Vacuum forming plastic machine.

[ynneb]

I have descided to also make a vacuum froming machine for plastic sheet moulding. This will then enable me to carve shapes on my CNC router and then copy them in plastic. I am hesitent to say what I want to make. ( dont want other doing the same thing )

I will mention some of the things I wont be making though, but could be made by other in this forum.

Plastic wheel carts. ( wheel borrows)
Plastic ponds for the garden.
Platitic sand pits for kids.
Etc


Any comments or design ideas would be appreciated.

I will put a stepper motor on the gas adjustment so as to justify it been in the CNCzone.

[buscht]

http://www.halloweenfear.com/vacuumformintro.html

I made one of these and it works pretty good.

T

[ynneb]

Nice looking machine buscht.

You mentioned that you used it regularly. What do you form with it?
EDIT: Sorry I didnt read your next page. Now I see what you make with it. Very cool.

Do you manage to make much money from this machine?

[buscht]

That's not my website, I just copied the machine. I used it for making prototypes of various parts for work.

Your idea looks very workable. Its important to get good even heat distribution and the alignment of the vacuum ports are very important. I tried just using a grid, similar to pegboard and it didn't work very well.

I then made a spacer board where I put vacuum port holes just around the perimeter of my mold and it worked much better.

[High Seas]

ynneb-
looks like you wanna make some bigger parts. I built one like this: http://members.aol.com/GCGassaway/vacuform.htm
works great. Did a lot of chasing about to get the plastics - and have tried oven and heat gun both. Didn't have the heating elements for the one like buscht built.
Jim

[njtermite]

I was looking into building my own machine to, but I don’t have the space for it right now.

buscht, or High Seas,
Would you be willing to vacuum form something for me if I sent you the mold? Is so could you email me with rates or any other information

Thanks,
Mark
njtermite@comcast.net

[ynneb]

I have a suspicion these covers were vacuum formed. I also have a suspicion the mold was cut on the same machine. It makes a good finish doesnt it?



Yes, I suspect if you had holes evenly spaced on a peg board it wouldnt work as well as having them around the perimeter of the mould.

I guess there are two ways to vacuum mould aswell. One where you suck the plastic into a cavity ( That would give a nice outside finish the exact shape of the mould) and the other where you suck the plastic over the mould. ( That would have a more rounded apearence on the outside but the inside was exactly the shape as the mould was.)

I guess you may need to have small holes in the mould itself to cater for indentations if the shape requires them. ( Does that make sence?)

I am doubting my initial design now. I think the down and forward movement of the machine will drag the plastic across the mould a bit and therfore stretch it in a slightly horizontal way causing stress lines. I think there is wisdom in the straight up and down design.

[buscht]

Benny, for some reason I cannot see the 1st picture you posted about the covers. I have seen parts trimmed two ways.

1. For high volume work, you would make a cookie cutter type tool that is the shape of the perimeter of the part and stick the formed part and cutter in a press and punch it out.

2. For lower volume or parts with holes, etc. Either a 3,4, or 5 axis router is used to trim the part and cut out the openings.

I would agree that a straight down pull is better. The material is in a plastic state and is very easy to distort. That is actually what is happening anyway, but hopefully controlled with the mold.

Professional molds sometimes have holes in the mold itself for helping mold into indentations. That is correct. I doubt that the shape you show would need them.

It is much easier to form over a male mold rather than in a cavity.

Also, tight corners and straight walls are difficult to mold. You want a draft angle in the mold. Your picture shows a perfect shape to mold.

I have used a textured plastic for my parts. This is normally on the outside of the part. It helps hide imperfections.

njtermite, I'll have to pass on your project. I don't have time to get my own projects done. If the parts are not too large, you can heat them in an oven and make a small vacuum box using a shop vac. Somewhere on the internet are directions for this. I've seen this done by people who make plastic canopys for airplane models. Space might not be an issue for something like that.

Good luck.

[High Seas]

njtermite - PM enroute
Jim

[ynneb]

I am thinking of a way to make the vacuum chamber more efficient.
I was thinking that if there was a chamber where the vacuum sucked out all the air, and just when you were about to pull the plastic down you would release this vaccum into the other chamber that connected to the mould.
I was thinking this would give a real boost to the preformance. A bit like a capacitor action.
Is this idea just overkill and unnecessary?

[vacpress]

I have used a homebuilt vacuum table to make hundreds and hundreds of posters : www.vacuumstudios.com. i have also designed a new device that can be built from 95% hardware store materials, and heating elements from indoor electric grills...


I have some 3d models and documentation if anyone is interested. Its mostly constructed of alumium angle and rivets for the parts near heat and the forming platen - the part that moves up and down.

[teilhardo]

yes, yes, please post some documentation, you can probably put it int he gallery or in the ftp section. The more hardware parts the better.
Thanks,
Tei