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Stefano

Fixing warped styrene parts - Advice needed

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Hi Gents!

How do you Master Modellers fix this?

My first effort with hot water and first kit (I bought a second one only to note that defect is endemic to all wing sprues) did not get well.

I would appreciate guidance on how to straighten heavily warped parts (styrene or resin): could any of you please direct me to a tutorial or perhaps be so kind and patient to jot a step-by-step instruction to successfully cope with this issue.

 

In my case, I don’t know if hot water treatment should be done on mated upper and lower midwings (using tape or rubber band) or on single components. 

An incomplete SH Brewster F2A-1 with its nice fuselage already completed (and the modelling mojo of a newbie) will be very grateful for all advices.

Thanks in advance and Happy Modelling.

Stefano

 

46820513372_a248bfbe93_z.jpgBC2B3EBA-3E67-41DA-A98F-930D67C9A9D3 by Stefano Salvati, su Flickr

 

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I don't know if it's the best way, but in the past, I have simply clamped (NOT tape or rubber bands) them together in the proper position, and glued them with thin CA or plastic welder. If they are clamped in the right position until cured, they should hold each other in the right shape after the clamps are removed. Hope that helps!

 

Tim

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Use boiling water to fix that.

 

Tape the wings leading edge to a steel ruler, boil some water and put the wing in a large container with the water and allow it to cool naturally.

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25 minutes ago, Dave J said:

Use boiling water to fix that.

 

Tape the wings leading edge to a steel ruler, boil some water and put the wing in a large container with the water and allow it to cool naturally.

 

Do you just leave it in the water until the water is back to room temperature? I have a few kits that will need this treatment, too.

 

Kev

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My experience with boiling water is that it can induce further (and much harder to fix) warping so I’d personally go with hot rather than boiling.  That said, if I could do it with clamping, that would be my preferred option.

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First, I wish to thank all for your valuable advice!

Tim, Dave, Kevin, Wegener and Mike: it is kind of you to provide guidance on something that may seem a trivial issue for an accomplished modeller: I really appreciate it.

In reviewing your replies, it seems that options are available to fix warped parts: having two wings in need for treatment, I will try both the hot water and the glueing method.

I will take notes on the processes so that some reference can be shared if successful.

Please wish me and my lovely (?!) Buffalo best of luck.

Fingers crossed and Happy Modelling!

Grazie mille

Stefano

 

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Stefano, I have used hot water and also a hair dryer!  It seems like hair dryers usually  have 2 temperature settings: high and low.  I use the LOW setting.  I have melted and badly warped plastic parts with a hair dryer on the hottest setting, in maybe 10-15 seconds of direct application.  I was surprise at how quickly the plastic was affected by the heat.

 

I think hot water allows more control, as you can vary the temperature of the water a LOT, but the hairdryers only shoots out air in 1 or 2 temperatures...

 

I would start with a low temperature and see if it works, then make the water hotter and hotter.  You can always make it hotter and re-apply to the model, but you can't undo warping or melting if the water was too hot at the beginning.

 

 

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Ringleheim, Thank you for sharing your experience.

I am rearranging my notes to report on my attempts.

In the meantime, here is poor Buffalo patiently waiting for its wings.

More to come (hope).

 

32118727957_e6d396059d_z.jpgD6C2D3E6-F622-487E-AEBE-A92DC85BFB0A by Stefano Salvati, su Flickr

 

40095626893_f11fbb1789_z.jpgF7B3BE15-5FEB-4922-ACEC-98D4BDC0C65D by Stefano Salvati, su Flickr

 

Stefano

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Hi Gents,

here are some notes on my effort in putting your advice into practice.

This is not meant to be a scientific dissertation on fixing heavily warped styrene parts, but rather a newbie modeller peer-to-peer list of do’s & don’ts on tackling the issue, based on pro modellers’ suggestions.

Please tune your expectations up accordingly and feel free to criticise, integrate or comment.

 

The approach I tested consists in using both methods, hot water bending and clamping, sequentially.

The purpose is to reduce initial warp to a manageable residual level using hot water, then clamp parts for a suitable fit and glue them.

 

I started taping the warped part to the flat bottom of a rectangular bowl

47035367381_ba290b7bfc_z.jpgA6CB1A5D-932E-4496-9707-80108BB28DF4 by Stefano Salvati, su Flickr

thus forcing the part to assume (at least partially) the desired plane shape.

 

Hot water is then poured in the bowl to allow for a desired and controlled plastic deformation of the part by thermal transfer.

This happens once a transition temperature (TT) is achieved: this is the key factor for a successful process.

TT depends on a number of factors (rheological characteristic of specific styrene used, mass of the part) and - alas - has to be determined empirically. It is essential not to exceed TT: excessive thermal transfer will melt the part beyond repair!

A fresh water rinse and bath after 3 mins. stabilises the part temperature back to ambient level.

 

The procedure is repeated by increasing water temperature by 5C intervals until TT is achieved.

A boiler with a kitchen thermometer will help.

 

47035367041_57231c370b_z.jpg67DC8AC1-2D4B-4FFB-BAED-1A3DA73B6B25 by Stefano Salvati, su Flickr

 

In this case, TT resulted to be around 90C: this was determined by gently applying pressure with a blunt tip prong to the warped part and observing it won’ t spring back to the original shape.

Please DO NOT assume this value works for every part of every model: do your testing even though it is a repetitive, time-consuming procedure if you don’t want to thrash your kit (my previous experience!).

Some weight is then added (I used a jug filled with water) to put pressure to the warped part and keep it adhering to the flat bottom of the bowl. 

47035366641_c1325607c0_z.jpg1742F469-18D5-42C6-8B1D-D5A176C31215 by Stefano Salvati, su Flickr

 

Further notes on clamping to follow.

HTH

Happy modelling!

Stefano

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Haha i laughed when i read “scientific dissertation” but then found out you were serious. Love the integration of chemistry as you shared knowledge about transition temps :goodjob:  definitely required pics. This will be a good future reference.

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