# Dti Suggestions For Newbie



## JPower6210 (Jul 17, 2015)

Hi All-  I need to buy a DTI and of course the options are endless.  Any suggestions for a reasonable quality, reasonable price unit?  What, as a beginner, should I be looking for in travel, resolution, etc.  Thanks!

JP


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## T Bredehoft (Jul 17, 2015)

DTI, is that a Digital Test Indicator?  I'd much sooner have one with a needle, its so much easier to visualize the movement with a needle.

If a DTI is something else (I'm one of the old timers) my apologies, but I'll stand by needles.

Oops. I never thought of *DIAL* test indicator........mia culpa.


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## JPower6210 (Jul 17, 2015)

I may not be calling it the right thing. But Dial Test Indicator is what I was thinking-  with a needle- for indicating, trimming, etc.


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## ogberi (Jul 17, 2015)

I may be incorrect, but I was taught that a Dial Indicator (DI) generally reads .001" per graduation, and has 1/4" or more of movement.   Dial Test Indicators (DTI) generally measure .0005 or less per graduation, and have limited measuring range.  

DI's are used for "fairly accurate" work, whereas DTI's are used for really accurate work.   When centering work in the 4 jaw chuck that needs to be dead-nuts accurate, I'll start with the DI (.001" graduations), and get the runout (needle movement) as small as possible.  Then I switch to the DTI (.0005" graduations), and refine the centering of the workpiece until it shows as small a movement as possible.  

DI's are available in digital flavors, but I dislike them personally.  I prefer mechanical DI's  with a needle, because  it shows more than increments of .0005".  

As for which ones to get?  I use cheapie indicators from Harbor Freight.  They're inexpensive (Around $14-15 or so) for a mechanical DI, and I have 3 or 4 of those.  I bought a DTI from Little Machine Shop, 0-15-0 (max deviation of .03" on either side of zero), with .0005" graduations.  I think it was around $30 or so.  It's not a Starrett, but it works for me and has proven accurate enough for my shop.   I have an old Federal DTI that I need to send off for repair, but the hobby fund is depleted.  

I highly recommend a Noga type indicator holder, with the single locking knob.  I bought one on sale about a month ago, and I love it.  They're around $40 or so at LMS, and worth every penny.  I've no complaints about mine.  Beats the heck out of the non-articulated type that have two locking knobs.   Indicators and magnetic base indicator holders are available all over the internet, and they're useful for far more than just holding an indicator.  I mount my camcorder on them, my Nikon DSLR, use them to position chip deflectors when fly cutting, etc, etc.  Handy little things.    

Also, if you have a lathe, one of the inexpensive back-mounting magnets for a DI is a great thing.  Sticks to the ways,  you position the carriage, dial the indicator to zero, and you can return to the same point repeatedly.  I prefer it to the depth stop on my lathe, unless I'm making multiples of an item.  You can power feed against the indicator without crashing the machine (provided you don't crash the tool into the shoulder), but power feeding into a hard carriage stop gets expensive in a hurry.  

Just my $.02


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## RJSakowski (Jul 17, 2015)

T Bredehoft said:


> DTI, is that a Digital Test Indicator?  I'd much sooner have one with a needle, its so much easier to visualize the movement with a needle.
> 
> If a DTI is something else (I'm one of the old timers) my apologies, but I'll stand by needles.



Dial indicators have a plunger that moves in and out of a housing which is connected to a rack and pinion mechanism that converts the linear distance to a rotary distance on the dial face.  Travel or measurement range can be as short as 1/8" or into multiple inches.

A test indicator has a lever which moves through an arc which is coupled with a mechanism that rotates the dial.  The lever is adjustable for angle and in best practice, is adjusted so the movement is in the direction of the desired measurement to avoid a cosine error.  Travel is limited to a few tens of thousandths or less.

Either can be obtained  in varying resolutions.  I have dial indicators  with .001"/div., .0005"/div., and .0001"/div. and I have test indicators with .001 "/div. and .0001"/div.

Bob


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## Wreck™Wreck (Jul 17, 2015)

A lever arm indicator is useful if one is finding the center of a very small hole or a small feature where a plunger indicator will not fit, if you insist on making parts to tenths  then by all means spend some money. Otherwise just use a plain cheap indicator.

