NOTE: This study is obviously very incomplete - both in its research and (especially as regards drawings) its execution.
In late 2014, I undertook a set of drafting and digital modeling projects. As I hadn't really done any serious drafting in decades, this required brushing off some old skills and (in some cases at least) bringing them up to date. (See the CircuitousRoot Drafting Notebook for more on the digital tools investigated and used.) For a starter project, I thought I'd do a drawing of a "1-2-3 block." I figured that it was a very common tool which, given its form, would make a perfect re-introduction to the field. I assumed, further, that it must be a traditional tool with a long history and many examples from the early literature (there is little that I love more than poking about in old machine-related books).
I was right on the first two counts: 1-2-3 blocks are quite common, and their form is ideal for introducing such elements of drafting as orthographic projections and geometrical dimensioning and tolerancing. But I was wrong on my third assumption. The history of the "1-2-3 block" is much briefer, and much more obscure, than I might ever have expected.
For those who may not be familiar with it, a "1-2-3 block" is simply a block of steel which is 1 inch by 2 inches by 3 inches in size. It has a pattern of holes drilled through it, and certain of these holes are tapped. This allows you to attach things to it with machine screws and to attach multiple blocks together to form other shapes (e.g., L-shapes). It is a precision item, usually hardened and ground, with surface flatness and parallelism measured in tenths (ten thousandths of an inch). It has any number of uses in machine tool setup and in layout. No machinist should be without at least a pair of them.
I have a pretty good collection of early 20th century (and some late 19th century) machine shop and technical drawing books, and I'm comfortable in researching them in the digital world as well. What I expected was that I could just go into my library and find many examples of "1-2-3 blocks" from the late 19th century on. I thought that I'd find them listed for sale in the old tool catalogs, shown in use in old machine-shop textbooks, used as beginner's projects in old machine shop textbooks, and shown as convenient examples in old drafting textbooks. But they aren't there.
In fact, to the best of my current knowledge and research, the item that we know today as the "1-2-3 block" did not exist by any name before 1946. It is a post-WWII development.
Moreover, it seems to have been developed not as a general-purpose shop aid but rather in a very specialized department of industry: jig boring.
As one significant example of this vacuum, they are not mentioned in the 1942 Catalog No. 58 of the Charles A. Strelinger Company (one of the major industrial distributors in the period). Yet this same catalog shows a dozen styles of V-blocks, magnetic blocks, several styles of box parallels and angles, toolmakers' knees, regular parallels of many styles and dimensions, adjustable parallels, step blocks, and packing blocks. No setup/1-2-3 blocks. {Strelinger 1942}
The earliest reference to a "1-2-3 block" that I have been able to discover is a 1946 press release by the Moore Special Tool Company of Bridgeport, CT (now the Moore Tool Company subsidiary of The PMT Group). It clearly describes this tool, but whether or not it claims it as a new invention is, unfortunately, made ambiguous by the nature of advertising language. It is claimed to be "a new development in 3-way parallel set-up blocks," which strictly speaking would mean that it was an improvement upon existing 3-way parallel set-up blocks, but the text describes it as replacing conventional parallels, not other set-up blocks. Once source, however ( Iron Age) claims clearly that these setup blocks were "developed" by the Moore Special Tool Co.
I have not yet tracked down the original source material for this press release. Currently I know of it through five Google Books "snippets" which quote from four appearances of it in journals in 1946 (in The Tool Engineer, Machinery, Modern Machine Shop, Iron Age, and Automotive and Aviation Industries. These are as follows:
[title:] 3-way Parallel Set-up Blocks [text snippet:] A new development in 3-WAY PARALLEL SET-UP BLOCKS, which built up to twelve different heights and take the place of a large number of conventional parallels, is now available from the Moore Special Tool Co., Inc. ... Originally designed for precision work in the Moore Jig Borer and Moore Jig Grinder, the complete set consists of six... { The Tool Engineer, 1946}
[title?] "Something New in 3-way Parallel Set-Up Blocks" { Machinery, 1946}
[title?] "Something New in 3-way Parallel Set-Up Blocks" [subtitle?] One Handy Set Speeds Set-up To 12 Different Heights. [text:] This handy, compact set of Moore 3-Way Parallel Set-up Blocks takes the place of a large number of conventional parallels. { Modern Machine Shop, 1946}
[title?] Parallel Setup Blocks [text:] THREE-WAY parallel setup blocks which build up to 12 different heights and are said to take the place of a large number of conventional parallels, have been developed by the Moore Special Tool. Co., Inc., Bridgeport. ... { Iron Age, 1946}
[title?]Set-Up Blocks Replace Conventional Parallels [text:] Moore 3-way parallel set-up blocks are drilled and counterbored for bolting to the machine table or faceplate and will not slide off... { Automotive & Aviation, 1946}
Whether or not an illustration accompanied this early announcement I do not (yet) know. A set of Moore setup blocks was, however, illustrated in the 1955 Moore volume Holes, Contours and Surfaces ( {Moore & Victory 1955}, p. 92) The book also shows the two styles of Moore set-up blocks in use in jig boring and jig grinding operations. These are typically fairly straightforward uses where the blocks are used as stand-offs for the workpiece (they're drilling holes, after all).
