Which way to orient parts to minimize surface roughness?

I'm working on a small aircraft model kit to be printed in FUD and I'm concerned about surface roughness, which seems to periodically show up on areas of parts, even those printed in hi res FUD. Looking at older posts, this seems to occur on the Z axis. I'm thinking about adding a thin sprue around the parts to try and minimize this problem by having the roughness oriented inside the parts where it won't be visible when the model is assembled. Does someone know if the roughness is occurring on the tray the parts rest on or closest to the print head?

Also, can I request Shapeways to reprint a part in a different orientation if I am dissatisfied with the result? Given the high cost of printing in FUD, I think all sides should be equally smooth, IMHO.

-Jared

shapeways will reorient your print as they see fit. they don't necessarily print as the file shows.

But if there is a problem with your print, you should speak to customer support and they'll resolve it for you.

Hey,
Nesting algorithms are used in laser cutting, water jet and cnc router cutting to place objects to be cut in the most efficient placements to allow for optimal usage of the cutting area. I would be interested to know if 3D printing software use a three denominational nesting algorithm to make optimal usage of the 3d space or if it is done manually by the operator? Either way, reorienting of parts will be necessary to achieve a good nesting.

Leigh

Hi all,

I really like to determine the print direction myself as a designer to make sure I get as less problems with the print layers. Perhaps Shapeways can include the option to have the customer select the printing direction or let the operator decide. I am happy to pay extra for the service.

Regards,

Leon

I agree Leon, though ideally we shouldn't have to worry about having a rough side in the first place, especially when paying a premium to print in materials like FUD.

I did some more reading on older threads in the forum and it looks like the rastering sometimes occurs underneath objects sitting on the support material - there is some interaction going on between the plastic and wax that's causing the roughness. I hope this issue can be solved in the near future.

This is a very interesting discussion, since it gets to the heart of my only concern about going all out and using the Shapeways service for a family of products (in the model railway space).

Here is a photo (not a good one) of two models I received today. The deck or "rig" behind the cab was done in Shapeways, the cab, wheels are plastic injection molded parts. Both rigs were printed in the same order. The one on the left is very smooth across most surfaces. The one on the right shows diagonal hatching - and on flat surfaces, pointing "up", shows layering lines. Both are primed white FUD material.

http://assets.roundmountaingroup.net/ljj/mow.jpg

I can live with some roughness here and there, but the heavy rough lines on the (right) model is impossible to sand out - because the doors are done in relief and thus cannot be sanded around.

I'm sort of at my wits end here - this is amazing that I can make these models and they are SO close to what I want. But they are simulating metal, not poured concrete and I have to be able to build them with a consistently smoother surface.

Any ideas? Thanks!!!

- Lou

This is exactly my concern Lou - thanks for your input and photo. I would love to design a series of small model kits and accessories for sale through here, but the printing inconsistency of FUD has me concerned - it would certainly cause headaches with my potential customers, who would expect consistently smooth and detailed parts free of random rastering. I may end up just creating masters through Shapeways, sanding and polishing them as necessary, then doing resin copies based off of them through another company. However, I wish I could avoid the latter step and sell the kits directly through here without worry. Like I said, I hope the issue gets resolved in the near future - I think services like Shapeways could potentially revolutionize the cottage model kit industry, among others.

Hi,

I am also a garage kit maker, doing small series of real space kits but I used it for making my master paterns which I later have RTV molds made and are cast in resin. I am able to rework and use filler before I sent them away for casting. But to have as less rework I like to determine the print direction myself.

Regards,

Leon