Smithing tool id

That is not a Black smith tool, it is a de-burring tool used on a Lathe to de-burr the inside edges of a part being turned with a hollow center. It is held at an angle and one of the corners makes contact with the burr on the sharp edge and with a small amount of pressure the burr is sliced off the edge and it can be used to create small champers on the edges also !

As agatemaggot said, an engineering tool, handy for cleaning up burrs on holes, drill holes as well as lathe bored holes. It could be used by hand for rough cleaning up the inside of rings, it is good for holes. You will find it is quite difficult to use for outside cleaning up though.

White container is probably Silver Solder Flux, the tool is used for de-burring on a part that is turning, on a stationary part it would be almost impossible at best. Used one for 55 years, trust me ! There are de-burring tools made for use on stationary work but they have a fairly good size handle and a removable / replaceable blade that swivels. The swivel blade type works very well on all types of machinable metal and is great for de-burring plastics.
These store bought triangle tools are a little pricey and after I had several ( BORROWED ) I started making my own out of old broken Triangle files I picked out of the scrap tub at work. I just ground the file to a point like the store bought and then hollow ground each side, files were harder than store bought and stayed sharp longer !

It looks too dangerous to use without drawing blood. Wonder what the old timer used it for? was in a box labeled bench tools. Thanks for all the replies.