This reference is intersting not only because it shows the full set as originally developed and used, but because it gives their sizes and tolerances. Sizes: 1" x 2" x 3" and 7/8" x 1 1/4" x 1 1/2" (this latter size is no longer common). Tolerances: "dimensions" to within 0.000,1 and squareness to within 0.0000, 2.
Here is the illustration from this volume (please see the legal notices section below before re-using this illustration - it is in copyright and not licensed under the same terms as the rest of this page; it is used here within the limits of "fair use" in US copyright law to identify a historically important engineering development.) This is the earliest illustration of "1-2-3 blocks" of which I am presently aware.
I know of no official description of the hole sizes and patterns for these blocks. Moreover, note that the hole pattern on the block shown lifted out of the case on this early illustration is different from that shown in most of the other illustrations in this book. (It has three small holes on 1x3" side where the others have only two, and it has two extra small holes on each endof the 2x3" side. It corresponds only to the block shown in use in Fig. 159, p. 137.) It is not possible from either illustration to see the hole pattern on the 1x2" sides.
Fortunately, an ebay seller listing various sets of Moore blocks for sale has measured them and published those measurements with his listings. See the section of Drawings of Moore-Style Blocks, below for more information.
Contrary to at least one opinion online, Starrett does not seem to have originated the "1-2-3 block." If anything, they were rather late into the game. They appear only to have made one style, their Catalog No. 706. This is a rather unusual block in terms of its hole pattern, and it does not generally resemble other 1-2-3 blocks of any era.
There is no mention of it in their Catalog No. 26 (1938) or in their Revised Price List of May 27, 1946 (applied to Catalog No. 26). {Starrett 1938/1946} It does not appear in their Catalog No. 27 (1976) through the sixth edition (1979). Curiously, it does not even appear in the 1985 printing of their Catalog No. 28 (1976 [the Starrett company appears to have become a little confused by their own catalog numbering over the years]), even though this catalog has both workholding blocks (V-blocks), measuring blocks (gage blocks), and coordinate measuring machines.
Neither can I find any reference to it in the Brown & Sharpe literature through at least the late 1960s.
It is not present in their 1941 catalog No. 34 {BS 1934}, though numerous V-blocks and related devices are shown.
It is not present in their post-1963 catalog STM-4 ( The Shop Tool Manual) {BS STM4}. (This catalog does list V-blocks, Jo Blocks, etc. - but no setup/1-2-3 blocks.)
The 2011 Mitutoyo America Calibration Price List shows four part numbers for 1-2-3 blocks (without indicating further details):
I can't actually find these on any Mitutoyo site. Here's some more information gleaned from third-party online information (primarily listings of items for sale where the seller provided measurements); this information is useful, but cannot be considered authoritative (everyone makes mistakes, however careful they are, and short of buying these rather expensive blocks neither you nor I have any way of checking this information).
961-901: I've discovered no further details.
961-911: An online listing of blocks for sale indicates that these are 1-2-3 blocks sold in pairs, with 11 holes (5 of which are tapped for 5/16-18). Square hole pattern. {G&T M961-911} See the Drawings of 11-Hole (5 Tapped 5/16-18) Blocks section, below, for more details.
961-912: An online listing with little information suggests that this might be a 3-block set of the 961-911 blocks.
961-921: An online listing of blocks for sale indicates that these are 1-2-3 blocks sold in pairs, with 13 holes (2 of which are tapped for 5/16-18). Square hole pattern. {G&T M961-921} See the Drawings of 13-Hole (2 Tapped 5/16-18) Blocks section, below, for more details.
