Removing fragile teeny tiny plastic parts from sprues.

Model Railroader General Discussion (Model Railroader)
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I learned something while assembling a stock car kit this week. In the past, I had trouble removing fragile parts from sprues. The smaller the part, the more likely I would break them as I removed then from the sprues. Any method I tried could still break the parts.

The kit I built this week was Mather Single Deck Stock Car made by Proto 2000 before Walthers bought Life Like. Before assmbling the kit, I read the directions.

What? Read the directions? Who does that? When all else fails, read the directions.

Anyhow, they explained two ways to remove parts from sprues. The first method is simply to use a new single edge razor blade. Nothing new to me.

The second method is why I am posting this thread.

They said to use a sharp hobby blade such as X-acto #11. They also said to heat the blade. … That was new to me.

Before, I never heated the blades before cutting parts from sprues.

I placed a hot soldering iron in its holder next to where I was cutting parts from the sprues. I heated the #11 blade. It made a big difference.

I experimented a bit. I found I could easily cut through the gates. ( Gates are plastic material connecting the part with the sprue.) It became even easier as I learned to hold the hot iiron against the blade as I sliced through the gate.

I did not break the parts. The gates sliced almost like butter.

There is more to the story regarding building my kit. I installed all of the brake rigging detail parts without breaking them. However, the itty bitty grab irons were still too fragile. I broke some of them inserting them into the holes in the car body. I tried drilling larger holes for a few of the grab irons, but I was still breaking them. I gave up on the plastic grab irons, and made some out of brass wire which if course required painting.

Now I am pleased with the final result. (The GN stock car coup

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Looks good!

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Garry,

Not to shut down You’re delightful experience…but I learned that back in the 50’s when playing with a wood burning set…soldering iron type holder with interchangeable tips, a knife blade similar to a xacto#11 was one of them…learned a lot of trick’s when I built wood ship models. As a matter of fact…I still use it to cut out doors on plastic buildings kits, so you can glue the door open without damaging the part you cut the door out of.

Have A Good One! [:D]

Nice car Btw. [Y]

Frank

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Dean … Thanks for the remark.

Frank … I figured some of you guys already knew about this idea, but I suspect many forum members do not know of it.

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Usually, something like fragile grabs…I always have a plan B…brass replacements.

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My experience has shown that double edge blades are even sharper and have a thinner cross section. Wrap the extra edge with tape to protect your fingers.

Charlie

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Garry: Thanks for the tip! I’ve been modeling in N scale for 40 years and never heard that before. Now I just have to remembe it when the time comes.

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Charlie: Another great tip! I recently switched back to a “safety razor” for shaving, so now have double edge blades in the house. (I’ll use fresh ones for both shaving and modeling).

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I got me one of those sprue nippers similar to the kind sold by PBL or Micromark. Works like a charm with those tiny parts. No heat needed. Was just using it this afternoon working on a kit.

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I second the comment on the sprue nipper…great little tool! In liu of one you could try a nail clipper

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The sprue nipper I have works a bit like a nail clipper, but it has one end that dips down into a sharp point, that allows it to fit in between the tiny gate and the tiny part so it can snip them clean off. The thing really revolutionizes and if it is even possible, makes the stage of getting all the parts of the sprue to be fun, and certainly a very minimal chore.

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Everybody.

Thanks for your thoughts. I sometimes use rail cutters which works okay for larger parts. I don’t have a sprue cutter.

Regarding the #11 blades and other hobby knife blades. I keep them sharp with a sharpening stone. Likewise for my single edge razer blades.

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Recently I had to make a cut on a fragile item and just heated on old exacto blade with a Bic type lighter. It made the cut so easy, like cutting soft butter, it was eye opening. For a cheap proof of concept on hot cutting you should give it a try.

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Like Garry mentioned, the rail nippers (I have a Xuron pair) work great for large sprues which are too thick for my tweezer style sprue nippers. (warning: never use Xuron railnippers to cut any metal other than rail, as it can damage them - plastic, being much softer than NS rail is ok).

Heating a blade makes total sense, although I prefer to use heat only when necessary such as soldering or hot glue, for safety purposes - so the sprue nippers are a little safer in that regard as no heat is required. Mine cost about $16 but as in some cases, some tools are really worth the investment, like a cordless drill as another example.

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I tend toward the tweezer-style sprue cutter, with flush-cutting rail nippers for bigger sprues, but that’s not the main topic of this post.

What I did want to mention is a tip I read on this forum sometime ago, and which I haven’t fully tried (but will on the next kit), which is to (if possible) tape the small detail parts with low-tack tape, so when you snip them off the sprue they won’t disappear into the n-ܐ dimension, but can be retrieved off the tape with tweezers. My first test of this was inconclusive (since the detail parts in question were sizable enough they wouldn’t have gotten lost in the first place), but the next kit has enough fine detail parts with “springy” characteristics where hopefully this system works as advertised.

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All good examples, one note regardless of the type cutting, especially sprue cutters or varios blades, cut the entire part away from the sprue leaving a portion/ gate attached. Then use your perfered method. This is especially true for quite intricate or longer fragile pieces (brake, air lines and brake rigging) The small force as you cut can force on the next gate if still attached and cause a break elsewhere of the piece.

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bogp40,

Agree with you 100% on whittling down around a part. I typically use Xuron (and Tamiya) micro sprue cutters to start to cut thick sprue around a delicate piece. This gives me the access to come in with my PBL extra fine tipped tweezer nippers to cut the gates to finally free the piece. This cut is so fine and close that there is no need to dress it. Too bad PBL no longer stocks these Swiss-made tools. I treat mine like gold. [swg]

Joel