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Machine Development…….Extrusion

This topic contains 32 replies, has 15 voices, and was last updated by  Sagar Sharma 9 months ago.

1
Hansie enviro

Machine Development…….Extrusion

30/03/2016 at 14:59

Please use this Sub category for all posts & information regarding the Extruder Machine Development. Thanks 🙂

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helper
30/03/2016 at 14:59
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first of all, Dave, congratulations on the awesome new site and very detailed materials. Thank you very much
You saved us from having to buy the extruder infinite screw 🙂

– a quick question about the bandheaters: what power do you suggest? 300W ?

– any specific model or other details about them?

also, we wanted to build the machines on sturdy wheels that have a break so that we can move them around easily. Do you see any inconvenience for that?

– what about building the extrusion machine without the base, so that it can rest on top of any table? Do you see any inconvenience with that too?

I’ve noticed that besides the intro video the plastic and building videos don’t have translations. I’d like to contribute with those translations (into spanish and maybe other languages). Are you aware if somebody is already working on that so that I don’t duplicate or that we can share the task?

looking forward to your answers
thanks
beltran

warrior
02/04/2016 at 08:23
1

– We use 220V band heaters. Which is already more then enough, 300W would do it!
– Not really, we found a shot in the Netherlands, but used the ones from Ebay before.
– Wheels are no problems at all, we also did that at the TU/Delft. Works fine. Except the injection might need some additional framing if you are putting a lot of force on it.
– Sure you can build the extrusion on a table! Only thing is make sure the heating elements don’t burn anything around them.
– We try to keep all the translation as open as possible, exactly for that reason to not have duplicates. So if you want to get involved, best to stay on top of that topic!

Good luck!

helper
03/05/2016 at 13:59
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Looks good – thanks for sharing guys!

new
03/05/2016 at 19:26
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Hello from Malaysia! I have been struggle for a long time on these question. Hopefully there is someone can answer me.

Question 1:What type of shredder plastic is that? PETE?HDPE?PVC?LDPE?PP?PS?
Question 2:What type of 3D printer filament produced? ABS?PLA?PET?PVA?HIPS?

Please leave you e-mail address here or get in touch with me so that i can deeper understand. I need help.
E-mail : [email protected]
Thank you!

helper
05/05/2016 at 01:12
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Hi guys, here is a few snippets from a conversation I had with a mate who 3d prints.

1. PETG, the stuff most 2L soda bottles are made out of, works as a pretty good 3d printing filament
2. There are number of guys looking at making their own extruder for 3d filament. I suppose it could work out a lot cheaper once setup, however you would have to make a lot of filament for it to become cheap. also, you would need to do tension control on the pull extrusion to control the filament thickness during extrusion, or have filament thickness sensors set up on your printer so it can compensate for changes in thickness.

Is that too much stuffing around for the average home person ? it’s not as bad as it sounds. Marlin firmware (what most reprap printers use) has that functionality built in. you just have to buy the right optical sensor, and tell it how much filament is between the sensor and the hotend.

Hope someone find that helpful 🙂

helper
05/05/2016 at 01:21
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Some more info on the subject here

helper
05/05/2016 at 07:45
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Hi all,
in this older topic is more info on the filament maker.
older topic

Filament maker

starter
10/05/2016 at 19:40
1

I’m a plastics engineer from the US, and I design screws professionally (among other things). I’ve created a design for an extrusion screw for this extruder based on V2 CAD that will give you much better mixing, a more consistent melt texture and color, and better control over your filament diameter. This is a much more complex and expensive screw than the wood auger that’s typically used in this design, but your product would be much improved.

If there is interest in having these made, please reply in this thread or email me at dustintweir gmail.com and I will have my shop quote them. I will post 2D drawings soon.

A word of warning: this screw is designed to generate higher pressures at the nozzle, so please be sure your valve is open (or removed) if you ever use this screw.

