Making Season 14 Roundels

[architect]

all I can say is wow. I am glad you did not think things through and kill this idea before it was born as I for one think it was worth every moment and effort put into it. any chance you might put together a tutorial on vacuformming? it seems there is a strong chance that you may have some new ideas that might get overlooked or tips for making it work better for some one who has never done it before.

[mordrogyn]

all I can say is wow. I am glad you did not think things through and kill this idea before it was born as I for one think it was worth every moment and effort put into it. any chance you might put together a tutorial on vacuformming? it seems there is a strong chance that you may have some new ideas that might get overlooked or tips for making it work better for some one who has never done it before.

He has details on how he did it on his website:

http://relative-dimensions.net/v2/console-room/vacuum-former.htm

[Scarfwearer]

It's split across 5 pages there - there's a short video of me vacuum forming at the bottom of the third page.



Crispin

[architect]

I got to see that. I have several shop vac due to my having a CNC machine and needing dust removal. How much better detail would have been had should you have been able to use say a really hard wood turned down on a lathe you think? I am guessing aluminum would allow to much heat and caused the plastic to melt so unless spray on teflon would have been available that would have been no good. I have a lot of personal projects that may be making use of this tech so I guess I may be setting a whole new room up for vacuum forming after all.

[architect]

oh and I forgot to mention how brilliant the method you came up with for making the mold with the pencil or what ever that stick was as a compass and the cut out for your forming tool, was.

[Scarfwearer]

oh and I forgot to mention how brilliant the method you came up with for making the mold with the pencil or what ever that stick was as a compass and the cut out for your forming tool, was.

I pretty much used the same method our dalek-building colleagues use for making dalek domes to a particular profile - just adapted it for the roundel.

If you could lathe an accurate buck from hardwood to vac-form against, I think you'd get a much better result, yes, though with more care than I took with a better plaster product (and perhaps more skill than I have!) you could probably do just as well.

Theta Sigma's been having a go as well - see here: [ref topic=1286]Kevin's Roundel Attempt[/ref].


Crispin

[philipw]

I got to see that. I have several shop vac due to my having a CNC machine and needing dust removal. <snip>

If you have a cnc, have you thought about using it to create the mold form? I recently built a 2 x 4' one for my shop and think it would be ideal for this. cut it out of a slab of poplar.

[architect]

I got to see that. I have several shop vac due to my having a CNC machine and needing dust removal. <snip>

If you have a cnc, have you thought about using it to create the mold form? I recently built a 2 x 4' one for my shop and think it would be ideal for this. cut it out of a slab of poplar.

that is an idea. or layered oak since it is one of the more abundant woods around here. I am lucky to have a local plastics supplier too that has just about everything you can imagine and at incredible prices if I am getting it from their scraps. those come in just about anything from 4 foot by 4 foot sheets on down. UHMW polycarb acrylic you name it I even bought a sheet of Teflon for a project. that is some truly weird feeling stuff. flexes like something that is soft and rubbery but it has no stretch worth mentioning and the surface is incredibly hard.

[philipw]

Yes, poplar is great because it won't really have a grain to worry about and carves beautifully. And cheap as well.

If your supplier has HDPE (high density polyethylene) that would be about the perfect material to make it from.

[architect]

yeah they have gobs of the HDPE and most of the time sell me the UHMW at the same price even though they are not supposed to mostly just because I buy so much stuff from them to build machines and make my goggles I sell.

[architect]

oh and just to note the UHMW is the same chemical as the HDPE and LDPE just a higher and tighter molecular strand (the ethylene mol) so it is harder to scratch and has an even higher viscous surface but I have seen no more difficulty in cutting and forming it. Usually more expensive but if you are building a tool I highly recommend it.

[philipw]

oh and just to note the UHMW is the same chemical as the HDPE and LDPE just a higher and tighter molecular strand (the ethylene mol) so it is harder to scratch and has an even higher viscous surface but I have seen no more difficulty in cutting and forming it. Usually more expensive but if you are building a tool I highly recommend it.

Yes, no doubt about that, especially the higher cost. You can't paint it though that I know of. I use it when I have jigs and things that need a dry near frictionless surface.

[doctor varney]

Crispin, I do believe that biting the bullet and going with glass fibre is probably your best option.  

Although GRP ain't great for anyone prone to allergies or eczema, etc... as long as you keep it at arms length and not in an enclosed space, you should be alright.  Just watch out in case you have any wasp nests near you... Even in winter, the odour I've found can force them out of hibernation, causing you to be suddenly surrounded by lots of little inquisitive friends.

Dunno if any of this will help and please forgive me if you already know most of this, but thought I'd just chip in anyway, in case any of it's any use.

The best thing to make your mould from would be RTV silicone rubber because it will outlast the large run you've got to do.  Many moulds tend to degrade with use, but silicone is recommended for long runs and is self-releasing.

Note, when we say 'mould' in the industry we always use it to refer to the negative.  The form you make the mould off is referred to as the pattern, master, former or plug, etc...  The finished product is called the casting or the 'run off'.

With silicone, you need to back it up with a hard glass fibre case, to keep the rubber rigid while laminating.  I would suggest making something like four + masters, using a thin rubber preliminary mould and then creating one large mould off those.  More work in the set up but in the long run, will make your runs a bit faster.

You can make your former in just about anything, as you've discovered and limited only by your creativity and inventiveness.  Clay is alright but the air-drying variety and oil-based ones will offer greater durability to your master.  There is also a great and inexpensive modelling material called 'Newclay' - a fine engineering clay which is fibre reinforced for tensile strength and when it dries out, won't be as prone to cracking as ordinary buff clays.  Sculpy is a favourite among many people as well.

Though my preferred method for creating non-organic shapes is to use found objects, such as, in this case, embedding concentric plastic hoops into a clay or wax base.

Otherwise, I would use a carvable foam, such as a styrene.  For larger base-shapes, such as boat hulls and human bodies, etc I will often use insulating polystyrene, which can be carved with a bread knife and then literally knocked into shape with heavy-grit carborundum paper.  I find old linisher belts glued to shaped wooden paddles ideal home-made tools for this.  Finally, you can surface it up with Polyfilla, imbued with a little PVA to make it harder and then sand to a factory smooth finish.

By cutting hoops, sanding them individually and assembling them on a base before making good with  Polyfilla, you could probably create a very accurate roundel master indeed.  Personally, I don't think I would attempt to carve it out of one single piece of anything - but of course, each has his own way of working.

If you do decide to take the plunge and need any extra advice on glass fibre - laminating or materials, I'll do my best to help, if I can.

Good luck!

[doctor varney]

Also, what colour are the walls? they seem to vary between grey, white and beige  

Don't quote me, but I'm guessing the walls were originally white in the show and that it's studio lighting that gives the impression of any colour.

As for the roundels - well, I believe they were originally GRP and in it's translucent state, that's usually a pale yellow-green.  A lot depends on the brand of resin used.  It doesn't surprise me to see them appear with a slight yellow tinge when lit.

[Scarfwearer]

Crispin, I do believe that biting the bullet and going with glass fibre is probably your best option.  

Thanks for the info on fibreglassing. It would be great to see someone have a go with this.

This topic goes back a few years and, for my TARDIS, I eventually vacuum-formed 100 roundels using a home-made vacuum former. The story starts here Vacuum Forming the Roundels and spreads across 5 pages (follow the tabs).

Crispin