Thanks: 0
Likes: 0
Needs Pictures: 0
Picture(s) thanks: 0
Results 1 to 14 of 14
Thread: Freeform Vacuum Forming
-
16th August 2009, 06:59 PM #1
Freeform Vacuum Forming
Hi All,
I am working on my final architecture design project for uni and have a question about vacuum forming. I want to make a model of my building site which is basically a farm landscape with gentle rolling hills. The final model size will be about 1200x600. The hills are not steep but not flat either, and have a maximum change in elevation of 40m (80mm at the scale i'm working at). What i'd like to do is to create a freeform plywood surface of this landscape (about 10mm thick). The problem is that the site undulates in all directions and i'm not 100% sure on how to go about forming the model. From what i've read, you should glue down the veneers in layers rather than a single sheet of plywood. That makes sense, but if the site undulates in different directions, will it not cause the veneers to crease or bubble? I'd prefer to make this a sculptural freeform sheet of plywood rather than carving out a stack of plywood to the desired finish.
What i had in mind was to carve out a mold from modeling foam (blue stuff) or hebel blocks, seal it, then glue down veneers layer-by-layer until i reach the desired thickness. Stick it into a vacuum bag, leave it to dry, trim the edges, bit of a sand and hey presto! Does anyone have experience with this or something similar?
Attached is a long section and short section through the site. The short section is taken at the top of the site, however as the site drops off toward the middle, it forms into a valley. So it's not simply a flat rolling hill, rather rolling N/S and E/W.
Finally, are large sheets of veneer readily available. Pine or whatever would be cheapest. Or would it be better to glue down thinner strips, say 40mm veneer edging?
Sorry for the long email, but any help would be tops!
Cheers
Johnny
-
16th August 2009 06:59 PM # ADSGoogle Adsense Advertisement
- Join Date
- Always
- Location
- Advertising world
- Age
- 2010
- Posts
- Many
-
16th August 2009, 07:54 PM #2
lots of model train geograhy is just made out of papermache. stick sheets of newspaper together with pva glue.
-
16th August 2009, 08:15 PM #3
Not exactly the look i'm after. I've done stacks of site models before but what i want is basically a sheet of plywood that conforms to a mold of my site. In essence, a single sheet of badly misshapen plywood that looks strangely like my site
-
16th August 2009, 09:22 PM #4Hammer Head
- Join Date
- Jan 2005
- Location
- Sydney
- Posts
- 1,205
i would have cnc routered out of a sheet of foam, if i had a cnc i would do it for you but i dont.
-
16th August 2009, 09:39 PM #5
-
16th August 2009, 09:50 PM #6
-
16th August 2009, 10:18 PM #7
An interesting technical challenge, but your ultimate objective escapes my comprehension.
In practical terms, a single planar material cannot be deformed into non-planar without serious distortions and locked-in stresses, which may tend to return it to an un-stressed state.
Scale models of block forms typically exaggerate the vertical scale by a factor of two, as an aid to understanding; you seem to seek this AFAICT.
Are contour models now out of favour? They've historically been used to enhance understanding. And, as Bob says, paper mache would easily provide the shape itself. Leaving the contour edges exposed would serve both purposes.
Notwithstanding all that, you could achieve your objective by making your own plywood from veneers, either strips or single sheets. In either case, a stout negative mold will help to clamp the pieces together while the glue cures. And a stout positive, cast from the negative, will help even more. Concrete has usually been used for these molds. Boosting the vertical exaggeration by another 10% should allow for elastic rebound of the cured sandwich. Either strips or single sheets should be softened by steam, and cutting the strips will be purgatory. I'd suggest at least 3 layers of veneer, more or less perpendicular to one another.
This sounds a little like repairing a steam locomotive under way: Technically interesting, but not much fun.
Cheers,
JoeOf course truth is stranger than fiction.
Fiction has to make sense. - Mark Twain
-
17th August 2009, 01:21 AM #8Senior Member
- Join Date
- Mar 2006
- Location
- Perth
- Age
- 57
- Posts
- 338
Perhaps another way to think of it is to imagine that you are using paper instead of veneer (ie the paper represents the softened veneer). Could you achieve what you want with sheets of paper? Would the paper require cutting in order to get the distortions right. Would it require many many strips of paper to achieve your contours?
If it can't be done with paper, I can't imagine it being done with veneer. You have set yourself a huge challenge.Graeme
-
17th August 2009, 09:38 AM #9
-
17th August 2009, 06:52 PM #10
sounds like you're making it really hard for yourself WW,
(unless this project specifically requires formed ply)
I've done a handfull of site models for architects (none in wood)
but stack laminating on the contours and shaping would be far easier than all the rigamarole involved in vac forming and IMO the end result would be just as interesting
what if the hokey pokey is really what it's all about?
-
17th August 2009, 07:17 PM #11
Fibreglass and resin??
-
17th August 2009, 07:18 PM #12
If you are going to carve a base to mould over, I would be inclined to do the the moulding in fibre glass matt and resin. You could use a foam base for the former, epoxy resin for the base coat on the foam (as it doesnt harm foam), a fill coat of resin to hide the weave of the cloth, then melt the foam blank with thinners to eliminate it.
-
19th August 2009, 10:01 AM #13
Easy to do but time consuming, sheet of ply for a flat base, hot glue gun/screw/nail on your high points(cardboard/strips of wood... what ever you can find that will hold staples).
Buy the cheapest 2 way stretch jumper material, some fine chicken wire and some spray adhesive(dont $kimp here), 1 or 2ltr's of fibreglass resin and a 2ltr tin of car bog.
Staple down the wire bending it to the desired shape as you go.
Spray the "rough side" of the material then the wire, wait a few minutes then lightly stretch the jumper material over the model stapling it around the back or side edges of your base padding/smoothing it down as you go.
Mix up a batch of fibreglass resin/hardener and paint the jumper material till its soaked, give it another coat once set(you can add some fibre matting for strength if needed).
Give it a clean up with some heavy abrasive(flap disc's on grinder are the quickest method)you may need to touch it up with more material soaked in resin if you cut through by accident, mix up the car bog and smooth it over using your hands(latex gloves might be handy here ) as a squeegee, let it set and rough sand it to shape then repeat the car bog again and sand it with a finer grit to finish it.....................................................................
-
22nd August 2009, 04:58 PM #14Awaiting Email Confirmation
- Join Date
- Jan 2007
- Location
- Goulburn NSW
- Age
- 89
- Posts
- 913
if you went to my hardware store and looked thru the bracing ply rack They are different shapes
les
Similar Threads
-
Freeform Mango Mirror Frame
By TEEJAY in forum WOODWORK PICSReplies: 14Last Post: 13th September 2008, 10:36 PM -
Forming a Boat building Co-op in Sydney - Botany?
By merrijig in forum BOAT RESOURCES / PRODUCT SEARCHReplies: 8Last Post: 22nd August 2008, 01:31 PM -
Using a bead forming tool.
By Sir Stinkalot in forum WOODTURNING - GENERALReplies: 7Last Post: 13th November 2006, 05:22 PM -
Which vacuum?
By davo453 in forum WOODWORK - GENERALReplies: 22Last Post: 19th May 2006, 11:37 PM