Infill strength relationship

Mostly Printed CNC - MPCNC Advice
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It occurred to me as I was making Alton Brown’s french toast this morning…

Ryan might have actually specified the infill recommendation for the mpcnc parts. Then it further occurred that those recommendations could be different from the mp3dp parts (which I remember looking at).

I assume you see where this is going… I’ve got a batch of mpcnc parts mostly done which are printed at 40% infill .27 layer height where Ryan recommends most at 55% infill.

So I became curious, what’s the strength difference between 40 and 55%? Weight is coming in at 80%-90% of Ryan’s table. So I theorize, perhaps strength is also around 80% of the preferred settings.

And Z axis strength should be less than the XY strength. (Layers on layers thing) that would mean after assembly that the XY direction would be less strong and Z more strong. Coolness.

but you have to confirm your hypothesis as an engineer… so I looked…

and sure enough, just about 80% (lucky guess).

and that tells me… if your MPCNC is used for:

  • 3d printing - shouldn’t be an issue
  • Milling circuit boards - shouldn’t be an issue
  • laser - shouldn’t be an issue
  • milling soft woods - very likely not an issue
  • milling hard woods - possibly an issue, go slower the first few times and watch it.
  • milling aluminum - possibly an issue, go slow and watch.
 

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I wouldn’t worry about it too much. Those numbers rarely coincide 1 to 1. Every printer is very different, layer height matters (probably more) build, printer calibration. Build it, enjoy it, If you break it rebuild it.

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I’m not terribly worried… by the time you’re my age as an engineer (I have lots of wizard hair) you have a very relaxed view of breaking stuff. The much younger engineer who I’m printing parts for, will probably worry. So, now I’ve pre-seeded the answer in a forum where she’ll look.

If you listen carefully, you can hear her future self calling me an evil genius when she reads this post.

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Plus anyone who cooks like Alton Brown doesn’t have to worry about much. :slight_smile: Have you tried his grilled cheese sandwiches?