by Keith Bohn
If you are of the type who easily follows shamans or gets fooled into get rich schemes you are the one I'm looking for. It's hoped, by me, that by the end of
this introductory article you will be hunting down the true meaning of Delta and becoming obsessed with *Born On Dates* and *vintaging* Delta on the fly. If
you are the strong type, not easily duped, please move along.
This write up will act as the jumping off point for anyone wanting to vintage an old Delta machine or for someone wanting to submit content on a machine of a
certain vintage. It contains the most rudimentary data required to start one's career dating Delta. Please read it carefully as there are subtle nuances and
while trying to vintage an old machine isn't rocket science it does require a certain bit of savvy. At the very least you will be able to establish date
ranges based on what you read here.
The easiest way to vintage a Delta machine is of course with the serial number. There are guidelines though. Delta only began keeping records of serial numbers
after 1941. This makes it difficult if you have a machine dating prior to that. The serial number plates basically came in three flavors.
The first style plates were made of aluminum and measured 1/2" X 3" with rivet holes approximately 2 3/4" on center. This style was used beginning circa 1939-1940 to sometime in 1942 (probably early 1942), and then again from sometime in 1944 to late 1947.
Older Delta Serial Number Plate
The second style plates were made of "oilboard" (dense coated cardboard) and measured 3/4" x 3" with rivet holes spaced the same as the first style plates. They were used between early 1942 to sometime in 1944.
Delta Oilboard Serial Number Plate
Presumably, the oilboard style was used during a period of WWII to conserve aluminum. Not being as durable as aluminum, they are often missing or in poor condtion.
The third style began in late 1947. They are made of aluminum and measure 1" x 4" with rivet holes approximately 3-3/4" on center.
Newer Delta Serial Number Plate
This aluminum serial number plate is from a 1947 Unisaw, and is attached with screws.
1947 Delta Unisaw Serial Number Plate
Some machines, for whatever reason, may have had their serial number plates removed, making a positive vintage identification more difficult. You can however locate the rivet or screw holes in the machine and perhaps a ghost image of the plate, and use the distance between the holes to narrow down the machine's vintage. Where plates were located on individual machines would take a paper unto itself. I should also note, plate locations on the same machines weren't always located in the same spot. For instance, I've seen plates on the back of a Unisaw cabinet as well as the front.
Please read the rest of this article though before positively determining your machine's vintage. It's also come to light, from various discussions on the OWWM discussion forum, that Delta used some serial numbers during the same period that don't quite jive with what's known by me. For instance, some five digit serial numbers on 1' by 4' plates don't compute with my list or Delta's. If ever this mystery is solved this write up will be amended.
About This Serial Number List:
I received this list from a fellow OWWM member. Someone had given it to him at his local Delta service center with no explanation or additional information.
For the most part I have found it to be valid but have run into a couple of instances where it has not been 100% correct. Therefore, take it for what it is,
do not expect it to be the 'last word' and always call Delta to confirm any dates that might be suspect. Delta can also give you the month the machine was
manufactured. This is something you won't get from the list below. I should note here, Delta isn't always right either, especially if they are looking at the
same source material as you have here before you.
The serial number list is broken down into three parts. Machines built in Milwaukee, Wisconsin and Bellefountaine, Ohio had an all-number code. According
to the list machines were built in Bellefountaine all the way up to 1976. Machines built in Tupelo, Mississippi had an alphanumeric code.
The serial number list starts with 1941. These machines would have been built in Milwaukee, Wisconsin up to 1952.
The following is based on this original document.
Straight Numerical Series used by Milwaukee-Crescent
The Bellefountaine Years:
Alpha-Numeric Series Used By Tupelo Division:
Letter prefixes: LP, LQ, LR, LS, LT, and LU were not used.
Letter prefixes: MJ, MK, ML, MM, MN, MO, MP, NA, and NB range in years 1979 through 1982, but we do not have information to tie these to a year of manufacture. Delta may still have this information.
Later date-coded serial numbers
Beginning July 30, 1982 (March 1984 in Canada and Brazil), serial numbers for Delta / Rockwell machines changed to an eight digit number. The first three of these digits were a date code, the remaining 5 made up the individual serial number for the machine.
The date code consisted of the two-digit fiscal year of production followed by a letter which designated the month of production according to the following code:
|A = October||G = April|
|B = November||H = May|
|C = December||I = June|
|D = January||J = July|
|E = February||K = August|
|F = March||L = September|
This sequence reflected Rockwell's fiscal year of October through September. In the example, the date code (83B) indicated a machine built in November, 1982 which would have been in Rockwell's 1983 fiscal year.
