Hey! I uploaded a model thats 2x3x2 for full color sandstone print. I know the requirement for an escape hole is 25mm (1in). However, I was wondering if the hole has to be a square-shaped like shown on the tutorials. Due to the design, I was only able to make a circle-shaped escape hole of at least 25mm. Also, my the hollow part of my model is a sphere,. The hole takes up just about the entire bottom of sphere. I mean, with a sphere, I doubt much material will be stuck even if the hole was smaller. In cases like this, is it okay to make the hole less than 25mm? When materials get stuck due to poorly designed escape holes, is the cost automatically calculated and added to the price when you upload the file? Thanks
The hole being rectangular in the tutorial is certainly just an artifact caused by choosing a cube for the demonstration, as the actual point seems to be to show how one can hollow out an object by doing Boolean differences with a smaller copy. The purpose of escape holes is to allow operators to remove the unused powder from cavities by means of compressed air (and I suspect small brushes or dentist tools), so surely practicality is the all-important factor. Trapped material counts in the price calculation only when there is no escape hole at all (either forgotten by the designer or filled in by automatic repairs when the geometry around the escape hole happened to be malformed). What can happen however is that the model is rejected in the production planning phase as "impossible to clean".
Or to put this another way: if you are happy with your model, try ordering it and see what Shapeways says. If they are satisfied, they will print it, if not they will reject it.
So what would happen if I make the escape hole tinier? I have no problem with trapped material as long as it's not going to affect the price.
I tried it and it uploaded just fine and I am able to add it to cart. At what stage is it does it get "rejected"?
When you actually order something the model will be inspected by a technician, and at this point it can be passed or rejected. If it is rejected, then your payment will be converted to a credit - if you want the money back mail service@shapeways.com
So if the design of my model does not allow for a 25mm escape hole, then I would have to make it into a solid?
If there is no hole, then yes it will be a solid! But if you read the Material page for FCS you will see that you can have 1 x 25mm hole OR 2 or 3 x 15mm hole OR 4 or more x 10mm hole. Without knowing the geometry of your model it's difficult to make any specific suggestions, and in any case I am certainly no expert in FCS (models printed in FCS = none!), but some people modelling figures have split them into parts to allow them to hollow the body and then glued the parts afterwards.
See if they reject it - if the part in question is basically a hemisphere, I do not think they will ask you to make the hole bigger than the surrounding part just because the design guidelines say so. On the other hand you will want to avoid creating a "salt shaker" thingy that strews gypsum powder for ages - this will interfere with the application of the final superglue coating, messing up the surface of your model.
Thanks for the suggestions. If I go for the hemisphere, what type of glue would you suggest is best for gluing sandstone together?
Cyanoacrylate "superglue" is what holds "full color sandstone" together in the first place, so works well for repairs. (We still have no idea what your model looks like - it was my understanding that the part in question is almost a hemisphere, not my suggestion to make it into one (two actually) though that should work if the wall size is thick enough.)
Ah alright. Yeah, it's pretty much a sphere, so if i cut it in half, I could just glue it together. Thanks.