want to vacuum form a shallow dome shape (clear)

[formingnewb]

Hi everyone - this is my first post here. I am posting to ask a few questions -

I want to vacuum form, or have someone vacuum form for me, a clear dome shape to fit over a clock (to cover the clock/protect the clock hands). This shape will be basically rounded conical, ~10" dia, at base, ~ 9 to 9-1/2" dia at top, ~ 3 to 3-1/2" deep, slightly rounded at the area over the dial face - generally a shallow dome shape.

So, I will need a form to pull the plastic down over. Will it be ok if I were to make this form out of laminated plywood ? Is surface finish of this form a critical feature ?

After this shape has been formed, will the finished parts shrink (will the diameter shrink) over time ? I was planning on using 0.060" petg, unless there might be a more suitable raw mat'l to use. What do you guys figure ?

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[smokediver576]

Do you have a CAD model of the part done that you could share?

3" to 3.5" is not what I would call "shallow", unless I'm misunderstanding the depth requirement. I'm imagining a pie pan turned upside down. How much of a flange at the base are you needing? If this is going to be used to see through then your mold surface quality will have to be like glass. Otherwise you will pick those imperfections up from the mold and it will make your lens look like a mirage.

How many are you looking to get done? I might be interested in the project.

Thanks,
Andrew

[formingnewb]

Do you have a CAD model of the part done that you could share?

3" to 3.5" is not what I would call "shallow", unless I'm misunderstanding the depth requirement. I'm imagining a pie pan turned upside down. How much of a flange at the base are you needing? If this is going to be used to see through then your mold surface quality will have to be like glass. Otherwise you will pick those imperfections up from the mold and it will make your lens look like a mirage.

How many are you looking to get done? I might be interested in the project.

Thanks,
Andrew

thanks Andrew - I'm in the process of drawing it up right now. I'm also just learning cad, so it might take me a while. I wanted to make lots of these, but we'll see how it works out. I think it will be something less than 3", but I haven't finished drawing it up yet, so exact dimensions are still up in the air. I'll send you a copy of what I've drawn as soon as I finish it, its really cool to have someone that knows the plan review this so I don't waste a bunch of time -

Sorry but when I posted this, the only "post" button I could see was a "reply with quote" button. Now that I've posted this, I see there is a reply button at the bottom of the page. Next time -

Should we be exchanging this info maybe via PMs ?

[smokediver576]

Hey FormingNewb - PM me your contact info and I'll send you an email.