Measureing C to C hole spacing with digital calipers.

[MBTcustom]

Here's a useful shop tip if anybody is interested. This only works with digital calipers (which I detest) but it's a good trick, and somebody might not know it or might find it to be useful. If you like digital calipers, just memorize it.

If you need to find the distance between the centers of two holes of equal size, measure one of the holes diameter with the ID nibs of your calipers.
Zero the calipers on this figure.
Use the same ID nibs to measure to the outermost wall of the two holes.
What you are reading is the exact C to C measurement.

Doesn't do me any good, because I can't "zero" my analog calipers, but it's a solid trick.

[W.R.Buchanan]

I don't have Digitals either. I have been measuring inside to inside and outside to outside and dividing by 2 for my entire career.

But this sounds good if I ever get some digital calipers.

Randy

[MBTcustom]

Usually, I measure outside to outside, and subtract one hole diameter.
However, your way is better if the holes are slightly different diameters. Might get you a little closer.

BTW, Tesa rocks, do they not?

[nhrifle]

I read your original post twice to make sure I got it and was left with one glaring thought -- DUH!!!!! The simple stuff escapes me from time to time, and this one definitely did! Thanks for posting!

[garandsrus]

I do the same thing when measuring group size. Set the caliper to the bullet diameter, zero the caliper and then measure the outside of the two farthest bullet holes. The reading is the group size.

[MBTcustom]

I do the same thing when measuring group size. Set the caliper to the bullet diameter, zero the caliper and then measure the outside of the two farthest bullet holes. The reading is the group size.

Bingo.

[fixit]

I always just measured front edge to front edge...gives the same thing as c to c

[MBTcustom]

How can you do that with any precision?

[aspangler]

Simply measure inside of hole to outside of opposite hole for CTC.

[MBTcustom]

So you're just eyeballing it?

[Big Rack]

Also works for studs just measure O.D. of one and zero, if you think about it after you zero it your just measuring inside or outside length plus/minus 1/2 the hole on both sides. Diameters must be the same or it won't work. Digital calipers also make a pretty good calculator by zeroing at a dimension open or close to the second dimension, zero and close completely for answer.

Digital calipers are just like any other good ones are good cheap ones are cheap. I have 2 Mit. a old one and a newer absolute style also have a battery eating Harbor Freight, guess which gets loaned out or taken to the saw? Any of them are a lot easier to use than the "need a good eye or magnifier" vernier ones. The biggest thing to remember is always check for zero before measuring saves a lot of "Oh S***!" moments.

[W.R.Buchanan]

Yes Tesa is the best, however there is also Etalon which is made in the same factory. I have 0-3 Tesa mics and 0-9" Etalon mics. they are about the same price.

The Calipers are identical, and some of the B&S calipers with the black dials were made by Tesa but had plastic pinion gears that were easily damaged.

I bought my Tesa Calipers used in 1983 they are still very accurate.

Randy

[izzyjoe]

most time's eyeballing get's you PDC!

[bangerjim]

I just measure from right side of one hole to right side of the other hole. Works for analog AND digital folks!

If you are a Democrat you can always measure from left to left if you choose!!!!!!!!!

bangerjim

[MBTcustom]

Again, how do you measure from the right side of one hole to the right side of the other hole? You can only touch one of them at once!

[Dan Cash]

Again, how do you measure from the right side of one hole to the right side of the other hole? You can only touch one of them at once!

Use a tape measure, for gosh sake.:kidding::kidding:

[smokeywolf]

Unless you're using the inside measurement nibs on the caliper to the far edges of the holes, you're not using your calipers to your best advantage. The only other way to achieve acceptable accuracy is to insert precision gage pins in the holes and measure across the outsides of the pins. Just remember, calipers are reliable to within one thousandth.

Best calipers? Yep, Tesa mechanical.

smokeywolf

[CountryBoy19]

I don't have Digitals either. I have been measuring inside to inside and outside to outside and dividing by 2 for my entire career.

