Hi there. I've been wanting to try scratchbuilding for a while, and finally decided to build a small cabinet-workbench thingy. I used Tamiya pla plate 0.5 mm thick. I somehow got the feeling that this plastic bends and warps too easily. I don't know if the Evergreen stuff is different or what? The cabinet looks OK for a first time attempt. Measurements were a little off. What I did was design the thing using Corel Draw and printed it out on photo quality paper(I think this paper is too thick) then I cut the shapes out and taped them to the plastic with regular scotch tape and cut them out (Still didn't get the perfect edges I was hoping for). Anyway, did I go about this the correct way? And, which thicknesses do you guys use for your various projects? Wish I had a digi cam to show you the result. Thanks in advance.

My friend 5 thou card is thinner then most paper. the minimun I use for strength is at least 10thou if not 20 or 30 thou.

You have to understand that to get the strength required to support most things in plastic you have to ignore scale thinkness to a big degree.

If you want strength and thiness you will have to go to sheet brass in various thicknesses.

I don't know what they translate to in milimetres, but I tend to work mostly with 20 & 30 Thou (thousandths of an inch) card. Very often scale appearance has to be sacrificed for strength and rigidity. (just worked it out -20thou = 0.5mm).
For example I'd use that for the detail on the sides of a truck with 30thou (0.75 mm) for the body sides themselves, and 40thou (1.0mm) for the floor.

Cliff... Like Dave said, the 0.5 mm is 20 thou in inches. Sorry but I'm used to the metric system. Like I said, the cabinet is holding together well. I just felt like the plastic was bending in my fingers! I guess it's the lack of experience. But did I generally use a good practical way of going about it, or do you suggest a better way?

For thinner stuff yes it is. For thicker stuff a steel straight edge and a sharpe knife or scoring blade is better. You have to often sand the edges as well.

I did know that 40 thou = 1mm but most of my ordering (from America) has to be done in thou so I work both ways.

and sorry I misunderstood the thickness you used. On 1/2 mm stuff and bigger I use a straight edge and knife.

Stay with your scale thickness if it's holding up after assembly. .5mm is pretty thick compared to .005 in. which is still very workable. I've found that some joints are better suited for liquid cement, some for CA glue. If you overlap the .005 (and I know you're using .5mm) the plastic sometimes dimples, or even dissolves. I like to use the CA in those situations.
What material do your cabinets represent? A cool trick for wood is to forcefully drag a piece of sandpaper down the plastic while wiggling it a little. It makes great wood grain.

My thoughts:

Get a small metal triangle & a small metal "square" (L-shape) & a small metal rule. Those will improve your corners & edges tremendously.

Find how you best cut consistently. After practice, I cut best from upper left to lower right at about a 45-degree angle. I also lean over the work to ensure my knife stays close & square to the metal edge.

Next, look at ways to build in stiffeners in out of sight corners & whatnot and you'll find you can build a good object of very thin sheet/strip. Only worry about scale thickness where it can be seen. Having a good supply of Evergreen strip & shapes makes this easy to do.

John (who still has to sand & trim & rebuild collapsed structures, but not as much as before ....)

John... Thanks, that's some good practical advice. That's the kind of thing I'm looking for. Which type of blade is best for cutting? Is taping the paper shapes to the plastic with scotch tape a good idea, or is there a better way? That type of thing. Thanks again.

I always start with one edge of the sheet as the standard to work from, if ther is any doubt about it being straight, I "qualify" it by recutting with a straightedge. I have found sheets fresh from the package that were not square, so I picked up this habit of checking everything back to this edge.
As far as the cutting goes, I use a fresh #11 blade. It is best to make a light pass first, then follow up with a little more pressure. This is often enough if scribing fairly thin stock, just grasp it firmly on both sides of the line and flex it to snap it into two pieces. For heavier stock or those situations where you need to cut all the way through, simply make more passes.
When building a box or similar structure, I often cut pieces of styrene strip a little shorter than the join and glue them on the inside to help keep things square.
Taping the patterns to the plastic is a good way to go. I try to cut the pattern out of the paper just outside the lines, then tape it to the plastic all the way around. This way I am left with the pattern in place and don't have to try to worry about re-aligning it if I cut through the tape.
To mark a line for cutting, I measure the proper distance, then use my X-Acto to make a small mark (it's much more precise than a pencil.) Do the same at the other end. If you have trouble seeing them, simply rub a pencil across them. When you are ready to cut, place the blade in one of the marks, gently snug your straightedge up to it, move to the other end and do the same, then scribe between the two points. I have found this to be the technique that works best for me.
When making multiples of the same part, cut them out, then clamp them together prior to sanding the edges. This will ensure that they are all the same, and help keep things square.

Hope this has been of some help,
Jim

Jim... Thanks a lot. You've given me several good ideas. Extremely helpful.