On Mon, 8 May 2017 06:15:10 +0100 Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:

On Mon, May 8, 2017 at 2:07 AM, doark@mail.com wrote:

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I apologize for DOS'ing the list, I can only get online about once a week.

On Sat, 29 Apr 2017 12:42:29 +0100 Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:

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On Sat, Apr 29, 2017 at 6:08 AM, Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:

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http://rhombus-tech.net/community_ideas/micro_desktop/news/

ok, ouch, onto the fourth revision of the corner-pieces already, and some minor changes to the plywood are needed as well. this really would have been awkward if someone else did it.

the anycubic 3d printer is holding up well. the higher-quality PLA from the company i found on aliexpress seems reasonable so far (the "standard" quality definitely isn't: it literally crumbles under pressure).

<snip>

Luke, (I can call you Luke, since you sign your name that way, right?) PLA stands for Poly-Lactic-Acid and if they are selling you something else you can complain, if not sue for false advertising. That's why we label things, so that we know what they are, right? So one PLA aught to be the same as any other. Aluminum is aluminum, titanium is titanium, why is PLA not PLA?

it's partly down to where the lactic acid comes from: like any chemistry you get a different yield and a totally different composition depending on the process, the purity and the ingredients.

most companies use corn for the raw materials, and they don't process (purify) it properly. the result is that the PLA gives off acrid fumes, deforms under pressure, does not adhere properly (to itself... which is kinda important) and is generally completely fucking useless for well... everything to do with 3D printing.

Is there a way to tell how good a company is with their PLA? Price would not seem to make a big difference since companies can just charge lots of moo-la even with a poor product.

<snip>

ok, i'd like you to do a test. take a small piece about 5cm long and bend it very very fast, as quickly as you can, making the loop as small as you can (8mm or less if you can).

good PLA will snap.

shit-quality PLA will discolour, going light-coloured.

another test - a really really important one - is to make a long rectangle (35mm high x 5mm x 10mm would probably do) - the height is important - then clamp one end to a desk. on the other end suspend a weight tied with string as close to the end as possible. make the weight... let's say.... 0.5kg or so. not very much. now leave it for a month.

<snip>

Like this?

+-+ <--- Rectangle | | +DESK++-+W <--- Weight | | | | | |

Thanks, David