Hi - I have a lot of trouble trying to drill accurately spaced holes, and have eventually hit on this method. Those folks who do any electronics will be aware of "stripboard", previously known as Veroboard, which has a 0.1" grid of 1mm holes with copper strips joining them. It's also available plain, without the copper.
You can often find a pair of holes the required distance apart, within 0.1mm or so. So you drill one 1mm pilot hole, then put a 1mm rod through the board into it, and then drill another 1mm pilot hole through the appropriate hole in the board. Then you can use the two pilot holes for drilling whatever size holes you need. Here's a chart of the various spacings available from a 10x10 grid.
I've just thought that the method could be used to drill a pair of accurate holes in the jaws of a pair of digital calipers. Then, with a bit of subtraction, you could adjust the jaws for whatever spacing you wanted. I've not tried that yet.
Just in case it's any use. I'm sure there are a thousand better ways!
Graham R.
You can often find a pair of holes the required distance apart, within 0.1mm or so. So you drill one 1mm pilot hole, then put a 1mm rod through the board into it, and then drill another 1mm pilot hole through the appropriate hole in the board. Then you can use the two pilot holes for drilling whatever size holes you need. Here's a chart of the various spacings available from a 10x10 grid.
I've just thought that the method could be used to drill a pair of accurate holes in the jaws of a pair of digital calipers. Then, with a bit of subtraction, you could adjust the jaws for whatever spacing you wanted. I've not tried that yet.
Just in case it's any use. I'm sure there are a thousand better ways!
Graham R.