Dial test indicator vs Dial indicator

[martianParticipant @martian]

If you can only buy one, which would you get and why?

Also would imperial or metric make much difference?

I’ve spent rather a lot on a lathe and milling machine recently. When I sell my old Myford ML10 I may be able to justify both but for now I want to avoid any complaints.

 

Martin

[DiogenesParticipant @diogenes]

Lever indicator – much more versatile, unless you want to measure deviation over multiple milli centimetres – hardly ever use a gauge other than for measuring table travel etc.

Choice of units? – whatever you feel most comfortable with.

[JasonBModerator @jasonb]

lever type for me too, although I use a plunger type for certain jobs like clocking work in the 4-jaw I could do it with a lever.

As said what do you usually work and think in? get the units that match though most of the time mine is used more to show movement and that does not need to be quantified as zero is zero in any unit of measure.

Don’t forget to add the purchase of a magnetic base and some way to mount in the mill spindle etc

[Bo’sunParticipant @bosun58570]

Be aware of “Cosine error” if trying to measure with a DTI.  My Mitutoyo DTI came with a table claiming to offset the Cosine error,  but I’ve yet to check it’s accuracy.  Also, a DTI has limited range (+/- 0.8mm in most cases).  If you’re not going to use the DTI to measure with, metric or imperial probably doesn’t matter much (in my opinion), although to match your machine graduations might be wise.  I’ve heard that the “teardrop” type stylus is less prone to Cosine error, but by how much I don’t know.  I think at the end of the day, they both have their uses.

[Julie AnnParticipant @julieann]

A dial test indicator (DTI), with a lever, is intended for jobs like centring work on the lathe in a 4-jaw chuck or on a faceplate. I also use mine for setting the vice square on the milling machine table. A dial indicator, with a plunger, is intended for making measurements. It is normally used on a surface plate as a reference and may be zero’d using gauge blocks.

If I was to buy only one I would go for a DTI as I use mine far more often than a dial indicator. Units are irrelevant as one is only looking for zero movement of the needle.

In my toolstore there are multiple versions of both in metric and imperial. But I have a metric DTI permanently mounted on a magnetic base and left in the workshop ready for instant use.

Julie

[old martParticipant @oldmart]

I agree with everything JA says, the lever type has more general uses if only one is to be bought. I have a couple of the plunger types which never seem to get used and in the museum odd and ends cupboard are about half a dozen more, including one which has accessory levers with it. I firmly believe that the plunger type are best used with the axis vertical as if used horizontally, there is always the risk of the weak spring not being able to overcome friction leading to errors. The tips of many Verdict lever type indicators are shaped like seabirds eggs rather than spherical to reduce the cosine error. I do not use the lever type to measure with, so any length of end can be used.

[peak4Participant @peak4]

Similar to others really, if I could only have one instrument, it would be a lever DTI for a (w)hole variety of reasons.
Fortunately over the years, I’ve acquired far too many of both styles in a variety of sizes, both imperial & metric.
I’d be incline to chose the units to align with your machinery.
Some of the ones I have are in excellent condition, others less so; for that reason be a bit careful buying second hand, but I’ve obtained perfectly serviceable far eastern plunger clocks brand new from as little as £4.50 each to use in one off applications, such as this mill tramming unit.

There’s more than one way to skin a cat, though no felines were hurt whilst setting this quick lash-up from some of my more tatty examples.

In spite of their appearance, both these clocks work fine, one has a very light action, the other needs a fair push, and thus a very rigid mounting; the lever attachments are available in straight and right angled varieties.
Beware wobbly levers in second hand DTIs though.

Bill

[HuubParticipant @huub]

Last year I dropped again my Mitutoyo DTI and had to replace it for the third time. I bought a new one from a dutch certified reseller and also 2 AliExpress 10 € versions. I compared the Mitutoyo to the 2 Chinese ones and found that the Chinese ones are doing a pretty good job. I had to adjust the play on one of the levers but that was a few second job.

I also compared my Mitutoyo plunjer type with 2 Chinese (HBM) ones I have and they perform equally OK.

Now I use the Chinese ones for non critical daily jobs and the Mitutoyos for more demanding jobs.

I must say, the readability of the Mitutoyos is far better (non glare scales), they feel more reliable and the dials rotate more smoothly. When I make pictures or video’s the Mitutoyos are also the preferred tools. If money wasn’t an issue, I would only use Mitutoyo.

[VicParticipant @vic]

If the earlier comments have persuaded you to buy a DTI then this site may be of interest.

https://longislandindicator.com/table-of-contents/

When it comes to measuring equipment, I was advised many years ago not to buy cheap stuff but to only buy well known brands. I’ve been lucky enough to acquire only Swiss and German DTI’s and didn’t have to pay a lot at the time.

[Howard LewisParticipant @howardlewis46836]

Although I have more than one of each type, the one that sees most use is a finger clock, mostly used for centering work in the four jaw.

With that, work can be centered, or the vice, or work, clocked on the mill to 0.0005″  (0.00125 mm) or slightly better.

At work, a finger clock was used to set the height of each insert in the big inserted tooth cutters used to machine the cylinder heads and cylinder blocks.

