How would you cut this?

[j ferguson]

This is a jig for drilling transverse holes in brass stand-offs, the kind that are used to stack pcb boards in electronic devices. They are hexagonal and the ones I'm using have sides which are 0.100 inch across the face. My plan was to mill to the depth that the flat needs to be in both parts, then use a 60 Degree chamfer bit to cut the angle. The 60 degree bits I see on-line all have very sharp points and I wonder if one of these will cut all the way to the flat. I suppose I could grind the nose flat to get rid of the point, but do you think I need to. Material will be 6061 T6 - mostly because I have a lot of that around.

FWIW, the model was made with OnShape which is a cloud solid modeling CAD application which is free so long as you are comfortable with your work being accessible to all of their users. I love it.

 

[RJSakowski]

I would simplify the jig by just cutting a slot .2" wide and .17" deep. The top plate would then just be a flat plate, thick enough to act as a drill bushing and with the two clamping holes and the drill guide. For more than just a few uses, the top plate could be hardened tool steel like O1.

 

[Winegrower]

The drilled hole would be on the flat in the OP, RJ’s guide would put it on the vertex.

But really, I would use a square end mill and tip the part.

 

[RJSakowski]

The drilled hole would be on the flat in the OP, RJ’s guide would put it on the vertex.

But really, I would use a square end mill and tip the part.

Actually, it does put it on the flat. The slot is .2" wide which is the distance across the points and .17" deep which is the distance across the flats. The standoff can only fit one way.

 

[pontiac428]

Yep, RJ figured it out spot on!

 

[Winegrower]

Yep, I surrender!

 

[j ferguson]

Bravo, RJ, the perfect solution and it saves a bunch of time. My spouse constantly reminds me that the things I design could be simpler.

 

[pontiac428]

A good machinist is a lazy machinist, as I once heard from an old hand in the shop. That is a great example of what he meant!

 

[Eyerelief]

A good machinist is a lazy machinist, as I once heard from an old hand in the shop. That is a great example of what he meant!

I’m half way there!! I got the lazy part down. Now if I can just find a way to turn all this exemplary laziness into good machining. Something easy, like a pill or mixing two flavors of kool-aid.

 

[pontiac428]

Oh jeez, I meant making a rectangular slot instead of a hexagonal one. The "lazy" shortcut to the same practical ends. I wasn't saying anyone was being lazy, just that the lazy solution works and saves trouble sometimes!