90 ton 1/14 metal excavator scratch build w/embedded PC

[RobotArms24]

Can you explain a bit about infill on 3d parts please. Is it something you put in the model, or something the printer settings control? What does it look inside when its partially filled in? Is it honeycomb or some other pattern? How would the strength of say 25% infill compare to 100% infill?

Thanks

[SteinHDan]

Hi RobotArms24!


The infill is set in the printer settings (not in the model) and it's typically only used for FFM-machines (the typical home desktop 3D printers). Shapeways will always make a solid model, I believe.

I usually print with something called "fast honeycomb". There are lots of alternatives, but I feel that fast honeycomb is a good combination of strength, speed, weight and also the zig-zagging gives less pull on the edges and less warping of ABS prints.

I use a software called Simplify3D. They have a lot of good information on their web site. This is a video on infill:
- https://www.youtube.com/watch?v=BMWTK2ZgJCM

And they also have and this very helpful 3D-printing troubleshooter:
- https://www.simplify3d.com/support/p...oubleshooting/

I don't know exactly the strength of different infill percentages, but to the hand it feels linear, i.e. 20% feels twice as strong as 10%.


Best regards,
Stein :-)

[SteinHDan]

Starting to paint the metal parts on the boom, stick and bucket linkage. Need a couple more layers on the stick parts.
The paint color is the closest match I could find to the ABS filament color in the previous step. It's this one:
- Dupli-Color 577789 AC 3-0600
Sanded (120 sand paper) and primed with aluminum etch primer first.

It's a shame, really, to cover shiny metal in this way ;-)

[SteinHDan]

Mounted the counterweight to the base plate. After testing with 4, 6 and 8 kg ballast, it seemed 6 kg (13 lbs) gives the best balance.

I bought 2 kg (4lbs) lead plates from a local scuba-diving shop:
- http://dykk.no/main.aspx?page=article&artno=MTDA-1

I don't like exposed lead because of the health hazards, so I covered it in liquid plastic and added a shrink wrap tube on top of that. Probably overkill and you can probably use whatever to cover the lead, but I had these things at hand.
- Polytek EasyFlo 60 Liquid Plastic
- PVC Plastic Heat Shrink Tube F/W:95mm

Then I printed a 3D clamp (ABS, 30% infill) that has two very long M6 110mm hex bolts going through it.
- M6 110mm stainless steel hex bolt

Finally adding some common furniture anti-skid rubber pads to both the clamp and the lead to avoid the lead sliding in the clamp.