Proto hopper question

Model Railroader General Discussion (Model Railroader)
1

I recently purchased about six Proto 2000 hoppers from the LHS ,its last day is this Sat. : ( , any way the hopper has all of these incredibly small parts . I broke several trying to remove them from the spruce ? Is there a way to remove these with out breaking the fine parts. I tried using a carpet blade and an exacto blade. I had more success with the exacto knife but still broke the brake line. Look forward to your suggestions. Thanks.

2

You need a sprue cutter, a special tool that looks like a small pair of wire cutters but is made specifically for cutting plastic parts off of the sprue.

If you do purchase a pair of sprue cutters, don’t ever use them for anything else such as trying to cut wire with them, or you will nick the blades.

You could also try using a single-edged razor blade if you can’t find sprue cutters.

Here’s what the sprue cutters look like: http://www.hobbylinc.com/htm/tes/tes50628c.htm

3

I am not sure of the size of the parts you are working with, but I am assembling a Branchline HO Blueprint Series car, which I have 3 more after I finish this one and I ran into a similar issue. I purchased a Despruing Tweezer from Micromark (http://www.ares-server.com/Ares/Ares.asp?MerchantID=RET01229&Action=Catalog&Type=Product&ID=82393A) that has made the process much easier.

4

I use a small fingernail clipper.

5

I haven’t had any trouble with the P2K hoppers which I think are brilliant but the Roundhouse 50’ tanktrain tank cars are diabolical. The only way to get any of the parts of these out of the sprue is by using a heated scalpel blade. This is slow, fiddly and annoying… but if i take enough time I can get the bits out without them disintegrating.

There are tricks to using a heated scalpel…

  • it doesn’t have to be sharp but some sharpness is useful
  • the scalpel blade must be held very tight in a metal holder.
  • A plastic scalpel holder will melt (or catch fire) before the blade is hot enough to work the sprue.
  • Hot blade cutting means you have a hot blade… this will melt or burn anything you touch wth it… including car bits and fingers… and the dining room table/kitchen work top/any paper you have around/the box the model is in… and much more.
  • If it drops let it drop… don’t try and catch it… it will go a long way airborne…
  • don’t change the blade while it’s hot!
  • How hot varies a bit with the thickness of the sprue being cut though.
  • Practice on other bits of sprue before you go for the part you want to release.
  • If the blade is getting a residue of plastic/gundge on it scrape it off onto something metal with metal… don’t burn or cut your fingers.
  • If the plastic is really nasty you may find your blades get messed up pretty fast. Burning the mess off cleans the blade but usually softens the metal making it useless. It’s better to change the blade more often.
  • The hot blade should slide like the proverbial “knife though butter” but not set fre to the plastic.
  • If the cut slows down or begins to receive more resitance back the blade out fast… it’s too cold and/or the plastic is too thick… you do not want to force it or have the blade end up stuck in the cut… both will end up with a broken part most times.
  • Don&
6

Jerry,

If it makes you feel any better, I had the same problem when I started building P2K kits, too.

For removing parts from sprues, I’ve found that a pair of flush-(vs. flesh-) cutting nippers are a real help. Another way to go about it is to use a sharp #11 or beveled X-acto blade and a small piece of 1 x 2 - about 3" long.

The problem you are running into, Jerry, is that your sprue is considerably larger in diameter than the pieces you are trying to cut. When you press down with a blade to cut the piece, the pieces have to flex quite a bit before they make contact with the surface you have it braced on. In turn, the pieces end up breaking before they are cut through cleanly.

If you use the corner of a 1 x 2 to support that portion of the part underneath, your part doesn’t flex and you can cut it clean with your sharp blade. Does that make sense?

Most of the time I end up using the flush-cutting nippers. However, there are those occasions that the nippers just can’t quite get into those tight spots that I need to use the method above to remove the tiny parts from the sprues.

The other thing to remember when putting together these kinds of intricate kits: Take your time!

