I have never had the time to do much in depth research but it sure looks like whoever wrote the laws wanted them to have as broad as coverage as possible 
]]> I have never had the time to do much in depth research but it sure looks like whoever wrote the laws wanted them to have as broad as coverage as possible ]]>adrian wrote:its not where its neccesarily moves z - its where it 'starts' and 'stops' a layer on each object.
It will do a loop on object 1, a loop on object 2, a loop on object 3, then move z-axis, then repeat.
Its where it starts/stops each of those object loops which changes on each object and each layer depending on what the gcode planner did at the time.
Anyway - still no mystery.
To 'hide' the layer change better, there is some special algorithmic sauce you can apply to wrap the layer ends inwards to give a cleaner transition, but Stratsys patented that back in January '13...
I don't know. Still seems mysterious to me. Like you said, it had to start and stop a loop on all 4 objects, yet only one got the groove up the side (till it switched the groove to a different one). Seems like if it had some kind of problem starting and stopping layers, all 4 of the blocks would have had some kind of similar artifact. The detailed reason for the groove appearing still eludes me :-).
So there is a checkbox in Slicer for 'retract on layer change'. If this is blank, it more than explains the problem. Even if it is checked, layer change is that extra 'pause' that would still explain what you see.
]]>its not where its neccesarily moves z - its where it 'starts' and 'stops' a layer on each object.
It will do a loop on object 1, a loop on object 2, a loop on object 3, then move z-axis, then repeat.
Its where it starts/stops each of those object loops which changes on each object and each layer depending on what the gcode planner did at the time.
Anyway - still no mystery.
To 'hide' the layer change better, there is some special algorithmic sauce you can apply to wrap the layer ends inwards to give a cleaner transition, but Stratsys patented that back in January '13...
I don't know. Still seems mysterious to me. Like you said, it had to start and stop a loop on all 4 objects, yet only one got the groove up the side (till it switched the groove to a different one). Seems like if it had some kind of problem starting and stopping layers, all 4 of the blocks would have had some kind of similar artifact. The detailed reason for the groove appearing still eludes me :-).
]]>you can make anything you want
Alas, I am no expert, particularly in an international jurisdiction, but 35 USC 271 explicitly states '...makes, uses, offers to sell....' . Note that 'makes' is entirely a separate statement from 'offers to sell'. "Uses" is also listed there, so ultimately, it doesn't matter how you came to be in possession of said patent-protected item.
It is also aginst 35 USC 271, section F (bold added for emphasis of relevant statements):
(f)
(1) Whoever without authority supplies or causes to be supplied in or from the United States all or a substantial portion of the components of a patented invention, where such components are uncombined in whole or in part, in such manner as to actively induce the combination of such components outside of the United States in a manner that would infringe the patent if such combination occurred within the United States, shall be liable as an infringer.
(2) Whoever without authority supplies or causes to be supplied in or from the United States any component of a patented invention that is especially made or especially adapted for use in the invention and not a staple article or commodity of commerce suitable for substantial non-infringing use, where such component is uncombined in whole or in part, knowing that such component is so made or adapted and intending that such component will be combined outside of the United States in a manner that would infringe the patent if such combination occurred within the United States, shall be liable as an infringer.
.
The above closes the door pretty hard on distribution of any firmware that contained the patented algo's.
So, at least in US Jurisdiction; you cannot reproduce the patented object except for the purposes of research into the patent itself, which is still allowed, however has a host of issues that mean its by no means an 'escape clause'...
This is of course disregarding the fact that an algo would outwardly appear to be 'mathematics' which shouldn't be able to be patented (but the *method* through which its applied can be, so you can use the algo, just not to hide layer seems... ) - and this has been upheld just last year in Texas ( https://www.eff.org/deeplinks/2013/03/t … atent-math ) . And I'm not going to touch the fact its software based, which again is globally a contentious issue when it comes to patents (as essentially, all software is purely mathematics.... ) ( https://www.eff.org/deeplinks/2012/10/f … are-patent ).
