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Posted by AndrewSpencer 
June 13, 2010 09:27PM
I'm working on rebuilding Mendel in my program of choice.
Working off of 2d sketches generated from the *.stp file I found that there are very few symmetries in the parts. For example the vertex pieces boundaries are not projected nor are holes centered!

Was this on purpose? or just bad drafting? If it was on purpose then WHY???


Re: drawing
June 14, 2010 12:36PM
What program are you using? How much off centre is it? Please post an example.
If it's a tiny amount, perhaps it could be from the conversion? And the tear drop holes would seem to be a bit off centre, so to speak.
Re: drawing
June 15, 2010 11:48AM

I am using Autodesk Inventor. Hmm. I can't find the reference file.... boogers.
No worries, ultimately I redesigned the whole piece. Most corners are now rounded and all holes are standard sizes. (Love metric fasteners but they are so much more expensive and I haven't a single reem, broach, or drill bit in metric.)

That brings me to the next question that you raised. Why are some "holes" tear drop shaped?


Re: drawing
June 15, 2010 12:03PM
That brings me to the next question that you raised. Why are some "holes" tear drop shaped?

The RepRap Logo
The teardrop shape is the profile of a cylinder with 45° angles above. Our commercial FDM machine can make a 45° overhang without support material, so - if you want a horizontal hole to put a cylinder through - the teardrop profile gets made without support. This is both faster and neater. And for the vast majority of cases it doesn't matter that it is not completely round.

The teardrop is also an important example of the fact that, with this technology, complexity of shape costs nothing.

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse
Re: drawing
June 16, 2010 11:18AM

Thanks for the reply! I suspected it was something to that extent...

Ok, next question. What is with the cutout on the bed? Is that a park area for the head?
Re: drawing
June 16, 2010 11:35AM
Yes, it's a temporary parking for heating up and testing extrusion before a print. See this video at about 13:37 - [vimeo.com]
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