Vacuforming clear acrylic?
- Thread starter Yorpheus
- Start date
division 6
Master Member
If it's not over heated.
But unless you have a really smoth surface or a open bottom female mold you will get bumps.
Blow forming will give you a clean bubble.
The Aquarium place I used to work at did blow formed bubbles for tanks out of 1/4"
See Picards Ready Room tank for an example.
Made by the company I worked at.
My friends an I have used the female molds for Storm Trooper lenses.
We've also use regular buck (male) for our X-Wing helmet lenses.
D6
But unless you have a really smoth surface or a open bottom female mold you will get bumps.
Blow forming will give you a clean bubble.
The Aquarium place I used to work at did blow formed bubbles for tanks out of 1/4"
See Picards Ready Room tank for an example.
Made by the company I worked at.
My friends an I have used the female molds for Storm Trooper lenses.
We've also use regular buck (male) for our X-Wing helmet lenses.
D6
minieffects
Well-Known Member
<div class='quotetop'>QUOTE(kimncris @ Dec 14 2006, 07:25 AM) [snapback]1377717[/snapback]</div>
I have vacuformed clear PETG, but the problem I had was that once it stretched over the mold, it destroyed the clarity of the plastic and became very hard to see through.
-cris
[/b][/quote]
add vasoline to the surface of the pattern.
I have vacuformed clear PETG, but the problem I had was that once it stretched over the mold, it destroyed the clarity of the plastic and became very hard to see through.
-cris
[/b][/quote]
add vasoline to the surface of the pattern.
minieffects
Well-Known Member
<div class='quotetop'>QUOTE(division 6 @ Dec 14 2006, 05:14 AM) [snapback]1377654[/snapback]</div>
All good info. I have found that if you want complete control over the finished product that acrylic is the best choice. Mainly because if you do get bubbles or inperfectios you can buff them out with micro-mesh (https://www.micro-surface.com/default.cfm?page_id=1). we used this on The Aviator for the 1:4 scale xf-11 and it worked great.here is an example http://www.aviatorvfx.com/index.php?cmd=fr...ndScreeningRoom
go to the end of the video and there is a close up of the canopy.
Now having said all that, the drawback to acrylic is that its fragile to a certain extent. It can be cracked or chiped or scratched. PETG is a great alternative and I have used it for years but the pattern prep is paramount. I have found that if you make a pattern and get the surface polished, then make a mold and cast the pattern out of urethane, preferably tc-1630 from bjb enterprises. http://www.bjbenterprises.com/
You then preheat the mold to about 200 degrees and then pull. Try to make sure its not damp outside as moisture can collect between the plastic and the pattern and cause bubbles.
hope this helps
minieffects
All good info. I have found that if you want complete control over the finished product that acrylic is the best choice. Mainly because if you do get bubbles or inperfectios you can buff them out with micro-mesh (https://www.micro-surface.com/default.cfm?page_id=1). we used this on The Aviator for the 1:4 scale xf-11 and it worked great.here is an example http://www.aviatorvfx.com/index.php?cmd=fr...ndScreeningRoom
go to the end of the video and there is a close up of the canopy.
Now having said all that, the drawback to acrylic is that its fragile to a certain extent. It can be cracked or chiped or scratched. PETG is a great alternative and I have used it for years but the pattern prep is paramount. I have found that if you make a pattern and get the surface polished, then make a mold and cast the pattern out of urethane, preferably tc-1630 from bjb enterprises. http://www.bjbenterprises.com/
You then preheat the mold to about 200 degrees and then pull. Try to make sure its not damp outside as moisture can collect between the plastic and the pattern and cause bubbles.
hope this helps
minieffects
minieffects
Well-Known Member
One more thing, if you are using a plaster pattern then you need to dry it out completely. You can then put a thin coat of vasaline over the top and vacuform. Another trick that works is to pull styrene first and leave it on the pattern. Then pull the clear over that. Ive had alot of success with that process.
minieffects
minieffects
Chris Martin
Well-Known Member
Two very important points about acrylic:
Firstly you need to use extruded acrylic sheet, not the more common cast acrylic. Cast acrylic won't vac form into anything but the most shallow shapes or gentle curves. Cast acrylic never goes beyond the consistency of a stiff sheet of rubber even at forming temperatures. If you're buying sheet, tell the stockist it's for vac forming.
Secondly the bubble problem is because acrylic is hygroscopic. That means it absorbs moisture. Freshly manufactured acrylic with the protective polythene sheet in place should be relatively trouble free but old acrylic is like to bubble horrendously at forming temperatures. This is caused by the moisture boiling in the plastic and it's not something that can be polished out. Commercial vac forming companies will always force dry acrylic sheets first by putting them in an oven for several hours before trying to form them. I know this because I used to design acrylic shop signs for one of the largest sign manufacturers in the UK and I still vac form acrylic to this day.
For a really good finish vac form a sheet of acrylic over your master, leave it on and then vacform a second sheet over this having first put cooking oil on the first sheet.
Firstly you need to use extruded acrylic sheet, not the more common cast acrylic. Cast acrylic won't vac form into anything but the most shallow shapes or gentle curves. Cast acrylic never goes beyond the consistency of a stiff sheet of rubber even at forming temperatures. If you're buying sheet, tell the stockist it's for vac forming.
Secondly the bubble problem is because acrylic is hygroscopic. That means it absorbs moisture. Freshly manufactured acrylic with the protective polythene sheet in place should be relatively trouble free but old acrylic is like to bubble horrendously at forming temperatures. This is caused by the moisture boiling in the plastic and it's not something that can be polished out. Commercial vac forming companies will always force dry acrylic sheets first by putting them in an oven for several hours before trying to form them. I know this because I used to design acrylic shop signs for one of the largest sign manufacturers in the UK and I still vac form acrylic to this day.
For a really good finish vac form a sheet of acrylic over your master, leave it on and then vacform a second sheet over this having first put cooking oil on the first sheet.
