Lowell Component Downbearing Gauge

[John Delacour]

At 7:07 pm -0500 12/5/07, David Skolnik wrote:

>...it has been an invaluable analytical tool for me over the years, 
>and it took years to get it back on the market, even without the 
>modifications I was hoping for, including better balance and 
>magnetic feet.  If I understand John D's post, it is still more 
>accurate than the Wixey, which, given the price, I will probably 
>try, just for fun.

I didn't actually comment on the Lowell gauge; my comparison was 
between the Wixey gauge and Dale Erwin's stick of maple used with a 
stepped feeler gauge, the latter being more accurate.  The Lowell 
gauge relies on a bubble.  For less than $2 I could buy one maker's 
_cheapest_ plastic bubble gauge (radius ca. 0.2 metres) and that will 
give me a bubble movement of 2mm for 35 minutes (ie. 1/3 mm. for each 
jump on the Wixey gauge). Ground or bent glass vials are made with 
radiuses up to 100 metres (as used,for example, in the Mitutoyo 
precision level) with accuracies far exceeding our requirements.

Looking through the archives I find a posting from Phil Ford that 
suggests the Lowell vial is marked with divisions of 1/6 degree. 
Supposing the spacing for the marks on the vial to be the usual 2mm, 
each millimetre would thus show 5 minutes of angle and the vial would 
have a radius of about 1 metre.  I personally would prefer a 
considerably more sensitive vial.

JD