Forum Replies Created
Can you take a picture of the end of the spool? Also can you push the shaft and bearing back in place? Does it rotate without wobble then?
Some experiments on dealing with wrappers here: https://davehakkens.nl/community/forums/topic/soft-plastic-recycling-research-and-feasibility/
I looked at the Drill press designs before I built the desktop machine in the other thread. The things that influenced me were the stroke volume and force I could apply. Even with the Arbor press design, I started with roughly a 30CC stroke volume. This worked fine but was very limiting on what you can make (you don’t get the full stroke volume into the part.) I then modified the volume and got 45 cc. This was better but still very limiting, especially since you want to have margin to minimize voids.
I then built a new hot end that gives me about 200 cc stroke volume. I can get about a 140-150 CC part out of this in HDPE. For me this is a usable volume. To get the 200 CC stroke volume on a desktop machine where vertical stroke becomes a constraint, I increased the diameter to 41 mm. This now requires significant force to achieve good injection pressure. I replaced the arbor press bar with one that is about 600 mm and I’m pretty sure I am applying more than the 1 ton rating of the press at times.
My floor standing drill press also has a limited stroke length and I believe significantly lower press rating. If I had used it, I would be limited to the much smaller volumes that I started with.
Before you go down the drill press route, I would recommend going through some of the volume and pressure sizing calculations and make sure it is worth it. I built my machine for about $100US. If I added a shop press frame (instead of the scrap wood) it would probably double.
@ppme , I always wondered if it would make business sense for you to make a version of your rack and gear that would bolt to the top of a shop frame and just sell/ship the rack/gear, letting the user source the rest of the parts which are relatively off the shelf or shop tool makes.
Actually, something like this may be a little stronger https://alexnld.com/product/4pcs-201-stainless-steel-spring-toggle-latch-catch-hasp-clamp-clip-duck-billed-buckles/ . Looks like it should be in the cabinet hardware section of the store.
To find stuff I don’t remember the name of I usually guess and google images. I either find it or get totally distracted with some other cool item.
Congratulations, sounds like a great event response.
With a second small shop frame you could add an arbor press based injection machine. DIY: https://davehakkens.nl/community/forums/topic/portable-desktop-injection-machine/page/3/ or something like this ready to go https://bazar.preciousplastic.com/en/listings/770058-arbor-injection-press-elena-catalonia
“something which doesn’t involve things like a nut”
Well, a bright orange pair of Vise Grips? https://www.amazon.com/Grip-Curved-Locking-Pliers-GR11105/dp/B008U4M0LU
If you are going to slot the top hole, then a stud (maybe a captive one that can pivot) and an orange knob might be easiest. You won’t have to unscrew the knob very far.
Looks like @patrick-bonsen used a similar configuration, perhaps he can comment on getting the spool off. Otherwise, perhaps you can borrow a gear puller or make an equivalent with a bar with a tapped hole on the center that you can then clamp onto the flange of the spool. A little heat on the spool core may help as well.
Yes, the first few parts off of the machine would be some signs and plaques for the wife’s hobby….I know how this works.
The MPCNC design is intriguing and fits well into my interest in the build itself.
I’m still interested in exploring cheaper/softer materials for limited use custom molds.
Thanks, the TipBlitz is great. The CNC is too pretty for my garage.
I have been thinking of making one of the MPCNC routers.
Good luck. While you are getting rid of the bubbles, if your team comes up with a repeatable way to determine internal void volume (perhaps just a careful density measurement) that would be a great step.
One question is how the strength changes with repeated recycling.
Your data will be of interest to the community, hope you can post the methods and results.
Those are great results.
I used an arbor press to provide the injection force in my DIY configuration. It works very well. https://davehakkens.nl/community/forums/topic/portable-desktop-injection-machine/page/3/
Thanks for posting, looking forward to how your improvements work out.
Have you seen this thread https://davehakkens.nl/community/forums/topic/polystyrene-transparency/ , especially the post by @imuh ? The image he posted is a lot closer to bubble free, perhaps he can comment on the process details.
The problem with concrete is that it is not dense compared to steel. The wheel in your second link is interesting in that filling the spoke area provides a lot of volume (and weight). If I was going to do that, I might add some wire mesh for a little bit mode reinforcement in case you drop the wheel during handling. You can also combine it with the metal weights on the perimeter or use a mold frame to make it bigger or thicker. The formulas above let you compare that case with the metal options. There isn’t enough volume in a tire to make filling it with concrete worthwhile, I don’t think (maybe the fat tire or motorcycle wheel).
To place the individual weights on the rim, the inertia formula does not care but you would want to balance it just for smoothness. How you attach them to the rim depends on shape of your weights. You could bolt them radially by drilling holes like your valve stem. You can also attach them to the side of the rim.
If you have access to scrap lead, you could make yourself a mold and cast weight segments that fit the rim.
I think any approach that puts on sufficient weight, is reasonably balanced, and does not fly apart should work.
Looks like a great experiment, good luck.
It would help if you described your process design. Is it limited to industrial sourced material?
I love the results Vanplestik are getting but I didn’t think they were using filament. I thought they used flakes and beads directly.
@benjamin50 , For your flywheel, the moment of inertia is the key parameter https://en.wikipedia.org/wiki/List_of_moments_of_inertia . For a solid disk like the 20 Kg plate, the inertia is 1/2 mr^2 whereas for the bicycle wheel with the mass at the perimeter, it is mr^2. The radius of the plate is around 205mm and a typical bicycle rim is around 300mm. This all means that the mass is about 4.3 times more effective on the bicycle rim. So if you found a way to attach a number of 1 kg weights around the perimeter of the rim (should not be that hard to do) you will have a more effective flywheel and you don’t need to figure out hoe to mount the plate to the hub.
Predictions of required torque are useful but recognize that they are for a unique cutting condition. You probably want as much flywheel inertia as you can get.
The waste plastic to usable 3D filament extruder will be a great invention. While some work is being done, this machine does not readily exist to my knowledge. Your solution to this problem may drive the design of the shredder (it may require very fine particle size).
Please post your extruder design concept. There will be a lot of interest.
If you have not already, take a look through the PP bazar https://bazar.preciousplastic.com/?category=products and see what types of products people are making with the different machines. It may give you an idea what might be useful in your area.
A lot of it will depend on whether you have access to a mechanical shop.
The shredder itself does not recycle plastic it just turns plastic into microplastic, Have you already built one of the recycling machines? Not all of them require microplastic to operate.
The shredder is potentially the hardest of the PP machines to build. There are builders in the PP bazar that can provide either parts or complete machines depending on your budget and skills.
Hopefully one of the builders gives you a detail process. In the meantime I would make a spreadsheet of what you have with measured thickness and gaps by location to help form a shimming strategy, or re juggling of your spacer blocks.
What machine will you be using for recycling the plastic (injection, press, extruder)? You don’t need a shredder for all of these.
What plastic? Avoid PET bottles, unless you’ve figured out what to do with PET (not many have).
With HDPE and PP you can get a lot of initial work done with manual shredding
Looks great. The injection machine looks like a convenient alternative to the PP design.
What was the lift and power rating on the winch motor/gear you are using?
Thank you..Looks great…I also like how you maintained the orange and green theme on your air compressor.
Looking forward to your description posts.
Yes, need to accommodate the CE inspector’s safety tie (or pony tail), though the Digital testing of the auto reverse sounds extreme.
Sorry, I thought Item 1 in you first picture was an emergency stop button. I was wondering if you put it on the control box or up near the mechanisms.
Looks clean. Where does the big red button go?
For the screen and select knob, could you use one of the typical reprap screens?