Author Topic: Micro DRO made from tyre tread depth gauge (Read 76022 times)

John Rudd · « **Reply #75 on:** August 17, 2011, 12:33:56 PM »

Mine arrived today...

Runs off a 3v CR20xx coin cell battery...Shame it wont accept the data plug on my remote readout...So cant tell if its compatible or not..like my scales are..Something to ~~work~~ ~~mad~~mod~~der~~ I guess

Pete. · « **Reply #76 on:** August 18, 2011, 02:32:09 AM »

These reader heads DO work with the cheap 6" digital caliper scales, coz I've tested it. Can't fit the boards onto the metal slides of the calipers though without milling a step in each side of the PCB.

saw · « **Reply #77 on:** August 18, 2011, 10:03:35 AM »

I'll got my today, but I am not shure how to build it. I have a minilathe and it don't looks exactly as the project show.

Here is a pic of my lathe.

I need a good advice how I should do.

ksor · « **Reply #78 on:** August 18, 2011, 10:33:23 AM »

I think the idea with the magnets is good - I'll use mine - when I get them - for both my mill and lathe - then the idea with the magnets is good, I think !

With the magnets you can place it whereever you want on then mill or the lathe - if it's iron of cause.

I'll make mine with magnets I'm sure.

ksor · « **Reply #79 on:** August 25, 2011, 08:43:27 AM »

Now I got mine in hand - thanks JohnC !

I dicovered a small hatch opposite the battery hatch - looke like 2 wires could be solded on the pcb !

Do some of you know what this is good for ?

Pete. · « **Reply #80 on:** August 25, 2011, 08:49:23 AM »

It's the dataport - you can run a cable to a serial interface and hook it up to a pc to make a cheap DRO, among other things.

www.yadro.de

BillTodd · « **Reply #81 on:** August 25, 2011, 09:18:57 AM »

Quote from: Pete. on August 25, 2011, 08:49:23 AM

It's the dataport - you can run a cable to a serial interface and hook it up to a pc to make a cheap DRO, among other things.

www.yadro.de

If anyone has a 'scope, I'd be interested in pictures of the waveforms etc. to see if is possible to add it to my PIC based DRO project

Bill

tumutbound · « **Reply #82 on:** August 25, 2011, 09:32:53 AM »

Quote from: BillTodd on August 25, 2011, 09:18:57 AM

If anyone has a 'scope, I'd be interested in pictures of the waveforms etc. to see if is possible to add it to my PIC based DRO project

Bill

The most commonly used protocol is this one.

ksor · « **Reply #83 on:** August 25, 2011, 09:38:59 AM »

I just tried to replace the moving "ruler" with a small "ruler"-like peace of aluminum - it seems to work too = the digits changes as I move the aluminum !

This implies that I can use all the full range of the digimeter 0-999.99 mm by just replacing the original ruler with a longer one !

I wonder what is the theory behind this small peace of magic - any link ?

Corvus corax · « **Reply #84 on:** August 25, 2011, 10:46:48 AM »

Quote from: BillTodd on August 25, 2011, 09:18:57 AM

Quote from: Pete. on August 25, 2011, 08:49:23 AM
It's the dataport - you can run a cable to a serial interface and hook it up to a pc to make a cheap DRO, among other things.

www.yadro.de

If anyone has a 'scope, I'd be interested in pictures of the waveforms etc. to see if is possible to add it to my PIC based DRO project

Bill

That's exactly what I was wondering about. I have been looking at your PIC DRO for some while now. Good work BTW!

Pete. · « **Reply #85 on:** August 25, 2011, 10:47:54 AM »

Yes you can. You can use any length scale you can find. Longest I heard of was 1.5m.

ksor · « **Reply #86 on:** August 25, 2011, 10:52:30 AM »

Quote from: Pete. on August 25, 2011, 10:47:54 AM

... any length scale ...

Yeah, but just a peace of aluminum ?

How does this work - it must have something to do with the pattern on the PCB and maybe small current circles induces in the aluminum or ... ?

John-Som · « **Reply #87 on:** August 25, 2011, 12:40:20 PM »

Forget about springs - the adaptation is easier than we all thought. As Aussie Jim pointed out why not simply put a magnet on the end of the probe. I am showing Mk l and Mk ll versions on my website and soon we will have Aussie Jim's Mk lll version on show.

