuum fibre glassing and laminating which gives super smooth lamination and bonding due to having equal pressure applied to the whole surface of the parts, not just the points of where the clamps touched. Such awesome potential here :)
 
Great thread. I would SOOOOOOOOOOO buy a vac formed dome from you for my Alien head. Even if it doesn't fit exactly, it's gotta be better than what I have now.

Keep the updates coming, these are always great projects to watch come together!!

(p.s. And sell me a dome pull when you have one) :)
 
skint, i will be leaving the type on.

toothboy, i wouldnt have a problem making you a dome. i will already have the mould so whats one more :p I didn't see any threads on what your head looks like. would you mind sending some pics for ref.
 
Cavx, I will def look into this process it sounds like the best option. i was thinking for a good seal you could use construction adhesive around the flange and just cut it off each form.
 
Cavx, I will def look into this process it sounds like the best option. i was thinking for a good seal you could use construction adhesive around the flange and just cut it off each form.

For sure it could help. Products like Ultracel30 might also be a cheaper way to go to build molds. I would think clay (test first for sulfur) would be idea for making a master part that you then box up and take a mold of. You may even be able to make fibre glass mother molds to save on materials and cost. Just that you would have to plan reinforcement ribs from ply into the design.

The reason I want to use hard silicone is that it won't scratch the plastic, regardless of how many pulls you make. Being rubber, it will seal at both the vacuum pump end and the plastic on top. I am kind of wondering though if the cheap bathroom silicone would work here? In the end of the day, one it cures, it is rubber. The challenge is the molds would have to be done in layers. Buying a good silicone that can be degassed in a vacuum means perfect detail and no release agent needed.

My plan for my rig is to remove the lid off my vacuum chamber and sit the molds directly over the chamber. I might have to make plastic substitute lid with a hole drilled in the centre first, not sure yet. As the vacuum is increased, it will pull down on to the top of the chamber and make a seal. Once you have a seal, you start to heat the plastic and just maintain the vacuum. Because I am using a true vacuum pump and not just a vacuum cleaner, I can pull -30" of vacuum if I have to. This means that I can evacuate all the air to get 100% of the detail of the mold.

I was thinking about parts like my Pred Bio and thinking there might have to be more than one vent hole, but at that a full vacuum, there is no air, so any cavity will be crushed by the plastic as soon as it is hot enough. Again, you would start heating the general area and then work in from the sides to the centre. The single hole would probably be located on the tip of the brow. Even though the snout is a hollow, you just heat that area up first and finish at the brow.

I have plans to do my Gen 2 NIKE FOOTWEAR Tube Bag using this method as well.
 
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