I have two surface gauges.

[-Matt-]

Not a brag! I'm sure people have more, but I was wondering if anyone could help me out on these that I have?
Firstly, which may be older?
The one on the left is taller (about 300mm) but has what appears to be a cast aluminium arm for the fine adjuster, and a repaired adjuster knob. It also has a less fussy tightening knob for angle of the main mast.

Right hand one is perhaps 250mm tall, has an older looking all steel simply cut steel adjuster arm and a step on the tightening knob. Also has the word "hardened" on the stamping which does not appear on the LH model.
Both identified as M&W No. 405

Thanks

Matt

 

[Pete.]

Can't help with your query but I can tell you that the ball end is supposed to be at the bottom. It's used for checking the squareness of items.

 

[-Matt-]

Didn't know that! Every one I've seen has had the ball at the top, wondered what it was for as it looked too detailed just to be decorative.
How does it work?

 

[gordon stephenson]

The ball was always at the top, It aids with lining up the slider (monkey) when fitting it onto the mast.

 

[brightspark]

https://www.google.co.uk/search?q=m...HXTACrYQ9C96BAgBEBs&biw=1536&bih=727&dpr=1.25

 

[Parm]

I’ve got two also, one is an old but brand new eclipse gauge, still in its original box.

Will be putting it up for sale soon

 

[-Matt-]

https://www.google.co.uk/search?q=m...HXTACrYQ9C96BAgBEBs&biw=1536&bih=727&dpr=1.25

Well helps a bit, clicking the shopping tab shows what they might be worth at least.

 

[Pete.]

The ball was always at the top, It aids with lining up the slider (monkey) when fitting it onto the mast.

It may well do - but that's not why it's there. It could be that the ball is kept up top to prevent the surface getting scuffed or damaged in normal use but IMO it's mostly put that way by the uninformed.

To use the ball end you lean the mast back with the ball lowest so that it can touch the part. A dial gauge/DTI mounted higher on the rod also touches the part but higher up. Now you pivot the gauge by rolling it around the ball and watch the DTI to see the highest reading. You use comparative checks to determine how square/out of square your part is. A cylindrical square really helps here as a reference piece, making one of those is a reasonably straightforward lathe project.

This youtube clip shows the basics of it except that he uses a separate ball trapped in the front vee of the surface gauge.