How to make an accurate layout

[justCNCit]

Currently in training to be a machinist, we just finished term 1 where we learn to layout and cut/mill/turn various projects. I never understood laying out very well.

Well, I understand it, but it doesn't work well for me in my home shop. I'm laying out the bolt holes in 2" square tubing right now, and my punch marks are not that accurate. I'm having a hard time with centering holes properly and my marks are usually off by about a 1/64".

So, does anybody else here have some superior layout abilities that could help me out by explaining some tips/pointers.

[Mcgyver]

what are you using to layout? if its a scale, square and scribe, unless your eyes are incredible, how much better where you hoping for?

you can do high class layout work, but the next level up is layout with a surface plate and height gauge. this will get your lines to withine a couple of thou, you can usually pick the lines up accurately with a prick punch or to keep it within a thou or two use an optical centre punch like "on-mark" spread the mark with centre punch before the going to the drill press. generally, start the hole with a spotting drill with the work held in the vice and the vice hand held held (not clamped, I always have a large angle clamped to the table for safety)

remember, if you need to hold a thou, its not really layout work. For the highest accuracy work you should be using tool makers buttons, gauge blocks and setting up with an indicator.