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Serial numbers can be divided into four series, Early, Intermediate, Late and Final. The first Model SG grinder made carried the identifier AA1 - the earliest machine known so far in this series being No. A62 - and No. 475 the highest. By 1945 the Intermediate series of numbering had been introduced with the first two digits now indicating the year of manufacture and the last four the machine number - the earliest and latest of this series so far discovered being, respectively, No. 45731 (machine No. 731 made in 1945) and No. 511421 the highest; sometimes a dash is found stamped between the year and the machine number. In mid 1951 the Late series began when a prefix digit "1" was added, Machine No. 1511471 being the earliest so far discovered. The Final sequence, which applied only to SG-48 models, had the identifier "48" followed by a space, then "1" and the year indicator, for example "70", followed by a space and then actual machine number.
Sold as a complete, ready-to-run unit, the Sanford was well constructed with close-grained Meehanite iron used on all wearing surfaces, the material being heat treated and annealed for long-term stability. Sliding faces were ground finished to close tolerances and checked to within 0.0001" - see the brochures for full specifications. The transverse and cross travel ways were randomly hand "spotted", the aim being to give a smooth, non-stick feel to the controls. Both vertical and traverse feed screws were precision ground and fitted with handwheels whose flat, outside surfaces were engraved so as to form large diameter, but non-adjustable, micrometer dials - that on the vertical axis marked to show a travel of 0.0005" and on the cross feed 0.001". Small adjustable pointers in sheet steel were provided to act as zero markers. Later models had a chrome plated finish to the handwheels and were finally improved by the fitting of adjustable dials, described by the makers as being of the "slip ring zero setting" type. While the saddle ran on a pair of V-ways spaced as widely as the base casting allowed, the table used a V and a flat and, as on most surface grinders, simply rested on its own weight.
Table drive was through the expected rack-and-pinion gearing using off-the-shelf items from Boston Gear products. While the handwheel shaft turned first in bronze bushings, on later models "sealed-for-life" needle rollers with felt seals were used. While very early models had a longitudinal table travel of six inches - later changed to eight - the original traverse remained at four inches and the vertical at six inches throughout the machine's life.
Made in a high-quality alloy steel - and described, rather coyly by the makers, as being expertly ground - the spindle was advertised in later years as running in adjustable, high-precision ball races lubricated by a tall oil pot, later models were fitted with sealed-for-life bearings. As the spindle assembly on the SG was described by the makers as being " built into the spindle housing", they strongly advised that no attempt be made to dismantle it when worn, instead they offered a 48-hour rebuild service that used two hours of factory labor and fitted the latest parts.
Spindle bearings varied over the years and, since many assemblies have been updated, if your machine appears to need new ones it is best to disassemble and check what's fitted. The earliest bearings were E-14 or E-15 "magneto" types, these being superseded by 202PP at machine number 1511501. Sealed-for-life bearings were installed after Machine No. 1612355.
Fitted as part of the regular equipment was a 4" diameter grinding wheel with a ½" hole. Widths varied, with 3/8" being standard, though ½" wide wheels will fit on some machines when equipped with special thin wheel flanges; it is best to check for fit. Bear in mind that these grinders use rather small motors and, should a full-width cut be attempted with a ½" wheel, the amount that can be removed in one pass is very limited. The wheels were carried on a straight, ½" diameter shaft and retained by a left-hand threaded flange nut. The supplied spindle wrench was a Williams #418, featuring 3/16" pins on a 1" center. A modern substitute is available from www.armstrongtools.com -  model #34-101.
Flat belt widths varied over the years with 1/2" x 17", 1/2" x 10" and 9/16" x 13" all being shown in the parts' list. Replacement belts are available from  http://www.wmsopko.com/products.htm. Variations in the drive pulley diameters have been noted, but the grinding wheel on all versions spins at a nominal 5000 to 5500 rpm.
Fitted to the earliest models was a motor mount formed as a large, cast-iron angle plate that carried the cast-in identifier SG-10. The motor was carried by the underside of the horizontal arm being curved to match that of the motor's body, two bolts holding it in place. However, the mounting was used not just to carry the motor, it also formed a substantial part of the machine with its precision ground and polished face used as the back sliding surface of the spindle carrier, the latter providing the front sliding surface as well as the side guides. The spindle carrier and motor mount bolted directly together and "sandwiched" the ground ways on the fixed, upright column - the whole assembly being machined with great precision as there was no means of adjustment.
Motor mounts were produced in several variations over the years including a few examples of an extra-wide version of the SG-10 with the mounting holes spread further apart,  "18" cast into the top and carrying a Wagner motor. The next known type was marked SG-10a and using a flat mounting surface that took motors with four feet cast integrally with their cast-iron bodies. Next came the S-626 mount, in cast iron, and then the aluminium S-785, this supporting the final MAC motors.
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An early 1/8th motor and its SG-10 motor mount. This machine carries the Serial No. 254  Can any reader help with high resolution pictures of a similar first-generation Sanford SG. If so, the writer would be most interested to hear from you