It is interesting to see how many machine shop textbooks from the second half of the 20th century do not mention setup/1-2-3 blocks. Browsing through my own library, I find that most do not. My hunch, and it is no more than a hunch, is that this is because these blocks originated in a high-end branch of toolmaking (jig boring and grinding) and took a while to spread to the machine shop in general. This would also explain why they do not begin to appear in tool catalogs until decades after their introduction.
1946: "Parallel setup blocks" are referenced in Moore's Precision Hole Location (1946) {Moore & Woodworth 1946} This is not surprising.
~1949: It is interesting to note that they are not mentioned or shown in the 1949 American Society of Tool Engineers' Tool Engineers Handbook, even though J. Robert Moore of the Moore Special Tool Company wrote the section on "Jig Borers and Grinding." {ASTE 1949}
1957: An article (of as-yet unknown title) in The American Machinist in 1957 says:
[title?] Universal Setup Block lower cost surface broaching [text] It is made of case-hardened steel carefully ground and stabilized, with six faces exactly square and parallel so that any face can serve as a try square. { American Machinist 1957}
1971: A comparison of the treatment of setup blocks beteween the 1971 first edition and the 1981 second edition of Moltrecht's Machine Shop Practice is interesting. In the 1971 edition, they are not named, their use is never discussed, and no 1-2-3 version is shown. The smaller Moore 7/8 x 1 1/4 x 1 1/2 block may be shown in one sequence of illustrations (supplied by Moore) in the Jig Borer section of Vol. 1: Figs. 15-19 (p. 347), 15-24 (p. 352), and 15-27 (p. 355). {Moltrecht 1981} The reason that this is interesting is that all of the illustrations of jig boring practice in both editions of Moltrecht (1971, 1981) were supplied by the Moore Special Tool Co. In the 1981 edition (see below), Moore supplied photographs showing both sizes of their setup blocks used in several applications, suggesting in doing so that their use was common. In 1971 they seem to have been much less important.
1973: Tool Design ( {Donaldson et. al. 1973}: "Parallel setup blocks are available for the jig borer in sets. Dimensions are held to with +/- 0.0001 in. and squareness within 0.0002 in. (The Moore Special Tool Company.)"
1973: A "1-2-3 BLOCK" appears as a project in Surface Grinder Operator: Instructor's Guide published by the State Education Department of The University of the State of New York in 1973. {NY 1973} The block in this project uses the diamond pattern of holes, but seems to be less sophisticated than the equivalent Moore block. See the section of Drawings of 1973 New York block, below for the project instructions and drawing.
1981: Setup blocks are named and shown, but not discussed separately as such, in the 1981 second edition of Moltrecht's Machine Shop Practice, Vol. 1. Suggestively, they only appear in the chapter "Precision Hole Location - the Jig Borer." They're called "precision parallel setup blocks" on p. 441. They are clearly illustrated on pp. 442, 452, and 454 (in photographs from the Moore Special Tool Co., so naturally Moore blocks are shown). Square "precision setup blocks" (1-2-2 blocks, I guess) are shown on p. 425 for aligning a workpiece on a jig borer. {Moltrecht 1981} However, they are not mentioned or shown at all anywhere in the second volume of this edition of Moltrecht, which covers milling and shaping setups. This is interesting because Moltrecht's book is arguably the finest machine shop textbook of the pre-CNC era, and the 1981 edition comes at the very end of that era. Yet in Moltrecht's opinion the object we now view as the common 1-2-3 block was a precision item reserved for jig boring work.
1987: In Olivo's Machine Tool Technology (1987) there is a reference to "setup blocks" on p. 490 (in the jig boring/grinding section), and setup blocks are incidentally shown (more or less clearly) without special note in Figs. 57-3 (p. 484) and 57-6 (p. 487) {Olivo 1987}
The original Moore blocks had a "diamond" pattern of holes (relative to the edges of the block). Current 1-2-3 blocks typically have a square hole pattern. I have no idea when this change happened.
In all of the entries below, McMaster-Carr calls these objects "1-2-3 blocks," not "setup blocks."
Google Books shows an entry (snippet only) for 1-2-3 blocks in the 100th edition of the McMaster-Carr catalog That's probably 1994. The snippet indicates a hardness to Rockwell C 58-60.
