need a little advice on ABS wall thickness for my first project.

[Marm]

Also remember, this is a layered manufacturing process. I know on my printer, that stresses work differently in the various axis (axis's?, axi?, axis?), ahem, directions. If you are putting a lateral stress across the layers, it may tend to delaminate (words are failing me tonight, that's poorly described). It really depends on the orientation of how you print it and how it is used and designed. The identical same design might fail catastrophically with minimal loads, but print it 90 degrees the other way, it can be a beast. Also, what may be rigid in one direction, might be flexible in another, and brittle in another, all relative to print orientation.

But it doesn't sound like you're putting a lot of stress on this frame (I've learned this through trial and error of supporting a 5kg load with 20kg lateral stresses on my racing boat parts), so I wouldn't worry too much about stresses. Because, if there are no other design considerations for the parts in question, again, why go with the smallest tolerance you can? Add a little redundancy to the design. Of course, if adding the 2mm to this part, makes you compromise another part, then it becomes an issue of priority.

[Marm]

If you're reaalllly concerned, run your design through a stress simulator. http://scan-and-solve.herokuapp.com/ was a thread here a while ago, and I use it whenever I have concerns about design strengths. It's kinda intuitive, but it does take some getting used to, especially if you've never run a sim like this before. Just remember, red doesn't mean bad, just the highest level of stress.

[ServiceXp]

Great advice Marm!

[dmehling]

I have finally finished my design. Have a look at it and see if there are any issues frantic_amur.stl. However, the weight has ended up being a whole lot more than I expected. Really, it's only 1.2 ounces more so I guess I could live with that. I still intend to refine it a little more.

At this point, I have a concern that I never thought about until today. I didn't really think much about the fact that most printers build up an object layer by layer. So, that leaves me wondering about sections that are suspended in midair. There is one area in my design where I have a section spanning a 30 mm gap, supported on either side by the two central wedges. I don't know if this is a problem or not. I also don't know if it depends on which type of machine is being used. At this point, I don't know which printer will be used by the service I found on 3d hubs.

[ServiceXp]

It shouldn't be a problem, they will use a support structure. The surface that needs the support will not be as smooth.

[curious aardvark]

it should bridge 30mm without any problem. the first layer will be a bit droopy. you can sand it flat.

Hmm, looking at the model - you've actually got one small suspended part - in the middle - and two very long parts either side.

you will need to use support.

But nothing complicated, so just use about 15% automatic support and it shoild be pretty easy to remove.

What slicer are you using ?
And what settings are you using for walls infill etc.
with 3 shells/layers and 25% infill AND the support it comes in at around 61gms. - 3 gms being the support.

And that would be pretty damn strong.