What size dovetail cutter? Mitutoyo test indicator

[Janderso]

Looks really good Jeff!

Thanks Evan.
Having more time on my hands has really freed me up to improve some of my skills.
Having a ball.

 

[Richard King 2]

Jeff, Your ears ringing? I was talking about you and your brothers and sisters ( My Kids) in my forum.....

 

[Janderso]

Surface grinders are so cool!
This piece is 4140, heat treated and ground.

 

[Janderso]

After case hardening this base piece, I’m planning on pressing 3/8” ball bearings then surface grinding them to the same height for a precision footing.
I used a 3/8 end mill and cut .200” deep.
I figured pressing past the center line by .025” should do it.

 

[WobblyHand]

After case hardening this base piece, I’m planning on pressing 3/8” ball bearings then surface grinding them to the same height for a precision footing.
I used a 3/8 end mill and cut .200” deep.
I figured pressing past the center line by .025” should do it.

What's the advantage to adding the ball bearings? I apparently has so much to learn...

 

[Janderso]

What's the advantage to adding the ball bearings? I apparently has so much to learn...

I‘m copying Stephan’s design. The four ground balls assure clean consistent contact on the surface plate.
Plus, they will look cool

 

[dkemppai]

After case hardening this base piece, I’m planning on pressing 3/8” ball bearings then surface grinding them to the same height for a precision footing.
I used a 3/8 end mill and cut .200” deep.
I figured pressing past the center line by .025” should do it.

Looks good!

But, is .200" deep enough to give you .025"? Also, Did the end mill drill the hole under .375? If the end mill drilled over .375, maybe a 13/32 ball would do the trick?

 

[Eyerelief]

After case hardening this base piece, I’m planning on pressing 3/8” ball bearings then surface grinding them to the same height for a precision footing.
I used a 3/8 end mill and cut .200” deep.
I figured pressing past the center line by .025” should do it.

Jeff this is looking fantastic!

 

[Janderso]

Looks good!

But, is .200" deep enough to give you .025"? Also, Did the end mill drill the hole under .375? If the end mill drilled over .375, maybe a 13/32 ball would do the trick?

We’ll find out .
I didn’t want to see gaps where the radius is smaller than the hole. Is that about clear as mud?
It’s all about learning the process. I may have to epoxy them in.

 

[dkemppai]

We’ll find out .
I didn’t want to see gaps where the radius is smaller than the hole. Is that about clear as mud?
It’s all about learning the process. I may have to epoxy them in.

I don't remember the exact interference Stephan used, I do remember hearing you can get away with A LOT more than you'd expect because the contact area is so small. Something like 10 or 20 thou can work.

If you do epoxy, etch or grind the surface of the balls. Epoxy will have trouble bonding to something that smooth. The shape isn't going to help either. JB weld would probably be fine there, also cleanliness...

I can't wait to see how this turns out for you. Keep us updated!

Dan