I have the 102nd edition (1996). It lists 1-hole, 11-hole, and 23-hole blocks, but illustrates only the 1- and 23-hole ones. The 23-hole block illustrated has a square hole pattern. The 1-hole block is not said to be counterbored; the other two are. Squareness for all is cited at 0.0001" per inch. (which is less than the original Moore blocks, which were 0.0002" absolute). Parallelism is cited as 0.0002" for the 1-hole and 0.0001" to 0.0003" for the other two (again, these are less than the original Moore blocks). As is the case with most McMaster-Carr products, there is no indication of manufacturer.
The current (2014) online McMaster-Carr web catalog lists the same 1-, 11- and 23-hole blocks, and illustrates all three. The 11- and 23-hole blocks have a square hole pattern. Squareness for all is cited at 0.0001" per inch. Parallelism is cited as 0.0002" for all.
Most setup blocks have screw holes which are, on one side, counterbored to receive the heads of socket-head cap screws so that they are flush with the surface of the block. These head dimensions are therefore important.
It's only right to start with the Moore blocks.
I should note, though, that these drawings are reverse-engineered from potentially unreliable online data (we all make mistakes, and I don't own any Moore blocks) combined with my interpretation of Moore blocks from illustrations in {Moore & Victory 1955}. They are not in any way authoritative!
This is the pattern shown in Fig. 82 of {Moore & Victory 1955}. The designation "pattern 0" is mine, not Moore's. I'm presuming that since it is shown in use only once in the book, while the "Pattern 1" (see below) is shown often, that it was an earlier design which was simplified. I could well be wrong in this guess.
The hole pattern of this block is not completely known.
Regrettably, neither this document nor the drawings in it bear any dates at all. The document was developed by James Spillane [Jr.] and Robert M. Reilly at the Eli Whitney Technical School in Hamden, CT. According to Wikipedia, this school was founded in 1956. James Spillane Jr. was the head of the machine tool department at this school until his retirement in 1979, so it cannot be later than that. It has a 1960s feeling to it.
NY 1973
[Extract of the 1-2-3 block project from Surface Grinder Operator: Instructor's Guide. Albany, NY: State Education Department of The University of the State of New York, 1973.
The icon here links to a PDF of just the 1-2-3 block project. For the entire document, see {NY 1973}.
Here is the drawing from the project. It may look pretty crude, but this is at present the earliest published engineering drawing of a setup/1-2-3 block:
After the "historic" blocks drawn above, I'll re-start with a series of blocks defined by their hole layouts. The first of these is a 0-hole block, which is about as simple as you can get.
The drawing on this block is compatible with:
The drawing on this block is compatible with:
The flickr user "becrowel" has done a conventionally dimensioned and toleranced drawing of a 1-2-3 block. It has 6 through holes on the 2x3" side, each tapped 3/8-16 UNC and counterbored. It has 3 blind holes (but intersecting the through holes) on each of the 1x3" sides, each tapped 3/8-16 UNC and counterbored. It has no holes on the 1x2" sides.
I have not as yet been able to discover a commercially manufactured 1-2-3 block with the same hole configuration as this one.
This drawing is in copyright, so I can't reprint it here. It is at: https://www.flickr.com/photos/24975580@N07/3509154588/in/set-72157617713340299
Although the manufacturers emphasize the assemble-ability of these blocks, their screw holes are not counterbored so that the screw heads fit flush with the surfaces of the blocks.
{ American Machinist 1957} American Machinist. Vol. 101 (1957), p. 144.
Presently known to me only through a Google Books snippet.
{ASTE 1949} A.S.T.E. Handbook Committee. Tool Engineers Handbook. NY: McGraw-Hill Book Company, Inc., 1949.
{ Automotive & Aviation 1946} Automotive and Aviation Industries. Vol. 94 (1946), p. 50.
Presently known to me only through a Google Books snippet.
{BS 1941} Brown & Sharpe Small Tools, Catalog No. 34. Providence, RI: Brown & Sharpe Mfg. Co., 1941.
{BS STM4} The Shop Tool Manual. North Kingston, RI: Brown & Sharp, [n.d.; after 1963]
This catalog bears no date, but it does use ZIP codes, which means that it must be later than their introduction in 1963
{Donaldson et. al. 1973} Donaldson, Cyril, George H. LeCain, V. C. Gould. Tool Design. (1973)
{G&T M961-911} G&T Precision Tool (ebay user "tngtool"), ebay listing 361120146693 for Mitutoyo 961-911 1-2-3 Blocks as made in Brazil.
