What is this one?

[Dave H (MI)]

Somehow I ended up buying another set of tools today. Long story...they find me. I'm tool stalked. In the box was this item. Carefully wrapped in a sticky cloth which clearly has oil in it and stored in the bottom drawer. I don't even have a guess on this one but it's owner really packed it carefully. Very heavy, steel. Three shiny spots on one side could be feet. Other side is reasonably flat...I didn't take an indicator to it. That's about all I got. Owner is deceased and brother sold me the box and has no clue. Obit says the guy worked for General Dynamics. That's all I got...hopefully someone has more. Roughly 4x6 inches.

 

[ihplowboy]

A small surface plate.
Jim

 

[Janicholson]

IH plow boy is correct. If the actual flat surface is covered in cosmoline or grease, and if cleaned is bright steel, it is usable. It would work well for flat sanding warped oil pump and carb flanges. If the discoloration is rust, it is a door stop. Jim

 

[Mike(NEOhio)]

I'd go with surface plate though I don't know what use such a small one would have. Is the flat surface scraped? Could also be a lapping plate.

 

[Moonlite37]

It is a surface plate. It is cast iron and not steel. Cast Iron is more stable and can hold precision.

 

[4wdtom]

Yes, a surface plate. The 3 feet keep it from being deformed slightly if set on a less than true surface. If rust pitted it could be resurfaced by surface milling or machining in a shaper or planer however it probably will not be really true after such as this may release stresses in it that will pull it out of true. And holding it for this operation will likely distort it too. It would need to be scraped true using a good surface plate. However it may be ok for less demanding work.

 

[Dave H (MI)]

I had no idea there were surface plates so small. This one has some issues on the surface that may be problematic. I will have to clean it and see how bad it is. Cleaning the oil off it is no problem but I will need to use caution if there is rust to remove. I guess Evaporust is safe enough. I don't think it removes any good metal. Then I can see if there is pitting or such. The brother of the deceased put this 7 drawer box outside in a storage shed. One drawer had a mouse in it briefly. The bottom drawer shows some surface rust on tools...including an otherwise nice set of adjustable parallels. Those look salvageable though.

 

[KenH(MI)]

Apprenticeship surface plate, about a hundred years ago many companies included this as part of machinist training, three apprentices would scrape rough planed surface plates against each other in sequence to obtain three flat plates. More of an exercise than anything else but the lesson was in scraping three semi finished surfaces to obtain three perfectly flat plates.

 

[David Snipes]

What is a surface plate used for?