What dial indicator to buy?

[Cameron Reddy]

I've learned that you can't simply go out and buy a good dial indicator. It's as complicated as buying a good bandsaw.

Read a bit at http://longislandindicator.com/index.html and, oh my!

So, you guys with machine shop expertise... what type of dial indicator would you buy?

This one looks really good. But it has a different type of actuator (not certain how it works):

http://longislandindicator.com/Resources/ga.jpeg

Or how about this one?

http://longislandindicator.com/Resources/s1.jpeg

I'm thinking I want about 25-30 thousands of range and I'd like a "comparator" type model, like the first one pictured.

What do you guys think?

Oh, I have a cheap Chinese unit that is a POS. So, I'm not going there again.

[Scott T Smith]

The first indicator is a lever type, and it measures by moving the lever back and forth. The item measured is usually rotating somewhat parallel to the flat back of the indicator and lever. The second one is the rod type and it measures by moving the rod up and down; the item rotating is perpendicular to the rod.

They both have their place; typically the lever type has a limited amount of movement yet can be more precise. It works better than the rod type if the item measured is not totally smooth.

In addition to a good DI, you will want a very good magnetic base. Flexible stem ones are more versatile than the round rod bases, but the rod type is more ridged.

MSC (J&L Industrial Supply) is a good online source for machinist supplies; usually their value brands are still better than what you will find at a Harbor Freight or Enco, and they also sell the more premium brands.

[Bruce Page]

Both serve different purposes. The 1” travel indicator has more uses in the wood shop, is more durable and is also less prone to damage & dust. The Test indicator with swivel tip is more suited to machine shop work but also comes in handy for machine setup.
Which ever style you choose do not get one with less than .001 resolution.
If you’re looking at the test indicator style I would do a search on eBay for the Starrett Last Word. It is a very tough little indicator and if you get one with the attachments it is very versatile.

[Tony Shea]

Both posters were right on with their assesments. Like all fine measuring tools one cannot go wrong with Starret. But the second picture you posted is a Mitutoyo and is of very high quality as well. I would not hesitate in trusting their brand of DI. Which ever you decide you need to understand how to properly take care of your investment. Don't let it rust whatever you do.

[Mark Bosse]

Unless you want to become a machinist, go with Starrett. I am sure that at something around 50/1,000,000" (actually sort of the std today), there is something better. I don't care.

Ya, I became a machinist and I wish I had not.

[Alex Shanku]

1/4" travel, .001" resolution....small/compact to fit in tight quarters..

Although I also have a standard 1" travel dial indicator, I think 1/4" is fine for what I use it for.

[Myk Rian]

Cameron;

What are your intended uses? Then we can give better advice.

[Steven DeMars]

I spent hours & hours looking, reading & asking questions . . .

Result of all that effort was the following . . . .

I purchased a Mitutoyo #2776S. $110.98 - 1" range & 0.0005 grad

http://www.use-enco.com/CGI/INPDFF?PMPAGE=363&PMCTLG=00

I also bought additional tips & a heavy duty stand.

Steve:)

ENCO is the best place to shop IMHO . . . .

[Dave Lehnert]

I would have to ask what are you going to use it for.
Woodworking? I just have a unit I purchased from Harbor Freight. Works extremely well for tool set ups and the like.
Are you going to build the Space Shuttle? Then you may want to invest in something a little better. :D

[Cameron Reddy]

OK! I'm learning!

I can see the lever indicator being better for reading something like the roundness and trueness of a bandsaw wheel. I can also see it "riding" along a fence better than the rod type. I was thinking I needed a wheel on the end of the tip, but I can see a lever doing a better job.

I want to align my shaper fence to the miter slot. I want to make sure fences are square. I'd like to square my bandsaw blade to the table. Stuff like that.

I just ordered the TS-Aligner Industrial version from Ed Bennett. Now I need to pick out a dial indicator. Actually, I can see having both the rod and lever types.

I have the magnetic base from my POS indicator. Should I invest in one of those nifty flexible ones?

Thanks!

[Bruce Wrenn]

Dial indicators come in two sizes, AGD-1, and AGD-2.The first is a smaller instrument, and usually is limited to about 0.250" travel. Most of the common ones will be from the AGD-2 class, with 1.0" travel. For wood working, the one from HF is more than adequate. Enco (use-enco.com) almost always has the SPI ones on sale. Currently they are offering FREE SHIPPING on orders over $25. Use the code PFSFEB to get free shipping.

