Indexing Bolt Hole Patterns

[Mercedes107]

I need to put a 4 hole bolt pattern on each end of a shaft. Problem is the hole patterns need to be indexed precisely to each other. Shaft is about 4 in diameter and 4" in length. Any ideas on how to do this.

 

[cbellanca]

calculate the x-y locations of the holes and drill through the 4". May need a pulley length drill.

 

[francist]

No idea what you have for tools or machines, but to lay them out by hand you could:

-clamp the shaft in a pair of V-blocks, set on surface plate, and scribe each end at half the diameter using a height gauge or surface gauge on the plate.
-scribe the desired radius, punch to mark, and drill the four holes (two on each end)
-take two close fitting pins and stick them into the holes on one end of the shaft
-return to the v-blocks and surface plate, but instead of orienting the pins horizontally like before, bring them up against the edge of a square so that they're now at 90 degrees vertical (six o clock and twelve o clock)
-take the height gauge that you used before, scribe both ends again at half height of the shaft and mark as before.

All you've done is scribe two horizontals on the first setup, and then using a couple of pins as registers to butt up against a known square you've oriented the piece at ninety-degrees so that you can mark two more horizontals for the second set of holes.

Let's see what other methods come in, there's quite a few ways to skin this cat.

-frank

 

[Jubil]

No idea what you have for tools or machines, but to lay them out by hand you could:

-clamp the shaft in a pair of V-blocks, set on surface plate, and scribe each end at half the diameter using a height gauge or surface gauge on the plate.
-scribe the desired radius, punch to mark, and drill the four holes (two on each end)
-take two close fitting pins and stick them into the holes on one end of the shaft
-return to the v-blocks and surface plate, but instead of orienting the pins horizontally like before, bring them up against the edge of a square so that they're now at 90 degrees vertical (six o clock and twelve o clock)
-take the height gauge that you used before, scribe both ends again at half height of the shaft and mark as before.

All you've done is scribe two horizontals on the first setup, and then using a couple of pins as registers to butt up against a known square you've oriented the piece at ninety-degrees so that you can mark two more horizontals for the second set of holes.

Let's see what other methods come in, there's quite a few ways to skin this cat.

-frank

Frank beat me to it. He can type faster than me lol.

Chuck

 

[mmcmdl]

Drill your 4 holes in one side and use 2 pins to locate your second side . That is assuming that your ends are square .

 

[Mercedes107]

Some interesting ideas. One of the things I would like to leverage is the DRO on my mill can place 4 equally spaced holes much more accurately than if I were to layout, scribe and punch and finding the center of the shaft is not a problem. The challenge is indexing that first hole to the hole on the one on the opposite side.

I like the idea of scribeing the lines with a V block and surface plate, but I'm thinking to take advantage of the DRO, just scribe a radial line on each end. Mount the shaft onto a rotary table, position the table on center and move out the appropriate radius on the X mill axis. Index the rotary table until the radial scribed line lines up with the mill spindle. Then I can either use the DRO or the rotary table to drill the 4 holes.

I will need to find some bigger V blocks for this.

 

[Mercedes107]

Drill your 4 holes in one side and use 2 pins to locate your second side . That is assuming that your ends are square .

Not sure what you mean by using 2 pins to locate second side. I should be able to get the ends as square as my milling machine vice can hold them.

 

[TakeDeadAim]

To align the pattern on one end to the pattern on the other end you can put dowel pins in the holes on the first end then use them to index the holes square to the vise. Then find center of the part and use the DRO to drill the pattern in the second end.

 

[Shootymacshootface]

Drill your 4 holes in one side and use 2 pins to locate your second side . That is assuming that your ends are square .

I like this one, but you could take it a little futher by finishing one end then bolt a square to the finished end and stand it up in a mill vice and locate the holes on the other end.

 

[jbobb1]

Is the 4" diameter critical? Wondering if you could mill 2 flats, wide enough, lengthwise 180 deg. apart. Clamping on these flats in the vice would accurately index.