Dated coded serial numbers are covered in this original document
On April 12, 1984, Pentair purchased the Rockwell machinery line. Sometime shortly thereafter the date-coding system changed to calendar year instead of Rockwell's fiscal year. The letter codes changed to A (January) through L (December).
When in doubt you should always try and verify the vintage of your machine with any subtle attributes of the manufacturing period. For instance, a Unisaw with a
cast iron base pigeonholes that saw for a certain time period. Raised sheet metal rays on the 14” bandsaw make it the earliest of vintages. As this project
goes on it's hoped that all of these changes will be brought to light and put in written form. In the mean time feel free to ping me on the back channel with
suggestions or questions. Most of what I find interesting comes from these requests.
If you do not have a serial number all is not lost. It's possible to get within a decade of your machine's vintage from a description or photo. Subtle changes
can narrow the focus greatly to within a couple or few years. Some ways to vintage without serial numbers are:
Decals and Plates: ¶
This will be written up for a later article as it requires way more time than I care to spend on it at this moment.
Using Catalogs To Vintage A Machine:
This can work fine for dating a machine but comes with certain pitfalls. I do not want to leave the impression that the catalogs lie but we can say they don't
always tell the truth. Where the catalogs work best is in establishing when a particular machine came onto the market. The artwork used for these was fresh.
Remember this fact. What happens next is, the same artwork would be used over and over for a number of years to the point where subtle changes would not be
reflected in later catalogs. An example of this can be found with the Unisaw. The 1940 catalog shows the Unisaw with a flat non-louvered dust door. This same
dust door is shown in the catalogs up into the late 40's indicating that this was the dust door vintage to those saws. However, there is a picture of a Unisaw
in a 1946 issue of the Deltagram that clearly shows a louvered dust door. My conclusion is, the dust door was changed *somewhere* in this time period, the
change, being an *upgrade* of sorts, wasn't considered significant enough to warrant new art work. The catalogs have been good at documenting changes when a
machined was 'lessened'. For instance, changing from the cast iron to sheet metal base on the Unisaw.
So, how do we use catalogs to vintage a machine? As previously mentioned, establishing a release date for a new machine. From there I use them to SWAG a
date for subtle changes. This creates a date range but not a positive single date or year for a machine. Sometimes this is all you can ask for. Be happy.
When I began my quest to date my Unisaw I was spread over three decades based on catalog artwork and what Delta told me over the phone.
Any plate with a Milwaukee address indicates a machine made prior to, and including, 1952. Any machine wearing a plate with a Pittsburgh address indicates a
machine built after 1953. Short and sweet? Not really. There was a recent instance where a machine tagged Delta/Milwaukee was found to have a serial
number indicating a 1953 born on date. I attribute this to Rockwell having left over tags and depleting that inventory before digging into the Pittsburgh plates.
As with the catalog art work, they were frugal. I should note, the exact switch over in 1952 is not known by me.
Stands and Motors: ¶
Stands and motors should never be used to establish vintage. Machines were available for sale without either and in some instance the stand or motor true
to the manufacturer could have been added later. This is not to say that the stand and motor on your machine should never be considered as vintage to the
machine, just that it shouldn't be your only piece of evidence. Use them only to firm up what you know.
The Peace Sign (Sign of the Devil):
In 1973 Rockwell Manufacturing was absorbed into Rockwell International. These machines are tagged with the easily identifiable R.I. 'Peace Sign'. Early
machines of this era are fine and dandy. Later R.I. went on a cost savings spree and many machines suffered. I typically look at these with some caution and look
for dates closer to the early 70's. I would consider a later machine if someone I knew and trusted was selling it.
Delta typically cast the parts numbers onto the individual parts. In earlier machines this shows up as an alphanumeric code like, DP-220, or, LTA-325. This
parts code pointed the part specifically to a particular machine. After the absorption by Rockwell International this casting code changed to some
insidiously stupid international multi-numeral code with no rhyme or reason. Well, I shouldn't say no rhyme or reason, just none that jumped out like the old
code. With the old code you could immediately recognize an orphan part sitting on a shelf and code it back to a machine. Something impossible to do with number
codes longer than an International phone number. You may find some of these multi-numeric code numbers on machines of an earlier vintage. This usually
indicates a replacement part from the later era. You might also note a difference in paint between these parts and the rest of the machine in a
slightly different color or sheen. Take this evidence for what it is, a part replacement and nothing more.
Got A Receipt?:
If you have the original receipt please step to the front of the class. This is like having all the tags on your machine in mint condition. This is like finding
a vintage machine still in its original cosmolene.
So there you have it. Play around with the above and feel free to ping me if something isn't explained right or you've found inaccuracies. Special thanks to Jeff Traeger, John Orvis, Dave Potts, T. R. Smith and other OWWM forum members for supplying graphics and information for this series.