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[steve mahoney]

Has anyone had any experience with vacuum forming? I need to produce some very simple shapes, but quite a few of them. Has anyone made their own equipment?

[Andyn]

Yes to both.


Had a small mdf box with a load of holes drilled in it for a bed (pegboard would have been better really), with a frame to hold the forming material that could slide over the box. Had a hole cut in the back for a hoover tube to sit in. It worked surprisingly well really given that our heat source was a heat gun


Also did have a commercial vacuum former available to me.


What do you need to know?

[steve mahoney]

Not boat related but I need a lot of very thin (0.5mm) plastic 'leaf' shapes. Simple shallow curved shapes. I'm an absolute novice to this.
I've found a 'how to' video online and the process doesn't seem too tricky – other than melting plastic in the oven. Don't think I'll be able to get away with that one.
What is the best type of plastic to use? I can get styrene that thickness but as I'll be using an A4 sheet each time it could get expensive. I need to be able to glue the finished product to a base board and I've had glue issues with PET and acrylic in the past.

[nemesis]

You cannot reuse styrene if you make a mistake, use ABS as you can reheat and try again. Heat your material to you see the "droop" then drop the material and apply the vacuum.nemesis

[Tug Fanatic]

Does a Dyson give enough suck to pull a hull of around 15in length from 2mm ABS/Styrene sheet.

If not then what are the reasonable limits?

 

[Circlip]

On deeper shapes, how fast you can get the air out comes into play.


 Regards Ian.

[Leaky Bottom]

I had a go at vac forming with little success until I decided to heat the mould with a hot air gun before putting the material over it and pulling the vacuum, the cold mould appeared to cool the plastic too quickly before it had chance to form properly

[Martin (Admin)]

 
Just for info, vac forming at Deans Marine:  https://youtu.be/l7ImdQR-8M8

[tigertiger]

I had a go at vac forming with little success until I decided to heat the mould with a hot air gun before putting the material over it and pulling the vacuum, the cold mould appeared to cool the plastic too quickly before it had chance to form properly

 


Yes, I worked in a factory that specialized in vac forming, and all of the moulds were very hot.

[Circlip]

What's the heat retention of a wooden mould like?


  Regards  Ian.

[Martin (Admin)]

Do you mean wear?
Apparently wooden moulds hold up very well, just compression forces involved,
 plus the wood is usually coated in some sort of 'shaping compound', ( car body filler ) that takes the brunt of the wear anyway.....

[Tug Fanatic]

Having been told that a hot mould makes the process more successful I think that Ian is asking if a preheated wood mould would hold heat well enough to promote success.

I don't know what constitutes hot enough but oven heated wood retains heat for some time.

[Vintage]

In my experience of vac-forming, the tooling doesn't need to be particularly hot to get a successful draw. Warm is fine so that it doesn't shock the pre-heated sheet when it comes into contact ...

Inevitably if you're doing lots of pulls in succession, as in a factory, then the tooling will get very hot as the heat in it builds up.

(I have a Formech 450 machine)

[Circlip]

No Martin, not wear. For the non commercial usage forum members are likely to require, hardly think attacking a wooden mould with a blowlamp is necessary. Looks like the other site has come up with the answers Steve.


  Regards  Ian

[JimG]

Do you mean wear?
Apparently wooden moulds hold up very well, just compression forces involved,
 plus the wood is usually coated in some sort of 'shaping compound', ( car body filler ) that takes the brunt of the wear anyway.....

There can be problems with wooden moulds with body filler on them. Around theDundee Clubs centenary we were involved in making hulls for a 36r yacht for our members. This started with a wooden plug that was covered with a fabric sleeve before adding resin. (The same method was used at the time for making prosthetics.) The plug shape was later modified to give fuller bows using filler paste and we found a local company that would produce vac formed hulls. While a few were produced the heat and pressure involved in the moulding led to the plug being damaged where the filler and wood joined. It would probably have been OK for one off mouldings but not for repeated use, also the thicker sheet used by the commercial process resulted in more pressure on the plug. We ended up taking one of the good mouldings and one of the members used this as a mould to produce glass fibre hulls.
Jim

[Martin (Admin)]

Maybe after the first successful  'pull', you could make a new plug out of more substantial material....