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Question about size correction

Posted: Mon Feb 08, 2016 7:18 am
by snakesrules
Hello there,
yesterday i've printed a very simple part on my Up Mini with ABS and soft temp mod .
The part is very simple : a drilled cylinder with 30mm ext diameter , 20mm height and 22.5mm int diameter .
I measure the part after printing , height of 20mm is perfect , ext diameter is 29.9mm , let's says OK , but internal diameter is 22 to 22.1 so NOT OK .
How to explain that ext diameter and height is OK and only internal diameter is really smaller than intended ?

Thanks for yours hints and answers .

Re: Question about size correction

Posted: Mon Feb 08, 2016 5:21 pm
by Robin
It is coming out within 0.1mm on a diameter. That's accurate to 50um, 2 thousandths of an inch, and you are complaining? :mrgreen:

Re: Question about size correction

Posted: Mon Feb 08, 2016 5:45 pm
by snakesrules
@robin : internal printed diameter is 22mm for 22.5 at original drawing , so a bit more than 0.1mm on diameter ... ;)

Re: Question about size correction

Posted: Mon Feb 08, 2016 6:10 pm
by Matchpoint
Those are good tolerances if you able to achieve that. I remember like 5 years ago a lot of 3d printers were like +/- .030"
There is expansion and contraction of the materials, especially ABS

Re: Question about size correction

Posted: Mon Feb 08, 2016 6:40 pm
by mr6k
Robin,
I think your assumption may be out by a factor of 10 !!!
His I.D is almost 0.5mm out Not 0.05mm

cheers

Peter

Re: Question about size correction

Posted: Mon Feb 08, 2016 6:56 pm
by Matchpoint
So OD is +/- 0.000"
and ID is +/- ).019"
is what is sounds like.

First thing I would do is double check your cad file.

Re: Question about size correction

Posted: Mon Feb 08, 2016 9:04 pm
by snakesrules
Hello,
my cad file is very basic , nothing simpler than a cylinder with a hole inside ...
And yes , outter diameter is ok ( 0.1mm is ok for me ) but inner is 0.5mm from original size so my question is about that difference .
Do i need to apply a coefficient when designing holes in my parts ?

Re: Question about size correction

Posted: Tue Feb 09, 2016 10:00 am
by Robin
Okay I got it wrong, but 0.5 mm on a diameter is probably 0.25 mm on one side and 0.25mm on the other. That is not bad.