Digital vernier innards

[neksmerj]

Evenin' all,

I have just pulled my digital vernier to pieces, down to the last nut and bolt. Why?

I am going to cut it up and convert it into a DRO for my lathe and mill, and a height gauge, a kind of a universal jigger.

It got me thinking, how does it work. Smoke and mirrors, magnets, what?

I placed a magnet near the read head, and it had no influence, what so ever, however, place the head on a piece of ordinary steel, and I got a response.

Can some clever member fill me in. My concern is, if magnetism is the key, will cutting up the main bar with the ruler on it, stuff it up?

All responses welcome.

Regards,

Ken

[joe greiner]

Probably not a good idea until you know more about how it works. Could be measuring capacitance (like older radio tuners), so changing the amount of material on the bar would scramble the results.

Searched "digital caliper" at http://www.uspto.gov/patft/index.html and got 147 hits. Examination of the patents might provide some insight.

Joe

[QC Inspector]

With the proliferation of cheap Asian tools around why not get one for the task? There must be a similar place in the Southern Hemisphere that sells these so you can still use the caliper for what it was intended........... Well assuming you can put it back together, that is.:doh:

http://shars.com/Online_catalog.htm

Page 01 in the Measuring tools section.

[Coldamus]

There is some relevant information here.

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

[glock40sw]

Google "Shumatech" and all will be revealed.
they have pages of pictures of calipers pulled apart specificaly for use as DRO's.

[Geberle]

I beleive digital verniers use optical technology, similar to that used in an optical mouse. It reads the tiny surface details off the rule to 'measure' relative distance from its starting location. Cheap models use lousy pickups that are easily fooled if you move the jaws too fast. Hmm, that give me an idea, grab the output from a decent high precision mouse (pulled apart to gain access to the laser head offcourse) and use that for a homebrew digital scale...

[Big Shed]

Google "Shumatech" and all will be revealed.
they have pages of pictures of calipers pulled apart specificaly for use as DRO's.

Some interesting links come up in that search, thanks for that!:2tsup:

One was a reference to Harbor Freight (http://search.harborfreight.com/cpisearch/web/search.do?keyword=digital+caliper&Submit=Go) as a supplier of digital verniers, check out their range and prices, unreal!:2tsup:

[glock40sw]

I beleive digital verniers use optical technology, similar to that used in an optical mouse. It reads the tiny surface details off the rule to 'measure' relative distance from its starting location. Cheap models use lousy pickups that are easily fooled if you move the jaws too fast. Hmm, that give me an idea, grab the output from a decent high precision mouse (pulled apart to gain access to the laser head offcourse) and use that for a homebrew digital scale...

G'day.
Mouse will not work correctly. They don't have fine enough resolution.

[Geberle]

G'day.
Mouse will not work correctly. They don't have fine enough resolution.

A modern laser mouse has precision down to .0079375 mm, my digital calipers certainly ar'nt anywhere near that accurate.

[neksmerj]

mmmmm, it seems there are a few guesses here on how the Chinese digital verniers really work. Following the links suggested, shed no real light, so I am still in the dark.

Does anyone really know how they work?

Thanks for all comments,

Ken

[Mick C.]

I have seem some (most?) that work on variable capacitance. The other half of the plate of the capacitor is behind the measureing label in the face of the vernier and is useally a triangle in shape (thin one end, thick the other), as the vernier is slid along it measures the change in capacitance and converts this to a reading. I see no reason at all why it cant be cut down to suit your application. The one and only requirement for it to maintain its accuracy would be for you to make sure that the original distance from the sensor to the label (other capacitave element) remain as it was when you started. Seems to me that you dont really have to pull the whole lot apart, but rather put a few mounts in the right places and it will simply work is it does hand held.

Maybe this is more money than you were hoping to spend... but Hare aand Forbes have what you are looking for in a few lengths! have a look here--->

http://www.hareandforbes.com.au/sample_2/home.php

Then go to Metalworking, and Digital readouts and scales.

[neksmerj]

Hi Mick,

Appreciate your comments. Already have the "Chiawonese" digital vernier, cost me a wopping $12, so I have no hesitation in cutting it up.

When I have finished this little project, I will post it up.

Regards,

Ken