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Arbor injection press | Injection v5

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This topic contains 14 replies, has 4 voices, and was last updated by  Stan 2 years ago.

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Anonymous

Arbor injection press | Injection v5

07/02/2019 at 21:16

hey,
as always we had this build requirements :
– doable with basic tools : angle grinder, welder, drill press
– best results with standard machines : CNC & lathe, and to make things perfect: a mill
– portable (fits in a car, max 45 KG)
standard components
– material bill below 1000
– scale-able
– re-usable for other purpose

the one in the pictures took 3 long days, 60 Kw hours, 40 euro consumables, 150 euro material

outcome – tests:
– very smooth, accurate plunge with little effort
– to be continued …

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helper
07/02/2019 at 22:19
0

That looks nice !

What size is the pipe / max volume of plastic ? Wouldn’t it be more compact if the rack & pignon were smaller to go inside the barrel and then having a smaller round bar (but then maybe not strong enough) ?

It looks a bit like Taller Esferica one, did you do it in collaboration with them ?

starter
07/02/2019 at 22:50
0

there is a smaller version in the forum, please search @s2019 ‘s posts. he’s doing incredible things with that, really impressive !

warrior
07/02/2019 at 23:07
0

Wow, That looks great. I really like how it maintained the compact, benchtop footprint.

A small note: I think if you add a couple of large washers on top of the yellow cross bar, you may be able to take advantage of thermal contact resistance and reduce the heat lost to the cross bar a little.

3 days well invested!

starter
07/02/2019 at 23:20
0

@lagrenouille, sorry but as almost dozen of other answers got deleted:  here again:
yes, building the transmission housing beneath the upper bar is really tempting, unfortunately, things won’t fit well with that, 24 cm by 25 mm was the max cylinder. i already exceed my standard parcel dimensions with the now 96 cm. taller esfrica, no but inspired by, like possibly a few other million on this planet, @s2019 is one of them too 🙂

starter
07/02/2019 at 23:22
0

@s2019, great! thanks so much, that will do. inside the middle bar sits the hidden 4th heater, 220W max.

warrior
07/02/2019 at 23:36
0

If you are running into packaging height limits, I wonder if you could get away with using angle (or channel) for the top cross bar and mount the gear box through the vertical face. I would guess it is hard to put more than a ton of injection force on that top bar.

new
09/02/2019 at 20:27
0

Hi!! where did you find the rack and pinion?

starter
10/02/2019 at 12:17
0

@virginiamanzano:
gear here , rack here but be advised that a gear of size ‘module – 2’ is fully sufficient. also you have to machine down the shoulder on the gear, its hardened steel and requires a solid lathe.

@s2019, excellent idea, thanks

starter
01/03/2019 at 20:48
3

hey there,
after a dozen hours of testing and producing almost 10 of these:

I swapped the handle against 3 x 25 mm sticks, 70 cm long. This gives so much ease and power, I think it’s still double the power needed to extrude. Some plastic was so easy to extrude by kicking the stick just; at least for simple molds.

Then I removed the 4 6mm thick enforcement plates from the middle and top bar. Those 3mm thick tubings were more than enough.

I still have to fine tune hopper and electronics but I consider this as first real release candidate. It’s the most pleasant injection I’ve ever used.

Some stats :
– build with heavy duty machines: lathe, CNC, pro-welder (unbeatable Fronius 2200) but i think that could be done without if you are really creative
– 60 minutes CNC, 1 hour lathe, 30 minutes welding and lots of time for drilling, grinding, etc…
– it took 2.5 days for 5 machines for 2 people. 5 days full-time to build one alone the first time
– material bill : 250 Euro (we have low priced suppliers) & 30 – 50 Euro for consumables (everything : CNC, lathe, electricity, ink, nuts, bolts …)
– bazaar price currently 610 but I think we increase; it’s just too much work after all. I think doing this even better would justify 800 Euro, considering that similar simple arbor presses are at 1300 Euro +
– 38 Kg shipping, 70 Euro within Europe (if you are part of a network)
– 25 mm by 24 cm volume
– Shipping size: 110 cm 55 cm x 30 cm

what’s next :
– we will try better heatbands (50e the piece), for some reason I don’t really trust those from AliExpress too much; after cutting a few shapes I noticed irregular consistency, even with 10 minutes waiting time (HDPE).
– easy & height adjustable clamp

warrior
01/03/2019 at 23:32
1

@cgoflyn That is a very clean design. I like how you simplified the drive gear bracket. A couple of additional ideas:
Since these are likely to be used indoors, you might enclose the top section of the frame with sheet metal, add a fan and an exhaust interface for flexible ducting (clothes dryer vent type) to create a fume hood. You might have to experiment a bit but I think if it stops 10 cm above the top of the tube, there should still be enough access to load the injector but still collect the fumes. This should make education applications and indoor demonstrations more likely to get approved.

