OK Wayne! Don’t rub it in![swg][(-D][(-D][(-D]
So, how do you do your corner joints?
Cheers!
Dave
Not especially square, obviously. [:-^][(-D][(-D] Perhaps I should get some of the corner clamps and make some repairs. [swg]
But to answer your question, I usually make square(-ish) corners using machinists’ and/or carpenters’ squares - solvent-type cement works pretty quickly, so there’s seldom any need to clamp stuff for long periods of time. I have a couple of machinists’ blocks - don’t know what number they might be, but they weigh about 3 1/2lbs. apiece - which are helpful for holding things in alignment. I build exclusively in styrene, and an easy way to create square corners is to cut some suitably-sized squares from fairly heavy sheet - .060" works for my purposes. I then bisect these into triangles, creating ready-to-use corner braces. For small structures, a full floor(s) does the same job, and if you need angled corners, simply cut the floor or bracing to suit. I usually back square corners with square strip material (.100" or .125") and angled corners with overlapping strips of .060" sheet material.
Another trick, useful for styrene kits where the corners are ill-fitting, leaving visible gaps at the joint, is to carefully sand the bevelled mating edges to an angle sharper than 45°. This will make the contact point of the walls only at their outer extremity. Coat the mating edges with solvent-type cement and allow them a few moments to soften, then recoat and bring the pieces together. This type of joint needs to be backed immediately with a length of heavy strip styrene, as it has almost no structural strength of its own. Where an already-assembled structure has visible gaps at the corners, fill them with styrene - suitably-sized strip material for large gaps - wet the gap area and the filler pieces with solvent and let them soften,
Waynemeister - Lot o’ great stuff in that for a guy like meself just embarking on my career in plastic civil engineering. I’m building an urban layout half downtown with abutting industrial area. I have 30 City Classic type buildings to assemble, and that’s only half what I’ll eventually need. Some great tips in your post. Thanks for taking the time to write all that.
Ditto!
Jim
What, you don’t have 73.57 degree corner clamps to make those angled structures? [(-D] [(-D] [(-D] [(-D]
–Randy
I have had a couple of Right Clamps for some time now, and use them a lot. One long and one original (short). You do have to be careful not to dump too much liquid glue into the joint, or it may wick out, get under the clamp, and mess up the surface. Another thing to look out for is any excess plastic on the inside of the joint. A couple of days ago, I was assembling a building that had a small rib on the inside of the joint. It was anly about 1/32", maybe less, but the joint would not square up because of it.
Another useful tool for squareing things up is a Toolmakers Angle Plate, also sold by MicroMark and others. I have two 1" plates. They are heavy enough to hold parts in place without clamping. If they get a bit of glue on them, I scrape it off with an X-Acto knife. They come in 1", 2’, and 3" sizes. This is the set of 3, but they are available separately as well. I would recommend getting two of the same size.
http://www.micromark.com/angle-plates-1-inch-and-2-inch-and-3-inch-set-of-3,7183.html
G - The picture in that link makes it look as though the inside angle is radiused . . . is it? If so, how do you mate two parts at a sharp 90 degree angle? That’s why I bought the extruded aluminum angle, and checked it with a square to be sure.
If the angle plates are used to square-up a structure, they’d need to be placed on the inside of the corners. The radiused interior corner could probably be milled-out, but if one opted to do so, it might be advantageous to cut even deeper and create a recessed area on either side of the corner - this would allow it to be used on the outside of the corners, and provide a space into which excess solvent cement could run, keeping it from marring the surface of the surrounding plastic.
Wayne
Looks to me like those things are cast and the outer faces machined after. Looking at the photo, the inner surfaces appear rough, and there is also that triangular brace that is cast into the piece. I think these blocks might be useful if used with that magnetic gluing jig that Micromark sells (http://www.micromark.com/magnetic-gluing-jig-10-1and4-inch-square,7038.html) as that item has the built in 90 degree outside corners where pieces to be joined can be placed.
They are likely cast as long bars, rough cut to length and then machined. They do not appear to be radiused on the inside corner.
I have the magnetic tray thing, and while I haven’t checked it with a machinist square, I’m not so sure on how accurate it is. The magnet pieces are actually two piece of sheet steel with a magnet in between - not permanently attached. Getting them to stand at 90 degrees to the base takes another tool to square them up. So far I’ve only used it where exact alignment wasn’t critical, or where the parts mated together well enough without an extra squaring device. I can’t imagine using it for critical assemblies.
–Randy
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