Page updated on 11-25-2017

Bending a plastic part


Blackm
05-05-2017, 09:18 AM
Hello.

I just found myself in need of bending a plastic part, in order to make it fit properly.

The hood of the car I'm building does not align with the front bumper when closed, on one side.

Idea would be heating it, and then proceed to bend it, but the operation seems to be quite hard: I did not obtain very good results, yet, resulting in some bulges.

It is quite hard, even because the correct "guide" for shaping the part would be the engine bay itself: by the time I place the hood onto it, it is already too cold.
Heating the hood directly on the bay does not seem a good idea, as I may deform the whole structure.

Some suggestion on how to proceed in an efficient way?
How do you deal with this kind of issue?

Thank you in advance.

rallymaster
05-05-2017, 09:46 AM
I sometimes use elastics to force parts to bend to take correct shape.
not the perfect solution but it works, depending on the plastic thickness and quality.

The 5th Horseman
05-06-2017, 05:33 PM
First of all, a picture would be helpful...
I think you have two options here, either heat the part in situ (that means protecting the rest of the model in some way, maybe coating it with aluminium foil) or create a copy of the part your hood rest on and then heat it all together. you could use epoxy putty for that or if the shape is relatively simple build it yourself. Hope this helps.

Borjacho
05-12-2017, 09:36 AM
I agree that a picture would help for a better advice, but I have used hot water for get correct shape in plastic bodies. Water must be as hot as possible to put the part and your hands into it, and with the whole part now hotter equaly you can adapt it. Hope this help :)

Blackm
05-30-2017, 05:05 PM
Thank you all.
Indeed, some more details.

The kit in question is Revell Mercedes-Benz 300SL-24. In pictures attached you can see the hood alone and taped in place onto the chassis, in order to see the deformation.

Heating it in place, with a proper heat insulation of the chassis would proabably allow to obtain the correct shape: I'd need to be sure that aluminium foil is enough, as deformating the chassis too would be an unrepairable damage.

I could try to replicate the engine bay frame, but it's very complex. Some hot water would be needed anyway, to correct internal buldges.

Plastic response, in terms of deformation, is very non-linear with temperature. An air-blower is hard to manage, as the flow alone would bend the part.

I hope that those pictures may provide a better comprehension of the problem.

http://imgur.com/a/Gz9rh

BVC500
05-30-2017, 11:05 PM
I'd scrap it and build the Tamiya 500sl kit. The chassis and suspension of the Revell kit are completely wrong (it uses the w126 chassis & suspension, but the SL is based loosely on the w124 E class), and the Tamiya kit is so much better. Plus, you're going to spend too much time trying to fix that warped hood.

The 5th Horseman
05-31-2017, 05:30 AM
Hey man, After looking at the picture you posted, and provided you don't want to build a jig of some sort to place and reform the hood using heat, i would suggest you try to order a replacement part from Revell. From what i heard their customer service is quite good, and they provide spare parts even for older kits like yours. Another option is to use a glass bottle filled with very hot water and lid on, and try to bend the part back to shape. It has to be glass (because unlike plastic it wont deform with hot water) and because it is sealed you will have more time to work the part. Hope this helps!

The 5th Horseman
05-31-2017, 05:35 AM
Hey man, After looking at the picture you posted, and provided you don't want to build a jig of some sort to place and reform the hood using heat, i would suggest you try to order a replacement part from Revell. From what i heard their customer service is quite good, and they provide spare parts even for older kits like yours. Another option is to use a glass bottle filled with very hot water and lid on, and try to bend the part back to shape. It has to be glass (because unlike plastic it wont deform with hot water) and because it is sealed you will have more time to work the part. Hope this helps!

Oh! don't forget to use gloves if you try the bottle technique or put the filled bottle inside an old sock !! he he !

Blackm
05-31-2017, 08:30 AM
Another option is to use a glass bottle filled with very hot water and lid on, and try to bend the part back to shape. It has to be glass (because unlike plastic it wont deform with hot water) and because it is sealed you will have more time to work the part. Hope this helps!

Thank you for your reply.

Building from scratch the frame for the engine bay is very difficult: I could try to, as it would provide the best reference for the shape. Maybe I could use some spare plastic, together with putty. I need to think about that.
Still, this would not allow me to correct the internal bulge.

Using a bottle filled with hot water is a nice idea. I could also use it to give the correct curvature to the hood.

Unfortunately, a replacement for this part is no longer available, as they told me: I have to manage to get the best result possible, with the hood I have.

BVC500
05-31-2017, 08:36 AM
I have a replacement hood if you need. Just pay for postage. PM me and we can work out details.

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