If you are chasing tenths on a lathe you will not live long enough to get it right, buy a cylindrical grinder.


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## Doubleeboy (Jul 17, 2015)

Cry once and get an Interapid, they are repairable, take a hit and keep working.  15 years or so I have had same one, hit the floor (concrete) twice, still accurate.  Conversely you could buy the Chinese type for under $50, they are not repairable and do not last.  Long Island Indicator has a great web page talking about the various brands, If I lost or ruined my Interapid 312b I would buy another in a minute.

michael


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## astjp2 (Jul 17, 2015)

Compac, Alaina, Brown & Sharp, Tessa, these are all good indicators.  I bought a few used one on Ebay, had to send most of the out to get repaired but it was money well spent.  Tim


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## mikey (Jul 17, 2015)

JPower6210 said:


> Hi All-  I need to buy a DTI and of course the options are endless.  Any suggestions for a reasonable quality, reasonable price unit?  What, as a beginner, should I be looking for in travel, resolution, etc.  Thanks!
> 
> JP



I'm going to assume you know what you mean when you say you need a DTI. In all likelihood this means you intend to use it on a mill to tram it or align your vise. You can get by with cheap Chinese stuff or you can buy good stuff that will last your lifetime and is repairable; I prefer the latter type. I would buy at least one that reads in 0.0005" units with a 0.060" range and it would be a Swiss unit like a Compac 214GA. Similar units are made by TESA, Interapid and Brown and Sharpe. My 214GA is going on 20 years now and it is buttery smooth, repeatable and accurate. 

Watch ebay. If not, Amazon usually undersells most retailers.


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## brino (Jul 17, 2015)

JPower6210 said:


> What, as a beginner, should I be looking for in travel, resolution, etc.



Hi JP,

Some of that answer depends on what you need it for. Are you squaring a vice (or the entire table) on a mill? or checking lathe spindle run out? or something else?
I find I use a Dial Indicator almost every time in in the shop, but use the Dial Test Indicator only a few times a year.

-brino


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## royesses (Jul 18, 2015)

Maybe middle of the road? - Mitutoyo DTI I've been looking at:
http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=1JAG31NA25MT368GAXT4

I have the $30 DTI from Little Machine Shop  as mentioned by ogberi and it does work well.

I have the Mitutoyo 2776S Dial Indicator and really like it:
http://www.amazon.com/Mitutoyo-2776...qid=1437191997&sr=8-1&keywords=mitutoyo+2776s

I also have a couple of China cheapies DI's and a Noga magnetic base. Got the Noga when on sale at Enco and a 20% off coupon code.I use the cheapies when there is a possibility of damage from operator error.


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## thomas s (Jul 18, 2015)

Operator error yes I have had a few one of them was with a nice  Starret dial indicator. thomas s


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## Wreck™Wreck (Jul 18, 2015)

thomas s said:


> Operator error yes I have had a few one of them was with a nice  Starret dial indicator. thomas s


Don't turn the spindle on with an indicator still in it, this never ends well.


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## Bill C. (Jul 18, 2015)

I bought a Starrett years ago. It has had it accidental falls over the years but has been very good to me. 

When I started there weren't many brands out there or known to me.  Starrett and Brown & Sharpe were the most popular brands in the late 1960's.


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## RJSakowski (Jul 18, 2015)

Wreck™Wreck said:


> Don't turn the spindle on with an indicator still in it, this never ends well.


+1 Wreck™Wreck.
I use a digital tenths reading dial indicator in the Tormach for setting my tool comp.  I always leave the spindle lock on and the spindle interlock activated when the indicator is in the collet.  A real problem happened when I accidentally hit the down arrow while in Mach 3.  The dial indicator crashed into the table and stalled the Z axis drive.  Fortunately, I was able to take the indicator apart and straighten the bent coupling band and restore the indicator to service.  Unfortunately, I don't know how to lock out the down arrow keys to prevent that from happening again.

