Counterbore to specified offset from base of material?

[iakovUmrikhin]

I'd like to do counterbore holes so that the bottom of the counterbore is a designated plane.

Context: Having a plate where you want to vary the thickness but always maintain the same amount of material underneath the counterbore. So I've got a plane set at 1/4" above bottom face. I'd like to be able to set counterbore to this plane.

Alternatively, can we specify counterbore to be "offset from a surface" then pick the bottom plane?

I see this post having similar challenges but it's not quite the same- I'm trying to avoid manually entering values and if the plate thickness changes I'd have to re-enter new counterbore depth. https://forums.autodesk.com/t5/fusion-360-design-validate/how-to-set-custom-counterbore-depth-with-h...

[davebYYPCU · Accepted solution]

Are you asking for a tool enhancement?, or

how to get the job done?

Use a formula in the depth of counterbore box, will get it done, 

Material thickness  -  remanent material.

MT - 1/4”

Doesn’t need a plane or a selection routine.

Might help....

[TheCADWhisperer]

What if the material thickness is continuously variable (like a machined surface on clamping face and a cast surface on opposing face)?  The distance from counterbore face to machined clamping face should be constant (for defined fastener length).  This is a common problem with castings.  I demonstrated how to do this with Autodesk Inventor - Punch tool more than 10 years ago at Autodesk University.  I can post link to video if desired.

[davebYYPCU]

The hole tool requires a planar article to commence from.

That position is discoverable.

[iakovUmrikhin]

Thanks Dave- I was mainly asking how to get the job done but could be a tool enhancement. 

Formula works for now, I'll use that. Thanks!