Need help with creating a counter sunk hole.

mcconnell113

So i know exactly what scew we are using but I don't know where i would go to find the exact dimensions I would need in order to create a flush screw head once it's counter sunk. It would be this screw but different length.

 https://www.mscdirect.com/product/details/67560169?rItem=67560169

tell me if this would be correct with my thinking. first off i measured the head to be half inch diameter and i see that it is 82 degree head so id go from the top face with a sketched hole down to a 1/4 hole at 82 degrees? Also if you didnt have a screw to measure how would you know how to draw the counter sinks? Lastly what is the best way to counter sign just use fillet or have two sketch planes and loft to one another? I'll probably answer all of my own questions in the next 5 minutes.

mcconnell113

ive managed to fine the hole/countersink option but still isnt there different head angles that come into play or are they all the same. Also is it a 45 degree angle if its just automatically putting an angle in?

andrew_troup

At present, the Hole feature in Onshape dictates the head angle (I think it's currently 45 degrees)
If you want another angle, you will have to model the hole, from a sketch lying on your desired hole axis, as a Revolve/Solid/Remove

peter_hall

@andrew_troup has given you the answer. The sketch should give you the angle,size and depth you require, then revolve/solid/remove would seem to fit the bill.

mcconnell113

okay perfect thank you. I've actually done that before when i modeled a corner rounding too i just haven't messed with design in a while so the ways of going about it have slipped my mind. Thank you guys

andrew_troup

A decent countersink screw drawing would dimension the "virtual sharp" intersection of the line representing the silhouette of the cone with a line across the flat end of the screwhead. Naturally screws are not provided with a sharp edge, so the Outside Diameter of the head is always somewhat less than this. 

The reason for the VS dimension is to be able to size the countersunk hole (off the bat, and/or without having a physical screw to try) so the head will be flush.

mcconnell113

do you have an example drawing so i can visualize what you're trying to get across to me? thanks

_Ðave_

You can find all fastener dimensions in the machinery's handbook.

andrew_troup

@mcconnell113



A1 is the virtual outside diameter
A is the actual outside diameter

mcconnell113

@andrew_troup
 Thanks you so much that helps being able to see it. I successfully drew and machined the countersink.