Hope that helps…

Tom

7

Finger nail clippers work, or if you have a Radio Shack near by…

http://www.radioshack.com/product/index.jsp?productId=2104641&cp=2032058.2032236.2032310&allCount=18&fbn=Type%2FCrimpers%26%23044%3B+Strippers%26%23044%3B+Nibblers&f=PAD%2FProduct+Type%2FCrimpers%26%23044%3B+Strippers%26%23044%3B+Nibblers&fbc=1&parentPage=family

8

I can endorse the despruing tweezer as shown in the micromark webpage. PBL also makes something almost the same. I bought my despruing tool at a train show for $16 - same exact thing. I believe these are what the chinese model assemblers use over seas who make the RTR cars from parts.

Anything other than the above despruing tool will get you worse results I guarantee you. Ever since I bought my despruing tool (tweezers) just like the micromark one, I have found it a cinch to remove those tiny teeny parts that come in Proto 2000 or Intermountain kits. You will almost never break a part after you start using them and if you are careful, you won’t need to trim or file any parts either. The despruing tool will cut the part off the sprue so nicely you can see almost no evidence of where it was attached!

Do yourself a favor and get a set of reamers too. They are like tiny needle files that you can put in the part holes and spin them around to ream the whole a little bigger so the part will actually insert in to glue it.

9

THANKS !

10

THANKS , I will love the idea of using the piece of 1x2,good suggestion. I will employee this .

11

I am going to purchase one of these. Thanks for the suggestion. Do you have any suggestions on fastening these parts in ? I have tried several methods. The most succesful is the use of a needle dipped into the glue and then applying the tip to the hole. However that still leaves excess around the hole.Very frustrating.

12

Jerry,

For applying thin or watery plastic adhesive to tiny areas, a very small modeling brush - e.g. a #5/0 or #10/0 - works very well for this purpose. Just make sure you designate it for that job and that job only. Your LHS might have them in stock. They can also be found in art supply stores or craft stores, like Michael’s.

Tom

13

De-spruing tweezers work the best as stated, but you can also use double-edged razor blades. Just tape one side the use the other, saw like across sprue area, the thinness of these blades have more flex, so pieces don’t brake.

For gluing, just use a finer piece of wire, I use a scrap of .008 brass, just dip into a puddle of glue and drop and drag in hole, there’s very little excess. You will have to clean wire end once it gets to thick from dried glue. mike h.

14

Tom , any particular glue you recommend ? What do you cut it with ?

15

Which glue do you use ?

16

Jerry,

I use Testors Plastic cement:

It comes with the applicator brush mounted in the lid but. The brush is fine for larger applications but not-so great for small holes and tiny areas. (That’s where the tiny brush comes in handy.) There are other similar brands (e.g. Plastruct and Ambroid) that are equally as good.

This type of cement is terrific for two reasons:

  1. It’s “wicking” abilities - i.e. since it’s thin, it seeps into tiny cracks and seams.
  2. It “melts” the outer layer of the plastic and “melds” the two pieces together for a stronger bond. That’s why when you are bonding two pieces plastic together, to apply a thin layer of the cement to both pieces.

Since this particular cement is runny, the key is to not apply too much. Otherwise, you can have an ugly mess on your hands (…and model.)

Hope that helps…

Tom

17

Appreciate the advice and tips.Where have you found Plastruct and Ambroid ?

18

I don’t know the “glues” recomended or if what I use would be available in the US…

Here we cabn get “MEK” cement at most larger shows from the regular traders. It’s basically polystyrene sheet solvent so that it just melts the plastic it comes in contact with. When two pieces of plastic melt next to each other and then the solvent evaporates you end up with the two parts welded together… evn if you didn’t mean to…

The stuff probably comes with all sorts of warnings these days.

I buy big bottles and decant… partly because of health and safety and you can lose the stuff to atmosphere… which isn’t good for you. Even with small amounts I try to locate the container securely… because a spill will melt things not just goo the surface. I also keep the lid on as much as possible.

A very fine brush is good for most work. you can also use a wood (not plastic!) toothpick.

[8D]

19

Dave,

I think that MEK is the basic ingredient in any of the plastic cements commercially available.

Tom