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Dealing with Seams

Fixing these problems
Now that we have some idea of what the most common problems are lets figure out what to do about them. The first thing I’d like to stress is having the proper supplies to deal with these problems. The most important thing you’ll need is a good assortment of wet or dry sandpaper. This is easily purchased at a local auto supply shop. An assortment of surfaces from 220 grit to 600 grit will deal with most sanding needs. A set of small hobby files.

These files come in assorted cross-sections, flat, triangular half round and round. Modeling putty. These are made with solvents that will partly melt, and bind with the plastic. I like to use an artist’s spatula to apply putty.

The best way to remove ejector pin marks from along a joint is by sanding or filing them flush. Care must be taken not to remove too much plastic, as that will cause a gap in the joint that will require filler. The object is to get the best joint possible without the use of putty/filler.

Miss-aligned locators are a problem because the only way to fix it is to remove them. Cut the locator pins of the joint and sand smooth by laying a sheet of sandpaper on a flat surface and rubbing the joint over it in a figure 8 pattern. Again don’t sand too much! Stop and check frequently. Dry fit the parts together often to check the fit. It doesn’t hurt to give the side with the alignment holes a go on the sandpaper either. This is an alternative way to remove ejector pin marks also. Remember, sand lightly and as little as is needed to ensure the best-fit possible. Too much sanding can alter the cross section of the assembly.

The only way to fix warped parts is to cement the parts together a little at a time until they’re joined along the entire length. You can sometimes achieve success by warming the parts in hot water then bending them carefully into the correct shape. It’s been my experience that plastic has a “memory” and as it cools it regains its warp.