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stretching sprue
Merlin
Staff MemberSenior Editor
AEROSCALE
#017
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United Kingdom
Joined: June 11, 2003
KitMaker: 17,166 posts
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Posted: Monday, May 26, 2014 - 08:13 AM UTC

Quoted Text

Hey Edo
I make sure to do any sprue stretching near the kitchen sink.
Just in case I need to cool my fingers if they get a little to close to the flame.

Chris



Hi there

To be honest, if you burn your fingers (assuming you're using a candle flame or similar), the plastic you're working with is too short. There's no need for pain when stretching sprue.

All the best

Rowan
Scrodes
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Ontario, Canada
Joined: July 22, 2012
KitMaker: 770 posts
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Posted: Tuesday, July 08, 2014 - 01:59 PM UTC
The biggest trick to stretching sprue is getting to the right heat.

I use a long piece of sprue, rotate it above the flame, keep rotating it until it sags - you'll see it go soft and the end will dip down forming a pretty clear angle. Then grab the other end and pull. experiment with speed for different diameters. When it stops stretching because the plastic has cooled down, continue holding both ends - it will set and be straight.
Joel_W
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New York, United States
Joined: December 04, 2010
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Posted: Thursday, July 10, 2014 - 03:14 AM UTC
Chris,
That's a 1st for me. Never heard of anyone burning their fingers stretching sprue. Just use a birthday candle as a heat source, and make sure that the piece of sprue is 2 inches or so, and you'll be fine.

Joel
RolyPoly
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United Kingdom
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Posted: Thursday, September 04, 2014 - 02:06 AM UTC
Hmmmm.... what are you stretching sprue for? I find it useful for armour modelling (radio antennas) but for aeroscale modelling, where its only real application would be for radio wires, then forget sprue stretching. I use fishing line, its plastic so works with pretty much all modelling adhesives and is easy to work with.
Merlin
Staff MemberSenior Editor
AEROSCALE
#017
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United Kingdom
Joined: June 11, 2003
KitMaker: 17,166 posts
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Posted: Thursday, September 04, 2014 - 08:08 AM UTC
Hi Roland

If making aerials was all it was good for, I'd be tempted to agree with you - but you are missing the countless applications it has.

It really is among the most useful techniques in modelling, allowing you to make lengths of styrene in any cross-section you choose, in any thickness, and any colour; likewise tubes (stretch the stems of cotton buds).

I'd turn your question around: why did I ever bother buying so much styrene rod in various diameters, when I could simply stretch sprue to get the exact size I need for the job at hand?

All the best

Rowan
plastickjunkie
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Florida, United States
Joined: December 31, 2009
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Posted: Thursday, September 04, 2014 - 12:59 PM UTC

Quoted Text

Hi Roland

If making aerials was all it was good for, I'd be tempted to agree with you - but you are missing the countless applications it has.

It really is among the most useful techniques in modelling, allowing you to make lengths of styrene in any cross-section you choose, in any thickness, and any colour; likewise tubes (stretch the stems of cotton buds).

I'd turn your question around: why did I ever bother buying so much styrene rod in various diameters, when I could simply stretch sprue to get the exact size I need for the job at hand?

All the best

Rowan



Stretched sprue has multiple uses. Can be used as filler when Tenax is added as it will melt the plastic taking care of gaps. Cut to smaller lengths they can be used as knobs, switches and levers. I just stretched some sprue to make the framing in a Fokker D VII pit. I have also used it as plumbing in wheel wells and engines. The uses are just too vast.
Scrodes
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Ontario, Canada
Joined: July 22, 2012
KitMaker: 770 posts
AeroScale: 762 posts
Posted: Monday, August 10, 2015 - 04:38 AM UTC
I'm sorry if I'm repeating previous advice.


Fun fact - Tamiya have a particular type of plastic that is made to be stretched. These sprues (it isn't all of them) are stamped with a two letter code. I forget what it is, PC, RD, two seemingly arbitrary letters.



The technique - twist a straight of sprue between your forefinger and thumb over a flame. Wait until the opposite end sags, grab and stretch at a constant rate.