Question for the Imperialists

[Hilton Ralphs]

Thanks John, those are the ones I'm looking at.

[Edward Clarke]

I spoke somewhat in error. I don't think I've ever seen a 10-32 bolt.

10-32 screws/bolts are used in computer rack and panel systems. I use a lot of them in my business.

[lowell holmes]

10-32 screws/bolts are used in computer rack and panel systems. I use a lot of them in my business.

That is interesting. I'm used to 10-24 bolts used in electrical devices, don't recall seeing them elsewhere. With them being used in electrical boxes, it makes sense that you would find #10 bolts in computer items and that the fine threads be used.

[Hilton Ralphs]

I suggest one of these if you are a visual type of person. I have several extras, PM me if you want one.

Short follow up to say that the above Bolt Gauge arrived safely in South Africa. Big heads up to Steve for kindly sending this to me. I find woodworkers (especially over here) to be the most friendliest and helpful bunch of people.

Thank you!

[Steve Rozmiarek]

You are welcome Hilton, hope it's slightly useful at least!

[Eric Brown]

Hi Hilton. The sizes of sheet metal is roughly based on how many sheets stack up to 1" thick. I say roughly because there are ferrous and non-ferrous sizes that are slightly different. Wire gages are also roughly based on the same principle. That is why the numbers get smaller as the size gets larger. Screws are typically made from wire or rod and the size is based on the material used. To make matters even more strange, our pipe sizes are based on lead pipes. When they started making them out of steel the wall thickness could be thinner than the lead ones. Then they made different thicknesses of the steel pipe and called them schedules. Example: A schedule 80 is much thicker (about twice) as a schedule 40. So our nominal pipe size doesn't even match inside or outside measurements. Tubing is closer, but there are still different wall thicknesses. Even England used the inch system as can be seen on antique tools. I worked on a Henry Brown brace (Sheffield) that had a 1/4-18 left handed thread. As I had to make a new nut, it took a while to find a tap supplier for this. I read once that the threads used for screws and bolts have been made in almost every pitch at one time or another. Because of demand, certain sizes became standard usually with a fine and coarse version. Nails are another matter. Hope this helps a little.

[Hilton Ralphs]

Thanks Eric!

I understand more why most of the world moved to the Metric system.