Bob the Alien (Giger inspired Alien)
- Thread starter Leigh
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Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
Thanks guy's
sskunky I have been making sure I've got no talc build up at the tips & I had thought about pre-loading the fangs. I could probably get away with it in one cast with the upper teeth but, I have a 3.5 min working time with the urethane. In order to get a clean cast by pre-loading the fangs in the bottom jaw, I would have to poor some resin into the fangs with the mould open & then let it set. Then close the mould & slush the rest... would this work?? or am I likely to have steps or lines in my cast??
Thanks guy's
sskunky I have been making sure I've got no talc build up at the tips & I had thought about pre-loading the fangs. I could probably get away with it in one cast with the upper teeth but, I have a 3.5 min working time with the urethane. In order to get a clean cast by pre-loading the fangs in the bottom jaw, I would have to poor some resin into the fangs with the mould open & then let it set. Then close the mould & slush the rest... would this work?? or am I likely to have steps or lines in my cast??
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
Yeah, can happen. I usually have a junk mould lying around for any leftover resin; I find that parts cast out of those moulds tend to pretty often be unusable. Different pours sometimes don't play nice together; the upper one'll foam up or the lower one'll weep or what have you. Can work fine too, but test under best possible conditions to be sure the urethane will adhere to itself. Cos another thing urethane likes to do is to totally NOT adhere to itself...
Yeah, can happen. I usually have a junk mould lying around for any leftover resin; I find that parts cast out of those moulds tend to pretty often be unusable. Different pours sometimes don't play nice together; the upper one'll foam up or the lower one'll weep or what have you. Can work fine too, but test under best possible conditions to be sure the urethane will adhere to itself. Cos another thing urethane likes to do is to totally NOT adhere to itself...
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
OK, Thanks mate I had a feeling I may be pushing my luck with that one
Since I've dried the Jaw mould properly now I'll give it another go & hope that the sprue will do trick this time. I should be able to pre-load the upper teeth as its a simple mould & I think I'll have the time to get away with it. I've got to drill the holes around the flange of the jaw mould for the new bolts & wing nuts. When I've done that I'll give it another run & we'll see how it comes out
Thanks again guy's
OK, Thanks mate
I had a feeling I may be pushing my luck with that one Since I've dried the Jaw mould properly now I'll give it another go & hope that the sprue will do trick this time. I should be able to pre-load the upper teeth as its a simple mould & I think I'll have the time to get away with it. I've got to drill the holes around the flange of the jaw mould for the new bolts & wing nuts. When I've done that I'll give it another run & we'll see how it comes out
Thanks again guy's
Alaneye
Sr Member
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
If there was no other way, I would mix a little resin for the teeth pour, then close the mould and mix up a bigger batch for the second pour. You don't have to let the first pour cure, in fact, the second pour will adhere better to the first if it hasn't completely cured. Because I am a stickler for wanting to get the most perfect casts out I can, I use a multipour approach to make sure I get into all the nooks and crannies of my Terminators.... but the truth is, there is no way to guarantee a perfect pour every time.
If there was no other way, I would mix a little resin for the teeth pour, then close the mould and mix up a bigger batch for the second pour. You don't have to let the first pour cure, in fact, the second pour will adhere better to the first if it hasn't completely cured. Because I am a stickler for wanting to get the most perfect casts out I can, I use a multipour approach to make sure I get into all the nooks and crannies of my Terminators.... but the truth is, there is no way to guarantee a perfect pour every time.
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
It's worth a shot though. I have a few garage kits where the caster did it with perfect results and I get them myself once in a while, just a difference in colour. Keep in mind I might have been working in humid conditions and I'm talking about just slopping excess resin about carelessly. A mile away from what you'd be doing, really.
Edit - what Alan said. Sometimes resin just doesn't want to be your friend. :lol
It's worth a shot though. I have a few garage kits where the caster did it with perfect results and I get them myself once in a while, just a difference in colour. Keep in mind I might have been working in humid conditions and I'm talking about just slopping excess resin about carelessly. A mile away from what you'd be doing, really.
Edit - what Alan said. Sometimes resin just doesn't want to be your friend. :lol
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
Those are great first castings.
All that time and effort certainly paid off.
Regarding the teeth, what about a resin with a longer pot life?
Appreciate you've already spent a lot on materials but the one I use all the time at work is Rencast FC52, as it has a pot life of 6 - 8 minutes.
RenCast FC 52
Your sprue method would have worked well here. You could probably have used spruces a small as 1 / 1.5mm diameter and plug the holes as the resin runs out.
Those are great first castings.
All that time and effort certainly paid off.
