Hi Abdul,
I am wondering about the same question. I think there are three reasons:
1. STL files are not bad enough, and given the amount of investment in legacy code and files, they will stay for as long as possible
2. AM Equipment manufacturers are dragging their feet on implementing AMF import (why? It’s not a priority, for reason #1)
3. The standard is not freely available (although it is available to all equipment manufacturers)
--hod
Hod Lipson
Associate Prof. of Mechanical & Aerospace Engineering and Computing & Information Science
Cornell University, 242 Upson Hall, Ithaca NY 14853, USA
Office: (607) 255 1686 Lab: (607) 254 8940 Fax: (607) 255 1222
Email: Hod.L...@cornell.edu
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One of the things that is currently holding back a wider scale adoption of AMF is because it carries lots of features which are not applicable to many of the system manufacturers.
Consider the STL file. It carries the same value to all AM systems because it describes the form of the part. There are many different technologies which build parts in lots of different ways but needing the size and physical form described in the input file is something that they all have in common.
Now consider the AMF file. It carries information such as colour and material properties which is not applicable to all systems. Indeed it is only applicable in a minority of cases.
The net result of these differences is that the majority of system manufacturers will look at the AMF file and say “the extra functionality offered here is of no interest to us because it doesn’t give us anything we need 0that we haven’t already got with STL. If you look at extrusion based processes for example they do not produce parts with different material sections so do not need this information. They also do not produce full colour parts so neither do they need that information. That is just one example of a process that doesn’t need AMF I could also have chosen SLS, EBM, DLP, SLM in fact the vast majority of processes.
Don’t get me wrong I am not arguing the wide scale adoption of AMF for a single second. I’m simply trying to explain why so many system manufacturers are not exactly rushing to adopt it. None of the 3D printing manufacturers have the programming resources of companies such as Microsoft or Apple so software changes whilst by no means impossible to make do however mean that the resource required to make changes (as a fraction of their software budgets) are large and I’m very much afraid to say that if there is nothing in it for them and it offers nothing in terms of competitive advantage or unique selling points then you can perhaps see why the change to AMF sits so low on their already loaded priority lists.
Jez Pullin.
Renishaw plc (company number 1106260), Wotton Travel Limited (company
number 01973158) and Renishaw Advanced Materials Limited (company number 04632041),
are companies registered in England and Wales with a registered office
at New Mills, Wotton-under-Edge, Gloucestershire, GL12 8JR,
United Kingdom, Telephone +44 1453 524524.
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All CAD companies need to do in order to output curved triangles is to output the normals at the vertices. That's not very difficult... especially that these normals are already calculated for graphics rendering.
As is shown in the AMF specification, for a sphere, curved triangles are 1000 times more accurate than flat triangles. That means that you need 1000x times fewer triangles for the same accuracy, or get 1000x smaller error with the same number of triangles. For other curved surfaces the factor might be different, but I still expect a 10x-100x order improvement.
But as long as equipment manufacturers don't import AMF, there is little incentive for anyone else to support it.
--hod
From: st...@googlegroups.com [mailto:st...@googlegroups.com]
On Behalf Of Mark Burhop
Sent: Wednesday, November 06, 2013 6:30 PM
To: st...@googlegroups.com
Subject: Re: Why is AMF not yet used for additive manufacturing?
"BTW - It is unrealistic to expect CAD vendors to output curved rectangles. They would much rather increase the number of flat rectangles."
The specification says each triangle needs to be subdivided exactly five times. That means that a single curved triangle is temporarily converted into 1024 flat triangles for slicing.
--hod
From: st...@googlegroups.com [mailto:st...@googlegroups.com]
On Behalf Of Leonid Raiz
Sent: Wednesday, November 06, 2013 5:48 PM
To: st...@googlegroups.com
Subject: Re: Why is AMF not yet used for additive manufacturing?
One can either use open source or implement the AMF prescribed subdivision algorithm for curved rectangles. Not a big deal. But how much to subdivide? What criteria to use if originating surface is not available and there is no way to estimate deviation. Just pick an arbitrary number?