DTI - mechanical or digital?

[AdeV]

Ever since I started this machining lark, I've been a fan of regular mechanical dial indicators. But, I'm curious, as to which really is the better - mechanical or digital?

FWIW, I work almost exclusively in Imperial (unusual for someone my age) - except temperature, somehow I never could get my head around Fahrenheit...

[John Stevenson]

Mechanical, for one there are tolerances on digital stuff so it hard to know just what id zero.

With a mechanical unit you can split division by eye, can't do that with 0.01, is it nearer 0.01 or 0.00 ?

[andyf]

I second John's remark. It's a bit like analogue v digital watches - if you want to leave home at 11.15, and it's now 10.50, you can measure how much time you have left by looking at an analogue dial, whereas arithmetic comes in with a digital one. And when you are watching a reading vary with a view to taking some action as a result (for example, truing something up in a 4-jaw), it's much easier to compare the readings on opposite jaws as you adjust them if you don't have to do any sums, and also to see just how much a dial pointer is twitching when things are almost right.

Andy

[AdeV]

OK, that's me convinced

Speaking of splitting the division, I just trammed the mill back in (since the vice is off, and it's done a load of heavy work), and sure enough, had to split the division quite a bit to get it bob on. That certainly wouldn't have been possible with a digital DTI.

Andy - the only time that seems to fail me is when I'm tramming the mill in the Y-axis (nodding the head) - I always get it arse backwards somehow... As usual, it took a good 15 mins to sort that direction out; yet only 5 mins to do the X-axis... I must make me a Bogs-style tramming tool...

[andyf]

.....Andy - the only time that seems to fail me is when I'm tramming the mill in the Y-axis (nodding the head) - I always get it arse backwards somehow... As usual, it took a good 15 mins to sort that direction out; yet only 5 mins to do the X-axis... I must make me a Bogs-style tramming tool...

Isn't there a simple answer to that one? Stand at the side of the machine to do the Y axis  

Andy

[John Stevenson]

Just done a search on the specs of these, can't find the cheap ones but Mitutoyo publishes their digital one as having a resolution of 0.01mm or 0.0005" but accuracy is 0.02 or 0.001"

So we have to take this as plus or minus so although it reads to the nearest thou it's only accurate to 2 thou.

That's a lot of split divisions for a lot more money than a clock faced one.

John S.

[AdeV]

Isn't there a simple answer to that one? Stand at the side of the machine to do the Y axis 

LOL - That's exactly what I do... but it still doesn't work 'cos I usually end up confused as to which way I'm going. Once it clicks into place, the process isn't so bad, it's just getting over the initial "what the hell? Why did that do that?? Now it's worse! Aaargh!" stage.

[John Stevenson]

Andy - the only time that seems to fail me is when I'm tramming the mill in the Y-axis (nodding the head) - I always get it arse backwards somehow... As usual, it took a good 15 mins to sort that direction out; yet only 5 mins to do the X-axis... I must make me a Bogs-style tramming tool...

Move the head towards the largest reading always.

.

[ieezitin]

Adev

Your post has struck a nerve with me.

Ever since those pesky digital calipers etc came out and was somewhat affordable I wanted a set. DRO and full blown electronic readings on my machines was just a dream, every time I was setting up for something it would flash through my mind ( if only I had real time coordinates.)
Well in the last two weeks I purchased some cheap Digiverns off ebay and started to play with ideas on mounting them, I was paying attention to people on here who have done just that taking advice and thinking of my own needs.
My synopsis>

The first thing that struck me was the accuracy, and being forced to read further to the right was without a doubt adding demands on my overloaded brain as it is!.
Then the zero feature!. You stretch out the caliper lets say 2” hit the zero button, slide it back and it reads and spits out a number then flutters + or - that. That made me not trust it. Then it says something like do not extend the caliper to quick as it may give false reading. Try using them in the cold point is you cant!. Then as I have learned you have to protect these little bits of quirky electrics from oil and swarf. Its all a load of camel gonads!.

Been using clocks, mics, verniers, height gages and the like for years, they have never lied to me ( my wife has ) they wont. When I have had a false reading its been my own nit-wit fault.

All my machines have set ups ready for clocks, as I machine and need fine measurements I whip one on and in a flash im on target!. Most of all I dont trust them!. I don’t trust electronics. Ask Toyota how much there little chip driven speedo cable is gonna cost them?

All the best.     Stuck in the stone age   Anthony.

[Artie]

Actually Anthony I dont think you are stuck in the stoneage at all. I would say you are displaying (un) common sense. 

I agree with all you have written, and I would add the following point, do you all wonder why your chinese digital stuff uses batterys fairly quickly? Also wonder why some of them come with spare batterys? My digital Mitutoyo vernier (for example) didnt flatten batterys hardly at all. It was great until I ...ah... had a moment and its life ended in a blaze of broken plastic. I then sought to replace it but opted (for cost reasons) to go chinese. Well I was surprised to see the spare battery in the case and not so surprised to need it so quickly.

I did some digging and believe it or not the cheap chinese stuff DOESNT TURN OFF when you hit the off button. It simply disables the display and has a constant drain on the battery. You get what you paid for. A bit like my old Ducati, constant trickle... if you want to ride today put on the charger yesterday, almost a mantra.... you can fix that but its part of owning a vintage Duke.... or so Im reliably told....

Ive since bought 3 sets of standard verniers and their batterys havent given me any trouble...oh right... they dont have batterys do they......

 

[John Stevenson]

Big deal, a battery is 10 pence, is the convieniance of large display digital worth 10 pence even if it only last a week.

At current labour rates 10 pence is about 10 seconds. At the end they are only a tool like others.


John S.

[kwackers]

I don't have any issues with battery life on my cheap Chinese callipers.

