Plasticard working tips?

[ge_rik]

Rik, I'm sorry to see the damage to your loco after using Evostik, however, I think it may be because it has not been used as an impact adhesive in your instance.  If thin layers are applied it goes off quite quickly before causing such devastation, but if it is poured in it will have time to react with the Plasticard before setting.
 My first choice would have been two part epoxy resin.  
It may be possible to repair your damaged loco with Milliput so not all is lost!

Hi Peter
Yes, I'm afraid I poured it in - lesson learned the hard way. For the smokebox, I did indeed use filler (white putty) but figured the boiler would be difficult to sand unless I dismantled the loco - which was not really an option. So I smoothed it down as much as I could and then cut some thin brass shim. I don't think anyone would notice the repair unless they looked hard.



Rik

[Peter Butler]

Well done Rik, I'm glad you were able to salvage your loco. It's so disappointing to see it go pear shaped after all your effort but satisfying when you can restore it again.

[steampig]

... I did indeed use filler (white putty) ..

Sounds useful stuff - I'm guessing it's not the linseed oil mix for holding glass in windows. Modeller's special? Car body filler? What should I ask for?
I'm beginning to feel there's an introductory book on this whole subject I should have read.

[GTB]

I'm beginning to feel there's an introductory book on this whole subject I should have read.

Not sure which white putty Rik uses, but my filler of choice for polystyrene is Squadron White Putty, available from the better purveyors of plastic kits in Oz. There is also a green version that some prefer.

Any shop that caters to plastic kit builders will have some form of body filler in a tube, some are better than others. I used to use Tamiya's version which is grey, before I found a source of the Squadron product.

The model railway magazines have articles from time to time on the basics of working with polystyrene. I'd be very surprised if there aren't any websites about working with the stuff. A quick google search 'working with plasticard sheet' turned up videos, blogs, etc. etc.

Slaters have a very basic guide here.....

https://slatersplastikard.com/assets/pdfs/userGuide.pdf

The book published by Evergreen Scale Models is the only comprehensive guide still in print that I've seen around. No idea how easy it is to get in the UK.

http://www.evergreenscalemodels.com/Book.htm

Graeme

[ge_rik]

Not sure which white putty Rik uses, but my filler of choice for polystyrene is Squadron White Putty, available from the better purveyors of plastic kits in Oz. There is also a green version that some prefer.
Graeme

Yep, Graeme, that's the stuff I use. I had a couple of bad experiences with Revell filler which seems to have about the same adhesive properties on plastic as biscuit crumbs. Not tried the green version.

Here's the finished loco btw - I probably could have got away with a less smooth finish to the boiler as it's largely hidden by the sandbox - but I would have known it was there!


Here's the same area just before the primer was rubbed down.


I hate close-ups pf my builds - too many warts!

Rik

[Peter Butler]

There is a product called 'Green Stuff' which is used by the wargaming fraternity, and we know how detailed their models can be!
I have never used it but have heard good reports from others.
Type in to Google.... Green Stuff... and all will be revealed.

[ge_rik]

There is a product called 'Green Stuff' which is used by the wargaming fraternity, and we know how detailed their models can be!

I've used Green Stuff in a limited way to modify figures (a la Wargaming). Mostly I've added hats or lengthened dresses/skirts to make bought models more appropriate for the 1930s - eg


I think it's an epoxy putty - two parts (yellow and blue) are cut off a strip and mixed together.

Rik

[GTB]

There is a product called 'Green Stuff' which is used by the wargaming fraternity.

Haven't seen that one around out here, but I use Milliput epoxy putty sometimes, which is much the same thing.

I mainly use it for filling large gaps, such as when I drill a hole in the wrong place and have to move it. I've also used it to build up parts that have chunks missing. I've even used it to add counterweights to spoked wheels on one of the steam locos. It has a longer working time than the epoxy putties you find in the local hardware store.

Graeme

[GTB]

I had a couple of bad experiences with Revell filler which seems to have about the same adhesive properties on plastic as biscuit crumbs.

Another one to avoid is Testors contour putty. It tends to separate in the tube into a liquid with suspended solid bits........

Graeme

[philipy]

I've used the 'Green Stuff' occasionally, no real probs with it. Got mine on ebay!

