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Wegener

Stretching styrene tube

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Hi all

 

I need to produce some telescoped tubes (for a series of 1/32 FW 190 projects, so legitimately LSP-related!) for the wing guns but there is no combination of commercially available tube that I can find which provides the combination of dims that I need.  I have found a length of brass tube in the stash which appears to match the outer diameter of an MG151/20 but I need another tube to fit outside it for the tube which runs through the wheel well.  Ideally I’d then need another for the short tube at the rear but I may have some drinking straw that would work there.

 

It occurred to me that it might be feasible to use a length of styrene tube and heat stretch it over the brass but while it does stretch, it does so rather unevenly (certainly compared to stretching solid sprue) and I think the brass may be acting as a heat sink and cooling it prematurely.

 

Anyone tried this with more success and have any suggestions to make?  Obviously I could stretch it without the brass but then I fear that the diameter would be hard to control.  It’s obviously also important to be able to remove it from the brass afterwards, which is currently proving challenging as my attempts are causing some damage to the stretched plastic.

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It’s really hard to stretch styrene tubing, if not downright impossible.  The problem is that the temperature would have to be the same along a length of the tube, and even all the way around the circumference in order for it to stretch evenly.

 

There is almost any and every size of micro metal tubing available online though, so you should be able to find what you need if you keep searching.

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Posted (edited)

Have you looked into hypodermic needle sizes (for agricultural animals)? You can pick them up cheaply and might be able to get them in the size you require. I have some 16 and 18 gauge (5/8", 1"and 1.5" respectively) at home and will be getting hold of smaller ones soon.

Edited by AlanG

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Can you guys in the UK purchase hypodermic needles?  Not very easy in the US.  A needle is a needle, whether you stick it into a cow or into a human.  I have a virtually limitless supply since I work in healthcare, but for most folks they're pretty hard to get without a doctor's prescription, and then only in the size needed for things like insulin.

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Posted (edited)
9 minutes ago, Jennings Heilig said:

Can you guys in the UK purchase hypodermic needles?  Not very easy in the US.  A needle is a needle, whether you stick it into a cow or into a human.  I have a virtually limitless supply since I work in healthcare, but for most folks they're pretty hard to get without a doctor's prescription, and then only in the size needed for things like insulin.

Not easy in the UK at all due to drug misuse.

Plenty of places selling the K&S metals tubing which I have used in the past.

Good selections of brass, stainless steel, alu etc.

This is a place I have used many times for a lot of modelling supplies and they stock it although a google search of "K&S Metals UK"  will bring up quite a few places.

 

https://www.shesto.co.uk/craft-model-and-hobby/materials-components/ks-metals/

 

 

Edited by PhilB

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Never really thought about access to them if i'm honest. I work in agriculture and have access to a few different sizes because of the animals. Thanks for the info though.

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So being a cheapskates, I have successfully heat stretched the plastic tubing used by some ear bud manufacturers as the shaft of the ear bud. Takes lots of attempts and patience to get anything decent but it can be done, and it tends to only give you thin diameter pieces 

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I have some success with the same Tim - and yes to the output being very fine!

 

Also have lots of hypodermic needles - and a stash of fine brass, steel and aluminium tubing that's become easier to find/acquire these days...

 

Iain

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1 hour ago, TimHepplestone said:

So being a cheapskates, I have successfully heat stretched the plastic tubing used by some ear bud manufacturers as the shaft of the ear bud. Takes lots of attempts and patience to get anything decent but it can be done, and it tends to only give you thin diameter pieces 

 

Me too. When I go to cut in lengths though, I always insert an appropriately sized plastic rod, to keep the tubing from cracking all to heck while being cut.

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Thanks to everyone who offered feedback.

 

Brass tubing was my original idea as none of the hypo needles in my stock telescopes over the piece I will be using for the barrel.  However, I can’t find the size I think I need.  I do have some plastic tube cotton buds somewhere (they appear to be illegal to sell now!) but not wholly sure where....  I certainly won’t be wasting them by using any as cotton buds though.

 

However, what has just occurred to me is that heat shrink tubing might work, as if I shrink it over a metal tube it will be constrained by the metal in terms of how far it can shrink and that should give me a suitably thin wall.  It seems pretty cheap so I’ll order some and see how it goes.

 

And thanks for moving this from what was evidently the wrong forum.

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I haven't tried it, but you may look into heat shrink tubing.  It is used in the electronics industry and is readily available in may diameters.  Find the size closet to your gun barrel and shrink the tubing around it.  Maybe two or three layers depending on what you need.  Then carefully trim away the excess you don't need.  The gun barrel tube will pass all the way through like the real one.

 

Similarly, you could use a plastic based tape like clear tape.  Wind it around the gun barrel until you achieve the desired diameter, then trim away the excess.  When you mount it in the wheel well, just make sure the final edge/end of the tape is facing up/away from the viewer so it cannot be seen.  Maybe even lock that edge down with a careful pass with extra thin CA.

 

Prime, paint, and there you go.  

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