Builders Iron Foundry was best known for their production of flow-control and flow-measuring devices for waterworks, water supply systems and similar. They became known as "BIF" and produced a wide range of cast iron venturi sections with flanged ends for use with flow measuring and flow recording instruments. Large venturis, big enough in some cases for a man to crawl thru. They eventually became known as "BIF", which they made a point of advertising as "Basic In Flow" rather than their original name of 'Builder's Iron Foundry'. I've run into their venturis and flow meters as well as other equipment used in control as well as measurement of large flows of water on aqueducts and dams.
What always stuck in my mind was the question of whether there was any connection between Brown & Sharpe and BIF. Both were in Providence, RI, and both use large quantities of iron castings. B & S moved out of Providence some years ago, out to Kingston, RI. The old shops and foundry became some kind of 'repurposed' use (loft housing ? Trendy shops ?). BIF became a part of one of the conglomerates that were gobbling up US manufacturers and merging them. I wonder if BIF produced a line of grinders to keep some steady work coming through their shops. The orders for venturi flow meters and flow control devices like sluice gates was not a steady thing, and almost every order was a custom order to suit a specific set of conditions. I remember seeing BIF venturi flow meters which were so old they used glass-tube manometers filled with liquid mercury. In my first office at a hydroelectric plant construction site, I had a Builder's Iron Foundry recording flowmeter (spring wound clock mechanism) on my office wall to record flows in a NYC water supply aqueduct. I think BIF ceased to exist a good 25-30 years ago. I also believe BIF had not built any grinders of any sort for many years prior to that.
Making a surface grinder in Providence, RI, on Brown and Sharpe's doorstep does not seem like the wisest thing. There was at least one other competing maker of surface grinders in Providence, RI, possibly 'Robot'. The surface grinder shown in this thread would not be taken seriously by B & S or any tool makers or machinists doing fine work. My guess is it was intended for fairly simple and not particularly accurate work such as sharpening punches used in sheet metal or structural steel or boiler shops. These punches only required being ground flat across the business end of the punch to restore a sharp shearing edge. Chances are a fixture with the correct angle (if needed) to grind off the punch faces was used rather than a magnetic chuck.