But this sounds good if I ever get some digital calipers.

Randy

This ^^^
is the best way to do it IMHO... most of the time the math is pretty simple to do in your head but if not pen & paper makes it pretty quick...

[oldred]

Well I see I am not alone in not caring much for digital calipers, I have been told I need to "get with it this is the 21'st century" and I suppose there are some really good reasons to choose a digital over an analog and maybe someday I will think of one! Right now I would not trade my 35 year old B&S caliper for a dozen digital calipers and it's not a case of "sour grapes" either because I do own two digitals (a Mitutoyo and Starrett, both gifts for a birthday and Fathers day) but I rarely use them. However I have found one use for them that's handy as a shirt pocket, they make EXCELLENT metric to decimal conversion calculators! Just set the decimal or metric value you need to convert and then select the opposite scale on the caliper and the conversion is instantly displayed.

[bangerjim]

Again, how do you measure from the right side of one hole to the right side of the other hole? You can only touch one of them at once!


Don't know how you are using your tool..........but...........

Using a standard set of calipers (I ONLY use digital these day!) you touch the right side of the left hole with one leg/finger/tooth/inside pointt/whatever-you-call-them and then open up the tool to touch the right side of the right hole with the other end and that measurement is the c-c measurement....accurate to 0.0001 in my case....digitally.

I have used digital for years and cannot understand why ANYBODY would waste their time squinting and glaring at an olde analog dial. Same with micrometers! The digitals also do the subtraction math for you when turning down to a diameter on the lathe. Just zero it on the diameter you want and read down as you turn. So simple and ease.

I have literally thrown away 5 sets of analog dial calipers in the past several years. My engineering firm has standardized on everything digital for NIST repeatable accurate readings. No guesswork - no errors - no parallax - no "whatever Joe have for breakfast" errors anymore.

But if you are still using HF tools........that is your problem!

bangerjim

[smokeywolf]

I've found that when I use digital calipers (9 in. Starrett) I don't have the same, for lack of a better phrase, "anticipation of movement". Also, on the dial, I can see the difference in measured value to target value, thereby acting as a visual comparison. If you're having to provide SPC data, obviously you're limited to using electronic measuring tools. And, for their convenience my 9 in. Starrett electronic calipers are great; beats the heck out of having to wear my head loop so I can read a vernier scale. But, my 6 in. B&S calipers are my go-to calipers.

Several of my mikes are Tesa mechanical digital; and a couple of those are direct reading. For splitting tenths I go to my Mitutoyo Quickmikes. Even the Quickmikes, although they'll resolve .000050 are only rated to .0001 accuracy.

bangerjim, wish you would put up a pic of that method. I just can't grasp how you achieve a c to c hole measurement accuracy of .0001 that way. Plus, I've not yet seen a pair of calipers that where rated to .0001 in accuracy.
You sound like you've been doing this for a long time, so I'm not trying to challenge your method; just want to understand it.

smokeywolf

[MBTcustom]

Don't know how you are using your tool..........but...........

Using a standard set of calipers (I ONLY use digital these day!) you touch the right side of the left hole with one leg/finger/tooth/inside pointt/whatever-you-call-them and then open up the tool to touch the right side of the right hole with the other end and that measurement is the c-c measurement....accurate to 0.0001 in my case....digitally.

I have used digital for years and cannot understand why ANYBODY would waste their time squinting and glaring at an olde analog dial. Same with micrometers! The digitals also do the subtraction math for you when turning down to a diameter on the lathe. Just zero it on the diameter you want and read down as you turn. So simple and ease.

I have literally thrown away 5 sets of analog dial calipers in the past several years. My engineering firm has standardized on everything digital for NIST repeatable accurate readings. No guesswork - no errors - no parallax - no "whatever Joe have for breakfast" errors anymore.

