Stick on metric vernier scales ?

AndrewC · Post by **AndrewC** » Thu Mar 19, 2009 3:44 pm

Have any of you ever come across any stick on linear vernier scales ?

Andrew

elf · Post by **elf** » Thu Mar 19, 2009 10:43 pm

I haven't seen any. Would an inkjet or laser printed one on plastic laminate be accurate enough?

augusthouse · Post by **augusthouse** » Thu Mar 19, 2009 10:55 pm

Andrew,

Double-sided picture framer's tape is good for sticking flat surfaces together. It is whisper thin and strong.

Craig

AndrewC · Post by **AndrewC** » Fri Mar 20, 2009 12:44 am

elf wrote:I haven't seen any. Would an inkjet or laser printed one on plastic laminate be accurate enough?

Well in principle all you need is the vernier with 9 divisions for the main scales 10, so it might be worth a try. I could try and make one on my mill but it seems a lot of repetitive work - perhaps I should just build a CNC engraver !

I did find a scale on eBay but it seemed ridiculously expensive. I'll just keep a search open for a while and see if anything pops up.

rjlittlefield · Post by **rjlittlefield** » Fri Mar 20, 2009 8:58 am

I printed one on paper and taped it next to the dial of my screw table. To get the scale right, I pulled the image into Photoshop and ran a few cycles of tweak-and-try with the numbers in the Image Size box, until the printed version lined up correctly. That was easy enough.

But there turned out to be a subtlety that I had not anticipated. The dial was just a hair smaller than the ring that I added the vernier scale to. That, plus the thickness of the paper, meant that the vernier scale was not in the same "plane" as the reference scale.

The difference wasn't much, but it turned out to be enough that parallax was a problem. If I moved my head, a different set of marks lined up. This same thing happens with an ordinary screw micrometer, but in that case it's so obvious that the user quickly learns to shift things around to get a nice perpendicular view. With this table set up for focus stacking, it wasn't easy to do that because of surrounding parts. Eventually I decided that the whole idea was more trouble than it was worth and stopped paying attention to the vernier.

In a different setup, it might work fine.

--Rik