More than likely a No.7 drill diam seems about right.
Letter and Number drills are as far as I know an old UK anomaly, not used much nowadays .... listed nicely in my 35 yr old Zeuss book (now that has been a value for money purchase)
I have a precision one ... steel plate with brass inserts for each hole
- accurately drilled for drills 1/64" to 1/2"
If I were making one, I'd get a piece of 1/4" thick perspex or similar and drill the holes.
Both UK and US - probably more common in US these days than in UK.
I made a gauge that's basically a long triangular slot in a piece of sheet steel. Slide the unknown drill down the slot until it stops, and read the imperial size on the left or metric on the right. I also put some yellow paint on all the metric drills.
You should patent that idea. It's a goodun.
I don't know how well any gauges work for masonry bits, though. The size of the hole seems to vary wildly depending on age of bit, manufacturer, density of material being drilled and pressure applied.
I may be imagining it but high quality bits (DeWalt) seem to make a more precise hole than cheapos (ScrewFix Titan, Wilko, PP). Odd, because I've heard people say masonry bits are one type where you can afford to skimp on quality.
Alex
Thanks. I found a picture of my gauge: http:/i43.tinypic.com/18kirp.jpg
Bit late for a patent:
Does anyone make one with Imperial and Metric on the same gauge? Our workshop uses both, since we repair very old vehicles from anywhere in the world, e.g. an 1869 fire engine.
world, e.g. an 1869 fire engine.
That axmister one is double sided.
Yes - as Clive said.
"Imperial and metric graduations" - which are found by flipping it over.
world, e.g. an 1869 fire engine.
You could have 4 scales on a slot type, or 8 if the metal's wider, but isnt it easier to just use metric and have a lookup table? I tend to treat all my bits as if they were metric. Perhaps I should rephrase that.
NT
easier to just use metric and have a lookup table? I tend to treat all my bits as if they were metric. Perhaps I should rephrase that.
I would find it much slower to look at a table than to simply read off say
13/64ths and put the drill away. I seem to need to sort out a hundred drills quite often when people misfile them. Same with bolts. I have made a slot gauge for bolts from 1/16th to 1.25" and have a single table in ascending diameter for metric, Whitworth, unified, and BA, since we use all of those.
it easier to just use metric and have a lookup table? I tend to treat all my bits as if they were metric. Perhaps I should rephrase that.
13/64ths and put the drill away. I seem to need to sort out a hundred drills quite often when people misfile them.have a single table in ascending diameter for metric, Whitworth, unified, and BA, since we use all of those.
I guess with a long scale you can fit all the markings you want on. Each scale in a different colour should make life easier.
NT
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