- Joined
- Oct 6, 2019
- Messages
- 10
My wife needed some boxes for her pills. I made an apparatus to compress melted HDPE grocery bags to make a pretty dense plastic. I also melted some Polypropylene yogurt containers which made harder plastic that was easier to single point thread. The HDPE worked well, but the threads get a little fuzzy where the thread starts. The PP is great to machine, but in my picture you will see some flaws on top where my parting tool deflected and tore the top and I didn't have enough excess material to machine away the flaws.
I made a form out of aluminum stock that I produced in my washing machine foundry. I then machined the od to be a friction fit with a steel pipe and pressed it into the bottom of the pipe.
I compress many bags in the steel pipe with the form in bottom in my 12 ton shop press while cold. I heat the grocery bags to 330 degrees in the steel pipe in my wall oven. When they are heated, they puff up. So I made a device to compress them while they are in the oven by turning the top nut. This device also is used to pull the plastic out of the form when it is cooled and after the mass is pressed out of the steel pipe by turning the lower nut. The yogurt containers were placed on a cookie sheet and also melted at 330 degrees. I used a wide blade to quickly scoop up the melted containers and put them in the steel pipe with the form in the bottom and pressed the material in the shop press.
Using 7tpi on my lathe, I cut a 1/7 lead with a double start thread resulting in 14tpi in order to have a coarse thread with half the thread depth.
Below are the pictures of the various parts. I think it is interesting to learn that those flimsy grocery bags can make a very usable and machinable plastic.
I made a form out of aluminum stock that I produced in my washing machine foundry. I then machined the od to be a friction fit with a steel pipe and pressed it into the bottom of the pipe.
I compress many bags in the steel pipe with the form in bottom in my 12 ton shop press while cold. I heat the grocery bags to 330 degrees in the steel pipe in my wall oven. When they are heated, they puff up. So I made a device to compress them while they are in the oven by turning the top nut. This device also is used to pull the plastic out of the form when it is cooled and after the mass is pressed out of the steel pipe by turning the lower nut. The yogurt containers were placed on a cookie sheet and also melted at 330 degrees. I used a wide blade to quickly scoop up the melted containers and put them in the steel pipe with the form in the bottom and pressed the material in the shop press.
Using 7tpi on my lathe, I cut a 1/7 lead with a double start thread resulting in 14tpi in order to have a coarse thread with half the thread depth.
Below are the pictures of the various parts. I think it is interesting to learn that those flimsy grocery bags can make a very usable and machinable plastic.