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Shaft/Shoulder undercut

Feb 5, 2016
Hello guys,
I wanted to ask suggestions/ideas for manufacturing of shafts,
typically when we make aluminum shafts and we have to put an undercut for when we grind the shaft and the shoulder, the company has used the 45 Degree 0.060 wide undercut shown on the "Orig" image
My boss wants to make new undercuts that are small on other tooling that we want to make out of steel(a2)
so I drew a drawing that shows the "roughed" shaft and shoulder with an initial undercut.
then tool number 2 comes in and creates the undercut as shown on picture "relief 2"
Question is, is there tooling that can do that(or something similar to that)? or do we need to make our own tooling for this?
my dimensions on the drawings are just as reference so any recommendations if they are do-able or forget about doing something like this?

Any help appreciated.



May 26, 2011
Shreveport/Louisiana USA
We have came across drawings with undercuts like pictured in this post, not often but have had to deal with them so I am very much curios how others handled these as well.

We got around it by doing a conventional undercut on the OD and never had an issue, this was because the customer didn't make the drawings, they were OEM so customer didn't know any better. Undercut it old school way, ground it and shipped it.
Of course that wouldn't fly for a customer who wants it made TO DRAWING.


Isn't that bad design?Now you have 2 stress concentration points
instead of a minimal radius?Might find some failures happening down the road.


Jul 3, 2013
How much comes off the faces? If your boss is open to your input then I'd offer some. I'd come up with a different way of doing that. Maybe with a altered OD turning tool (maybe milling the stick part of a 35deg diamond tool at 10 or 15deg) allowing you to do this in one shot. Obviously it wouldn't be exactly what you have now but achieve the main objective, a square corner after grinding.

You better make a few of those tools on account of the tink factor. I'd be looking at something in a carbide insert the operator could just change.