Vacform blues

[Hobbes]

I've been looking for a suitable surface for placing a sheet of sandpaper on (so I can sand down vacuformed parts).
It has to be absolutely flat, and preferably waterproof (so I can wet-sand). Which eliminates most materials.
At the kitchenware shop, I bought a glass 'cutting board', thinking I'd use that. No luck (again), as the damn thing is concave instead of being flat. Can't return it either (packaging has been opened). I suppose I could have some plate (window) glass cut to size, but then I'd have to contend with sharp edges.

Any suggestions for an alternative?

[Captain Canada]

just make yourself a border to go around the glass.....make a frame

[Sentinel Chicken]

Even cheaper, go to any arts/craft store or discount outlet and get a picture frame, take it apart and use the glass front.  

[Jennings]

You're making it harder than it has to be.  I've been building (or rather, starting) vacforms for nigh on 30 years.  I've never yet used the "tape the sandpaper to a board" method.  I've always (and highly successfully) used a hand-held sanding block to sand them down.  For really thick ones, I use a sanding drum on my Dremel (clone) to do most of the work, and then finish with the sanding block.

I find the block gives me *much* greater control than moving the part around on a sheet of paper.  When I've tried that method, I always end up with too much off of some areas and not enough off of others.  I think that is due to the fact that the human hand is not a perfect mechanical object.  Despite our best efforts at keeping things straight & true, your hand/arm will always introduce uneven pressure, odd angles, etc.  It's just a fact of nature.

Like I said, I've had ultimate good success using a sanding block (about 4x6"), so give that a try.

J

[cthulhu77]

Ah, there is one inexpensive material that was made for vacs...go to your local home supply or tile store and pick up a piece of granite...yep, it's ground flat, it's smooth and shiny, it's heavy...and easy to attach paper to with spray on glue...for about ten bucks total, you can have the sanding platform and the glue!

[Sentinel Chicken]

Of course there are those in the modelling community who think the desire to build a vacform is reason for committment to a psychiatric institution!

The last vac I built nearly turned me to the recreational pharmaceuticals.

[K5054NZ]

Jennings' comments regarding the unsuitability of the human hand to vacforms are indeed true - the tailplane of my just-started Execuform Electra are proof of this. I'll try a block today on this beastie, but I see now *just* how much work is ahead of me. And to think, i've got THREE vacs in the stash. Sigh.............



Speaking of which, where are everyone else's entries into the Vacform Groupbuild, "Zac's Little GB Of Madness"? Is anyone else actually working on theirs, or did they commit themselves just to make me feel better?


Seriously - I'd love to see folks' efforts. And if you happen to know of a vacform kit of the CAC Woomera (or, in fact, the NKR Resins kit) please get in touch with me when practical. Cheers.

[Alvis 3.1]

I've successfully used a scrap piece of plexiglas sheet for over 20 years, with the wetNdry sandpaper attached with contact cement. Most plastic shops have a scrap plastic department from end cuts etc, and they are pretty cheap. I think my piece is about 1/4" thick.


HTH


Alvis 3.1

[Nigel Bunker]

I just use an offcut of a piece of pine shelving, with wet and dry taped to it. When I finish, I rinse it down and let it dry. Hasn't warpes in the 12 years I've been using it.

Mind you, for big vacforms like 72nd scale VC-10 and Nimrod, I used a Bosch sander mounted upside down in a Black and Decker Workmate. The mouldings are big enough so that if you keep the piece moving so the plastic doesn't get too hot, you can sand dry. Definitley not recommended for wet and dry sanding!

[RotorheadTX]

1) My work-desk is one of those cheap Melamine-laminate drafting (draughting??) tables - it's reasonably flat, and I've just taped a sheet of wet-n-dry to it. It works fairly  well, but I have to agree with Jennings - after separating my Dragonfly fuselage halves from the backing sheet, it still needed a lot of hand-sanding to even things up. It still isn't perfect, but it's not too shabby for my first serious go at a vac-form.

2) Progress report: the kit templates for the cockpit bulkheads and deck were much too small, so I've fabricated new ones, and assembled and painted them. I've primed some of the white metal bits, and will be finishing up the cockpit this weekend. Yesterday I found a killer photo showing an R-5A with the engine compartment open, and some of the fuselage skinning removed, so now I'm considering going overboard on the AMS...
(I've secured 3 copies of the kit now, so I have plenty of room for errors.  :dum: )

[noxioux]

I have a big, thick piece of tempered glass that I set on my wal-mart card table.  I'ts nice and flat, impervious to just about everything short of a hammer, and it's easy to clean up, too.  A good heavy piece of glass would be perfect for vac-form sanding.  Even if you were wet-sanding.

I got my big piece of glass from the art department at a college.  They used it in the printmaking lab for lithography and whatnot.