Frequently Asked Questions about Styrene
Frequently Asked Questions about Styrene
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A. Cutting straight lines freehand leads to a lot of things namely a lot of frustration, a lot of filing and a lot of gaps to fill. Even on a small project it is quicker and a lot easier to outfit your ruler or straight edge with an anti-slip backing. Rubberized cork is the best, but thin rubber sheets or very fine sand paper applied with rubber cement, or in a pinch, rubber cement alone are also good.
Q. How do I get square edges when I cut styrene? A. Correct cutting techniques help. Be sure the knife is perpendicular to the sheet when scribing. Then fold on the scribed line (scribed line up, fold down) and fold back until it snaps. Do not separate the pieces with a tearing motion. If the edge is still not square enough, place the sheet flat on the table with the edge to be squared projecting just over the table edge. Hold the knife vertical with blade upward and perpendicular to the edge of the styrene. Draw the knife along the edge. Watch the thin curls of styrene that are scraped off. When they are the full width of the edge of the sheet, the edge is flat. To use this technique to square one edge of narrow strips, first square the edge, then cut the strip off the parent piece.
Q. I hold the pieces together and apply solvent cement but the pieces don't stick or stick in only a few places. What am I doing wrong? A. The pieces may not be tightly together. A ridge left over from cutting may keep all but a tiny corner from touching - scrape off the ridge before gluing. Or the pieces may be meeting at an angle - scrape or file at that angle to create an area of contact rather than just a line of contact, or use a filled cement (tube glue.) Or the cut may be rough which is particularly troublesome when edge gluing - see the question on squaring up edges. The joint may not be getting enough solvent. On long joints, it can take many trips back to the bottle to carry enough solvent to the joint when you are using a small brush.
Q. I can't keep the whole piece lined up all at once so parts of it get glued on crooked. A. The great thing about solvent welding styrene is that you don't have to put glue on a long joint all at once. Just be sure the first few inches are properly aligned and add a little solvent. Wait a few seconds until the joint sets, then align the next section and glue it. Keep repeating until you get to the end of the joint. Don't forget to keep going back to the bottle for more solvent cement. This technique is actually a lot faster than trying to flood a long joint with solvent all at once, leads to better results, and is much easier on the nerves.
Q. I have trouble cutting square pieces square. Can you help? A. Either you square isn't square, or it is creeping while you
are cutting. If the latter, try scoring in more than one pass. Make the
first pass very light to avoid moving the square; subsequent passes can
be heavier as they will tend to follow the first pass. To find out if your
square is off, cut one edge of a sheet of styrene so that it is straight
and true. Then working from that fresh-cut edge, scribe a light line perpendicular
to it. Flip your square over* and scribe a second line right next to the
first. The two lines should be the same distance apart for their entire
length. If not, it is time for a new square.
Q. I try to glue things together at right angles but I always seem to be off a bit. A. The human eye is good at some things, poor at others. It is great at seeing if two pieces are in a line, good at telling vertical, fair at telling horizontal, and just plain lousy at measuring right angles. Using a mirror can compensate for the eyes' inefficiencies. Lay a piece of styrene flat on the mirror. Hold a second piece of styrene at about a right angle to the first piece. Look at the vertical piece edge on, and look at its image in the mirror. When the edge and its image are in line, the vertical piece is exactly at right angles to the mirror, and to the piece of styrene laying on it. A flat piece of glass is an excellent work surface for assembling styrene, and a piece of plate glass mirror is the best. In places where a mirror cannot be used, a small machinists square can be useful. No machinists square? Cut your own out of a scrap of styrene.
Q. I carefully glue the pieces together exactly square but when I get back after a day or two they are out of whack. Why and what do I do about it? A. Tube glue is bad for doing this. And when it is applied as a fillet, it is terrible. This is because tube glue shrinks as it dries and creates a lot of force while it is shrinking. Solvent cement is not nearly so bad as there is no glue filled space between the pieces being bonded. But edges that are a little off square or perhaps a bit more solvent on one side of the joint than on the other or relaxing the pressure on the joint too soon and letting it rebound can all lead to a solvent welded joint being off a little. Taping, clamping, or placing heavy blocks against the joint as it dries can all be used to prevent the angle from changing. Sometimes gussets can be added. These can be made quickly in large quantities by scribing squares on a sheet of styrene, then scribing diagonals both ways, and finally snapping apart all the triangles. For buildings, adding a ceiling and a floor is often a quick and easy way to keep them square. For access, the centre portion of the floor can be cut out, leaving only a rectangular ring.
Q. Why do some pieces that I have very carefully aligned move as the solvent cement dries? A. Sometimes we correct the alignment of pieces by moving them after the solvent has been applied. This can set up stresses in the styrene which tend to move the pieces back out of alignment. Using gussets or glue blocks as an aid to getting the alignment right the first time can lead to neater, stronger joints. Glue blocks need be nothing more than scraps of styrene solvent welded to one piece where the edge of a second piece is supposed to intersect it. Although they won't help in alignment, glue blocks are sometimes added after joining two pieces to strengthen the joint.
Q. How did you make those neat railings on your Saloon balcony?
Q. I have a questions about working with plastic that you haven't covered here. Who can I ask? A. Give us a try. If we don't have the answer, we may know somebody else who does.
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A. I drilled
3/32" holes every 1/4" along two pieces of 1/16" styrene cut 5/16" wide.
Then I countersunk the holes slightly on one side of each strip to make
it easier to insert spindles. I used the hard, rolled paper shafts of Q-tips
for the spindles of this indoor-only building, but 3/32" Evergreen styrene
tubing would have been a better choice for outdoors. I cut the spindles
1-1/4" long, then forced one end into one of the strips. After all the
spindles were inserted in one strip, I carefully aligned their other ends
with the holes in the second strip. I worked a few at a time and gently
tapped the strip home with a small hammer. Once they were all in place,
I brushed some Testors solvent cement along the strips to keep them there.
Then I added a 1/16" x 3/8" strip of styrene to the top as a hand rail
and a 1/16" x 5/16" strip to the bottom for more strength. These strips
nicely covered the ends of the spindles. In the photo, there are two pre
drilled strips and some spindles, plus an assembled railing. Note that
the hand rail and bottom strip are applied to only half of the railing
to show the ends of the spindles, which have been darkened to show up better
in the photo.