Construction of a Vernier

You didn't look very hard:

http://en.wikipedia.org/wiki/Vernier_scale

Thank you. I saw that site but it didn't give any useful information on how to actually construct such a scale. I saw that site and several others. Its practical advice on actually making a scale that I need.

You could just buy a used one. They can be found pretty cheap. Here's one for 30 pounds (whatever a pound is)

http://www.ebay.co.uk/itm/401136-Precision-Universal-Bevel-Magnifier-Vernier-Adjustable-Protractor-0-360-/291038773632?pt=UK_Measuring_Tools_Levels&hash=item43c3434180

Of course, it's on the UK site, so their circles probably have 360 imperial degrees rather than good American degrees, but there must be a conversion. Anyway, seeing that one would show you how to do it, and you could probably sell that one for about as much as you paid (minus the shipping).

Thank you. I saw that on E Bay. The idea is not to buy one but to learn how to build one from scratch. A pound is what is used in England as money. It used to be divided into 20 shillings and each shilling divided into 12 pence. Each of these were divided into 4 farthings. Then England went decimal and the pound was divided into 100 pence. All very confusing to a young yank when confronted with that system the first time. I remember asking if a pound weighed a pound. The teacher thought I was trying to be smart.

There also grads, 400 of which make a circle.

A degree is a degree, and someone here might just be a degree short. Rather than use the old-fashioned vernier, why not use an optical encoder to digitally convert rotation to bits, (and computer converts that back to degrees, minutes, seconds, and what have you).

Of course there are other devices than optical encoder (this is also slightly dated).

"A degree is a degree, and someone here might just be a degree short."

!!!

Why not ask Del why he doesn't just buy a shotgun instead of wasting all that time making those gorgeous Yew bows by hand? Who needs Yew bows, anyway? Anyone? Would you say Del is a degree short, too? How about all the other craftsmen and artisans here on CR4 who enjoy making otherwise archaic, 'useless,' outdated, obsolete works? Why bother restoring a '55 Chevy? Who needs '55 Chevys? How about the joy of learning new things? Of creating a finely crafted tool when it would have been far easier to slip on down to Harbor Freight and buy a piece of imported Chinese sh!t? Dude, you've sooo missed the point of his post.

Well, at least I can see I did touch some nerves there. I am not saying throw out the old stuff, because the sextant of old was indeed a glorious instrument, with craftsmanship far beyond what can be had now, unless one has the skills, time, and intent to do so himself. I am just saying that there might be some modern tools that could be utilized to make the thing even higher in resolution, if one knew how to implement that. I do not.

I like people who learned any craft to the point of fine art. It shows something about their character, and I would trust someone like that to build a large project much more than someone with lesser dedication to details. But thanks for reminding me why we are all here.

Truly, each thing we make with our own hands, do for ourselves, or test on our own, leads to deeper understanding of how to operate in the present world, or in a world where "technology" is gone. Knowledge is indestructible if you can pass it along, but piling it up in one place is just so much cow manure.

So thanks again, for helpful suggestions? Again how to read the Augsburger scale with zigzag vernier? I could not exactly figure it out?

An optical encoder would hardly allow "simple surveying, measuring star positions and teaching my grandson some simple skills".

You can teach your grandson immense amounts of simple skills with a plastic protractor that can be had for less than one US dollar. On the other hand, the sextant of Tycho Brahe would be priceless. So for one a few dollars, 10 arcsecond precision is totally out of reach, or is it?

Suppose you have a circular protractor for arcminutes, and another one for arcseconds? Now make some gears so that one rotates once per degree of main hub rotation, and the second one rotates once per 6 degrees of the middle protractor? Would you not have arcseconds as 6 degrees of the inner protractor? To make this happen, one would have to have a clockwork of gears with high precision and all in the correct ratios. Or at least have circles with sixty marks on them for the minutes and seconds.

Good luck to OP with your project. I will anticipate completed work photos.

