Finding center

[drizzle]

I have a 1.5" piece of 1" solid bar that I need to drill and tap. I have a precision tool makers vise that is missing the part that the bolt screws into. I also need to drill a hole in the side for the dowel pin to go through. I dont have a lathe.

 

[BaronJ]

Hi Drizzle,


Does this help ? Its intended to find and mark the centre of a bar.

 

[JimDawson]

Do you have a mill and an edge finder?

 

[drizzle]

i have a mill, no edge finder yet and no DRO yet. I'm sure I can find it with the old school way and if I am off a C hair it will be ok but want to practice doing it the machinist way and testing to see have precise I can be.

 

[JimDawson]

Well, the ''machinist'' way is to use an edge finder. But since you don't have one, an endmill shank (or any straight rod) will suffice. Just touch the sides of the rod to the part in the X & Y directions, and move over 1/2 the diameter of the rod + 1/2 the diameter of the part and you're on center.

The other method is to use a tri-square, scribe two lines about 90° apart, and where they cross in the center is center.

 

[drizzle]

Well, the ''machinist'' way is to use an edge finder. But since you don't have one, an endmill shank (or any straight rod) will suffice. Just touch the sides of the rod to the part in the X & Y directions, and move over 1/2 the diameter of the rod + 1/2 the diameter of the part and you're on center.

The other method is to use a tri-square, scribe two lines about 90° apart, and where they cross in the center is center.

aaaaaaannnnd how do I calculate what half the diameter is and then mark that location?

 

[RJSakowski]

If drilling a cross hole, a V block can be used. Adjust the block until the drill bit is centered on the bottom of the V. and clamp the block. Place the shaft in the V and spot with a spotting drill or center drill. Drill your hole to size.

A tool like this can be used to find the center of a shaft,

If using Jim's method, remember to account for any backlash. I would buy the edge finders They are cheap and accurate and c;lose to essential for setup work on the mill

 

[higgite]

If you're trying to align the spindle on the radial center of the rod to drill the cross hole, follow what others have told you already. If you want align the spindle with the center of the end of the rod to drill a concentric longitudinal hole, you now have the perfect excuse to buy a coaxial indicator. I wouldn't leave home without it.

Tom

 

[Bob Korves]

The cross pin and nut that tightens to the underside of the toolmaker's vise is a pretty easy home shop project. There are no critical dimensions. Make that vise fully functional again...

Also, for me, designing and making custom parts to make tooling and machines whole again (or better than new!) is highly satisfying work.

 

[P. Waller]

If drilling a cross hole, a V block can be used. Adjust the block until the drill bit is centered on the bottom of the V. and clamp the block. Place the shaft in the V and spot with a spotting drill or center drill. Drill your hole to size.

A tool like this can be used to find the center of a shaft,

If using Jim's method, remember to account for any backlash. I would buy the edge finders They are cheap and accurate and c;lose to essential for setup work on the mill

Someone gave me one of these about 20 years ago, I found it about the most worthless tool that I have ever owned, it went straight into the scrap.