Bob


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## joshua43214 (Jul 20, 2015)

I have a soft spot for Mitutoyo. I suggest getting a Mitutoyo indicator and mic.
I keep a premium Shars (the black face model) kinda perma mounted on my lathe in a Noga holder. I use it instead of the dials when advancing the cross slide. I have found it to be remarkably accurate and I cut to the line with confidence using it. It does occasionally stick a bit, you want to always tap lightly on the face to make sure it is settled, and lightly pull the plunger out a bit and let it drop.
I also suggest the Browne and Sharp shock proof dial caliper as a daily beater. Don't buy a cheap digital unless it has a low battery indicator (most cheap ones don't). They will start to give bad readings before the face starts to dim. Either get a good (and expensive) unit or use a dial caliper (this goes for mics as well).
A small dovetail mounted dial test indicator is almost irreplaceable on the mill for centering over holes.


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## stupoty (Jul 21, 2015)

I have a mixture of acuracies and range,

The 0.0001 inch ones can be a pain unless you have got it close witgg a 0.001 indicator first.  A lot of the 1/10000 ones have about 1/8" of travle. 

As somone said a pointer analogue type clock is handy due to batteries and seeing it get towards its mark.  If i'm using tthe clock as a soft stop for threading or turning i find the pointer much easier to use vs the digital.  

If you do get a digital i have found the mititoyo ones are very good and the batteries last well (opps i left it on for 5 days i shold switch it off, as aposed to looking for new batteries 

Stuart


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## Wreck™Wreck (Jul 21, 2015)

RJSakowski said:


> +1 Wreck™Wreck.
> I use a digital tenths reading dial indicator in the Tormach for setting my tool comp.  I always leave the spindle lock on and the spindle interlock activated when the indicator is in the collet.  A real problem happened when I accidentally hit the down arrow while in Mach 3.  The dial indicator crashed into the table and stalled the Z axis drive.  Fortunately, I was able to take the indicator apart and straighten the bent coupling band and restore the indicator to service.  Unfortunately, I don't know how to lock out the down arrow keys to prevent that from happening again.
> 
> Bob


Ouch, if I did that on the 40 X 20 Fadal we have here the indicator would be in many pieces before the Z axis servo would stall (-:


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## RJSakowski (Jul 21, 2015)

Wreck™Wreck said:


> Ouch, if I did that on the 40 X 20 Fadal we have here the indicator would be in many pieces before the Z axis servo would stall (-:


That is one advantage to having an anemic machine!  I think my heart crashed harder than the machine.  I was sure it was toast but the 3/8" shaft took it.  It did shove the pointer up further than it was ever intended to go, bending the bronze strip that coupled it to the digital scale.  I had to pull it apart to fix.  Don't want to ever go through that again!

Bob


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## Wreck™Wreck (Jul 21, 2015)

RJSakowski said:


> That is one advantage to having an anemic machine!  I think my heart crashed harder than the machine.  I was sure it was toast but the 3/8" shaft took it.  It did shove the pointer up further than it was ever intended to go, bending the bronze strip that coupled it to the digital scale.  I had to pull it apart to fix.  Don't want to ever go through that again!
> 
> Bob


We ran 11,000 aluminum parts through that mill in Feb. of this year, 1 1/2" 6061 aluminum rounds 1 1/2" l0ng, one end had a 1/4" wide X 7/8" deep slot across the center 1/4-20 X 1/2" deep tapped hole in the other end. Six parts in V fixtures in 3 vices. Face mill to square the ends, . ran 020 X .020 chamfer around each part. The end mill Manufacturer recomended that we run the slotting OP at 17.000 rpm, 165 IPM feed rate. This mill has a max 10,000 RPM spindle, it worked yet was slow and made  a lot of noise


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## RJSakowski (Jul 21, 2015)

Wreck™Wreck said:


> We ran 11,000 aluminum parts through that mill in Feb. of this year, 1 1/2" 6061 aluminum rounds 1 1/2" l0ng, one end had a 1/4" wide X 7/8" deep slot across the center 1/4-20 X 1/2" deep tapped hole in the other end. Six parts in V fixtures in 3 vices. Face mill to square the ends, . ran 020 X .020 chamfer around each part. The end mill Manufacturer recomended that we run the slotting OP at 17.000 rpm, 165 IPM feed rate. This mill has a max 10,000 RPM spindle, it worked yet was slow and made  a lot of noise



It's a different world!


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## bfd (Oct 18, 2016)

.0005" is a good accuracy with a .030 plus minus swing interapid  is a very good tool. Ive have found these at pawn shops for good prices, make sure it works by running it through its paces slowly gently andwatch for sticking and a return to zero. slam it a couple of times and watch for zero return (not too hard) bill


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