My height gauge for example I never turn off, typically I stick a new battery in it probably about every 18 months....

I think it's definitely a case of each to his own, but personally I think modern digital calipers are great tools. I don't know how fast you have to move them to 'outwit' them (I've tried and failed), but if nothing else the ability to switch instantly between metric and imperial, measure relative sizes etc is brilliant - mind you I am a relative newbie and thus don't have the ability to do the maths in my head like I suspect a lot of old hands have...

[ieezitin]

Big deal, a battery is 10 pence, is the convieniance of large display digital worth 10 pence even if it only last a week.

At current labour rates 10 pence is about 10 seconds. At the end they are only a tool like others.


John S.

John.

On the contrary, I don’t believe its about money or convenience.

The original question was ( which is better Digital or Mechanical? ) .

In my post the essence was trust and reliability. That’s a human emotion about something, since these little innocent measuring tools play such an important role, the information they give us is so valuable and must be correct.

Using badly engineered sub quality tooling that has ample room for errant readings, is not doing justice to our skill and hobby.  Mitutoyo and other high end digital tooling are worth every penny spent on them, why? The engineering, specs and quality materials make up for a valuable tool meant to last a lifetime if used with care. But I still personally don’t trust electrics.

So imho tools are not just tools there is a vast difference.

Kwackers.

Welcome to the forum.

I agree its nice to have at ones fingertips the ability to switch from metric to imperial, but its also important to know how to work such problems out in ones mind and use the brain. Believe it or not your brain needs exercise too if not used it will go idle.

Mind you my wife has told me more than once my brain and body are perpetually stuck in idle. So you may not want to take my advice! 


All the best.                Stuck in low range idle     Anthony.

[Artie]

Big deal, a battery is 10 pence, is the convieniance of large display digital worth 10 pence even if it only last a week.

At current labour rates 10 pence is about 10 seconds. At the end they are only a tool like others.


John S.

I think it IS a big deal John, on a sunday afternoon when you turn it on and it is flat with no battery to hand.... what do you do then?

[Dean W]

I prefer dial type measuring tools because they are definitely more reliable, from my experience, and much easier to use when it comes to seeing the big picture.  You look at the face of a dial indicator, and it's like a pie chart.  Our brains are well suited to making quick comparative analysis, which a dial face provides.  Not quite so quick with a hard number expressed in numerals, though most machinist types get used to that kind of thing from reading prints, and such.

I think it IS a big deal John, on a sunday afternoon when you turn it on and it is flat with no battery to hand.... what do you do then?

Just my opinion, (and I'm not John, nor speaking for him);  That's not really a valid argument against digital battery powered tools, in itself.  If that's the kind of tool you prefer, you simply keep extra batteries on hand.  You don't have just one lathe tool bit in your whole shop, right?  Or only one end mill.  Why keep only one battery?  These are consumable items, just like a can of soup.

Dean

[Artie]

I think it IS a big deal John, on a sunday afternoon when you turn it on and it is flat with no battery to hand.... what do you do then?

Just my opinion, (and I'm not John, nor speaking for him);  That's not really a valid argument against digital battery powered tools, in itself.  If that's the kind of tool you prefer, you simply keep extra batteries on hand.  You don't have just one lathe tool bit in your whole shop, right?  Or only one end mill.  Why keep only one battery?  These are consumable items, just like a can of soup.

Dean

Well we all live in different worlds, in my world, for me, it is indeed a valid arguement, although who you think Im arguing with is not clear to me. Your world is a different place Dean, each to their own.

I have used both styles of measuring device and I feel most comfortable with analogue dials. My experience with A (one only) brand of chinese calipers is not a definitive statement, just that, my experience. Compared with my Mitutoyo digital calipers (owned for over 10 years), it wasnt a positive experience.

I think I will leave this thread alone.

Artie

[Dean W]

Artie, it wasn't an accusation that you were arguing with someone, and I surly didn't mean it to sound that way.  "Argument" referred to the logical presentation of point and counter-point, in the manner of a debate. 
Sorry if it came off as some kind of slight.  It wasn't intended.

Dean

[DMIOM]

Going back to the original question "Analog or Digital for a DTI?"

I think for most of us its a question of what you're going to use it for.

In (very general terms) an Indicator is used to Indicate - not measure. Its use is to show if something is varying, and possibly by how much. The absolute doesn't tend to matter - its which way it varies, and trends.  A moving needle is ideal to see relative jumps. If you're clocking or centring something, a graphical indication is probably hundreds of times easier to use than a pure pure digital one - imagine trying to centre something with a pure digital indicator, watching and trying to read each value and then if its higher, is it more the the biggest I've seen so far 

On the other hand, if you're making absolute measurements (this needs to be 87.46 mm long), or a height gauge, or a CNC tool length gauge, then I'm quite comfortable using a digital instrument.  And, once I fitted my manual mill with digital DROs, rather than squinting at dials and trying to count reliably, and still watch the work - absolutely no contest!

Its quite noticeable in the professional broadcast market, which is one of the greatest embracers of digital technology, that key indicators, such as sound levels, are still done with either moving coil meters or bar graphs (and an alarm if you're approaching broadcast maxima). One of the reasons I think is that you can monitor them with peripheral vision rather than have to make them your prime focus.

So, as they say, horses for course .....

Dave

[Darren]

I agree, it's easy enough to buy a pack of 5 or ten batteries and keep them for when you need them. They have a good shelf life.

If your digi is eating batteries then throw it away. I have four, one is quite old over ten years and none of mine eat batteries and I use them all the time. My last two purchases were from Aldis, very cheap and they have auto on and off. I've never switched either of them off manually and they seem fine.

I think you need a new digi  

[75Plus]

When buying batteries for these digital tools you might consider the information provided here:

http://www.truetex.com/buttons.htm

Joe