Other Paper Products

[justme]

Hello,
Whilst taking a coffee break from my Kormoran project (coming along nicely - all decks, formers and frames are cut and they fit (nearly!:)) I was reading an article about resin moulding and I was reminded that back in the forties, toy soldiers commercially made by moulding a shredded cardboard and glue mix were on sale in toy shops. It raised a question in my mind as to why this technique is not used commercially today. The advances in moulding techniques and binders should surely making it viable for a range of paper accessories to be made from a shredded paper and glue mix. Material costs would be minimal once the masters have been made and the moulds would have very long life as they would not be damaged by the moulded items. Some examples immediately spring to mind : Nose cones, wheels, air intake lips, drop tanks, bombs and wingtips etc for aircraft, blast bags, capstans, watertight doors, bollards, paravanes, depth charges , torpedoes etc for warships. Many similar objects for other subjects could be made and I am sure that they would sell in worthwhile quantities as sometimes making these sort of items from sheet carton/paper does not always yield good results and can be very frustrating.
(I am not talking about the Superman type modellers whose stunning work can be seen on this forum - who I am sure could make a 1/50th scale Titanic from bales of old newspapers!:))
Just a thought.
VBR
jm

[jagolden01]

Good thought, JM.

As a side, have you seen Ken Tyler's Panzer build that's in progress. He's using a moulding technique on the road wheels and track links of his build.

Never seen this done on this scale before and the results are quite nice. I think it's given many builders food for thought, just like what you've mentioned.

Joe

[rickstef]

When I started reading this topic, I remembered that Gil has provided quite some electrons on this subject

The following three links were quickly gleaned from Gil's thread list.
http://www.papermodelers.com/forum/tutorials/1948-art-paper-casting-card-modeling.html
http://www.papermodelers.com/forum/design-threads/2290-experimental-shell-forming-technique.html
http://www.papermodelers.com/forum/tips-tricks/1930-paper-casting.html


There maybe more, but this might provide a start

[Tex]

Howdy y'all!
Well .. one of the major problems here is shrinkage. When the "pulp" dries, it shrinks as the water (or whatever) evaporates, and that shrinkage is real hard to calculate, making this method right hard to use for parts of scale models. With toy soldiers, it doesn't really matter so much if they stand 5'9" or 6'4" in real life, but for scale model parts, you'll want precision, and I'm afraid this method may not produce the exact measurements.
Just my two pence worth ... and maybe, hopefully (?), I'm wrong ...
- Tex

[EvilTessmacher]

Tex, you're right on with the shrinkage factor. It is practically impossible to calculate without some hydrodynamics calculations that are so far above my head I can't even see the bottom. Then again, I sometimes can't pour glue out of a bottle when the instructions are written on the bottom... Having said that, I have a friend who has a relative who makes gimcracks for architectural students, who did some paper-pulp molded items, but he stopped selling them because they ended up being so fragile, it was not cost-effective to produce and sell for what he had to have in them.

He ended up buying a 3D printer with some of those super-tiny nozzles, and makes all sorts of tiny little things for sale. I don't know the name of his shop, but he's on the west coast somewhere.

It would seem to me to be better suited to find someone who has one of those 3D printers, and have them do your gimcracks.

[justme]

Hello Rickstef,
Thank you very much for that.
I was not aware of these.
See and ye shall find - ask and ye shall be given!:)
(I am going to try and make some Paravanes and Orepesa Floats in due course.)
Hello Tex,
Thanks. Yes, shrinkage would be a factor but could it be be controlled by mixture thickness? and I think that for the common scales of warship models any shrinkage could be rectified by an extra coat or two of paint.
Hello EvilT,
Thanks. Maybe you could suggest to your relative to mention this topic to the chap that is making small items from a 3D printer?
It could be feasible and maybe a possible business opening for him.
Hello, JG,
Thanks for that. I must have a look at this thread.

Another suggestion - Card embossing tool to form this type of water-tight door?
201448
(The door - note the rounded corners - is 16mm x 7mm while the strengthening squares are 4mm x 3mm. )

Now back to the Kormoran!
jm

[John Wagenseil]

The old time pattern makers (19th c.) in metal shops had to deal with shrinkage. I am pretty sure they did not have a set of complex formulas, but used seat of the pants intuition and empirical tables to help them size their patterns.
Also after the casting was made, the surfaces that had to meet specifications were machined.
I think the dimension changes when molded paper pulp dries might be taken into account by making some rough tables showing estimated shrinkage for a given dry paper pulp to water ratio.
Also has anyone tried substituting alcohol for water when molding paper to see if this might reduce dImension changes when the molded object dries?
Also press forming of glue coated, only slightly damp paper, building up an object layer by layer, using little extra water as possible might a way of building up an accurately dimensioned object.

[Tex]

Howdy y'all once again!
I'm afraid shrinkage will remain a problem no matter what kind of solvent y'all might use, and I'm not sure it's possible to dissolve paper, and be it the cheapest gray toilet paper, in alcohol.
A couple of years back, I had my good ol' car welded, and the seam received a good treatment with body filler. Now, nigh on a coon's age later, you can see where exactly the seam is, due to shrinkage of the (cellulose thinner-based) body filler ...
The next problem might be to find some kind of glue that's alcohol-based; I wouldn't know of any, but that doesn't mean a thing.
Yet another problem might arise with the choice of material for the mold. As far as I know, the paper pulp needs to be pressed into the mold, if just gently; a mold made of silicone rubber might be too soft, or, if inflexible enough, too big, and thus, costly, while a plaster mold will not release the paper part unless the surface is somehow treated ... and plaster, depending on the size and shape of the part to be cast, might break. For a multi-part mold, a mix of stearin or paraffin (from candles) and talcum powder might work; given the right mixture, it's tough enough not to break, can be used several times, is inexpensive and easy to obtain ... but it can't be used with anything alcohol-based (or using any other (?) chemical solvent), nor is exposing it to anything above room temperature necessarily a good idea. And, of course, when you've cast the mold, the stuff will shrink considerably (and uncontrollably), too!
Asides, when casting a multi-part mold (two parts at least for most purposes), I wouldn't know what kind of release agent to use; most of the ones I know are (somehow) wax-based - and wouldn't work with that mixture!
Unless y'all love long-term experiments, coming up with empiric charts showing average shrinkage is going to be a tedious, messy affair, I'm afraid.
I'll keep thinking all this over, no doubt, since I'm still convinced that it's basically a great idea!
So much for my two cents worth ...
Good luck, y'all!
- Tex