Regarding the teeth, what about a resin with a longer pot life?
Appreciate you've already spent a lot on materials but the one I use all the time at work is Rencast FC52, as it has a pot life of 6 - 8 minutes.
RenCast FC 52
Your sprue method would have worked well here. You could probably have used spruces a small as 1 / 1.5mm diameter and plug the holes as the resin runs out.
sskunky
Sr Member
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
You can use a resin with a longer pot life but the next problem you'll encounter is that you are slush casting and by the time it starts to set your arms will be good for nothing! You really need a rotocasting machine for this. Ebalta is a good place to get resins. They are really helpful, first class resin and good value. They do lots of different types and timed ones too.
You can use a resin with a longer pot life but the next problem you'll encounter is that you are slush casting and by the time it starts to set your arms will be good for nothing! You really need a rotocasting machine for this. Ebalta is a good place to get resins. They are really helpful, first class resin and good value. They do lots of different types and timed ones too.
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
Thanks Guy's
In hindsight I think I should have built the mould differently. If I'd have put a partition through the tooth area I probably wouldn't be having this problem. I'm stuck with this one now though so it has to work. I had thought a couple of extra minutes might have helped but I have an idea...
I'm going to cut a small strip of the jacket away on the inside of the tooth area, just big enough to get my finger tips through. The plan is to pour the resin in the mould (teeth down) so the weight of the resin is all on the teeth. Then squeeze the outside of the mould (through the hole in the jacket) where the sprues are, in an effort to push the air out. hopefully it will draw the resin in, in place of the air. It sounds complicated but it's really very simple & will only take a second or two. The hole I'll cut in the jacket wont compromise the structural integrity & it'll be next to the sprue & not the teeth so wont cause any distortion to the casts.
Anyway I now have two casts of the jaw & the upper teeth. One set will be used to create the lip's & tendons, both sets have tips missing. The other set is fine & will just need a tiny bit of filler to rebuild the tips.
In an effort to get some progress, I'm currently prepping the head for moulding. I'll be making the partitions for the head mould in roughly the same place as the original, so the mould will be in 3 main pieces. I may need to add a 4th piece to the mould to get the pallet area sorted as there's quite alot going on there.
Thanks again for the suggestions
Thanks Guy's
In hindsight I think I should have built the mould differently. If I'd have put a partition through the tooth area I probably wouldn't be having this problem. I'm stuck with this one now though so it has to work. I had thought a couple of extra minutes might have helped but I have an idea...
I'm going to cut a small strip of the jacket away on the inside of the tooth area, just big enough to get my finger tips through. The plan is to pour the resin in the mould (teeth down) so the weight of the resin is all on the teeth. Then squeeze the outside of the mould (through the hole in the jacket) where the sprues are, in an effort to push the air out. hopefully it will draw the resin in, in place of the air. It sounds complicated but it's really very simple & will only take a second or two. The hole I'll cut in the jacket wont compromise the structural integrity & it'll be next to the sprue & not the teeth so wont cause any distortion to the casts.
Anyway I now have two casts of the jaw & the upper teeth. One set will be used to create the lip's & tendons, both sets have tips missing. The other set is fine & will just need a tiny bit of filler to rebuild the tips.
In an effort to get some progress, I'm currently prepping the head for moulding. I'll be making the partitions for the head mould in roughly the same place as the original, so the mould will be in 3 main pieces. I may need to add a 4th piece to the mould to get the pallet area sorted as there's quite alot going on there.
Thanks again for the suggestions
Alaneye
Sr Member
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
Yeah, that should work. The same principle works with the tiny, thin jaw piston I made for the Terminator 1 bust. It's a small two part block mould. I ran sprues from the ends to stop air getting trapped and also put a little ball on the end of each sprue, (my mould halves go through it)... when I pour resin in, I squeeze the mould which forces the air out of the sprues, I see the bubbles come to the surface, let go, and the resin is sucked into the sprues and also through the actual piston parts of the mould. You are hollow casting aren't you, so the bubbles won't get stuck somewhere else, with they?
Good luck with the head, I am daunted even just thinking about the logistics of it
Yeah, that should work. The same principle works with the tiny, thin jaw piston I made for the Terminator 1 bust. It's a small two part block mould. I ran sprues from the ends to stop air getting trapped and also put a little ball on the end of each sprue, (my mould halves go through it)... when I pour resin in, I squeeze the mould which forces the air out of the sprues, I see the bubbles come to the surface, let go, and the resin is sucked into the sprues and also through the actual piston parts of the mould. You are hollow casting aren't you, so the bubbles won't get stuck somewhere else, with they?