–Edit: STP and STL files not allowed… ? Here are my Drive links:
https://drive.google.com/file/d/0BxHR8WWZjrjSdGZoSWl0UUlXV1k/view?usp=sharing
https://drive.google.com/file/d/0BxHR8WWZjrjSWnc0b094V2hvQmM/view?usp=sharing

warrior
10/05/2016 at 20:34
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Hi Dustin,

That looks great! It looks like a proper injection moulding screw with 3 different zones. What would you recommend this be made from? Stainless? And how critical is the clearance between the barrel and the screw? Obviously it needs to be tight to maintain pressure, but does there need to be a gap to avoid seizing, especially with the temperature gradient? Can the screw and barrel be made of the same material, or would you recommend a different material for the barrel, maybe bronze?

starter
11/05/2016 at 04:06
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Good questions. It’s a proper extrusion screw, that’s right. It’s s single flight general purpose extrusion screw with a 2.5:1 compression ratio.

I would recommend you match the hardness of whatever barrel hardness you have. Most likely this will be 1018 if you have a regular old pipe, or 4130 if you have a higher grade pipe. Having dissimilar metals does two things: they grow at different rates leading to binding or jamming, and the hard one will wear down the soft one and put a bunch of metal shavings in your extrudate. I don’t recommend stainless unless you’re going to run PVC. Stainless is expensive, and it’s available in a narrower band of hardness ranges as much less expensive alternatives. PVC creates acidic byproducts which can eat away regular steels, so only in that case would I suggest the extra cost for stainless.

Commercial screws have welded-in bimetallic hardfacing and barrels have tungsten carbide liners or are nitrided. This reduces the long-term wear when you’re running 24/7 for a couple of years. You’re probably not going to run your machine enough to ever see an appreciable drop in throughput due to wear.

You do need some clearance because, you’re right, the screw can bind up in the barrel if there’s not enough. The consequence of having too much clearance is “leakage” flow, which reduces your throughput rate and pressure. Err on the side of extra clearance (I would use 0.005″ (0.1 mm). The temperature gradient isn’t the problem with binding as long as you have a similar metal barrel, it’s misalignment that’s very likely in a homemade machine. Along those lines, check that the pipe you want to use for a barrel doesn’t have a big fat weld bead sticking out on the inside. Cheaper pipes are rolled over and welded, leaving a big goober on the inside wall.

warrior
11/05/2016 at 06:07
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Impressive. This is always been high on our to do list! A custom screw. Do you think its possible to make them yourself or somewhere local? And what would it cost if you made them?

warrior
11/05/2016 at 12:28
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@dustintweir

Thanks for the excellent information! About the compression ratio too, I was wondering about that.

starter
11/05/2016 at 14:48
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I can get a quote. I’ve been working on ideas to make them locally. One idea is to make a grinding machine that “copies” an existing screw. Another is to weld on the flights after the shaft is made and grind down the outer diameter after. This would allow it to be made with a standard lathe and welder.

starter
11/05/2016 at 14:56
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See copy machine sketch.

Attachments:
warrior
11/05/2016 at 15:48
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This has got me thinking, It wouldn’t be too hard to construct such a grinding machine, and you wouldn’t actually need an original screw to copy. Since the pitch of the screw doesn’t change, you only need to couple the linear motion of the grinder to the rotation of the screw being ground at the right ratio (could be varied for different size screws). And for the minor diameter of the screw a simple 2D template could be followed by the grinder.

starter
11/05/2016 at 18:15
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Good idea. Of course if you can add actuators you could program in the profile easily. A 2d template could work too but you have to account for the rotation of the screw. If you had two templates: one for the root diameter profile and one for the flights, you could shift over the flight template for every partial turn of the screw (1″ per turn).

starter
15/05/2016 at 04:34
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Thought of using a Chinese manufacturer.
Quick turn around and cheap

starter
27/05/2016 at 01:20
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We have been investigate about this process, but we can’t find how the 3D printers can identify this material and can work with it, so, is it necessary a special 3D printer that can work to this material? or it need a special additives or something like that? or maybe is it the extrusion procces the key?.

I would really appreciate if you help me with my research, thank you.

helper
09/06/2016 at 12:31
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@keesdeligt
@davehakkens

Hi Guys,

I was unsuccessful finding your motor & worm gear specs. I’m sure you went through allot of trial and error before deciding on the gear and motor that you used in V2.
That is why I’d like to use what you used – do you have the specs for us?