[george wilson]

Indicol is perhaps the most highly dial indicator,but they are very expensive. A Mit should do just fine. DO NOT get an electronic model. Starrett dial calipers' batteries apparently don't hold a charge,and they are Chinese made now,I believe.

[Bob Wingard]

I want to align my shaper fence to the miter slot. I want to make sure fences are square. I'd like to square my bandsaw blade to the table. Stuff like that.

I just ordered the TS-Aligner Industrial version from Ed Bennett. Now I need to pick out a dial indicator. Actually, I can see having both the rod and lever types.
Thanks!

When I first realized you were the same person who got my freebie steel plate with the bearings on it, I was a bit confused. Why?, I thought would you possibly want my homemade gizmo when you've just ordered the TS-Aligner ?? Ed Bennett makes a very nice, very precise, very expensive piece of equipment that you absolutely do not need, but I think you will soon make that determination on your own. I can't knock his instrument, but I CAN tell you that you will probably never use more than about 10-15% of it's true potential. In fact, the device might drive you to drink. The aligner will tell you that your fence is out of square to the table by 0.0003", and if it is due to twist (which is pretty normal) there is no reasonable way to fix it .. not that it is significant in the first place. You will drive yourself batty trying to "perfect" things that have tolerances and are within those tolerances.

I hope you enjoy using the plate, and I would suggest you get a decent magnetic indicator base (flexible or rod type) and a good machinest's square. With those few tools, you will be able to duplicate just about every feature of the aligner that you will ever use. Ed may pop in here and criticize my opinion on all of this, but he can't ever convince me that I or anyone else REALLY NEED the level of precision his aligner provides. I cannot criticize the quality of his product .. .. it is remarkable .. .. AND it might be worthwhile if one were setting up a tool & die shop or some such equipment .. .. but for what most of us here do in the woodworking field, this thing is such overkill, I can't it.

Anyway .. .. good luck with both gizmos .. .. let me know if, after time, you agree that you have overbought your needs.

[Cameron Reddy]

Hey Bob. I appreciate your comments!

I really do want your gizmo! When I make acoustic guitars I find myself working VERY hard at getting things square, straight, parallel, centered, etc. Martin Guitar specs the distance for frets to four places to the right of the zero! Who the heck can do that?

Doesn't mean I don't try, though.

[Tom Adger]

Whichever one you buy, there is an item to consider. Most come with a point. If you are going to use it to adjust jointer or planer blades, make sure you get a button end as well. The tips just screw on.

[Tony Shea]

Like one poster has stated, the precision of these high end alignment tools may send you to the looney bin or drive you to drink. Most of the tools we are using for woodworking are built with certain tolerances in mind that are much greater than the precision of these measuring devices. For example, extruded aluminum fences will show significant deflection on such devices and you will try all afternoon to square it to the miter slot or blade. Then only find out that there is a .005" bow in the center and that the top of the fence is out of line with the bottom by .002". When seeing this deflection on the dial indicator it looks significant, but if you never measured with such precision in the first place you wouldn't even know that the "problem" existed. Chances are this "problem" is really not even a problem. This is wood, which moves much more than these miniscule amounts from season to season. But knowing these values can play havock with your mental and may drive you nuts.

[G. Brad Schmidt]

Cameron,

You might want to consider purchasing the aforementioned Mit. or Starrett DIs & TIs off Ebay.
I've bought several DIs, TIs, Verniers and Dial Calipers from Ebay. After receiving my purchase I send them off for cleaning and recalibration. When all is said and done I've saved between 50-75% over new, and they work flawlessly.


http://www.clicksmilies.com/auswahl/ernaehrung004.gif (http://www.clicksmilies.com/s1106/ernaehrung/food-drink-smilies.html)

[Bruce Page]

Indicol is perhaps the most highly dial indicator,but they are very expensive. A Mit should do just fine. DO NOT get an electronic model. Starrett dial calipers' batteries apparently don't hold a charge,and they are Chinese made now,I believe.

George, do you mean the Interapid indicator? I have been using them for years and agree, they are probably the best test indicator made. I have two of them, one I bought about 30 years ago and fairly new one. They aren’t cheap tho..

