streaching sprue

john bange · Post by **john bange** » Sun Jun 25, 2006 9:25 pm

I have never done it and would like to try. Where do you get sprue? I guess before I ask where, I should ask what is sprue.
john

RNfanDan · Post by **RNfanDan** » Sun Jun 25, 2006 10:12 pm

John, sprue is the interconnecting plastic that the individual parts are attached to. It's basically any injection-molded plastic rod that isn't itself, a molded part. When you cut off say, an anchor the part you are cutting it from, is the sprue.

To stretch sprue, it must be heated until it's soft enough to be pulled (like taffy). Pulling sprue requires some practice, in order to learn how hot to get it, how far to stretch it, keeping it uniform (the hardest part, IMHO), and so forth.

I've stretched sprue for years, into rigging lines, gun barrels, derrick/crane cables, vent pipes, spreader booms, pikes, yardarms, flag and jack staffs, degaussing cables, prop shafts---just about any cylindrical part I can think of.

Post by **Timmy C** » Sun Jun 25, 2006 10:19 pm

Jim Baumann's article on such: http://www.modelwarships.com/features/h ... hering.htm

john bange · Post by **john bange** » Mon Jun 26, 2006 12:23 am

thanks guys, I will try it
john

les · Post by **les** » Mon Jun 26, 2006 10:03 am

John, be aware that all plastic doesn't stretch the same. If you find in a kit that is easy to stretch, keep it on hand as the next kit's sprue may not stretch as well.

john bange · Post by **john bange** » Mon Jun 26, 2006 12:02 pm

MAN! is this going to take some practice!!!!!!!!!

Francisco P. de Nanclares · Mon Jun 26, 2006 2:20 pm

You bet!

john bange · Post by **john bange** » Mon Jun 26, 2006 4:19 pm

may never learn how to do this right but at least I learned how to spell stretch

RNfanDan · Post by **RNfanDan** » Mon Jun 26, 2006 5:27 pm

john bange wrote:may never learn how to do this right but at least I learned how to spell stretch

John, you may go down in modeling history as the person who coined the word "streach", when the term is adopted for sprue-pulling!

After all, someone had to invent "broast"!

les · Post by **les** » Tue Jun 27, 2006 10:52 am

John, the best way I've found to do it is to hold it by one end over a candle flame. Keep it high enough so the flame doesn't touch it. When the side that isn't being held starts to drop, take it away from the flame and stretch it. If the plastic breaks continually, it probably is bad plastic. Try a piece from another kit. Hope this helps.

By the way, stretched sprue maintains it's shape. Round stays round and square stays square, etc. Haven't had any luck stretching Evergreen plastic.

Neptune · Post by **Neptune** » Tue Jun 27, 2006 12:36 pm

I never succeeded in making thick parts,but at least now I figured out why. I just put the sprue on fire, then extinguish it and stretch fast. It's very efficient to get narrow rigging, but it doesn't seem to work for barrels or stanchions etc. Even by pulling slowly it doesn't work this way.
So it basically better to just heat it I guess...
Now I have to start burning candles in my room, my parents will think I got mad!

kevinb120 · Post by **kevinb120** » Wed Jun 28, 2006 1:10 am

some sprue is definately better then others. I find that most cheap car model sprue seems to stretch easilly(plus you can get it in black, white, non-chrome silver, grey, etc.... If it breaks right away though, let it cool for a couple seconds then start slowly and pull faster as it cools. Sometimes you can save it by kinda wraping it back together under heat and trying again. If you kind of 'slide' it back and forth over the flame it helps too. Hold it for a few seconds when its the desired thickness to make sure it doesn't shrink up. I think the Tumpy sprue doesn't really stretch all that good.

Rob · Post by **Rob** » Wed Jun 28, 2006 12:30 pm

Neptune wrote:I never succeeded in making thick parts,but at least now I figured out why. I just put the sprue on fire, then extinguish it and stretch fast. It's very efficient to get narrow rigging, but it doesn't seem to work for barrels or stanchions etc. Even by pulling slowly it doesn't work this way.
So it basically better to just heat it I guess...
Now I have to start burning candles in my room, my parents will think I got mad!

Twist it as you pull slowly for think sprue.

Rob

kevinb120 · Post by **kevinb120** » Wed Jun 28, 2006 8:33 pm

For something that needs to be as consistant as barrels, depth charges, oxy bottles, or stanchions, evergreen rod stock is probably much more appropriate then stretched sprue. If its very thin(like for stanchions at 1/200 or smaller), then copper wire would work better.

Avery Boyer · Post by **Avery Boyer** » Thu Jun 29, 2006 5:02 pm

I've had luck with strecthing Tamiya and ICM plastic. Trumpeter's is more brittle and breaks.

RNfanDan · Post by **RNfanDan** » Thu Jun 29, 2006 9:20 pm

One of the neatest tools to have around, if you use a lot of sprue and/or make parts other than rigging, is a shrink-tubing heater. They are available at electronics supply houses and on the web. Unlike candles and other single-point heat sources, these noisy but nifty devices have a "thrust reversing" vane that helps the hot airstream surround the wire for about 70-75% of its circumference.

Because they distribute the heat much more evenly, and without the charring/sooting problems that candles introduce, you can usually heat a greater length of sprue. This allows you to stretch a much greater portion and/or a thicker piece than a candle will heat, in turn allowing you to make more substantial objects than rigging.

Speaking of shrink tubing, I've used tiny pieces of the stuff to "stage" gun barrels, masts, and even make hawsepipes. An even better option for some applications is shrinkable "spaghetti" tubing, which can be used to make items for smaller scale stuff in 1:600-1:800 scale ranges.

seahorse · Post by **seahorse** » Sun Jul 09, 2006 3:15 pm

You may also want to try this, http://www.bismarck-class.dk/shipmodels ... ldorf.html