If you have posted these already – sorry (I did look).

Greetings from Durban,
Paul

warrior
09/06/2016 at 13:16
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Yes please, I’d like to know this too. More specifically, the torque required to turn the screw. I’m guessing it’s in the region of 10Nm (considerably less than the shredder) but I might be way off.

helper
09/06/2016 at 14:50
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Hi,

well euhm..
We experimented a lot ;).

With the drill we used Drill the RPM was around 30 to get a decent stream.

The cheapest solution, was a scrapyard setup. A 24V windowwiper motor from a Truck.
Powered by 2 Computer powersupplies. wired to get 24V out of the 12 V supply.
Power/Speed regulated with a simple DC dimmer like regulator.
Worked well…

We found out for making filament you want a very stable rpm. So we used a 3 phsed motor with a 220V 1 phase to 380 3Fase frequency inverter..

Regards Kees

warrior
09/06/2016 at 15:01
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Interesting, thanks. I don’t suppose you’d know how much current the 24v wiper motor drew under load?

helper
09/06/2016 at 15:09
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@keesdeligt thanks!
Do you know how many watts the 3ph motor was?

helper
14/06/2016 at 12:40
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@dustintweir
Are there too many variables for us mortals to roughly calculate the torque (Nm) needed to turn the screw? …And ultimately the minimum size motor needed.

starter
14/06/2016 at 14:37
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@paulfreed Yes. Even in industry the torque demands are generally determined experimentally. Once you have a baseline of an existing screw and current draw on the motor you can estimate what similar screws will require.

It is easy to figure out how much torque would break your screw, in case you want to determine the maximum motor size, but it’s not easy to determine the minimum.

If anybody with an existing machine wants to provide their details: gear ratio, screw length, screw diameter, motor size, and amperage used, I could provide some estimates.

starter
15/06/2016 at 05:29
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Hi Dave/Community members,

I’m Ferdin from India, I’m working on a Thermocol (EPS) machine which is on similar lines as “precious plastic” project.

Has anyone tried to use Dave’s (or Dave have you?) design for shredding and extruding/compressing EPS before?

Since EPS is a form of plastic, I’m looking to integrate both plastic and EPS recycling into a single machine. The temperature and a few other things will have to be changed.

Also what happens to plastic if its dirty, wet, muddy; shredded and extruded out of the machine. Do you anticipate any blocks or jams? Has anyone encountered or experimented with dirty plastic?
Reason I’m asking is because during my EPS recycling ground work and waste conditions, I realized the machine will have to be able to handle dirty EPS as well.

The modular structure is an awesome touch, hope to work together with you guys to make it even more versatile.

Warm Regards,
Ferdin
[email protected]

warrior
21/06/2016 at 13:06
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What are the specifications of the motor used for extrusion?

starter
28/07/2016 at 09:27
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@paulfreed @dustintweir We are building the extruder in Belgium. We also have our doubts about the power of 2 kW for the extruder. The only thing it should do, is push the plastic further. We are thinking of using a motor of only 800W. A lot easier to find. We’ll try it, and post our results. Is anybody building their machines close to Belgium?

starter
29/07/2016 at 08:51
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@davehakkens @dustintweir @lyricalpolymath @paulfreed

Like we said, we have troubles finding a right motor for the extruder screw (it’s not that difficult, but we have a lack of time and budget) and we came up with this idea. I would like to have your comments on wether this could work or not.

The extruder’s screw is from a normal (or maybe bigger) drill. We want to buy a drill, put the screw in it, and attach it firmly to the barrel holder. The mayor benefits could be that you can just find a second hand drill. And the biggest win could be that you can adjust the speed very easy in a drill, so you could bypass the screw in the nozzle. Knowing that this is what makes the extruder the most difficult machine to make (in our point of view). Correct me if I’m wrrong, but now we could just mount the drill, adjust the speed, hence we can use very easily the nozzles with the plumbing sizes.

Any reflexions? Is this tried out already? Or is the idea ridiculous? 🙂

new
01/06/2018 at 08:54
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@dustintweir Do you have by chance the source files for the STL file you posted here ? I have a hard time to re-construct this in Fusion-360 (to make the CAM operations). Thanks

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