Good luck with the head, I am daunted even just thinking about the logistics of it
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Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
Ah cool, so it could work then
I'll give it a go next time I attempt a cast.
I'm finding the head quite a daunting prospect at the moment. I'm worried I might damage the surface of the soft area's, I'm trying to be really careful.
I deliberately incorporated hard area's into the head, thinking it would make life easier when it comes to building the moulds.
I couldn't get the clay to stick to the surface so I've had to improvise a little I needed a structure to build the partition onto, it doesn't need to support a huge amount weight wise but it does need to be fairly sturdy.
I'd been keeping the boxes the cat food sachet's come in, just in case they come in handy & they have
The structure is mostly self supporting, it rests on hard area's & is all reinforced, triangulated & held together with CA glue, its not glued to the head though.
I've bought some cheap erasers that I've cut into small blocks, I'm going to glue those to the foil & they will be my key's for the next mould part.
I cant get a perfect seal against the head surface but it is very close, rather than messing about I thought I'd knock up the first cup of rubber with just a touch thixo, hopefully this will have enough surface tension to bridge a tiny gap & I'll run this round the gap first. Then I figure I should be able to build up the layers as normal, ie a skin coat followed by a few thixo & non-thixo coats untill I reach a thickness I'm happy with.
I then plan to build the jacket for this section, I'd like to add two lengths of light weight wood to the top of the jacket so I can turn the whole lot over when its all dry & rest it that way.
Then I can build the other 2-3 sections
It's all good fun
Ah cool, so it could work then
I'll give it a go next time I attempt a cast.
I'm finding the head quite a daunting prospect at the moment. I'm worried I might damage the surface of the soft area's, I'm trying to be really careful.
I deliberately incorporated hard area's into the head, thinking it would make life easier when it comes to building the moulds.
I couldn't get the clay to stick to the surface so I've had to improvise a little
I needed a structure to build the partition onto, it doesn't need to support a huge amount weight wise but it does need to be fairly sturdy. I'd been keeping the boxes the cat food sachet's come in, just in case they come in handy & they have
The structure is mostly self supporting, it rests on hard area's & is all reinforced, triangulated & held together with CA glue, its not glued to the head though.
I've bought some cheap erasers that I've cut into small blocks, I'm going to glue those to the foil & they will be my key's for the next mould part.
I cant get a perfect seal against the head surface but it is very close, rather than messing about I thought I'd knock up the first cup of rubber with just a touch thixo, hopefully this will have enough surface tension to bridge a tiny gap & I'll run this round the gap first. Then I figure I should be able to build up the layers as normal, ie a skin coat followed by a few thixo & non-thixo coats untill I reach a thickness I'm happy with.
I then plan to build the jacket for this section, I'd like to add two lengths of light weight wood to the top of the jacket so I can turn the whole lot over when its all dry & rest it that way.
Then I can build the other 2-3 sections
It's all good fun
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Alaneye
Sr Member
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
You don't mind giving yourself a challenge, do you ... I think I'd have gone for a two part mould divided right down the middle, unless there was some compelling reason not to. Another approach that I have never tried myself, but seems like it might have been a good option for you with you having soft clay in there, would have been to cover the whole head with a few layers of silicone... once you have a few millimeters of thickness. then create your partitions on top of the silicone (you would still have to be careful not to press on the vulnerable areas, but at least you aren't putting hard edges against your soft clay). Once all the sections and the mother moulds are done, you take it apart and carefully slice though the couple of millimeters of silicone with a scalpel.
You don't mind giving yourself a challenge, do you
... I think I'd have gone for a two part mould divided right down the middle, unless there was some compelling reason not to. Another approach that I have never tried myself, but seems like it might have been a good option for you with you having soft clay in there, would have been to cover the whole head with a few layers of silicone... once you have a few millimeters of thickness. then create your partitions on top of the silicone (you would still have to be careful not to press on the vulnerable areas, but at least you aren't putting hard edges against your soft clay). Once all the sections and the mother moulds are done, you take it apart and carefully slice though the couple of millimeters of silicone with a scalpel.
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
I only recently read about that "skinning" method. It sounds brilliant. I can't wait to try it on a project someday.
I only recently read about that "skinning" method. It sounds brilliant. I can't wait to try it on a project someday.
Clutch
Master Member
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
What they said. I would skin it first with some resin and make sure it is brushed/pushed down into the teeth first, then pour.
Edit: I hate it when I think I'm on the last post and there's a page left. Lol!
What they said. I would skin it first with some resin and make sure it is brushed/pushed down into the teeth first, then pour.
