Here's a shape that was accepted for printing. Dimensions shown are in inches (0.1mm roughly equals 0.004 inches): The thickness at the center of the column is 0.028" (0.7mm), the minimum thickness allowable for White Strong & Flexible material. The four 'points' of the column extend from the 0.7mm wall 0.35mm and taper from a thickness of 0.7mm at the wall to 0.35mm at their tips - all within reecejames' rule-of-thumb for allowable surface detail dimensions.
GWMT, thanks for showing this example, this is really very helpfull! I just wonder a bit about the width of your column which is 1.4 mm (0.056 inch), if I correctly understand your drawing. The Shapeway design instructions state that each axle has to be at least 2.5 mm in order to get an object printed? Maybe this rule is handled flexible if one of axles is very long (like the length of your column)! Are there other examples with printed objects where one axles was less than 2.5mm? PS: would you share a picture of the printed column, I really would love to see it in real?
Thank you, Noshaper. I didn't explain that the column is an extrusion attached to a larger 4cm x 4cm x 20cm body. I suppose if you wanted to print just the column you could add a small piece of sprue to the 1.4mm side protruding 1.1mm and another piece to the 1.75mm side 0.75mm long to meet the 2.5mm x 2.5mm x2.5mm minimum dimension requirements. I'm waiting for the model to be printed and shipped (assuming it can be printed and it arrives in one piece). Here's a 3D closeup shot of the model There's a sprue connecting the top of the columns together to hopefully prevent anything from breaking.
Thanks, Reece! Your advice was crucial to making it work out on the first try. The posts are 38mm tall - it's right on the edge of what can be printed as an unsupported extrusion. See how the post in the middle has twisted slightly to the left? I'm going to add some sprue to the center of the posts to stabilize them.
I think the most annoying "feature" of Shapeways is the seemingly arbitrary rejection of parts due to thin walls. I just had a model rejected because of this. What's ironic is that I made the new parts thicker than the same part which had successfully printed many times before. The image below shows the ""thin wall" error, with the successfully printed thinner parts below (all more than 1.7mm thick at the thickest). I believe that the error is in the large wings at the bottom of the image. So why does a thicker part (2mm thick at the thickest) get rejected when in the past I've had at least six of the large wings printed - with absolutely no errors? The new wings are as thick as the smaller wings in the image above. It's like throwing darts -blindfolded. Frank
OK, I can see where detail becomes wall thickness. I can see that a tapered edge could get flagged. But I still can't see what's wrong with the following models. Both have been printed many times and now they are being flagged as having thin walls. In both cases the walls are 1.5 or 2.0mm (well above the 0.7 for SF) the the section flagged seems to be across the face of a curved surface. Support could find nothing wrong with it but could also give me no remedy other than to "adhere to the design rules for the material."
Option 1. Grab yourself a copy of NetFabb Basic, measure the wall thickness at the same point, take a screen shot and reply to the rejection email with your image and ask for an explaination in further detail exactly what is wrong. Option 2. Update the model with the exact same file and re-order - different operatives see different things
Thanks for the hint about netfab, needed that in my toolbox. Looks like there may be a scale issue (out of the blue, as this has been printed many times already) as the walls are 2mm at the point indicated yet the screen shot shows .002. Anyhow, I've gone the route of downloading and re-uploading the same model. Passed validation and ordered to see how it goes this time.
Ah... that old chestnut! I've had models rejected for being too thin by a factor of 1000 too. Looks like some operatives have their settings to millimeters and others to meters.
I'm just glad this is being worked on. It is very disheartening to upload a complicated model, finally have it pass all the checks after fixing it many times, then ordering it just to have it rejected when you are ready to print and by. I have had to cancel many orders because of this. So anything that Shapeways does to make this more accurate and better with less overall rejections is fantastic and I thank all you guys for constantly striving to better your much appreciated service. To kind of add on to what dadrummond said, I guess you will have to draw a line at some point to what is considered detail on a surface or whether it sticks out far enough to be considered its own object. Like a nose on a miniature is always very small. But since it is not very big then it would/should be easily passable and printable. However a nose like Pinocchio on a miniature would be too long and thin and subject to breaking. Thus getting rejected. I think one of the best things is to simply eyeball the problem areas on your side, considering the size of the print and make a judgement call if the print is practical or not. For instance, one upload I did that got rejected, the miniatures teeth in his mouth were too thin which I totally understood. However I had some larger teeth as part of his necklace that were considered too thin as well, however they were sticking out of his chest so I think they would easily and safely print. But they were hanging out pretty far so that was my fault in design. But yeah, it is a fine line and something I need to remember when I am designing. Its just not up to you guys, I need to work within practical limits. but some solid understanding and realistic flexibility would also be greatly appreciated. Thanks for your time!
Ok I'm new to this whole process and recently had two separate orders flagged as having walls that are too thin walls. I realize now the wall thickness error is really caused systemically in my modeling. I'm wondering if there is actually any tool which will calculate the thickness out there or if it is all just a manual thing were I need to start the habit of cross sectioning and measuring every part. I found a blender plugin on these forums but since it doesn't work with any of the versions of python and blender I've tried installing (probably my fault) I'm kind of hoping there is another option out there. It seemed that "tools" were vaguely mentioned at the start of this thread, anyone know what those "tools" are?
Grab yourself a copy of NetFabb Studio Basic (free), it has all sorts of measurings tools including wall thickness.
Thanks, Netfabb seems pretty useful. I was hoping for an automatic script or something that would flag areas of models without me spotting dangers before hand but this is the next best thing. Is there any word if Shapeways is building such a script to check wall thickness on upload?
This is one of the reasons I'm loving Lightwave for my modelling. If gives you some amazing tools during construction that prevent you from making thin walls, but then also lets you measure between two surfaces, edges or points while editing. (It's an Lscript plugin called pnt2pnt I believe) It's the semantics that catch us all out from time to time, but there's always a way around it
Blender itself can print edge length or face area among other things (press F9). Of course, not so useful if the distance is no a single edge... so others just create a cube or sphere of the right size, move it around, and try to check if it's visible from both sides of the thin areas. Or flip the normals (adjust normal size to match minimum) as rulers to check if they poke out in some place.
I see, so inspite of shapeway's assurances back in 2009 that they were working on a checking tool the community is actually relying on the tools available in rendering packages designed for non-solid modeling or using work arounds created based on the community's personal experiences. Well as I said its good to know where we stand. Since I can't afford to buy lightwave and frankly blender baffles me i'll probably try that cube/sphere thing. But if shapeways staff actually is reading this thread still, it would be really nice to be able to have an automated checker of some kind, or maybe even a submission cue were the model is actually manually reviewed before someone orders it. Personally i'm trying to be proactive to fix my modeling before I submit the models but I feel horrible when someone else orders my model and I get that "order canceled" email hosing a potential customer. Its not shapeway's fault i know its mine, but some help fixing it would be really... helpful.
I skimmed through the 78 posts before me and didn't see this addressed, my apologies if it is. Can we have the option to print a model even if it doesn't meet min wall thickness, knowing that the integrity can't be guaranteed? The one time I had wall thickness issues, the issue came from detail work. This option would be great for rapid prototyping, as in my case once I received the print it ended up being too small and I need to scale the whole thing, which would have solved the min wall thickness issue, if I hadn't already spend the time to remodel objects. Something simple as another check box when you upload the file would suffice. This would also save production time, because your employees would not need to manually check any walls. Obviously Shapeways is conscious of the quality of product they deliver, but customers should be allowed to forgo the quality insurance measures if they choose.