scanman Posted June 19, 2011 Share Posted June 19, 2011 Having been watching the group over the last few days, and following some of the web links, I'm a little puzzled by the various processes mentioned such as SLS (Selective Laser Sintering), SLA (Stereolithography), FDM (fused deposition modeling), LOM (laminate object manufacturing), 'riprap' etc. Whilst I'm not looking for a 'blow by blow' explanation of each process (although that too would be helpful), I suppose what I am looking for is some indication as to which process works best with what model i.e. is one process more suitable for flatt(ish) surfaces such as coach sides, whereas others might be more suitable for small, detailed parts. Any help gratefully received. Back to practicing with 123D... Regs Ian Link to post Share on other sites More sharing options...
Atso Posted June 19, 2011 Share Posted June 19, 2011 I think that this is one of the questions that really comes down to personal choice. Each has its merits and drawbacks (usually cost!). SLS in nylon usually works out the cheapest option (with Shapeways anyway). A nylon powder is sintered in layers ultimately producing the a representation of the finished model. The finish of the model will be dictated by the size of the nylon particles as well as the resolution of the laser (and your STL file!). With a nylon sintered part the finish will be porous and will need sealing if you wish to use if for a mould. I tend to find the surface finish quite rough but can be cleaned up by sealing the model and rubbing down. Shapeways has released a polished sintered nylon option, I've got a model on order in this but can't yet comment on the quality. Sintered Nylon: Pros - quite strong and cheap Cons - Porous surface finish, slightly rough SLA, usually a laser cured resin, again quality depends on the resolution of the laser, quality of the resin and STL file. I find that SLA usually (although not always depending on the company and machine!) provides a much smoother finish. Hollywood Foundries has had some really fine prints done by Finelines in the USA - if he's reading this maybe he'll post some more pictures of his 'green stuff'! SLA: Pros - much finer finish, can be as strong as ABS (depending on material) Cons - much more expensive compared to SLS FDM, in my opinion the closest match to the term '3D printing'. A print head deposits material onto the work piece layer by layer. Depending on the machine resolutions of upto 4000 dpi are possible (for a high price!). Materials vary but include plastics and waxes. Waxes usually need to be investment cast to get a usable model (increasing cost further), I've tried this using a Solidscape machine - awesome quality but a total of £300 spend on the print and casting!. Most plastics leave traces of the layer process which can be carefully cleaned up. Shapeways's FUD material would appear to be the best trade off at the moment between quality and price. FDM: Pros - Potentially very high resolutions (costs vary) Cons - Build lines usually viable, need cleaning, lower melting points of plastics. Reprap - again not tried this but most indications are that the technology is not yet up to a good enough standard for railway modelling. LOM - I can't really comment of as I've not tried it. I would have thought that the quality of the build would be highly dependant on the thickness of the material used. I normally use SLS to produce a cheap concept model, ensuring I've not made any silly mistakes (I usually have!) and then go with either FDM or SLA to produce a finer final piece. Others may have a different opinion to me though! Hope this helps a bit! Link to post Share on other sites More sharing options...
scanman Posted June 19, 2011 Author Share Posted June 19, 2011 Steve - Brilliant! Many thanks for such a comprehensive reply. The darkness lightens... Regards Ian Link to post Share on other sites More sharing options...
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