Hi Justin

Thank you for contacting Mearto with your appraisal inquiry.

This Singer sewing machine with the serial number AD599412 was manufactured in 1917. Singer's serial number system used a combination of letters and numbers to identify the manufacturing date of their machines, with the letter "A" corresponding to 1910, and each subsequent letter moving forward in time. In this case, "AD" indicates 1917. It was made in Elizabethport, NJ.

So few people use sewing machines these days that the market is somewhat flooded by them. With considerably less demand than supply, prices remain modest with most models by Singer - the gold-standard in sewing machines - bringing less than $200. Ones that are not built into tables and retain their original domed cases are worth a little more: $300-400 (mostly because the table-mounted ones take up a lot of space).
Based on the photos and information provided, and subject to examination, this is:

An antique gilt stencil and ebonized Singer Downing sewing machine
Serial number AD599412, made in Elizabethport, NJ, in 1917.
Electrified; retains its original domed top.
CONDITION: This sewing machine appears to be in generally good condition.
PROVENANCE: Inherited
$300-400*
*represents a fair-market value for auction purposes; retail or asking price may vary.

Please let us know if you have additional items to appraise, or questions/concerns, and thank you again for using Mearto.
~ Delia