1 Topic by TonyLin

  • TonyLin
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Topic: How can print out a 3mm diameter hole?

There is problem.
I can't print out a 3mm diameters hole.
Is there a limit?or I have to set up something?

2 Reply by IanJohnson

  • IanJohnson
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Re: How can print out a 3mm diameter hole?

Holes always come out smaller than designed. It's the nature of the process, and the fact that you are taking a physical line of plastic and wrapping it around a circle.  The plastic on the outside gets a little stretched, the plastic on the inside gets a little squished.  To get a 3mm hole you will need to make it larger in the design, or drill it out.   You can mitigate the effect by using polygons to make your holes rather than circles.

3 Reply by jawhn

  • jawhn
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Re: How can print out a 3mm diameter hole?

Design a sample print with varying hole sizes, then choose the one that works.

Hope that makes sense. Whenever I want a perfect fit, I always have to "figure out" the correct size that is *not really* the correct size.   wink

Two SD3s - One with Sang, One with Printrboard, Fans on control boards!!! Do this!!!, Dual Glass Beds, Blacklight "EZ Bake Oven" - Improves Ambient Temp, Sketchup, Repetier, Slic3r. Graphic Designer & Makeshift Engineer. Drinks Lots and Lots and Lots of Rum.

4 Reply by grob (edited by grob 2014-06-23 23:36:10)

  • grob
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Re: How can print out a 3mm diameter hole?

Yup. If you really need tight control over hole sizes, you're going to have to drill them.

That said, when I model a 3mm hole I'll get a hole, just slightly undersized (2.5-3mm). Are you not getting a hole at all?? A photo of your part would be very helpful (upload it to imgur or similar and post the url; the forum will block you from posting hyperlinks/images until you've made a few more...).

I use the undersizing to advantage as it gives a bit of material for the drill to clean up (a "machining allowance").
* If the hole is a clearance hole for an bolt, I usually model them oversize, and don't bother drilling (e.g. 3.5mm hole for an M3 bolt)
* If the hole is going to have a thread or shaft put through it, I'll size it exact, it will print undersized, and I'll drill it out.
* If it goes through the bottom layer, it will need that bit drilled out regardless.

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