Engineers level

Ian J, if you find it's not sensitive enough, you could try these folks **LINK**

I'm almost certain they are the ones I visited when I was looking for some round bubble levels for photographic use; tripod indicator.

Couldn't have been more helpful, with drawers and drawers full of assorted vials.

Bill

The travel of the bubble in the glass vial is due to the polished/ground curve put into the internal tube by experienced operators, now mostly overtaken by CNC machines which are more precise. Liquid used in the bubble tube has a slowing effect on the bubble run, wetting of the tube by the fluid/surface tension etc. Compasses are much the same as a thin liquid will not damp the movement of the card and nobody wants a wildly swinging compass card.

As I have mentioned before, a vial and level need to be accurately end for end adjusted and should be allowed to settle for a period of time between adjustments. Heat from fingers and hands and sunshine all have an effect on the adjustment and my adage is never trust a bubble !

The curve or arc of the inside of the tube is for a 20" something like 60 meters rad.if I remember correctly.. Some vials are just curved completely like in cheap builders levels.The arc is clearly visible.

Clive

No.

2mm in 45" is 0.533mm in 12", or 0.021" per foot. It's OK for woodwork but I wouldn't use it to level a lathe.

Is this thread suffering from mixed units? (Inches -v- minutes/seconds)

This is from Wikipedia

The sensitivity is an important specification for a spirit level; its accuracy depends on its sensitivity. The sensitivity of a level is given as the change of angle or gradient required to move the bubble by unit distance. If the bubble housing has graduated divisions then the sensitivity is the angle or gradient change that moves the bubble by one of these divisions. 2 mm (0.079 in) is the usual spacing for graduations; on a surveyor's level the bubble will move 2 mm when the vial is tilted about 0.005 degree. For a precision machinist level with 2mm divisions, when the vial is tilted 5 arc seconds the bubble will move one graduation. This is equivalent to movement of .0005 inches measured one foot from the pivot point; referred to as 5 ten-thousandths per foot.

Ian P

Just an update.

I decided to bite the bullet and buy the vial swarf mostly bought from Level Developments,but when I contacted them that item was not in stock and there was no plans to produce any in the near future.

So a bit more research and I think one for a Starrett level will be suitable, but not stocked by the UK branch so it's on it's way from the US (3-4 weeks !)