[Harvey Melvin Richards]

I have a least a dozen dial and test indicators. I also wear a machinists hat regularly. When I'm checking various tools in my shop I almost always reach for a test indicator (lever type). They are much easier to get into tight situations, The main place I will use my dial indicator is in setting joiner blades.

As far as quality goes, even a Harbor Freight indicator will probably work for what you need, and for how often you will use it.

I have a Compac similar to the first photo. It reads in .0005, has a large dial (easy to interpolate to finer precision) and it has a .060 range. It's every bit as good as an Interapid and it's was a lot cheaper. I wouldn't get anything more precise than .0005, even .001 will be fine for most situations.

One problem with a test indicator is that the measurement isn't linear. The indicator tip moves in an arc, not in a straight line. This most likely won't cause any problems for woodshop use.

http://i811.photobucket.com/albums/zz35/HarveyMelvinRichards/P2100928Large.jpg

http://i811.photobucket.com/albums/zz35/HarveyMelvinRichards/P2100927Large.jpg

[brian c miller]

Bottom line here is you are going to have to buy what will work with your gauge. There are lots of ways to skin a cat but you went with a TS Industrial Aligner and now you must buy a ADG Type 2 travel DI

I'm guessing after dropping $390.56 on the gauge you've got a pretty large budget and I am also going to go ahead and guess that you don't have an indicating square or a set of angle blocks...

That being the case I would get the DI through EJB / TS aligner. He will calibrate the DI to his gauge. Without one / both of these tools you'll have a very fancy measuring gauge but no way to tell if it's telling the truth.


I'd get a "good" square with a thick blade (Accuracy Class II which is commonly referred to as "Toolroom grade" or "Toolmakers" will have an error of 0.00080 + L/100,000). This will allow you to check 90* of initial set up of the gauge and to set the miter gauge 90* to the slot.

Remember that the 400 gizmo is only going to be as good and the square it was calibrated to.

To measure angle you'll need a set of angle blocks. These are hardened and ground triangle with an exact measurement.

For example if you want to set the blade tilt to 45* you need to stack a 30* and a 15* block on the blade and tilt the blade to the approximate angle The blocks will cancel out the angle of the blade when the blade is tilted to the correct angle. Then running the stylus up and down the edge of the angle blocks should yield no change in reading. You are effectively measuring 90 here again (the blocks are setting the angle)

The same is true for any other angle mow you just need lots more blocks. Aka 22.5* you'll need a 20* block, two 1* and a micro Tangent bar to set .5*... you get the idea.

Here again your 400 dollar gizmo is only as good as the blocks you're using.

The other way to measure the angle is to use trig to determine the angle based on raising the DI a known distance. You'll still need something a "know good distance" to raise the DI (usually a ground pin) to raise the DI 1.000" inches and use b = Arc Tan (A/B) to find angle b based on raising the DI a know distance of A and reading the DI to find B. If you opt for this method you will need a ADG Type 2 DI with 1.000" travel and .001" resolution to cover from 0* to 45*

[Harvey Melvin Richards]

That being the case I would get the DI through EJB / TSaligner. He will calibrate the DI to his gauge. With out one / both of these tools you'll have a very fancy measuring gauge but no way to tell if it's telling the truth.



I don't understand how or why you would calibrate a dial indicator to a TS Aligner.

[Matt Meiser]

I've got an import 1" travel dial indicator from MSC and a test inicator from Harbor Freight. I just got 1/2" travel Enco import dial indicator used off Ebay for $10 shipped because there's a small scratch on the crystal and the seller didn't know what they were talking about and said it was out of calibration since the needle wasn't pointing to zero.

The dial indicators are much more useful than the test indicator for what I use them for. If I was going to buy just one, I'd get the smaller dial indicator.

There's a machinist in the club I'm a member of who says that the import stuff is more than accurate enough for woodworking.

I also don't get the comment about calibrating to the gauge. You don't use a dial indicator to make an absolute measurement but rather for making comparison measurements. Doesn't mater if it reads 0.123 or 0.456 as long as it reads pretty close to the same at the front and back of the blade.

[brian c miller]

Simple: Cosine Error.

The arm of the DI can only move in a straight line. The "relative" measurement will have error based on the fact the arm may / may not be moving the in same plane as what you are measuring.

In the case of the TS Aligner, if the arm of the DI is not perfectly perpendicular to the rods it rides on you cannot rely on trig to give you the correct blade tilt angle.