Also, a finger clock can be used to centre a bore, where a plunger type requires the lever set up to do this.

The one place where a plunger type is used (permanently fitted) is in the Jacques Maurel Tension Meter for the bandsaw blades.

So, on balance if only none was available, the choice would be for a finger clock, although it has a shorter range than a plunger type.

Howard

[Neil LickfoldParticipant @neillickfold44316]

I always try to encourage the apprentices to by Girod long stylus indicator with a 2mm ruby stylus and the small bezel diameter. I recommend these, because they last a very long time, and can get inside or a lot longer reach to indicate the inside of parts.  They are only about 0.8mm of range but is enough when used as a comparator. The other piece I recommend now, is a hydraulic locking arm indicator stand. They are alot more ridged than the Noga type, which I have a few of.

Last week for the 1st time in a long while I did use a plunger type DTI when setting a piece with the 4 jaw chuck , it was a rectangular block and was 6mm different from one side to the other 3mm offset effectively. The plunger meant that I only needed one setting and could to the pairs quite easily for getting it central.

The finger type are also very good on the mill for indicating a bore or for tramming the spindle to the workpiece or table etc.

[DiogenesParticipant @diogenes]

..whilst there are undoubtedly benefits in having ‘pro’ measuring gear, for ‘everyday setting’ any half-decent indicator will do to get started with.

– as suggested elsewhere above you will need various holders and a magnetic base to mount it on – and IMO making a ‘good purchase’ here requires more care than choice of indicator

– first off, I don’t think the cheap generic ‘push-button’ type bases are generally worth the metal they are made of – buy one with a proper switch and an advertised holding capacity of at least 40kilos minimum.

The ‘arm’ & ‘clamping’ arrangements of the cheaper offerings are invariably poor – I prefer solid metal bars because it’s easier to re-make, upgrade, or customise the holding arrangements than it is to remedy a poorly made flexible arm.

You’ll have to hunt around for the best price, it varies wildly as far as I can see (- I have a dark blue-and-red one which is no better than my light-blue-and-white one tho’ it cost twice as much).

..work beckons..

[JasonBModerator @jasonb]

I suppose anyone having difficulty deciding which of the two to get due to funds will be looking at the far eastern ones rather than a £200 name brand one. The time one will last is really based on amount of use so one in a commercial enviroment may see a lot more use than a hobby workshop.

My main use of the plunger is setting the 4-jaw. Either setting a ctr mark/hole to minimal runout but also if it is an eccentric that I am turning I find the larger range of a plunger can be used to set the work to give the actual eccentric movement. this is why the plunger one lives with it’s mag base stuck to the headstock.

Sometimes it is just nice to have both

 

[JasonBModerator @jasonb]

When I started out in the hobby I made one of these and it worked to machine a couple of Stuart engines.

[Dave SParticipant @daves59043]

Interesting that if I could only have 1 it would be a plunger type.
I generally use that more than my DTI – probably because to use the DTI I have to be within the amount of it’s travel which is quite limited.

Dave

[Bo’sunParticipant @bosun58570]

I tend to agree Dave.  While a couple of posts suggest a DTI is fine for centring work in a four jaw chuck (and for some that may well be the case), I find the range of a DTI too limiting.  Unless of course I’ve missed a trick along the way?

[JasonBModerator @jasonb]

The trick is to use something pointed in the tailstock to get you close and/or use the rings on the face of the chuck to get the chuck jaws reasonably even on opposite sides then you should be within DTI range when you start to clock it.

[Dave SParticipant @daves59043]

On “none round” stock in the lathe I find the ability to just pull the plunger out of the way for centering in a 4 jaw useful.

I indicate the end of a bore with the plunger at an angle – I’m not interested in the measurement, only that the comparison is zero.

My DTI is 0.0001” mitutoyo – if I actually need to get bang on then I use it, otherwise the plunger clock is faster / less faffy for me.

On the mill I more often use a wiggler than a Dial gage of either sort.

Dave

 

[Martin ConnellyParticipant @martinconnelly55370]

DTI and big error? Find the high spot and reduce it. Reposition the DTI. Repeat until eccentricity is low enough to suit your needs.

Martin C

[DiogenesParticipant @diogenes]

I think that regular and repeated use of whichever instrument ‘trains’ the eye and brain to recognise appropriate proportions, doesn’t it?

– more often than not I’m ‘within range’ by eye, but I don’t think it’s a clever skill that I’ve learnt, just some relict benefit from whatever ancestral activity gifted us with unusually strong binocular vision; some subconscious ‘Instructions’ still being passed on to accompany the Tools we’ve inherited.

[PeteParticipant @pete41194]

Just starting out or with limited funds, a plunge type Dial Indicator. It can do some of what the lever type DTI’s can do. I use a DI every time I use my lathe to measure carriage travel since I don’t use the top slide for that. I bought a good Starrett DI and magnetic base first, and went quite a few years before buying a couple of decent DTI’s. And they will do some tasks that a DI really can’t do, or not easily without more accessories like peak4’s 90 degree attachment. With more than a lathe and having a mill, a DTI as soon as you can. They can do a lot that might be almost impossible with a DI, do so easier, faster and much more accurate. Centering round OD’s & ID’s under the spindle with a DTI’s adjustable for angle lever is a big part of the difference.