But if you are still using HF tools........that is your problem!

bangerjim
First of all, I appreciate the passion for tools you believe in. However, there is a big difference between accuracy and resolution.
The problem I have with many digital calipers (all that I have used in fact) is the fact that even if they resolve to .0002, they can only be trusted to .0015 reliably. For most, that is plenty of accuracy, but I am a toolroom machinist. There are many times when the only tool that can be used to measure a dimension, is my calipers. Often I have called on my calipers to deliver dimensions of less than .0005 because there was no other way to measure. I understand that this makes many people very nervous because you can make calipers measure anything inside of .002 depending on how you handle them, and a simple digital gives them all kinds of tingly fuzzy feelings of awesomeness.
I dont give a rip how I have to read the darn thing. All I care about is what I can use to give me real numbers that are accurate. It's not a matter of weather its a digital or not, all I'm saying is that a good set of Tesa calipers are accurate. I trust them to .0004, and I stake my reputation on it on a regular basis. I don't make tinker toys, I make things that peoples lives depend on, and by golly, it's got to be right!
If your digitals work for you, then by all means, don't let me discourage you! (enjoy the cool trick that started this thread) but my stock and trade is my ability to use measurement tools better than 99.9% of the people in the world, and I will use nothing but Tesa calipers. I prefer calipers because making measurements down into the ten-thousandths of an inch takes about as much "feel" as shooting good scores on a rifle range. Not everyone has the touch, and being able to see that needle is a big part of it.
At the end of the day, I will concede that digital calipers are much more versatile than analogue (hence the tip up yonder), but if I need precision, I'm going with the Tesa calipers, and any machinist I have worked with that's worth his salt has done the same.

[W.R.Buchanan]

OK, here's the deal guys. When you use dial calipers it makes it much easier to see when you have gotten the smallest actual reading on an OD and largest on an ID. This occurs when the dial stops when you are wiggling the jaws when taking a measurement.

When this happens it insures that you have the Calipers at exactly 90 degrees in relation to the measurement taken. Any other measurement is meaningless and will probably result in a scrapped part.

Learning how to use calipers properly is probably the hardest thing to master in a machine shop. And learning when a measurement is valid and when it is BS is the key.

Here's the hot tip of the day.

You must take any given measurement several times to insure that it repeats, because unless it repeats you have got a bogus reading.

Second hot tip: You must learn to apply the same amount of pressure to the caliper jaws everytime to insure that you are not flexing the frame which will result in bogus readings. The gib adjustment on the moving jaw is what keeps this to a minimum.

Believe me I have scrapped enough parts in my 30+ years of doing this machine shop thing to know exactly what I'm taking about here.

When the dial gets on the right dimension it stops moving up or down. this is easiest to see with a dial. Having to constantly process multi digit numbers flashing before your eyes gets old pretty fast. You can see the dial move to a point and then settle out.

I have used a few digital calipers but I have never owned any and likely will never unless someone gives me some, and then I probably won't use them..

They are no more accurate than a quality dial caliper and have many down sides. One of the major down sides is the fact that everytime you turn them on you must calibrate them to zero. If you don't do this right, like by cleaning the jaw faces and applying the same amount of pressure to the jaws holding them closed, you will get a bogus zero, which will affect every reading you take.

This is one feature, or more properly "Idiosyncrasy," That will cost me money!

I eliminate variables in my shop area every chance I get. I eliminated this one about 1984.

Randy

[scb]

"What you are reading is the exact C to C measurement."
Assuming the holes are exactly the same diameter

[Cap'n Morgan]

Randy's suggestion of measuring inside and outside and divide with two will give the best result - and it will also work even if the holes are of different diameter.

[carbine86]

.

Sent from my SPH-L710 using Forum Fiend v1.0.1.

[Big Rack]

Just to add to the discussion:
Tessa stuff is great, beware newer B&S as they now have a hard chrome colored plastic housing.

I was taught to accurately measure you need a tool that is a magnitude better than your measurement, needs to measure .0001 to accurately measure to .001.

