? about Lathe Chuck Keys

[Splat]

I did not receive a 7/16" chuck key for the Bison 3-jaw chuck I got with my Heavy 10. I figure to make my own from a 1/2" drive socket extension but have a question about the actual squared key. My chuck has its key holes squared at the corners, not true 90º corners. Do I need to make the key squared on the edges (don't know the technical term for this) or should I mill it square to 7/16"? I figure squaring down the corners of the key makes it stronger, no? Thanks.

 

[Tony Wells]

If you mean sharp corners, then the objective is to move the stress point away from the inside corners of the socket. That's where it would be most prone to crack. So if you want, break the edges on your square.

 

[Ray C]

BTW: The contour you are talking about is called a "Bevel" i.e. beveling the edges is equivalent to "breaking the corners". In terms of CAD, a bevel is specified by a width -unlike a radiused edge (called a Chamfer) that is specified with a radius dimension.

Side note: Make the chuck wrench of low or medium hardness material so it does not wear-out the corresponding socket. Wrenches are cheap, worn out chucks cost money to fix...

Ray

 

[Splat]

Beveling! Yep, forgot about that. Thanks Ray and Tony. I'll bevel them down enough to have the square fit snugly, yet still be able to be removed.

 

[Tony Wells]

Ray, a chamfer is not rounded, but straight. A chamfer is symmetrical whereas a bevel need not be. Normally you will see a bevel called out as a given angle and either a length of the longest side orthogonal to the part axis or in the case of much lathe work, a bevel diameter as it breaks out on a face.

 

[Ray C]

No reason to doubt you and I'll check into why my CAD program seems to enforce the rules that I described... As I think about it, I agree with you -but took it for granted my CAD program was "all knowing"... Hmmm, a mystery to resolve...


Ray

Ray, a chamfer is not rounded, but straight. A chamfer is symmetrical whereas a bevel need not be. Normally you will see a bevel called out as a given angle and either a length of the longest side orthogonal to the part axis or in the case of much lathe work, a bevel diameter as it breaks out on a face.

 

[Ray C]

OK, my bad. -Sorry... I had a senior moment. Fillets are rounded and specified with a radius. Chamfers are flat and specified with a distance. My apologies...


Ray

No reason to doubt you and I'll check into why my CAD program seems to enforce the rules that I described... As I think about it, I agree with you -but took it for granted my CAD program was "all knowing"... Hmmm, a mystery to resolve...


Ray

 

[Tony Wells]

No problem Ray....it's easy to mix things up. I remember as a young man having a terrible time getting the difference between a bevel and a chamfer, seeing that technically, there are times they are both proper terminology for a particular feature. I've often wondered how the draftsman decides how to call it out. I'm sure there are standards that cover it. I know there is an ANSI drafting standard, but it's been so long that details like that are long gone from this feeble mind.

 

[Ray C]

Thanks for softening the blow but trust me... it was a senior moment -sad that they happen in the early 50's.


-rc

No problem Ray....it's easy to mix things up. I remember as a young man having a terrible time getting the difference between a bevel and a chamfer, seeing that technically, there are times they are both proper terminology for a particular feature. I've often wondered how the draftsman decides how to call it out. I'm sure there are standards that cover it. I know there is an ANSI drafting standard, but it's been so long that details like that are long gone from this feeble mind.

 

[Tony Wells]

Believe me Ray....I know the exact feeling. I just have this somewhat futile hope that as things in life slow down it gets better, but I really have my doubts. You and I are about the same age, so I know of what you speak and also how it feels to realize that not too many years ago, things that were childsplay mentally now are either totally impossible, or massively difficult.