At work I have worked with some high end printers (objet and 3ds) at home I am running a printrbot simple. Today some of my co-workers and I had a discussion regarding the resulting prints. Can anyone weigh in on the uv curable/dlp methods used in the hobby level printers? Our discussion summarized below.
We found that yes the print resolution and surface finish is amazing on the objet/3ds systems. However the prints fail in these respects: material cost is through the roof( a fff print that would use $1-$2 of filament would use about $200-$300 in resin), the prints are quite brittle, the tensile strength is quite poor, the part melts a low temp, the material change over wastes alot of material, the colors bleed during change over.
Realize I don’t make parts at work I receive them. But how does the print short comings compare to the hobby level light cured solution.
At work we have an Objet Eden 350V. I have witnessed the same issues when comparing it to an ABS FDM part, especially one that was made in a Stratasys FDM machine (I recently came into “inheritance” on one). I have a reprap FDM as well as a UV curing system too. While the parts I have made on my UV curing system are not by any means good looking because it is under development they have allowed me to see the properties. The Makerjuice resin I use with that is also brittle like the commercial systems. I have not worked a lot with UV curing resins by any means but in college I studied composite materials and worked at a testing lab. Testing neat UV cured resins was always a pain in the ass because they were extremely brittle and sensitive to notches, bending, misalignment of jaws etc. So it has been my experience that UV cured resins in general are much more brittle than traditional thermosetting epoxies, styrene, vinylester etc.
That said, a few of the SLA parts I have gotten from vendors at work seem to be somewhat tougher than the jetted photopolymer ones or the Makerjuice ones.
It seems to me that my company “upgraded” to the Objet because a lot of the parts we rapid prototype are painted and not generally used in a mechanical applications. FDM parts are a pain to sand, fair, and paint compared to photopolymer.
I have no experience with the polyjet machines for comparison but have recently been working on a comparison of the Form1. Given the same STL, printing in PLA on a personal FDM machine costs about $1-2, FormLabs simple grey resin $23, Shapeways frosted detail $326. Of course the first two are materials cost only. The grey is the best material Ive used on the Form1 so far - its very similar to acrylic sheet (plexiglas) in terms of brittleness and durability. Failed prints happen infrequently with the peel process used by the Form1 responsible for most failures. Once the part comes out its pretty durable until you drop it on a concrete floor or something. Overall the Form1 is a good compromise between personal FDM on the low end and industrial SLA on the high end while still being reasonably affordable.
I was not at all aware how brittle those pieces were. This is very valuable information, thanks. It makes my decision not to get the Form1 so much better.
@Will_Jones on the Object and 3Ds systems self tapping screw into screw bosses rarely work. Typically i find that when i put the screw in the screw boss breaks in half. It is really frustrating when you break a part and you know it is like $50-$60 to print it again. In PLA i have not had this issue, the same screw boss in PLA is much more resistant.
PLA is about $33-$40 a Kg density is between 1.21g/cm3 and 1.41g/cm3 so the material cost would be between $.04-$.06. the form1 resen is about $149/1000cm3=$.15 So with shipping your numbers a about right.
The problem i have with UV curable is the waste material in the vat. you are looking at a few dollars of plastic sitting in the vat. You cannot print without the vat being filled so this material is effectively waste. Larger print volume=more waste (yes it is recycled, between prints, but think about it you will never be able to use that material)
Compare this to the remnants that you have when using the FFF method, those can be used for smaller prints until you have your feed length left (ie wasting a few cents)
When I referred to its brittleness that doesn’t mean its brittle. Just about the same as a sheet of acrylic. Not ABS tough but close.
My numbers were based on a model 76x60x98mm in size. With supports (most Form1 prints use supports) that comes to 155.4mL estimated resin. At $150 per 1L thats $0.15 per mL or $23.21 for the print.
Again, this is significantly more than a PLA print done on a Printrbot but so much better print quality for a fraction of the print costs and machine costs of an industrial setup. I think that is a worthy trade.