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Oven temperature lower limit for bending styrene


colinlp

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Hi, help needed please :)

 

I am in the process of building my 144 scale Saturn V launch tower. I have completed the basic shell of the launch platform which is basically a 50mm high box that is built from 1mm styrene with a series of cross bracing inside to support the surfaces. It has gone pretty well for my first attempt at scratch building but I have a small wind in it so whenplace on a flat surface it has a small wobble of a couple of mm. What I think I can do is put it in the oven with some flat plywood under and over with say a brick in top to add weight then hopefully it will slowly sag down to flat before I let it cool.

 

Is this feasible? OK it wouldn't be that difficult to compensate but adjusting other bits to suit but it would be nice to get it flat. If it is feasible what temperature would you recomend for this so it doesn't end up in a free-form fried egg shape at the bottom of the oven?

 

Hoping someone out there who has more experience than me has some idea, I have googled but I can't find anything useful at all

 

Many thanks

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Even the plate warming setting on my oven is far too warm for polystyrene.  The usual recommended temperature for working it is to run the hot tap just about as hot as you can bear it.  It might survive a little more than that, but only with very brief exposure.  Your plan to apply weight will probably squish it flat before you can drag it out again.

 

If I were you I'd just try again - possibly with heavier-gauge polystyrene if you can find it, or laminating the thinner stuff.  The real secret to keeping it square is to be utterly precise about your cuts and angles, and with practice you'll find that easier.

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I don't know if this will be of any help but, when I was building my Pocher Mercedes, I had a warp in both hood panels and I used hot water to reshape them. The plastic was fairly thick and I used a digital thermometer to control the water temperature to an exact 185 degrees. This worked with the heavier plastic and it only took a short amount of time for it to be pliable enough to get the warp out of it. The size of your piece and thickness will dictate the temperature and length of time in the water. 

Your oven idea sounds like it could be a problem with the brick on top because how do you know if it's too heavy and when to stop the heating process?

I would try different methods of heat on spare parts or bits of sprue close to the same thickness. 

Here's what I did with the Mercedes.  Go to page 7 if the link doesn't take you there.

 

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Thanks, I don't think there is any need to rebuild, I remeasured this morning on a piece of thick glass and the wind is only 1mm which I can live with easily if I can't get the thing perfectly flat. The trouble is joining 10 90degree butt joints end to end over about 400mm is always going to have a little inaccuracy but maybe I should have used 2 or 3mm stock for the main surfaces but what I have is fine.

 

Maybe the brick idea is a bad one, point taken. Hot water wouldn't work because most of the bracing is hidden inside and a good as sealed in hence the oven idea. Our oven is controllable from 40C upwards so maybe something like 60C-80C then remove and weigh down during cooling? All it needs is just enough to relax slightly and then hold its new position. I'm starting to think though that unless I get it quite hot, maybe too hot to achieve what I want

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Off the top of my head, if you was to sandwich it between two pieces of glass and use an hair dryer blowing into the affected area to heat it up then dunk it in cold water ?

 

Robert

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