[steampig]

but I use Milliput epoxy putty sometimes, which is much the same thing.

Got Milliput, both black and original dirty green on my shelf. I have used it to 'cast' pieces by pressing it into siligum moulds (greatest success was a replacement screw-on pressure-release stopper for a plastic petrol scan that had split and so leaked fumes; the set Milliput seems to be impervious to petrol).

What sort of adhesion do you get to what materials?

Today I tried to assemble 1.5mm version of the cylinder. I learned

1) The only way to get a right-angled butt-joint accurate is to file the edge to be butted square. In this thickness a score & crack edge is too out of true to be persuaded in the welding, and also leads to dimensional error

2) Roughing the other part of the join, the flat surface of the HIPS face, greatly speeds and improves the welding process

3) I really need a jig to assemble these things on - fingers and lining-up onto various right-angles in mitre-boxes etc. don't hack it, and sooner or later a joint leaks and the visible surface you are trying to preserve the finish on gets damaged. If I were making 20 of the things the jig (and mass-producing squared up parts) would be the way to go. As I only want one to get the loco running I think it's time to stop, possibly sand and fill, & paint.

[ge_rik]

What sort of adhesion do you get to what materials?

My experience with Green Stuff is that it bonds to resin, styrene and whitemetal very strongly. Not yet used it with other materials.

Rik

[GTB]

What sort of adhesion do you get to what materials?

Milliput and 'Green Stuff' are epoxies, so they will adhere to the same range of materials as Araldite. ie. metals, wood, glass, resin castings and some plastics, but adhesion will be low to things like polyethylene, polypropylene, Teflon and acetals like Delrin. I've also used it to repair old bakelite mouldings.

Sounds like you are getting the hang of working with polystyrene.

I can't remember the last time I used a jig for glueing polystyrene. A joint made with MEK only takes a few seconds to harden enough to support itself. I usually just hold the parts together and run the brush down the joint, wait a bit and let go.

The trick is to make sure the line of the joint is a good fit and not in contact with anything. Capillary action will take solvent through the joint and that's when you find the part is glued to either the benchtop, or your fingers. If the joint is pointing at fresh air, all you should see on the outside of the joint is a shiny line, that disappears as the solvent evapourates.

Graeme

[steampig]

Yes I had under-estimated how accurate a joint had to be to achieve a successful weld - my previous experience had been welding broken pieces back together, and if the plastic hadn't distorted in the break (some don't), it happens naturally. I'm wondering whether trapping some HIPS dust in a made-up joint before flowing in solvent might help to fill residual voids and improve the weld.

The problem that a jig would solve is that I am attempting to assemble parts that are generally no larger than my finger tips, so even if I get them correctly aligned, visibility and solvent-brush access are poor! There's a 105/75 degree joint that's a particular pain.

In fact, construction of the part needs re-engineering (to achieve the same external outline) to be HIPS friendly, rather than just slavishly copying the injection-moulding  construction as I have been doing. It's not as if I want to pretend the part is an original, just have something that gets the job done and doesn't look glaringly out of place to a casual glance, and a bit more durable than just painting the original cardboard mock-up black.

Time to get out the siligum and make a mould for a batch of the buffer-plate lamps (usually missing from these Faller locos by the time I receive their remains) out of Milliput - I'll see how it sticks to HIPS and whatever the 1mm stuff is. My problem is I only ever use tiny quantities of both materials at a time, but there's a practical minimum to the amount you can prepare and still get a reasonable 50/50 mix of the components. Being mean as stink I hate waste, particularly of the very expensive siligum.

[steampig]

Almost no adhesion of Milliput to the 1.5mm HIPS or the mystery 1mm sheet - this is not the filler I am looking for.

Made a couple of Milliput lamps using a siligum mould taken from a pair of originals - not too bad. I need to make 4 more lamps to give all the locos I have hanging around a full set.

[Peter Butler]

Perhaps it would help if the plastic surface was scratched with the knife point or abraded with sandpaper to give it a key?
Sorry if you have already thought of this..... just ignore me!

[steampig]

The plastic was smooth this time as I wanted to simulate a repair I was contemplating (and will not now attempt). I'll rough it up some for the next Milliput mixing and see what happens.