See the picture below. If the arm was off by a few degrees when you moved up your know distance 1.000" inches the difference in the indicator readings would be 1.004" inches vs 1.000" if the DI Arm was square to the rods.

This would translate into an error of .25* in the blade setting. May not seem like a big deal but if you close the miter you'll now be .5* out of square when you try to close the miter or over 1/10" per foot off from square. Say you opted to miter your cabinet carcass you'd be about 5/16" from being able to close the gap.

[Cameron Reddy]

Brian,

I'm trying to understand ... but I can't make out what you mean when you say:

"... if the are was square."

And you are correct. I don't have an indicating square or gage blocks. I've ordered a square from Mr. Bennett....

[brian c miller]

To clear things up this is not a problem with the TS Aligner, it's a issue with ALL Measurements.

For all you guys who put you indicator on a stick and tilt is down say 30* so that the tip of the DI is right at the surface of the table and you go to measure you blade // to the miter slot.

You zero it at the front of the blade, more to the back and it's out .0085 inches. You think man, this (insert brand here) saw is supposed to be great... what's up with this POS.

Well because you've tilted your indicator to get a "better" reading close to the table you've created error. In this case the true movement is only about 85% of the measured movement. For example, your indicator reading of .0085″ at an angle of 30-degrees is equivalent to .0085″ x .87 = .0074″

If you tilted it 60* to get a reading the true distance is only about 50% of the observed measurement.

So maybe "calibrated" was a bad word to use but unless the measurement is taken 90* to the movement you've got error. Clear things up?

contact point angle-------- correction factor

10° reading times 0.98

15° reading times 0.97

20° reading times 0.94

30° reading times 0.87

40° reading times 0.77

50° reading times 0.64

60° reading times 0.50

[John Harden]

There's a machinist in the club I'm a member of who says that the import stuff is more than accurate enough for woodworking.

I also don't get the comment about calibrating to the gauge. You don't use a dial indicator to make an absolute measurement but rather for making comparison measurements. Doesn't mater if it reads 0.123 or 0.456 as long as it reads pretty close to the same at the front and back of the blade.

Agree completely. I must have five or six dial calipers scattered around the shop. One next to the saw, another next to the J/P, another at the bench, etc. All are imports of varying quality and cost and they all provide readings that are WAY more than enough for woodworking.

I calibrated my J/P with a dial caliper and set the digital height gauge on the machine to match the thickness of the board as it exits the planer. Does it matter to my woodworking if the reading I get off my import caliper is .0005 off a "TRUE" measurement? Nope.

Don't get too wound up in chasing accuracy. Calipers, test and dial indicators all have a place in a WW shop, but its far more important to understand how and when to use them.

Regards,

John

[Cameron Reddy]

Brian,

Excellent! I've wondered about that.

So, I assume you would agree that this is a far better method of taking a measurement:

http://www.ts-aligner.com/tablesaw.jpg

To everyone else, I've no doubt that the import devices are accurate enough. The problem I have with them is the quality of their construction and how that degrades what my wife calls "gage R and R." When she tried to zero my Chinese DI she couldn't get it to stop jumping around when she turned the bezel. And every time she turned the bezel to "zero" the zero had moved and required yet another attempt to adjust it to zero. She runs a prototype shop for engines at Ford Motor Company where such a POS would quickly end up in the garbage.

[brian c miller]

I am not advocating making measurements of you projects, using a DI to check the depth of a dado is probably over kill. However, I will use a DI to check the machined reference surfaces on my tools.

That’s what this thread is about. You can argue the merits of measuring your fence to .001” vs rubbing the blade with a screw and a stick in the other thread this guy started but the fact of the matter is he’s already spent the $400 on the TS Aligner.

For the gauge he bought to work he’ll have to calibrate the DI to his gauge. It’s clearly outlined in the service lit and I’ve tried to explain the theory of the mathematics already.

To answer your original question you'll need an ADG Type II with 1.000" travel and .001" resolution to get the most out of the TS Aligner.

An ANOVA Gauge R&R is a MSA (Measurement System Analysis) that tries to prove a measure is precise (not accurate) by being BOTH Repeatable and Reproducible.