Now - none of this is rooted in the real world. Lets face it, you wont be sued by Stratsys if you did it yourself in your own home - the cost to them would far outweigh the 'damages' you might have caused them. But sticking it into firmware, then putting that firmware out there publicly.... Means their 'damages' would be significantly higher (potentially) and thus they will be far more inclined to potentially send you formal "cease and desist" letters....
And I am completely disregarding the fact that patents aren't actually enforceable like most people perceive - there is a world of difference between patents and 'copyright' (where most people base their patent opinions from). Courts can rule patents invalid, they can deem you to be non-infringing, to have arrived at a similar outcome through own-works, etc. They can strike down existing patents as they weren't 'effectively being worked on' within that country that the infringement occured, etc.... At the end of the day, each and every patent lawsuit is ultimately a bit of a crap shoot... This is why its an entire specialty of law into and unto itself 
... but it also means that whilst patent holders will often 'lawyer up' and send out nasty letters ; they are actually hoping 99 times out 100 that people get scared, and 'comply' with their wishes. Taking it to actual court, unless you are 100% certain you are going to win, can end up being very very expensive.... This is how patent trolls make a living. Convincing other people they are infringing, extorting a licence, and hoping that they don't get challenged in an actual court (where they might actually find their pile of patent numbers aren't as relevant as they thought,......)
I'm also not even going to touch 'materially different' .. which would take splitting hairs on the original patents claims in this particular instance, but could also be the difference between 'infringing' and 'non-infringing'....
Anyway - I've more than digressed into an area that I have little idea and other people get paid the big bucks for... But just don't assume because you live in the 'land of the free' that legally speaking, you are free to make a patented item at home for personal use Other jurisdictions are different in this regard, but the US for whatever reason has shut the door pretty hard on this ... which surprised me as well when I learnt of this issue a few months back (last time patents were raised here on soliforum, I went and did some reading 
) ..
(References: http://www.law.cornell.edu/uscode/text/35/271 ; and http://www.wipo.int/export/sites/www/ab … df/ch2.pdf
The patent I'm referring to: https://www.google.com/patents/US834923 … CDkQ6AEwAA
)
]]> patents only relate to commercializing.]]>its not where its neccesarily moves z - its where it 'starts' and 'stops' a layer on each object.
It will do a loop on object 1, a loop on object 2, a loop on object 3, then move z-axis, then repeat.
Its where it starts/stops each of those object loops which changes on each object and each layer depending on what the gcode planner did at the time.
Anyway - still no mystery.
To 'hide' the layer change better, there is some special algorithmic sauce you can apply to wrap the layer ends inwards to give a cleaner transition, but Stratsys patented that back in January '13...
I have a question??? Just because it's patented, why does that stop us from using it in an open source environment? We aren't trying to sell it just use it.
]]>It will do a loop on object 1, a loop on object 2, a loop on object 3, then move z-axis, then repeat.
Its where it starts/stops each of those object loops which changes on each object and each layer depending on what the gcode planner did at the time.
Anyway - still no mystery.
To 'hide' the layer change better, there is some special algorithmic sauce you can apply to wrap the layer ends inwards to give a cleaner transition, but Stratsys patented that back in January '13...
]]>You can tell slic3r to randomize layer starts - but if you don't have good layer change to begin with, it will just put those pimples all over the object.
It will appear at different places on each object depending on how it did the movement planning.... The newest slic3r (1.0RC1/RC2) also offers an option to hide the layer change in a concave section or underneath an overhang...
No mystery at all
I printed 4 copies of hex blocks at once and on one of them, the weird diagonal groove marched up the side, then decided to switch to a different block near the top.
More info and a close up at: http://home.comcast.net/~tomhorsley/har … 20artifact
I can't form a theory for this one :-).
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