Extruder barrel help!
Hello! I am currently in the process of attempting to make an extrusion machine from the V3 plans and I have some questions regarding the barrel and the drill piece (I have a 26mm Auger drill piece).
1- How much clearance is needed/recommended to have between the barrel and drill piece?
2- Is the surface finish on the inside of the barrel necessary? If so, how could this be done?
3- Where have the barrel been purchased from (and what material)? I’ve tried looking for the recommended barrel (35mm diam., 5mm wall thick.) and I’ve struggled to do so.
4- What other methods are there of attaching the nozzle to the screw?
Hi Alib! I’ll answer the questions to the best of my ability.
1 – The distance should be small, (~1mm) however it depends on the length of your auger. The longer the auger then there will be more deflection. If you want a precise answer then I calculate how much it will deflect which will dictate how much clearance you need to provide me with the dimensions and mass of the auger.
2 – A surface finish will extend the life of your barrel. It is not imperative if you plan on running the machine for only a couple hours a day/ recycle as a hobby. If you plan on running it for long periods of time then you will want the life of your tools to last as long as possible. There are ways to make the interior diameter of a barrel smooth such as burnish and internal surface grinding. However, the longer the barrel the harder and more costly it is to do these processes.
3 – I’ll take a look at the V3 barrel alloy PreciousPlastic is using. The limiting choice of alloy(s) will depend on ultimately how much money you wish to spend on the barrel. If you plan on purchasing a burnished barrel or getting one burnished this will narrow down your alloy choice. I’ll update this post tomorrow on what alloy I’d recommend when I take another look at the V3 plans. The barrel isn’t subjected to intense forces/temperatures/materials (acids, bases etc…) so there is will be a range of alloys which are suitable.
4 – Again, I’ll look at V3 documents tomorrow.
Thank you very much for your response! I really appreciate this! Any extra information and advice would be very useful and appreciated! 😀
I can’t actually find the V3 design sheets so I can’t see what Precious Plastic used. I did just check the V4 documents and they recommended mild steel for the barrel which is a bit easier to machine since it can have a bit of lead in it. I don’t know if lead will leach out at 200C (this is a thing which can happen) over time but I don’t think 200C is a high enough temperature for that to be an issue. Another suitable choice is 1018 steel (this doesn’t possess lead) since it is very easy to obtain, you don’t want to spend too much on the barrel, you need to weld it easily, you have an operating temperature of ~200C and you don’t want thermal expansion to be substantial.
I didn’t look too much into using 1018 steel so for safety concerns I would use Precious Plastic’s suggestion since they probably did more research than I did. If you have any other questions let me know.
Again, thank you very much!
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