Opening up hatch on 3D printed AFV model

Before ruining my 3D printed model, I would like advice on the safest way to open up the commander’s and driver’s hatches, both of which are presented in the closed position. Drilling out on an injection moulded plastic kit is a simple operation, but I am concerned that the resin may shatter in the process. Naturally, I will have to scratch-build new hatch covers once the hatches are open.

Thanks,

Paul

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I wish I had a photo to go along with this - one of the two AEF Designs Sho’t Kals I did had an open panel on the engine deck. It wasn’t 3D but their resin was notoriously brittle. The raised engine deck was quite thick - probably 3/8 inch. Before I made the first cut, I thinned it out from the inside using a steel cutter. You can check your progress and avoid cutting all the way through by simply holding it up to a bright light. When it starts to thin out it will become translucent. When you think you’re thin enough (and you don’t have to be exact) then you can drill a largish hole in the center. Thinner material means less of a chance of your bit getting caught and causing a crack. In fact I didn’t even use a bit, I just rotated an old dull no, 11 blade until it made a hole. In my case I continued to trim the rectangular shape with a new blade. After I had the shape I just filled away the edges at angle until they were all the the same, relatively thin thickness.
In your case you can use round files to roughly finish off the shape, For final finishing of circular cutouts I like to use a tapered dowel wrapped with sand paper - it keeps the hole perfectly round and you get a larger diameter as you twist it further in. Finish edges once again usinf\g files for a uniform depth. Sounds way more complicated than it is. In fact if you are lucky you won’t even have to thin out the roof.

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18Bravo,

Many thanks for the response.
My subject is a 1/72-scale CRARRV. The overall detail is excellent, only let down by the closed hatches. Since I plan to have the vehicle moving along, it is logical to have the hatches open, to allow me to include a driver and commander.

Paul

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We will need WIP photos. :grinning:

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I have the same problem with SS-Models. Beats me why the designer didn’t think of printing separate hatches. The resin is hard and brittle. After doing some other cutting of some parts, I’m afraid to try drilling, or cutting out a hatch opening. :scream: :cry:
:smiley: :canada:

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I can’t remember where I learned this, or even when (decades at least) but if you’re worried about the brittle resin cracking while drilling or cutting, scribe a rough circle as deeply as you can around the inside edge of the hatch. When you drill, if a crack does form, the scribed line may stop it from going too far. But even if it does, my thoughts are once you clean your hatch shape the crack will mostly be invisible. I’ve had this happen with resin, and once painted you don’t even know it’s there.

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Hmmm… :thinking: :thinking:
:smiley: :canada:

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