When measuring a hole use a pin gage you can get these in .00005 increments if you have the money. I don't never will, but the shop had them and we used them (medical/aerospace).

If you look real close at your calipers ID jaws there is a small flat so you will never actually measure a hole's diameter.

All aside I get by with a tape measure most days and used a Mauser vernier caliper for precise work in the garage. Kept the good stuff at work to earn my living. Now that I'm broken I have my good stuff at home but still am cautious about casual use cause it's gotta last the rest of my life or until my body wears out completely.

Now a question I own a B&S mechanical digital 0-1 mic. which reads to .0002 without a vernier scale. It has carbide faces .1 markings with digital "wheels" to .001 or .0005 (been awhile since I played with it) and lines that read to .0002. How old and how rare?

[smokeywolf]

Big Rack,

I think the micrometer you have is a "Digit-Mike" 83427; I have 3 of them. They are superb mikes for routine machine shop measurements, more than sufficient for reloading. They have a very nice feel and are an amazing feat of engineering.

First time I saw one of these mikes was in the hands of one of the old timers in the MGM Studio Machine Shop; that was in 1981. I wouldn't say that they are rare, but they seem to hold their value pretty well. The ones seen on fleabay I think are usually sell-offs by retirees or widows.

smokeywolf

[Big Rack]

I must have an older version, mine has a standard round style frame is black enamel and hard chrome digital part is similar but it's black and the window is larger. Yes it is neat as heck and I can just imagine the wheels and gears whirring like mad.

[W.R.Buchanan]

Smokey Woof: That mike is a Tesa made for B&S. My Tesa 0-1" mike has the exact same "C" as yours does.

Randy

[smokeywolf]

Yep, B&S and Tesa have been one in the same for many years. The Tesa version of the modern day "Digit-Mike" carries the name Tesamaster. The B&S Digit-Mike(s) resolve .0002, while the Tesamaster resolves .0001 and has a rated accuracy of .000080 or 2 microns. Its as close as one can get to a hand held supermike.
I haven't gotten into all of my tools and measuring goodies in a long time. Was forced into retirement about 4 to 5 years earlier than planned. Doing just garage machining, I rarely require +/ - 50 millionths accuracy, and being that the garage is not climate controlled couldn't achieve it anyway. So, I don't have occasion to get all my high end goodies out. I have 2 of the B&S 0-1" Digit-Mikes, same thing in a 1-2". Then, Tesamasters in 2-3 and 3-4.

Pretty much all of my measuring tools are Starrett, Lufkin, B&S, Tesa or Mitutoyo. Can't remember the brands on my Jo Blocks and Gage Pins.
Just sitting here looking at a Johansson Gage Block accessory set and thinking about selling it. Thanks to the fine Cadillac and digital height gages available these days there's not much need for them anymore.

smokeywolf

[W.R.Buchanan]

I used my Jo blocks for the first time in 20 years earlier this year while making a go no go gage for a friends shop. I have a complete set of 0-9" Etalon mikes, which are on par with Tesa's. Both are Swiss made in the same factory.

I got the whole set at a garage sale and paid about $250 for the whole group. 6 of the 9 had never been used and still had the thin grease on the spindles.

When I priced them thru SPI they came out to $2700! Ca Ching!

As I wind my shop down they will go on the block. The 0-6" are in one big wooden cabinet and the 7,8, and 9 are in individual wooden boxes. All of this stuff constitutes nest egg stuff or investments in retirement. It all has value and lots of it is worth a lot more than I originally paid for it due to the fact that I seldom bought new instruments especially when you can buy used ones in perfect condition and
pay a lot less.

I've got a ways to go before this will occur anyway.

On another note, I really prefer my Mitutoyo Dial Calipers to the Tesas simply because the graduations are easier to read on the Mitt's

The three brands that people should be looking for are Tesa, Etalon, and Mitutoyo. For some things B&S made some good tools along time ago, as well as Scherr-Tumico, and I'm sure there are others I have forgotten about.