It's pretty easy to make a rotating instrument. It's the dividing that gets complicated. Linear scales are a piece of cake, but circular? You can make a pretty simple indexing head, but you need a lathe of some sort to start.

If you look around enough junk shops, you can probably find an old drafting machine for a few bucks where somebody has stole the good linear rulers off, and then forgot the rotating part.

You could also use the motor out of an old floppy disc drive. You can buy those for a buck or two at the local Good-will computer store.

I smell a good challenge problem. A cheap and easy way to divide an acute angle into 7 increments and 6 increments.

I hope Del sees that instrument! Beautiful!

A picture is worth a thousand words. I have just played with this method and found it to be what I need, so thank you. I wonder if there are alternative ways to do the same thing. Now all I have to do is get my old eyes to cooperate when I start marking such small lines. You have been very helpful and thank you.

Instead of scribing your scale manually, use photolithographic techniques similar to those used in making printed circuit boards. If you want to try a really cool technique, use a combo of galvanic etching and plating.

Say for instance you want etch lines into brass and then backfill them with copper (not necessarily to make a vernier scale, where it is better to fill with black oxide or enamel for contrast), you can do it easily with this combination.

The nice thing about PL over manual techniques is that you can draw and edit the artwork on a computer at a scale comfortable for you and then reduce it to the actual scale when it comes time to create the lithography mask(s). Just be sure to use a program that creates vector-graphics images, as these can be arbitrarily scaled without introducing 'jaggies'. There is a lot online about all of these techniques (and more) and far too much to cover here. Check it out if you're interested.

Thank you. I will certainly check it out but my first reaction is that I will probably be in over my head. Still, you never know if you can really swim till the water gets over your head. More research coming up. Thanks

Please note that if you go for a transverse goniometric design, the diagonals can only be straight line segments if the *spacing* between adjacent circulars is a function of radius.

Or

If the spacing between circulars is uniform, the diagonals cannot be straight lines.

Why? In both cases, the diagonals must intersect the circulars at equi-angle intervals, else your scale will have a cyclic inaccuracy with a period of one diagonal. Draw a series of evenly-spaced concentric circles and consider that a straight diagonal is a section of a chord. If you draw the complete chord you can see that it does not intersect the inner circles at uniform angular intervals when the circles are evenly spaced.

I'm sure this is clear as mud but I'm writing from my mobe and cannot include illustrations at this time.

Making the "tiny" little lines is one thing, for us older gents, reading them is quite another!

I have a question about reading the Augsberger vernier: I see it between I think 34 and 35 (degrees), and then there are six vertical lines, ten horizontal lines, and with diagonals. Is each vertical line considered to be 15 arc minutes? and is each horizontal line an indication of how many arc minutes to add? If ten divisions, explain how this is read, please.

34 to 35 degrees is divided by 6 divisions of 10 minutes and there is 10 horizontal divisions giving a reading of 1 minute each line.

Wow, I really should try sleeping at night, instead of here in the day time. I had six division of 15 minutes each somehow adds up to 60 minutes. OOps. Thanks for clearing my noggin. I was totally stumped, still trying to figure out how they arrived at 10 arcseconds. The answer is that they did not.

For what purpose?

Score one for a good question. Mostly for knowing how its done and then for some simple surveying, measuring star positions and teaching my grandson some simple skills. Even though I am retired I still have a drive to learn new skills.

Learning how to make some of these instruments is really fascinating.

As a drafting excercise in university we were required to make a linear vernier. That was an interestinng and simple construction to make the basic scales. (Now, my drafting skills where not so great, so the lines wobbled a bit, but at least you saw the method. Using screw feeds and engravers would proviced far better accuracy.)

Thanks for your reply. I had thought of this method. At the time I thought it would be more complicated than making a simple vernier scale but I might re-examine the question and see if it ties in with what I am trying to do.

I am reminded of a microscopes' travel mechanism. I know it's not what you asked but it would still be a fine challenge to machine a worm wheel of correct diameter and number of teeth to make the graduated drive knobs from a microscope meaningful in degrees.

Jim