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Flanged and bolted to the front of the spindle carrier with four cap screws, the spindle housing could be adjusted to set it parallel to the table, each of the cap screws being fitted with a matching setscrew to nudge their position and so set the alignment. N.B. The spindle housing can be unbolted without disturbing the setscrew settings and - without removing the housing from the carrier - the spindle can be easily removed from it by unscrewing a lock nut on the back side of the spindle shaft and sliding it forward.
It is necessary to unbolt the motor mount from the spindle carrier to change belts, at least on the early designs. I have not had the opportunity to change belts on a V-belt drive SG-48.
Motors: the earliest type was made by Robbins & Meyers and marked, "Made Exclusively For Sanford Mfg Co". Of just 1/8th h.p., this was a single-phase, 3450 r.p.m. type with its on/off switch located on the right-hand face of the base. As this motor was marked "Made Exclusively", one wonders if, like the those fitted to many other grinders, it was balanced to reduce vibration marks appearing on the work. Obviously underpowered, the first motor was soon replaced by a 1/6 hp ball-bearing unit supplied by Robbins & Meyers, Bodine, Wagner, or General Electric. By the time the company had moved to Commerce Street other options were also listed, including a 110-volt DC unit, ball-bearing spindle motors, ones to run on a 3-phase supply and even a 50 Cycle, 2875 rpm. Type. Finally, SG-48 models were given a more powerful ¼ h.p. "MAC" type by the Motor Appliance Corp., this being described as a smooth-running, dynamically balanced, 115/230-volt, single-phase, plain-bearing, fan-cooled type running at 3450 rpm. 
A small electrically-excited magnetic chuck was offered from the beginning of production, the necessary rectifier unit being housed within the base and suitable plugs, wiring and switches provided as part of the installation. The earliest version of the power supply used a Lafayette #4612, type 80, full-wave rectifier vacuum tube of only 1/8 amp output, the components being fitted to a metal plate inside the base. Later versions used a solid-state diode providing only half-wave rectification, although this was boosted by a matched capacitor. This much smaller circuit mounted directly on the switches, isolated by a fiber sheet, with the switch positions marked "On", "Off" and "Demagnetize". To replace the old, now-unobtainable components, a modern solid-state, full-wave bridge rectifier power supply has been designed and the schematic is available on the Internet.
Always listed amongst the accessories was a Browne & Sharp #255 manual magnetic chuck, this being required when the coolant system option was specified and the electrical chuck likely to be short circuited. This manual chuck reduced the overhead clearance by an inch, had a working surface of 2 ¾" x 5 ¼" and was not bolted down, a magnetic clamping action on the bottom surface being used to secure it. Machines sold with a manual chuck fitted had two holes in the right side of the base, while those with an electric chuck had a third hole machined to take the required wiring. A machine found with a manual magnetic chuck and three holes will have been converted by the owner.
Although several accessories were shown in the sales brochures, few seem to have been sold, or have been lost over the years - the writer javing failed to locate anything other than the cabinet stand. Although now often missing, each SG grinder came as standard with a cast-iron vacuum extraction nozzle mounted on the left-hand end of the wheel guard. The first accessory, offered from the start of production, was a cutter-grinding attachment, marked as "Sanford". In addition, a wet grinding set-up was offered complete with a shield that fully enclosed the table, a separate 7-gallon sump/pump unit with hoses and nozzles and a manual magnetic chuck to replace the electric type. Two stands were offered - a full cabinet base and a portable table, the latter having a 20" x 34" wooden top, two wheels and a folding handle for moving.
Prices:
1941 - $495
1951 - $675
1955 - $700
1957 - $735
1962 - $779
1964 - $805
1996 - $6160
As with the products of many other smaller machine-tool makers, all three Sanford grinders were reproduced as un-authorized copies by another concern - in this case the "Harvey Company", based in Long Island, New York and well known for their 'Butterfly' brand of die filers. There were several small detail design changes on the Harvey version: handwheels were a solid disc instead of spoked; the small covers over the saddle ways were rectangular instead of peaked and the scatter shield at the left end of the table had deeper sides to better capture sparks.
Few surface grinders of similar size and capacity to the Sanford and Harvey have been produced. The Builders Iron Foundry in Providence, Rhode Island, manufactured a simple, fairly crude table type with a hand-lever feed - and it appears that this pre-dates all the others. In England the Herbert Company offered, in pre-WW2 years, their somewhat larger "Ball-bearing Bench Surface & Die Grinder" (and later a floor-mounted hand-operated model) and EXE their very fine bench machine. A French Company, Lipemec, produced the beautiful LIP 515, this having the same capacity as the Sanford SG-48 at 8" x 4" (200 x 100 mm), a somewhat similar base, saddle and table but with a completely different, double-column upright to carry the grinding head - the solid steel bars being hardened, ground and protected by bellows. Grenby, an American machine maker better known for their cylindrical grinders, offered a slightly larger table-top unit, the design (in a modified form) being used as the basis for the Australian Macson. From Taiwan came the Richyoung and, in recent years, a version of the "Grenby-Macson" has been produced in China to be sold under various brand names including Harbor Freight and Tormach.  The Tormach, manufactured to a higher level of accuracy and finish is, today, available with automatic feeds and has travels of 6 by 12 inches - travels for the hand-feed Grenby are not known. Another example is the very high quality, superbly constructed unit from the Swiss Bulova watchmaking company - though this model might be considered too large and heavy for the description "miniature" to be applied.
Other hand-operated surface grinders include the 2B and 2LB Brown & Sharpe models, the Capco,  Eagle,  Superior,  Feinprüf,  Jones & Shipman Model 540H and  Norton Model TS,