Long Island Dial Indicator Repair has excellent information, but I don’t agree with there assessment about Mitutoyo DTI’s. Mine have been excellent. Although I haven’t yet used any of the Swiss or German DTI’s. However, DTI’s aren’t really meant as a tool for accurate linear measurements. I’d trust mine over a few thou, past that, the DI’s are more accurate. DTI’s are more of a zero indicated movement on the needle type of tool for most uses.

One metrology term is given far too much importance by many than it should. A tools resolution, if it’s divisions are within what the user wants or needs, the resolution it has after that should be ignored. It has zero bearing on the tools actual and far more important Repeatability and Accuracy. A tools Resolution does not mean nor does it have anything to do with how accurate it is. All it really means is how many digits there are after the decimal point.

I’ve got an extremely good Mit. digital caliper with a resolution and .0005″ digit. That’s wishful thinking to even think it’s that accurate because it isn’t. No digital caliper I know of can actually measure down to that level of accuracy just due to there mechanical design. On my gauge blocks I have seen it happen sometimes, but that’s random luck and proves that it can’t do so every time. Just because the display says so, doesn’t mean that’s what the actual measurement is.

Those cheaper magnetic bases are somewhat ok, and I usually use one for rougher tasks. When used on a horizontal surface, the magnetic force is just about enough. On a vertical or even worse, an overhead surface, not at all. It’s only how long and not if your going to have it happen, and almost for sure destroy any DI or DTI that it’s being used with. If I had to start over, I think I’d buy just the magnetic base from Noga and build all the rest if funds were short. A couple lengths of silver steel / drill rod, a bit of additional steel, lathe, mill, knurling tool and rotary table could replicate anything my Starrett or Mit. magnetic bases have.

[SillyOldDufferModerator @sillyoldduffer]

The “If I can only buy one” constraint is unfortunate.   These are two different tools and it’s worth owning both.  Mine get used roughly 50/50.

I’m not impressed by the “buy the best you can afford” argument.  If spending more than you can afford on an expensive plunger DTI means you can’t have a lever instrument as well, then think again.  Think about what you need rather than trust what might be a outdated cliche, or inappropriate in your circumstances.

In the past there was a sharp divide between good and “too cheap” tools, with very little in the middle. Thus it paid to buy the best.   Much less true today: manufacturing improvements have resulted in a plethora of mid-range tools.   Though not as well-made as top of the range, mid-range tools are affordable and “good enough” for many purposes.  Times have changed.

Anyway, I suggest two inexpensive instruments bought to last a few years are more valuable than one expensive item bought to last forever, or going without!   To my mind buying for immediate value makes sense in a hobby workshop, where delicate tools might be damaged and we don’t have to work against the clock.

I started with a plunger DTI, and soon realised a lever was highly desirable too.  Both were bought inexpensively as disposables about 15 years ago.  If either becomes unfit for purpose I shall simply replace them, but they’re still going strong.

Yes, it’s nice to own nice tools, but insisting on them is a good way of wasting money, unwise if one is on a tight budget…

Dave

[Michael GilliganParticipant @michaelgilligan61133]

Some very good points made by Dave … to which I would only add that both of these instruments are [by their very names] Indicators.

Sensitivity and Repeatability are therefore paramount … so handle the instrument before you commit to buying it. [no guarantee of longevity, but the ‘feel’ should be instinctively right]

MichaelG.

[Clive FosterParticipant @clivefoster55965]

My plunger type instruments see very little use these days but the lever type are as busy as ever.

My go to lever is a small dial 1 thou resolution Verdict bought 50 years (ish) ago on special offer at a Model Engineer Exhibition. Which i think shows some benefit from buying good equipment right from day one. I have others in both imperial and metric calibrations, including the incredibly tedious 1/10 thou and equivalent metric ones. In all honesty it is little trouble to estimate changes of the order of a tenth a tenth when using 1 thou lever unit. Which is mostly good enough for 12 inch to the foot scale guys and gals like me.

Although plenty of heat and light has been generated by discussions of cosine error the whole concept is pretty much irrelevant. A lever indicator is a zero detector. No more and no less. Graduations merely allow you to decide when you have reached the acceptable error in your set up.

A plunger type is a difference measuring instrument not a true linear measurement device. Simply counting the turns and reading the dial should be pretty close but ultimately you have to calibrate the difference if you need to be really right. Folk tend to forget how small a thou or 0.02 mm is let alone a tenth or 0.002 mm. Tedium in calibration is inevitable.

Really it’s quite remarkable how good job can be done with quite primitive instruments.

My starter that came in the box of bits with a “2 packs of Players and 3 beers” Portass “S” lathe.

2 bob back in the day I think.

Calibrations are 1 thou. I checked it and got a tenth or less error over the middle 5 thou. Not quite so good at the ends but still well within useful.

Clive

[martianParticipant @martian]

Thanks for your replies. I think a lever type will be most useful for my current needs.

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