Stan

It might help if you said what the purpose of the workshop is (produce a specific product?, education? pilot program for a larger municipal program? etc.). Does it need to make money or do you have a sponsor? If you are at the “there is too much plastic and I want to do something stage”, you may want to work out the detail objectives and business…[Read more]

Well you can always go for a record http://www.guinnessworldrecords.com/world-records/largest-tape-ball …that should raise awareness. Especially if it becomes public art that everyone can add to.

Yes, for that simple mold the next step would be to redesign the aluminum block that forms the 90 degree turn at the entrance to have a more positive seal.

One thing I’ve done both with the injector as well with some press molds is make a collection of stock material that I use on short notice to make some simple items. Yes you can buy Delrin,…[Read more]

I tried 210 C for the garden stake. It came out well but I could only push out about 65 cm before the nozzle end of the mold leaked under high pressure. To go further I would need to change to more positive connections. Not going to pursue that at this point, but it was a good capability test.

I need to get back to making more of the large black…[Read more]

@davidsharma777 I don’t have experience with the labels, but I found this that might be helpful. http://www.plasticsrecycling.org/resources/reports/sleeve-label-study

If you have industrial recycling available, it may be better to let them deal with it . Trying it at the small scale, you may end up with a bunch of oil contaminated water that is difficult to deal with.

I think I’ll try slightly higher temperature (210-220) with the full tube to see if I can produce the .9 m, After that, this was mostly an exercise in finding the limit of pushing HDPE in narrow channels.

My setup isn’t really usable for long vertical molds.

The outer skin issue is something to work on. One of the attractive things about using…[Read more]

@frogfall thank you for running the numbers to confirm what many have suspected…..

Eindhoven just doesn’t get enough rain

Not sure. MDF is fabricated at temperatures comparable to the  plastic temperature. I don’t know what is released at that point. If you look at section VI of a typical MSDS http://www.hardwoodweb.com/architectural/docs/MSDSUltraStock.pdf it talks about some of what can be released during thermal decomposition (without specifying a temperature). I…[Read more]

Yes, fun stuff.
Though you bring up an interesting question. We use shredding PET as a benchmark for the motors but is there anyone using (at the small scale) shredded PET for anything? Fortunately in our area there is a deposit on PET beverage bottles that helps keep them out of the trash but is there a good process for DYI recycling them? Your…[Read more]

Just for fun https://www.youtube.com/watch?v=PN1ZJMFMGNs . I don’t know why @pporg keeps pushing these multi-KW motors.

Actually, I wonder if his approach for making the shredder blades can be scaled up to get a functional replacement for the elegant PP v3 blade shape.

Very cool. I remember long ago visiting a company that was making 3mm diameter turbines with EDM. Very impressive. If this becomes hobby priced it will be a big deal.

The typing I had in mind was not so much for repair but to identify a large piece of unmarked plastic, something like a trash bin for example. In that case the “does known plastic stick to it” criteria may be worthwhile.

I’ve tried the wooden plug approach in the past. It helped reducing voids in high aspect ratio tubes when I had less injector…[Read more]

I think this forum should have a sticky about (not) using recycled plastic for food containers, especially wet contact containers. A quick google of something like “recycled plastic food contact” brings up links to a number of regulatory sites on the topic. While a large company may be able to work their way through the requirements, PP using…[Read more]

I also tried the same approach with my square tube mold. The first image shows the configuration after injection. The tube is 15 cm long.

The second image shows the outside of the section view. There is a skin layer that is predominantly one color. The third image shows the interior of the part. Again some creativity in forming the flow theories…[Read more]

I tried the short forming tube followed by expansion into open air.The setup is shown in the first image. The aluminum tape was also sprayed with some mold release. Once it leaves the tube the HDPE expanded quickly and does not proceed down the v-trough very far. After the large blob formed the tube slipped in the clamps and the rest came out near…[Read more]

Thank you for posting the datasheet example. How are you measuring the melt temperature and pressure?

I wonder if that would be a good place for a soft coupling (some examples in the middle of this page https://davehakkens.nl/community/forums/topic/extruder-development-v4/ ). It may reduce shocks from jamming and make everything last a little longer.

Perhaps a poster of the Eindhoven standard wool cap and three layers of hoodie?

Yes, the ghosting presents an opportunity, but not knowing which image will show up first makes stocking the gift shop difficult.

The plastic welding is an intriguing topic. It can expand the usefulness of a limited capacity injection machine. It may also allow the use of simpler (non CNC) molds.

I also want to check the plastic typing…[Read more]