{G&T M961-921} G&T Precision Tool (ebay user "tngtool"), ebay listing 361117637417 for Mitutoyo 961-921 1-2-3 Blocks as made in Brazil.
{ Iron Age 1946} Iron Age. Vol. 158 (1946), p. 68.
Presently known to me only through a Google Books snippet.
{ Machinery 1946} "Something New in 3-way Parallel Set-Up Blocks" [probably article title] Machinery. Vol. 52, Nos. 11-12, p.42.
Presently known to me only through a Google Books snippet.
Mitutoyo Calibration Laboratory. Calibration Price List. Effective Date June 1, 2011. Aurora, IL: Mitutoyo America Corp., 2011.
{ Modern Machine Shop 1946} "Something New in 3-way Parallel Set-Up Blocks" [probably article title] Modern Machine Shop. Vol. 19 (1946), p. 317.
Presently known to me only through a Google Books snippet.
{Moltrecht 1971} Moltrecht, K. H. Machine Shop Practice. Second Edition. Two Vols. NY: Industrial Press, Inc., 1971.
{Moltrecht 1981} Moltrecht, K. H. Machine Shop Practice. Second Edition. Two Vols. NY: Industrial Press, Inc., 1981.
{Moore & Victory 1955} Moore, Richard F. and Frederick C. Victory. Holes, Contours and Surfaces: Located, Machined, Ground and Inspected by Precision Methods . Bridgeport, CT: The Moore Special Tool Co., 1955.
This book is still in print, and is available from the Moore Tool Company division of The PMT Group: http://mooretool.com/publications.html Note: They also have Wayne R. Moore's The Foundations of Mechanical Accuracy (1970) in print and available. While Holes, Contours and Surfaces may be thought of as a specialized volume, The Foundation of Mechanical Accuracy is a classic which belongs in the library of every thinking person.
{Moore & Woodworth 1946} Moore, J. Robert and W. J. Woodworth. Precision Hole Location for Interchangability in Toolmakin and Production. Bridgeport, CT: The Moore Special Tool Company, 1946.
This book, which together with Holes, Contours and Surfaces (1955) and The Foundations of Mechanical Accuracy (1970) forms a kind of a trilogy of precision manufacturing, is out of print.
{NY 1973} Surface Grinder Operator: Instructor's Guide. Albany, NY: State Education Department of The University of the State of New York, 1973.
This document has been reprinted by the Education Resources Information Center of the United States Department of Education. It is available online at: files.eric.ed.gov/fulltext/ED134735.pdf Below is a local copy of that PDF (of the entire document).
[click image to read]
{Olivo 1987} Olivo, C. Thomas Machine Tool Technology and Manufacturing Processes. Albany, NY: C. Thomas Olivo Assoc., 1987. [later distributed by Delmar/Cengage Learning]
{Starrett 1938/1946} Starrett Precision Tools, Steel Tapes, Dial Indicators, Hack Saws , Catalog No. 26. Athol, MA: The L. S. Starrett Company, 1938.
One of my copies of this catalog has bound within it (and references in a notice printed inside its front cover) the "Revised Price List Effective May 27, 1946 Applying to Catalog No. 26 of Numbers and Sizes We are Now Manufacturing."
{Strelinger 1942} Strelinger. The Charles A. Strelinger Company: Tools, Machinery and Supplies. Catalog No. 58. Detroit, MI: The Charles A. Strelinger Co., 1942.
{ Tool Engineer 1946} "3-way Parallel Set-up BLocks." The Tool Engineer. Vols. 16-17 (1946), p. 72.
Presently known to me only through a Google Books snippet.
The small image extracted from Holes, Contours and Surfaces is Copyright 1955 by the Moore Special Tool Company (now the Moore Tool Company division of The PMT Group). Its use here to identify the first known setup block set is, I believe, within the limits of the doctrine of "fair use" in US copyright law. Please note that it is not licensed under the Creative Commons license under which the rest of this page is presented, and may not be used further except within the limits of "fair use."
The 1973 NY Surface Grinder Operator: Instructor's Guide is in the public domain. The reprint and extracts from it here remain in the public domain.
All portions of this document not noted otherwise are Copyright © 2014 by David M. MacMillan and Rollande Krandall.
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