John-Som

BillTodd · « **Reply #88 on:** August 25, 2011, 01:22:48 PM »

Quote from: ksor on August 25, 2011, 10:52:30 AM

Quote from: Pete. on August 25, 2011, 10:47:54 AM
... any length scale ...

Yeah, but just a peace of aluminum ?

How does this work - it must have something to do with the pattern on the PCB and maybe small current circles induces in the aluminum or ... ?

No, the slide has to have a pattern of conductive pads (it cannot be just plain) the sensor is capacitive
see:
http://madmodder.net/index.php?topic=4444.msg48960#msg48960

ksor · « **Reply #89 on:** August 25, 2011, 01:37:32 PM »

I've tried with a peace of ordinary aluminum and it worked - the digits changed as I moved the aluminum and was fixed when I hold it still.

Pete. · « **Reply #90 on:** August 25, 2011, 02:05:00 PM »

Maybe so, but plain aluminium won't have the proper pattern for the quadrature encoder to give an accurate result.

ksor · « **Reply #91 on:** August 25, 2011, 02:10:15 PM »

Quote from: Pete. on August 25, 2011, 02:05:00 PM

Maybe so, but plain aluminium won't have the proper pattern for the quadrature encoder to give an accurate result.

I see no pattern on the original slider - OK, maybe it's on the backside of the aluminum strip of the slider.

BillTodd · « **Reply #92 on:** August 25, 2011, 04:29:27 PM »

Quote from: ksor on August 25, 2011, 02:10:15 PM

Quote from: Pete. on August 25, 2011, 02:05:00 PM
Maybe so, but plain aluminium won't have the proper pattern for the quadrature encoder to give an accurate result.

I see no pattern on the original slider - OK, maybe it's on the backside of the aluminum strip of the slider.

Curious

The typical digital vernier has a plastic cover over the patterned 'pcb'

Is the aluminium strip actually aluminium or just aluminium coloured (like paint)?

A typical read-head will see almost any change of capacitance as movement, so I'm no too surprised a plain metal strip will cause the digits to change, but I would be surprised if they have found a way to 'read' the surface capacitively in a similar way an optical mouse can with reflected light.

Bill

Pete. · « **Reply #93 on:** August 26, 2011, 12:58:38 AM »

Quote from: ksor on August 25, 2011, 02:10:15 PM

Quote from: Pete. on August 25, 2011, 02:05:00 PM
Maybe so, but plain aluminium won't have the proper pattern for the quadrature encoder to give an accurate result.

I see no pattern on the original slider - OK, maybe it's on the backside of the aluminum strip of the slider.

It's under the silver sticker. The pattern itself is a stick-on part too.

Corvus corax · « **Reply #94 on:** August 30, 2011, 05:04:33 AM »

Yesterday I tried one on my mill.
Since I wanted a bit more travel I left the spring out altogether. Just gravity allowing the probe to touch the head.

Worked very well and it gave me the the full 25mm of length.

Pete. · « **Reply #95 on:** August 30, 2011, 12:07:20 PM »

I think you need the spring to keep the slider aligned. I just flattened mine so that it has very little friction.

John-Som · « **Reply #96 on:** August 30, 2011, 05:51:16 PM »

This is my Mk lll version of the Micro DRO and IMHO the best so far in terms of both ease of construction and use. As suggested by Aussie Jim I have dispensed with the use of springs to maintain contact with the lathe cross slide (or carriage) and fitted 3mm rare earth magnets to the tip of the probe.

Many thanks to Rob in Australia for the concept and Corvus Corax for bringing this useful little gizmo to our attention.

John-Som

dickda1 · « **Reply #97 on:** August 30, 2011, 07:36:38 PM »

John-Som,

Your post about using a magnet is simply brilliant!

I have some small cylindrical magnets with a appropriately sized bore that will fit my gauges. As you say, this will eliminate the need for springs.

ksor · « **Reply #98 on:** August 31, 2011, 02:30:59 AM »

> John-Som

Did you drill a hole in the magnet or ... ?

Stilldrillin · « **Reply #99 on:** August 31, 2011, 03:18:07 AM »

John.
Love your Mk lll version!

Such a simple/ clever solution......

David D

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Author Topic: Micro DRO made from tyre tread depth gauge (Read 76022 times)

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