Vacuform help

[Psychographic]

I'm trying to vacuform a simple shape and am having no luck. Here is the mold I made, it's a simple flat piece with a 1/4" x 1/2" x .060  raised panel.  The mold has a hole on each side that angles down to the center in the bottom with grooves to hopefully aid in the suction (it didn't seem to help any). I'm using a dental style Vacuform loaded with .030 PET.

 

 

I'm allowing the PET to droop about 3/4-1" before moving the heat, quickly placing my plug in place and hitting the vacuum  and dropping the plate.

Here's what it looks like fresh out of the form.

 

 

I'm not getting anywhere near a tight enough pull around the raised panel, the tighter I can get this spot the better. You can see how poorly it pulled in with this pic.

 

 

Does anyone have any suggestions on what I need to do? Do I have it raised to high? Would making the base bigger help? This is for a back window so I can make it any size and trim it later.

 

 

 

 

Edited October 15, 2016 by Psychographic

[MrObsessive]

David, you might want to try a thinner sheet of PET perhaps a .020 size. When I was molding the windows for my '59 Chevy, that's the thickness that I used. Also, I'd try lowering your base a bit. The vacuum has an awful lot to pull against, and that may be what's inhibiting the shape you want. 

Hope this helps!

Edit: Here's some pics off my Fotki album of the buck I used to vacuform for the Chevy..........

 

Edited October 15, 2016 by MrObsessive

[Psychographic]

Thanks Bill. And how's this for brotherhood, check out how far on other ends of the spectrum Bill and I are by reading our signatures. How funny is that!

[MrObsessive]

LOL!! That IS funny! 

[GLMFAA1]

It appears in the photos that you are trying to vacuum form a negative form, that being the top is wider than the bottom, If that is true you have hard task to complete.

To get the upper edge of the plate you might put some small holes in the corners that allow the vacuum pull towards the edge. If it has to be clear then make another form that fits around the upper form and push it on the plastic after the pull but still in the pliable state,

my experience is with the Mattel toy

greg

'I don't build with rivets'

Edited October 15, 2016 by GLMFAA1
added remark

[Harry P.]

Or easier yet... just scratchbuild the thing out of styrene sheet. Forget vacu-forming it.

[Psychographic]

It appears in the photos that you are trying to vacuum form a negative form, that being the top is wider than the bottom, If that is true you have hard task to complete.

To get the upper edge of the plate you might put some small holes in the corners that allow the vacuum pull towards the edge. If it has to be clear then make another form that fits around the upper form and push it on the plastic after the pull but still in the pliable state,

my experience is with the Mattel toy

greg

'I don't build with rivets'

What I'm trying to make is a back window with a recess for a license plate. I made the plug by cementing the panel for the license plate box to a piece of .030  cut slightly larger then the window opening. I then wrapped it with 2" masking tape and mixed some plaster and filled the taped area with it to make a stand. It is not part of the finished  piece, just a way to hold it up. I can add material to make it wider at the bottom if it will help. While it tapers in on the sides the top and bottom are the opposite.  Here is a pic of what the shape of the finished part should be , but with the poor pull around the box.

 

Or easier yet... just scratchbuild the thing out of styrene sheet. Forget vacu-forming it.

As it needs to be clear and done neatly, I think it's out of my skill level and definitely out of my patience level.

Edited October 16, 2016 by Psychographic

[GLMFAA1]

If I understand this the raised part is going to be a recess with a license plate inside. then lower the whole platform you have it on and drill holes in the top plate at the corners to draw the vacuum. the license plate will cover them up.

Or... reverse your mold and make the draw into the recess by little holes in the corners of the recess that would be able to draw the vacuum and pull the plastic into it

greg

1 rivet, 2 rivet, 3 rivet, 4 rivet, oh darn lost count....

[Psychographic]

If I understand this the raised part is going to be a recess with a license plate inside. then lower the whole platform you have it on and drill holes in the top plate at the corners to draw the vacuum. the license plate will cover them up.

Or... reverse your mold and make the draw into the recess by little holes in the corners of the recess that would be able to draw the vacuum and pull the plastic into it

greg

1 rivet, 2 rivet, 3 rivet, 4 rivet, oh darn lost count....

That worked great, thank you.

 

I removed the plaster base and filled the base of the Vacuform with the metal beads it came with, drilled a small hole in each corner of the recessed box and got a good pull. It did bend a little but it's thin enough that gluing it in place should straighten it out. If not, I'll make a thin backer to give it strength and form another one.

 

 

Silly human, it's futile to count rivets in my presence.

Edited October 16, 2016 by Psychographic

[GLMFAA1]

You are very welcome, my pleasure helping out.

greg

[aurfalien]

That worked great, thank you.

 

I removed the plaster base and filled the base of the Vacuform with the metal beads it came with, drilled a small hole in each corner of the recessed box and got a good pull. It did bend a little but it's thin enough that gluing it in place should straighten it out. If not, I'll make a thin backer to give it strength and form another one.

 

 

Silly human, it's futile to count rivets in my presence.

Wow, that looks kewlll!

I like it!!!