Lesson 2: Cutting Out Pieces and Removing Nubs



Sprues are a necessary part of the injection mold process for model kits, but removing your kit's pieces from it can be a pain. However it pays off in the end, as nothing makes a kit look bad, especially after painting, like leftover bits from the sprue (usually called nubs). The techniques I use tend to get the nub flush while avoiding damaging the part itself.

Don't Be This Person

 

First, use a pair of side cutters (also called nippers or clippers) to cut off the piece leaving as much of the sprue attached as possible to it.

Cut Here

Then cut bits of the sprue off bit by bit until you reach the point where the sprue narrows. Then you use a hobby knife to shave off bits of the sprue until it would be possible you might accidentally cut into the piece. Try to make sure you cut downwards with the knife toward the desk. Don't cut toward yourself unless you want your workspace to look like a shrine to a dark god. The reason you cut like this is because plastic is a fibrous substance at the cellular level, and any major cut will bend and snap it, leaving stress marks in the plastic that's left, which can show up even after painting.

After that,  take some sandpaper and sand what's left of the nub down until it's smooth. I use 400 grit sandpaper, which I would put as the minimum grit for modeling. Anything lower than that and you'll star to scratch up the rest of the piece. 400 grit is usually listed as "ultra fine grit" or "super fine grit," but these are lying to you. Those descriptions are meant for woodwork, which needs rougher material. 400 grit should be very cheap at Lowe's, Home Depot, or maybe even Wal-Mart. You might need some higher grit sandpaper if you end up accidentally getting some deeper scratches in the piece. I use 1000 grain sandpaper buff out scratches, and you'll more than likely need to order that on Amazon.

 Finally, test for smoothness with the single most precise instrument in your arsenal: your finger. If you can't feel much of a difference between where the nub was and the rest you've done it (bonus points if you can't figure out where they were to begin with)! Now that you're feeling proud it's time to do the same thing with the other 175-ish components of an average High Grade gundam kit.