Edit: I hate it when I think I'm on the last post and there's a page left. Lol!
garlicbread
Well-Known Member
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
I'm loving your updates Leigh, though I can't wait to see it finished, though I suppose your wife is thinking the same
I'm loving your updates Leigh, though I can't wait to see it finished, though I suppose your wife is thinking the same
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
Alan, I did briefly think about doing an all over brush up mould & cutting him out afterwards, it would be easier to build the mould doing it that way. I also considered just a two part mould.
I went for a the option to build partitions because I want a good solid key, for each mould part to lock together tightly with no leaks & no distortion or overlapping of the mould parts. I figured by building partitions it "should" make the casting process a little easier with a better chance of a good result with each cast.
I've opted to make the moulds in 4 sections comprising of the 3 large parts & 1 small part. My reasoning here is in an effort to reduce wear & tear to the mould due to heavy undercuts & deep detail. the small 4th part is going to have to handle the pallet, the roof of his mouth which is cluttered with various complicated shapes that hold the tongue & jaw in place with room for movement.
I know I'm making myself more work than maybe I need too, but I figured if I make more effort with the mould I have a better chance of success with each cast.
Bear in mind though, all this is based on knowledge I'm picking up from here & online, with a little over thinking & caution on my part, I have no practical experience & I'm learning as I go along. I don't mind a bit of a challenge now n then, but I don't like making mistakes! especially costly ones
I do appreciate all advise & any info that can help me do this effectively & all the advise & support I've received so far has been fantastic, Thank you
Thanks for the kind words Guy's
Alan, I did briefly think about doing an all over brush up mould & cutting him out afterwards, it would be easier to build the mould doing it that way. I also considered just a two part mould.
I went for a the option to build partitions because I want a good solid key, for each mould part to lock together tightly with no leaks & no distortion or overlapping of the mould parts. I figured by building partitions it "should" make the casting process a little easier with a better chance of a good result with each cast.
I've opted to make the moulds in 4 sections comprising of the 3 large parts & 1 small part. My reasoning here is in an effort to reduce wear & tear to the mould due to heavy undercuts & deep detail. the small 4th part is going to have to handle the pallet, the roof of his mouth which is cluttered with various complicated shapes that hold the tongue & jaw in place with room for movement.
I know I'm making myself more work than maybe I need too, but I figured if I make more effort with the mould I have a better chance of success with each cast.
Bear in mind though, all this is based on knowledge I'm picking up from here & online, with a little over thinking & caution on my part, I have no practical experience & I'm learning as I go along. I don't mind a bit of a challenge now n then, but I don't like making mistakes! especially costly ones
I do appreciate all advise & any info that can help me do this effectively
& all the advise & support I've received so far has been fantastic, Thank you Thanks for the kind words Guy's
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
At last the main game. Awesome. Leigh, you're really going to need to put in some hard yakka on the ribbed tubing, ouch! I know you know this already and your success on the jaw shows you're definitely able to produce a bubble-free mould, I'm pretty confident you'll nail this too.
Are you still planning to build a roto frame for this?
At last the main game. Awesome. Leigh, you're really going to need to put in some hard yakka on the ribbed tubing, ouch! I know you know this already and your success on the jaw shows you're definitely able to produce a bubble-free mould, I'm pretty confident you'll nail this too.
Are you still planning to build a roto frame for this?
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
Rotoing this this by hand would be impressive.
Rotoing this this by hand would be impressive.
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
Thanks guy's
That small convoluted pipe will get the skin coat via an artist brush It'll take a while, but it'll be worth it
Yep, I've got to roto it by hand, I'll have 3.5 - 4 mins to pour it in, plug it & get a relatively even coat over the inside
Thanks guy's
That small convoluted pipe will get the skin coat via an artist brush
It'll take a while, but it'll be worth it Yep, I've got to roto it by hand, I'll have 3.5 - 4 mins to pour it in, plug it & get a relatively even coat over the inside
Re: Bob the Alien (Giger inspired Alien) Sculpting finished page 45
If that's the case then having two big mold halves might be optimal. You could slush cast the two open molds first, taking advantage being able to see where parts of the mold aren't getting evenly coated and add additional resin to coat those sections before closing up the mold and doing the final roto to seal the two halves together.
I just worry that a blind roto by hand wont coat evenly on something that big in one shot.
Of course I could be completely wrong. In fact it's very likely!
If that's the case then having two big mold halves might be optimal. You could slush cast the two open molds first, taking advantage being able to see where parts of the mold aren't getting evenly coated and add additional resin to coat those sections before closing up the mold and doing the final roto to seal the two halves together.
I just worry that a blind roto by hand wont coat evenly on something that big in one shot.
Of course I could be completely wrong. In fact it's very likely!
