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Drawing sheet for a POM gear

Question asked by Eg Gloo on Mar 27, 2017
Latest reply on Mar 28, 2017 by Dennis Dohogne

Hi all,


I'm trying to design a 28 teeth POM gear for an education project. We'll need about 3,000 units, so we decided injection moulding is probably the best way to go. I have several questions:


1) The injection moulder's draft angle is 4 degrees - is it too big for POM gears?


2) I have produced a drawing sheet, but I can't seem to specify the draft angle. Is it typically acceptable to specify the draft angle as a note?


3) Usually, what tolerances are acceptable for POM gears? Is 0.05mm (linear? angular?) too tight?


4) Are tolerances usually specified for each dimension or stated as a note on the sheet?


5) Are fillets needed around the teeth?


Here's the sheet so far:


spur gear_am2a.JPG

Does it look adequate for manufacturing?


Any help appreciated.




A 4 degree draft angle is too big, so I'll find a manufacturer that can do 0.5 degree.


spur gear_am2a.JPG