Flathead screw taper depth

[Fueler]

Search didn't help so if I am repeating something please forgive.

The bolt feature assumes that the flat head taper is a sharp edge.

This does not take into account the part highlighted in blue in the picture.

As a result of not taking this section into consideration the bolt sits proud above the surface.

The interesting part of this is that the bolts/screws listed and do not take this section into the length specification.

You can measure this section or download the part from McMaster.

Then use the measurement tool.

In this case a 3/8-16 bolt has a head diameter of .781 and the blue section is .0117 or .012 rounded off.

I need a way to move that taper down so the head is actually flush with the surface or slightly recessed.

Anyone got a way to do that?

Note that just making the top diameter larger to drop the bolt will work but looks like doo doo. Not cool.

[Fueler]

yeah, ok. Talked myself through it.

Scenario 1: Using the move command you can move the taper down the .012 listed.

This results in a top taper diameter of .801. (measured w the measure tool)

The Flathead will now sit flush with the surface.

If that is satisfactory it's all done.

Scenario 2: If a counterbore with a taper is required machine a counter bore with a bit more OD clearance and the .012-.013 depth.

Then use the hole command and position it at the bottom of the counterbore.

I do think this upper thickness should be added into the bolt feature.

[etfrench]

It would be simpler to just use the hole tool and specify the correct diameter for the countersink, 0.8013413096648997 in.

[TheCADWhisperer]

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@Fueler wrote:

yeah, ok. Talked myself through it.

If that is satisfactory it's all done.

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Can you File>Export and then Attach the *.f3d file of your "solution" here?

[Fueler]

ETFRENCH

Yes, that is the obvious solution that only works if you know that number.

I do not possess a math background deep enough to figure out what that number should be.

My visual way was to use the tools on hand to determine the thickness of the head by zooming in and measuring the height of it.

I then move the hole taper face down the amount of that height via the move command.

The hole auto widens at the top and the bolt now sits flush.

Used the measure tool again on the hole diameter.

This tells me what the diameter should be for future use.

[etfrench]

You're working way  too hard 😀  Simply project the screw body to a sketch. Extend the tapered sides to the top line. Measure.  Create a user parameter.