How to make a venier scale ?

compact8

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I have got a tilt & swivel vice which is quite well made in all regards except for the swivel venier scale block which is a piece of junk ( second picture ). The markings are not equally spaced ! I am thinking about re-marking it but I have never done anything alike before. Grateful if you guys can share some thoughts. I have a hobby lathe ( Emco Compact 8 ) and mill ( Emco FB2 ) so equipment wise I should be ready. Only the knowledge and skill are lacking.
 

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Verniers aren't supposed to be "evenly" spaced. One scale will have (for example) ten marks per inch, the other will have nine- that allows you to divide each mark by ten. Or 5/4, or 25/24, and so on. Degree scales may be 6/5 to give minutes. They can do logs or radians. Vernier scales are a beautiful thing.


VernierscaleHow_a_vernier_scale_works.gif
 
I'm looking at your second picture and the vernier scale looks quite good to me. It's calibrated in seconds of a degree, so 60 marks on either side. A vernier scale for linear measurements is equally spaced, but not the same spacing as your main scale.
 
Perhaps this close-up picture will illustrate the issue better. On the left is the venier for the tilt angle ( good ) and the right is that for the swivel ( bad ). The misalignment and asymmetry of the swivel venier scale is quite obvious.

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It looks like 60 on both sides of both scales aligns with 19 when zeroed, so it looks right to me. Read it from both sides of zero and split the difference?
 
Both scales look good to me. I believe the problem is reading them. On your 7789 picture, you look for the zero on the top scale. That is the Venier scale, look down and that goes just beyond to 26 degrees. Go to the left until the lines both top and bottom line up. That is the bottom 20 degrees line those lines up with the 21-minute line. Why 21 minutes? Because each space on the Venier scales is 3 minutes apart. Where as the bottom scale each space is a degree apart. You can also double check by going to 27 degrees. Then go to the right and line up the scales. It appears to be at the bottom 30 or 29 degree scale. Can't quite tell, must be the angle, so I'm going to go for the 29 degree and subtract the 3 tics to zero. That is 9 minutes from 30 degrees which comes out to 21 minutes. This is tricky to read since you are dealing with both degrees and increments of 3 minutes. When you set your angles, you need to look straight on. That is why I can't read the scale on your first picture, it's at an angle. Practice will help a lot. I hope this explanation makes sense.
 
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