After completion of first project the NEU 3D Laboratory decided on working some medical operational instrument with thin features and “tendon retractor” is chosen.
From the design aspect this instrument has some very important features which has to be kept and some features can be arranged for the convenience of the doctor. Engineering point of view the instrument is a long stick with a very short tip and a non-slip handle.
Firstly problem to tackle is the strength difference in between hospital grade steel and PLA. The solution to this problem is to design the instrument thicker, but in this case the advising doctor insisting on how important the thickness of the instrument. So we start talking about how much this instrument goes under forces also making a %100 infill on the print will give us some more strength.
As a laboratory we do not want to loose time on post processing of the prints so the non-slip handle must be designed and printed in a way that it will not damage the operation gloves of the doctor. Considering the working tolerances of the 3D printer the fillets drawn also made some improvements after couple of prints.
The short tip on the instrument is the main problem, because if there is no fillet on the inside corner the tip is to weak to pull anything if there is a large fillet to give strength to the tip then the instrument becomes useless in medical aspect. The solution was not to alter the original design a lot and increase the length of the tip and give it a nice support with a fillet inside of the corner.
After 4 different versions are drawn and printed we decided the third design is the best fit for the purpose of the instrument and started experimenting on the build quality and have the end product after couple of prints.