Repair Parts
Although Sanford-produced parts are no longer available, some items are commercially available - or easily adapted from substitutes:
Spindle wrench: from www.armstrongtools.com -  model #34-101.
Flat belts: from http://www.wmsopko.com/products.htm.
Bearings: check for the type needed, available through numerous suppliers.
Leadscrews: can be machined from Acme threaded stock. 5/8" - 10 Acme, left-hand for the cross feed shaft and right-hand for the vertical leadscrew.
Cross feed nut insert: this can be machined from a larger 5/8" x 10, left-hand Acme available from McMaster-Carr.
Table rack and pinion: the pinion is Boston Gear Part NB16b, 16-tooth, 16-diametral pitch, 14 ½-degree pressure angle, 1/2"-bore and matching rack; available from McMaster-Carr. You will have to drill and counterbore the mounting holes as they go through the teeth, not on the side. Be sure to counterbore deeply enough or the gear will hit the cap screws - those on the Sanford having thinned heads.
Shaft bearings - bushings or needle bearings: replace with the same from McMaster-Carr
Top bevel gears: Boston Gear part L149Y-G, 32-tooth, 16-diametral pitch, 20-degree pressure angle, ½"-bore. On the Model SGm the vertical leadscrew gear needs to have the hub machined to diameter and threaded for 5/8" - 10 Acme right-hand (available from McMaster-Carr).

Other Sanford Grinders
Model MG  A surface grinder of conventional size designed by Walter Zigahn in the late 1940s. Although the brochures called it the MG 612, that was the size of the magnetic chuck. It had a table travel in traverse and longitudinally of 8" x 12" and 12" vertically, Sanford also making a version for sale by DoAll. The saddle and table were larger versions of the SG design, although the Vee and inverted Vee ways for the cross travel were swapped from the SG. The motors were ½ hp and the basic grinder, without its stand, weighed 540 lbs. Base price in 1951 was $925, rising to $1125 in 1964.
Model LG-1016 Introduced after the company moved to Rahway in 1959, this large grinder had a 10" x 16" x 16" work envelope (actually travel was 11" x 18"). A 10" diameter wheel turning at 1725 rpm and could be specified, or a 12" at 1590 rpm. Both hand operated and hydraulic models were produced. The motor fitted a 2 hp 220/440 volt, 3-phase, weight complete with a stand 1780 lbs and the base price in 1962 was $2150, rising to $3500 in 1964..

An early example of the Sanford SG with an almost antique look to its base and a tall, externally-protruding vertical feed screw.

Another very early - and completely original example - Serial No. 254. Note the plain, non-counterweighted handles, the lack of a name cast into the wheel guard and the array of flip-top oilers - these appearing in different positions on the early SG and SG-2 models and possibly supplemented by screw-sealed oiling holes

A Second Generation machine (Photo Essay here)
Easily spotted distinguishing features included the word "Sanford" cast into the wheel guard, a 19-inch long table (without the earlier raised plinth) and often two 90° oil cups set into its front face. The base casting was less antique in form, being of a more rectangular shape, and the handwheels now had a counterweight cast between two of the spokes. The traverse shaft was relocated in the base and its design altered. From serial 1572081 the bronze cross-feed nut was replaced by one in cast iron with a replaceable bronze insert

A Sanford
from the 1960s

Views of a Sanford SG-48, still in its maker's original finish, manufactured in 1970