I’ve finally decided to start compiling some of my personal shop notes here to share with you. Because I am no expert, please don’t take this information as gospel. I’ll try to include my sources of information where possible.
The appearance of this section may also change over time as I get more organized.
Copy Scale Chart (rev. D) This pdf table provides percentage values for enlargements and reductions between most major scales that you might need. If you’re enlarging or reducing drawings, find the original scale on the left and locate the desired scale along the top. Where they cross, that’s the percentage to put into the copier or to provide to the copy service.
Just beware that copy machines may not be very accurate in enlargements or reductions. I’ve found that it’s best to scan an image and to resize it using on a computer using a program like Photoshop, saving it back out and then taking it to a service to print on large format paper.
Drill Size Scale Chart This pdf table relates common small drill bit sizes #60 through #80 to the sizes of holes they make at different scales. It also provides actual bit size measurements in inches and millimeters, plus the closest wire gauge size. Most common scale sizes are provided (at least the most likely that I am going to use).
The way I use this chart is to look at the closest hole size I am interested in scale and use it to determine which drill size I need. So, at 1/8″=1′ or 1:96-scale, a 2″ diameter hole (closest is 2.02″ in the chart) requires a#75 drill bit and if you are going to insert a wire into it, you’ll need approximately 24 gauge wire, though it will be slightly loose in the hole.