Thursday, November 16, 2017

3D printed LS3 V12 motor Part 3

Here are two more pictures comparing the roughness of two 3D printed parts, 10 years apart. The blue wrench looks like 0.5 mm between passes with the printer head (two furrows per millimetre) while the valve cover from Shapeways is more like 0.12 to 0.20 mm between passes (5 to 8 furrows per millimetre).

Painting with Testor's enamels and a brush leaves a relatively thick paint layer that obscures the ridges, especially when a light sanding has taken off the high points as identified by a coat of primer.

I completed the engine with starter motor, oil filter and a water pump from the parts bin. One important point: drilling out a hole, even carefully with a pin vise, will be challenging because the material is quite brittle and will split and crack if you are not careful. In the photos you can see where I was trying to hog out the hole for the crank in order to fit a pulley and belt assembly from the parts bin.

I filled in the hole around the crank pulley once it was all glued up, but the rigid, brittle nature of the material is worth keeping in mind. Of course it is possible to select different materials in the ordering process; I picked the Frosted Ultra Detail option, but the White Nylon option may be more forgiving as well as cheaper.

Overall, a mean looking engine. Now I just need a mid-engine chassis suitable for a 9-litre V12 ...

(PS it has been pointed out to me that the Chevy logo on the valve cover is backwards ... I have flagged this for the people making the parts, and presumably this is a minor software edit. I hadn't actually noticed, given that most of my past work is on imports ...)

So are we there yet? Not for bodies, unfortunately, until the resolution can be improved significantly beyond the current level of about 0.15 mm (about 0.006"). That being said, the possible level of detail is also 0.006", or about an eighth of an inch at 1:24 or 1:25 scale. This is minuscule -- bolt heads on a water pump are going to be 3/8" or 9/16", for example. Just be careful what material you select because this can have an impact on what you can do with it. To summarise:
Selection of subjects
Mainly high-volume, high demand markets
Mainly specialised markets for low-demand niche products
Potentially very extensive once the necessary computer files exist
Excellent, smooth surface
Poor today, visible ridges due to tracking of printer head
Depends on molds
Potentially very high level of detail at the scale of the printer head resolution
Variable, can be brittle
Depends on material selected – can be brittle
Prep needed
Dish soap, dry, primer
Alcohol or acetone to remove mold release agents. Putty for pinholes and bubbles. Heavier filler-primer needed for more porous castings. 
Dish soap, dry, primer

1 comment:

  1. PS it has been pointed out to me that the Chevy logo on the valve covers is reversed (mirror image). An error in the computer file obviously... perhaps I'll file them off.