In using my small unit, I tend to preload the injector piston (with the nozzle blocked off) to apply compression during the heating phase. This seems to compact the plastic, and reduce air/voids. When I see plastic starting to ooze through the piston clearance, I’m generally ready to inject. Maybe a way to maintain preload might be useful for your machine (this would make adding a press feature in the future easier). In my shop I would just use a simple spring or strap but you probably have something more professional.

Since you have lots of torque margin, perhaps you can offer a range of piston diameters for the people that may want high capacity.

You mentioned the band heaters, You probably have it in your wiring diagram, but the drive mechanism and the frame probably should be well grounded in case one of the heaters fails in a bad way.

Great job, this is a very professional design that opens the door for a lot of options and functions.

starter
02/03/2019 at 13:01
1

Hi Stan,
thank you so much for the input. Obviously, I haven’t spent  much time on such issues yet but it worth gold to us 🙂 We indeed have various requests from educational enterprises/foundations and also governments but since we’re not quite there yet, we often suggest them other machines. It’s a little pity considering there’s quite a lot of $$ we could get from such sales, enough to finance other but related projects.

so now i will take quite some time, getting your thoughts into hardware. luckily the frame provides enough space and mounting possibilities that users can do that themselves for now.
i’ve a metal sheet bender to make a good fume intake and for block the plastic during pre-heat, i guess i just weld a cap with a hole on a M20 nut since the nozzle is basically a M20 thread with a 14 mm hole, possible i better just tap it and use a bolt. play time ! thanks again.

warrior
02/03/2019 at 18:43
1

I am happy to hear that you are getting educational and institutional interest. I think getting these machines into the educational system and into the art/craft world will do a lot more good than just the small amount of plastic they will process. If you’ve had recent inquiries,  you might ask them what certification would be needed for the machine to be readily used in the school systems. You may be able to find a university that would collaborate with you on getting that done (sounds like an ideal project for an industrial engineering course). You may also be able to get a grant from a foundation for this. I think getting the electronics certified is straight forward, getting the fume management in place and reviewed should not be an obstacle either. In the end you may end up with a version with some higher cost parts, but for the educational application this should not be an issue. In the end, if you end up with an approved machine that
can do injection and possibly compression, can accept larger, hand cut strips of plastic (so the schools can avoid the shredder), and fits conveniently on a bench, there should be good demand for it.

Good luck. I’m very impressed with your team’s rapid progress.

starter
02/03/2019 at 19:14
0

yeah, actually I worked in a educational context professionally for 10 years, I just started picking up that old steam again. I have these funny and awkward moments recon this lately, And yes, thats what i did with the last requests, asking for indoor only, session length, max. weight and size, functionality, etc… I have to wait for some feedback first but this ‘edu-pp-kit’ seems to get shape 🙂 Thanks to you and the others btw. Apart from the machine stuff, I am still puzzled how a final and ready-to-use dossier for presentation may look like. Whilst there is enough input on the PP homepage, there is still lots of work to sell this to town-hall officials.

we had today a meeting with some locals interested in getting a mobile and permanent PP workshop. here in barcelona there are already a couple of projects being supported for activities around plastic, not exactly my cup of tea since I just want to mess with stone-age machinery but ok, let’s combine 🙂

g

warrior
02/03/2019 at 20:32
1

Yes, I think the edu-pp-kit is the way to go. You would think that the new Chinese restrictions on accepting recyclables would kick start a lot of efforts in this area. Unfortunately, here in the states, that topic is not in the media. They have figured out there is more money to be made giving speeches and trying to ban things. Oh well.
But yes, a science curriculum around the recycle/re-use approach is much more valuable. You could also tie it into simple CAD product and mold design where the mold is carved into a constrained plaster block with a cheap cnc router/engraver. This way the student gets a souvenir at the end.

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