· Repeatability: The variation in measurements taken by a single person or instrument on the same item and under the same conditions.
· Reproducibility: The variability induced by the operators. It is the variation induced when different operators (or different laboratories) measure the same part.

To do this you'd need a gauge block and be able to measure the same block over and over again and get the same statistical reading. I think EJB did perform a statistical analysis of one of his gauges ( only ten sample so is not the greatest from a 6 sigma stand point but does indicate repeatability). As a side you could get the wrong answer EVERY time and pass the GRR with flying colours. So you could have a scale the would weighed a 10.00# object as 22.23# ever time regardless of the operator, the day, the time and you'd be alright. The scale would need to be calibrated to be accurate but it is far better to be precise FIRST then you can adjust for accuracy.
Unless you are planning on having many people in your shop setting your blade angle a GRR is overkill. I've done them, they are expensive and time consuming.

[brian c miller]

This text is taken Directly from the TS Aligner Manual:


"...relies upon basic right triangle trigonometry to help you set angles on your saw. There are two adjustments that are absolutely critical to your success in achieving accurate measurements. The first is the calibration procedure outlined in the TS-Aligner user's manual. The second adjustment involves making sure that the dial indicator is exactly parallel to the table surface. When the dial indicator is not parallel to the table surface, the right triangle trigonometry that is used to measure angles will be subject to what is called "cosine" errors.

That is, the error in your angle settings will be equal to the cosine
of the tilt of the dial indicator."

You will have to calibrate your DI, end of story. If you don't understand why read up on measurement systems.

[Cameron Reddy]

Thanks everyone. I learned a lot. I just ordered the Mitutoyo #2776S. It cost a bit more from Long Island Indicator but I learned so much from their web site I felt I should give them my business.

I can see that I'll probably also get one of the lever types... Probably the first one pictured in this thread.

Cameron

[Howard Acheson]

Curious. What are you going to use it for?

I have been a woodworker for about 40 years. I have had my own amatuer shop, was involved with a large professional shop, taught woodworking for a few years and set up woodworking equipment for a dealer for a few years. I never had a dial indicator until I was given one that I used to show students that they could align their tools as accurately without expensive gauges.

[Cameron Reddy]

Howard,

I plan to align my shaper fence with the miter slot, square the shaper fence to the table, check the shaper spindle square with the table, check the drill press quill movement for square with the table, check the disk sander square with the table and alignment with the miter slot, square the band saw blade (this is badly needed as I don't have the visual acquity make sure the my Starrett square is flush with the blade), square and align the table saw blade and fence, possibly square the jointer fence, and check run out on all of the above.

Perhaps more.

[Bill Farlow]

Why is it that whenever someone asks about dial indicators, there's always got to be at least one person who ignores the question entirely and feels compelled to proclaim that they don't need one and never did? The proclamation is always accompanied by a laundry list of woodworking credentials. It's as if they trying to say that real woodworkers don't use dial indicators. Does this happen when someone asks a question about table saws, routers, drill presses, shapers, planers, or jointers? I don't think so. What is it about this simple measurement device that causes certain people so much insecurity that they have to mount a full blown defense when no attack exists? I don't think that anybody questions the fact that you can do woodworking without a dial indicator. Just like nobody doubts that woodworking can be done without a table saw, or a jointer, or a planer, or a shaper or a router.

Bill
(...who has been a woodworker for 40 years and finds using a low cost dial indicator far preferable to wasting all day with the stick, screw, rub, scrape, test cut, trial and error techniques)

[Van Huskey]

Why is it that whenever someone asks about dial indicators, there's always got to be at least one person who ignores the question entirely and feels compelled to proclaim that they don't need one and never did? )

I agree with the basic sentiment of your post but over the years I have learned forums are much more than just a Gogglesque place where you get answers for a specific question they are more like a conversation between several people. There is always a Luddite who provides an alternate view which is actually a VERY good thing because a forum doesn't just answer a single persons question but becomes a bank of knowledge for the next person who has a similar question, so when another person serches the forum the Luddite's answer may be just what he/she is looking for. Bottom line as long as it is civil all topical information is useful in a thread if not directly to the OP it will be to someone else either reading the thread now or in the future.


Why is it that whenever someone asks a question, there's always got to be at least one person who ignores the standard forum font entirely and feels compelled to reply to the thread using a font seemingly picked for its relative lack of legibility, apparently making a typographic statement when they don't need one and never did? ;)