All this is fine and good and I am talking about high quality tools used in a machine shop in everyday use. There is little sense in spending big money on new high grade measuring tools if you can't possibly get the usage out of them. It is a waste of money. That said you can usually get most all of your money back when you sell them as long as you sell them in the right place. A Garage Sale is not going to maximize your investment. You might get .10 cents on the dollar.

For most of what people do in the reloading world a decent 0-1" mike and a set of decent dial calipers will get you where you need to go. You should be able to find those used or new from HF for <$100.

Learning to take accurate measurements is more important than the quality of the tools you use. Not bragging here but I can probably take more accurate measurements with a Chinese set of calipers than most here could do with the most expensive ones out there. 30 years of practice helps.

Randy

[smokeywolf]

I have 3 B&S Intermiks, which on fleabay sell for about 60% of what the "new" prices are. The discounted rate of the used Intermiks vs. new seems to be unique to the Intermiks. However, I have not found that any machinists tools maintain their value all that well. Maybe it's because I'm a choosy and patient shopper. Maybe it's because I'm just cheap. It's unlikely that I will sell much of my tools, as I have 4 sons. If I did decide to sell the Intermiks I still wouldn't get hurt.
My father acquired them back in the late 50s or early 60s while working in aerospace. Because tooling costs were included in what the company charged the government for a project, at the end of a contract, the tooling had to be sold off and that money returned to the government. The company would box all the tooling, weigh the box, mark the weight on the outside of the box and auction the boxes off to the employees. So, in essence, the guys were buying these fairly gently used tools by the pound. I remember my father telling me he paid about $7.00 per pound for the B&S Intermiks, which means he paid about $4 to $5.00 each for them; less than 10 cents on the dollar even back then.

As far as using your Jo Blocks only once in the last 20 years. Many machinist tools are like that. They're like a fire extinguisher; not worth a dam until you have a fire. But, like a fire extinguisher, when you need that tool, you need it now and nothing else will do.
Because I'm usually prototyping, I've gone several months at a time without using my collet stops. Then, all of a sudden, I'll use them 2 or 3 times in a month.

Because my B&S calipers have .0005 divisions on the dial, I find they are easier to read than my Mitutoyos

When I liquidated the assets in the MGM/Sony Pictures Machine Shop, I sold a large floor model Scherr-Tumico Optical Comparator for $600.00.

Guns and tools, there's no such thing as having too many.

smokeywolf

[W.R.Buchanan]

Amen and +1 on that.

Would have loved to work for the studios, under the right circumstances. I have several friends that made really good money of them. One in particular that worked directly for James Cameron on the Titanic Movie, He still had problems getting paid, and finally had to hunt Cameron down and tell him what his minions were doing. He got paid the same day! Most all of the stars and higher ups have no idea what their underlings are doing, and the underlings are usually tasked with eeking out every $ they can in profit for the head guy..

The closest I got was working on the Water World Airplane that they made for the Universal Studios Amusement Park. I was a sub on the job and got paid and the guy I did the work for ended up getting stiffed by letting the airplane go before the studio paid the bill. They shipped it to Japan, and then bankrupted the company they had formed specifically to manufacture the plane.

It is hard to believe that a business with so much money won't pay it's bills.


Good bragging rights however.

Randy

[smokeywolf]

Movie industry is feast or famine and yep, the producers hire bean counters to figure out ways, regardless of how ethical or legally shady, to minimize the amount of money paid out to hourly workers.
I also had a friend who went down to Mexico and worked on Cameron's Titanic. He also worked on Spiderman and was killed on the set because the director was in a hurry to get a shot and cut corners by using a bucket lift instead of a proper crane to place a large prop on the side of a building. Bucket lift operator lost control of the prop and it crushed my buddy's head.
Producers and directors make millions on projects but have no problem risking the lives of hands-on folks if it might shave ten or twenty thousand dollars off production costs.

smokeywolf