DTI recommendations required

[asimpleparsonParticipant @asimpleparson]

[asimpleparsonParticipant @asimpleparson]

Hi all.

Can anyone suggest a DTI for using to set up work in my 4 jaw chuck? I have seen them from £10 upwards, although I wouldn't expect much at that price. What is a reasonable price to pay for such an item? Is it worth looking at second hand kit?

SP.

[Michael GilliganParticipant @michaelgilligan61133]

May I suggest that you read this very recent thread: **LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=148113&p=1

My only caveat being that Verdict is a brand name, and [despite common usage] does not exclusively refer to the lever type of indicator.

MichaelG.

.

https://mjallen.co.uk/catalogue/metrology-catalogue

Edited By Michael Gilligan on 22/12/2019 17:56:05

[Pete RimmerParticipant @peterimmer30576]

I use a plunger type dial with 1 thou markings to set stuff up in the chuck. It's plain-backed so I have it stuck to a piece of flat plate which I put in a tool post holder. If your dial gauge is too sensitive or has too little travel then it'll make for a miserable time setting stuff up.

[Howard LewisParticipant @howardlewis46836]

Since I work almost always in Imperial, my clocks are Imperial.

A plunger clock is graduated in 0.001", and for more accurate centering, I use a "Verdict" type finger clock to try to set better than the 0.0005" graduations.

The larger the dial diameter, the wider the graduations will be, so that working to closer limits will be easier.

But a larger clock, can end up fouling on the chuck jaws as you rotate it by hand.

HTH

Howard

[Tony Pratt 1Participant @tonypratt1]

I would suggest a 'lever type' DTI, as to what make or new vs pre-loved that's near an impossible question to answer. Verdict, Mercer, Starrett, Compac, Mitutoyo, etc, etc, are all good makes, if you buy off of Ebay & the item is not any good get a refund via PayPal

That being said I am using a no name clock atm which is good enough for day to day work, we have just bought a Mitutoyo for the fussier jobs

Tony

[Clive FosterParticipant @clivefoster55965]

£30 to £50 seems a sensible budget for a sound lever type DTI. As ever ArcEurotrade are a good reference point for home shop guy/gal friendly price – performance ratio. They will sell you a 1/2 thou – 0.02 mm sensitive one for £32. Plenty of choice of good looking ones on E-Bay in that range too. You can find the wrongly labeled or "nobody wants one this week" superbargains on E-Bay, Facebook, local Free-Ad sheet et al but its doubtful if the gain is worth the wait.

As Micheal says Verdict is a brand name but its the most common by far and cuts down the time spent looking. I'd be expecting a hard case and mounting accessories included, especially if buying used. Verdict rectangular bodies are generally slimmer and longer than other breeds with a shorter pointer. The small dial versions are a bit less in diameter too. Verdicts generally mount via a spigot fixed to the end opposite the lever. Many other brands have dovetails on two or three sides with one or more spigot adapters. On balance I prefer the slimmer Verdict style to the shorter, deeper modern type. But, like so many personal preferences, that may simply be because its what I'm used to and what my working style evolved to suit.

I'm also unconvinced that the extra sensitivity of 1/2 thou – 0.02 mm calibration is worth the general twitchyness and shorter operating range when compared to a 1 thou – 0.05 mm device. When looking for smallest possible movement of the needle, objectively, the difference in twich doesn't seem that noticeable. A 0.1 thou – 0.005 mm sensitivity will drive you to drink and profanity in very short order! I have one, rarely used, and make sure I've taken the calm pills before getting it out. You will see all the tool marks and surface imperfections.

Do make sure that the spigot, whether fixed Verdict style or dovetail fitting, mates up with your mount. Whether already in possession or bought along with the indicator. I'm unsure whether dovetail mounts are truly interchangeable between brands but probably safest to assume not and make sure yours comes with the appropriate spigot. Although you can use fixed magnetic mounts and carrier arms without fine screw adjustment, especially if you exploit the cross slide movement, such can rather try your patience. I would regard a switch style magnetic base and carrier arm with fine adjustment as being essential. Mine are old style Eclipse of a quality you will not find today.

Don't forget that the cross slide dial is a great help when initially setting up in the 4 jaw. Start by using the lines on the face to get the jaws roughly equal. Put a nice solid bumper block in the toolpost and set one pair of jaws horizontal. Move the cross slide so the bumper gently touches the workpiece and note the reading. Spin the chuck 180° and repeat. Set the cross slide to half the difference (remember to take out backlash) and move the jaws so the workpiece just touches with the chuck jaws gripping lightly. Repeat with the other pair of jaws. Assuming the job is round or square it will be close. Maybe a thou or three error for me. For jobs that don't need to be dead on I often leave the indicator in the box and just go round twice and re-check after final tightening of the jaws.

Clive

[VicParticipant @vic]

I read something about them on Long Island Indicator some years ago. The best are Swiss made apparently, but German DTI’s come a close second. **LINK** Surprisingly they don’t seem to think that much of Japanese and American DTI’s. These look to be a pretty good price. **LINK**

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