Consider the following specifications prior to submitting your additive manufacturing project request.
Contact me_aml@iastate.edu with additional questions.
FDM Tips
Soluble Support
The Stratasys FDM printers use two different materials – the model material (the material that makes the actual part) and a soluble support material. The support material is designed to help print parts with large overhangs or geometry that isn’t supported by the model itself (think of an upside down cup – the last few layers that make up the base of the cup would be printed in open air if not for support material), and is removed by placing the printed part in a tank of solvent that dissolves the support material.
The Ender 3 does not have soluble support material, instead it uses the same material that makes up the part. This leaves a rougher surface finish and makes internal voids impossible to print since the support material can’t be dissolved away.
Layer Height
There are 4 different layer heights for the Stratasys FDM printers – 0.005″, 0.007″, 0.010″ and 0.013″. Not all layer heights are available for all materials. For a comprehensive list, please view the Pricing Info. Smaller layer heights give a finer resolution, at the cost of time and tip wear.
The Ender 3 has 3 layer heights – 0.10mm, 0.15mm, and 0.20mm. Please contact the Additive Manufacturing Lab if you need help deciding.
Infill Density
There are 3 main infill densities – Sparse (mostly hollow), Sparse High Density (partly hollow), and Solid. The various infill options change the weight and the material required for each part. This article by Stratasys goes into more detail on design decisions regarding infill density – please give it a read before submitting a project.
Cost Saving
The Ender 3 is by far the cheapest printer to use, however it lacks the soluble support material.
The smaller the layer height, the more tip wear. Larger layer heights have less tip wear. Since tip wear is used to generate the quote, larger layer heights will result in cheaper parts on average.
ABS and ASA are the materials loaded in the printer by default. Any material request that isn’t one of those will have an extra hour of labor charged.
Extra labor is charged if the parts need to be placed in the solvent tank to dissolve the support material. Designing a part to eliminate support material usage can go a long ways towards reducing cost – both in material, and in labor.
Design Choices
Check your shear planes. The shear strength of FDM parts is great if the shear direction is not along the layer planes – but if the part is subject to shear tangential to the part layers, it may fail. If there is a specific orientation you want the layers to be printed, please specify in the form comments.
Try to keep feature sizes larger than 0.100″. The smallest wall that can be printed is roughly 0.008″, however components with feature sizes that small are not very rigid. In particular, cylinders with a diameter of less than 0.100″ print at very poor quality.
Threaded inserts are necessary for small threads. If you have a hole that needs small threads, it is strongly recommended to use threaded inserts like this from McMaster Carr: https://www.mcmaster.com/heat-set-inserts. All that is needed to incorporate these into your solid model is to make a hole with the diameter and taper specified on the product page. If you prefer, you can request the Additive Manufacturing Lab purchase them and install them for you. Just specify in the comments in the project request.
If you want the Additive Manufacturing Lab to install them, you must make the hole with an 8° taper with the diameter shown below. The Additive Manufacturing Lab can purchase inserts for you, but the hole must be sized and tapered for the inserts below.
SLA Tips
When designing for the Formlabs resin printer, it is important to understand that the resin printer does not have a dissolvable support material. Rather than retype all of the relevant design choices here, you can simply view the guide from Formlabs themselves at their design guide page. Please read that page before submitting any projects for the SLA printer.