Gauge Blocks

Can someone please explain what Gauge Blocks are?
And what are they used for?

Thanks,
Jack

Jack, gauge blocks are extremely accurate and certified components made from high grade tool steel or ceramic. They are normally used as a means of setting or checking measuring equipment. For example they will allow you to check a micrometer, or even set the postion of a DTI in a height gauge etc.

Google is your friend incidentally.

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Hint: The name Johansson is very good place to start.

MichaelG.

Gauge blocks can also be 'wrung' together to create lengths not available as a single block. This can be useful for setting sine bars, or for calibrating, or checking, specific dimensions. It is important that the gauge blocks have a very thin coating of oil before they are wrung together. See this thread on 'practicalmachinist' which also includes links to some manufacturers notes:

**LINK**

Regards,

Andrew

They used to be referred to as slip gauges when I was an apprentice many many moons ago.

Andrew,

Thanks for posting that link ...

The NIST "Handbook" linked within that thread is a valuable reference.

[also available via the Wikipedia page on Johannson]

MichaelG.

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For the sake of completeness ... here is the NIST page

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Edited By Michael Gilligan on 30/10/2014 08:33:27

Edited By Michael Gilligan on 30/10/2014 08:35:31

Edited By Michael Gilligan on 30/10/2014 08:48:08

Nice things to have occasionally (for my uses) and do come under the heading "Likely to be unaffordable"

IanT

If you search on Ebay for "slip gauges" you will usually find second hand sets for about £40.They can be made from ceramic or tungsten carbide as well as the usual hardened steel. The big advantage of the carbide or ceramic sets is that these do not go rusty. Sizes can be from 0.020" to 4" on the imperial sets. Normal sets start from 0.100".

The usual sectional size is about 9mm x 35mm but gauges blocks can be square (made by "Precise" ).

Slip gauge prices have reduced a lot over the years. I remember the early sets were over a £1000.

Length standards have not changed much over the last 70 years and slip gauges are still widely used as the reference standard.

A set of slips will last a few lifetimes and will not depreciate in value if they are not abused.

Edited By Dinosaur Engineer on 30/10/2014 13:42:04

Edited By Dinosaur Engineer on 30/10/2014 13:42:35

Edited By Dinosaur Engineer on 30/10/2014 13:44:06

Edited By Neil Wyatt on 30/10/2014 16:38:08

Tried to remove "smiley" from my post without success. ! ?

Dino,

Put a space between a quote and a closing bracket.

Neil

I bought a second hand set of imperial slips in a Bakelite case some years ago from that auction site. They are inspection grade and were made by Matrix of Coventry and I use them constantly.

Very, very handy for setting the vernier height gauge prior to marking out, as stop registers in the T slots on the lathe cross slide and milling table, (although purists would frown on this treatment) and of course for sizing milled slots to mention just a few uses. A very versatile addition to any toolroom.

As has already mentioned, these were always referred to as slip gauges when I was doing my bit years ago. The first time I heard "gauge blocks" was when I came on here - I guess that's what our friends across the pond call them.

Rik

Thank you all.
I doubt that I will rush out to buy a set in the near future.

Michael is right - slips should be "wrung" together without oil for the reason he gives.

Rik

I have some chuck jaws that will wring together dry.

Neil

As explained above Gauge blocks / slips are used to measure to very precise dimensions. In a full set of imperial there are normally 81 blocks plus two protective slips and in a metric set there are usually 88 blocks + two. I have seen and actually own sets with larger numbers of blocks however with a standard set you can combine blocks together to make any size going up in .0001 imperial or .001 (or finer) in metric up to the capacity of the full set. Normally there are standard sizes 1" 2" etc or 25mm 50 mm then there are increments of smaller amounts .1 .2 etc then even smaller units .01.02 etc. So by using the correct combination any size can be wrung together. When a good undamaged slip is wrung to its neighbour due to the lapped surface finish the slips "stick" together and can only be parted by using a twisting motion NO OIL should be used. Immediately the slips are finished with they must be separated. If left for a long period it will be found that they cannot be parted without considerable damage rendering the blocks useless.

A type of gauge block was first developed by Joseph Whitworth of screw thread fame when he was standardising the inch measurement using them he developed a micrometer measuring to 1 millionth of an inch accuracy. The Government of the day showed no interest in these and they were ignored for years. However on the outbreak of the first world war it quickly became apparent that an easily transported system of gauges were needed in order to produce weapons, shells, bullets etc. in factories all over the country to a standard size so that they fitted together. So the government imported a large number of sets from Johannson in Scandinavia hence the name joey blocks sometimes used by the more mature engineers.

Without wishing to make purists shudder, whilst operating a shaper in the toolroom as an apprentice some 50 years ago, there was a box containing a large quantity of out of calibration slip gauges. As a quick & dirty method they were used by shapers, millers & turners to set step heights & lengths, also with a piece of HSS with a chisel edge on one end a scribing tool. Bearing in mind that the only other use would be lining a skip. The ones in my toolbox from that time are still in use on my acorntools shaper today

robjon44

So why does Starrett recommend wiping the mating surfaces with a cloth impregnated with a light machine oil, wiping the excess oil off with a second cloth, and the wringing the blocks together?

Andrew

Like most people I could never buy a set of slips. I find a couple or 3 old bearing rings and balls are near enough for my use. If real accuracy is needed, say for setting a mike, take a suitable ring down to the nearest place with a tool room and get them to measure it, note the readings.Wipe with an oily rag.

Andrew,

I was always told to ensure that the surfaces of the slips were clean i.e., free from grease, oil and finger marks before wringing the slips. I can understand them being oiled when they are returned to the box. I think the main idea was to ensure that there was nothing between the slips to ensure accuracy. In addition, the slips do not need oil or any other lubrication to wring.

Interesting.

PhilH