Resolution Drawbacks

17

1

With an ABS or PLA extrusion 3D printer, are there any potentially negative quality differences that could occur if I try to print at a higher resolution?

I am not concerned about print time as the equipment is not under high demand. I am, however, worried the device may be more prone to fracture, likely to have defects, or have other issues I cannot currently imagine.

kaine

Posted 2016-01-12T19:18:57.943

Reputation: 930

@kaine Or just plain "fdm".Tom van der Zanden 2016-01-13T10:35:12.733

@TomvanderZanden "fdm" was already tagged. While far less common, there are other types of fdm that aren't based on plastic filament.kaine 2016-01-13T13:58:16.773

The question isnt actually about pla or abs at all; the wording was only used to indicate a plastic filament one as opposed to resin or metal.kaine 2016-01-12T21:05:42.683

I see, what about [tag:plastic-filament]?the third dimension 2016-01-12T21:23:12.090

@thethirddimension, thats better. I think a "plastic-filament-fdm" tag would actually be useful.kaine 2016-01-12T21:24:46.543

Answers

15

The biggest effect I've see on resolution is due to plastic stress due to thermal gradients.

The higher resolution prints build up more layers of material, and each layer has a cumulative effect on thermal stress. The upper layers pulling up more as they cool, and the lower layers curling up more strongly as the layer count is increased.

To counteract this, a heated (or even just a draft free) enclosure makes a big difference. Having a heated print bed helps significantly, as long as the bed itself resists deformation (a sheet metal or PCB bed will bend more than glass under the same tension, for instance).

The actual plastic strength, however, appears increased. Laying down thinner layers of material appears to increase the bond strength between layers.

Adam Davis

Posted 2016-01-12T19:18:57.943

Reputation: 1 783

1Finer layer heights tend to decrease warping, not increase it. The thermal contraction stresses are applied more evenly and gradually as layers build up, which allows the print to form a stiff and stable "foundation" that resists curling as additional layers are added higher in the print.Ryan Carlyle 2016-01-20T16:00:31.677

5

Regarding the sturdiness of the final print, I believe it depends on the inter-layer adhesion of the filament itself - which varies greatly. Also, normally, thicker layers would increase the strength of the print up to a certain point.

An informal study of strength/layer height ratio can be found here: this study suggests that the strength of the print increases up to a layer height of 0.25 mm, and then stabilizes.

On the other hand, printing at high resolution often will hide defects that occur from bad quality filament, in particular filament that has degraded by absorbing too much moisture. Due to the less amount of plastic extruded per layer at high resolutions, some general printing defects also tend to be less pronounced and easier handle afterwards.

Tormod Haugene

Posted 2016-01-12T19:18:57.943

Reputation: 3 764

4

It's also worth noting that the ratio of nozzle diameter to layer height affects strength. The layer height is typically set slightly smaller than the nozzle diameter, so the nozzle "squeezes" the new plastic onto the previous layer. This is especially important for the first layer, because it affects how well the object sticks to the bed; but it also affects inter-layer strength.

TextGeek

Posted 2016-01-12T19:18:57.943

Reputation: 2 973

3

In my experience building with smaller layers also makes bridging and overhangs more pronounced and less likely to fail.

The smaller layers allow gradual changes for overhangs that are more abrupt with thicker layer.

Pete

Posted 2016-01-12T19:18:57.943

Reputation: 411