A hobby blacksmith I had rented a house to left this behind. is there a use other than heavy duty hold down??

Not unless you use it for something else.

 

That has got to be the strangest holdfast I have ever seen.  Obviously, the previous smith made it himself, and even though it looks strange, it must have worked for him!

Depends on what type of smithing the owner made, and how it fitted into his anvil, I assume that is your anvil, rather than the one the tool was originally made for

 

It could have been used at 90 degrees to the anvil as a stake for forging narrow spaced tines like on forks etc, or for opening and fullering out the hot cut split in them

 

Or it could have been used to form curves in bars

 

Would be interesting if the original owner/maker is on site and can tell us what he made/used it for, or any other ideas what you would use it for, at least it looks useful

I saw something similar in a book on smithing, with emphasis on large stuff for trains and machinery.  I'm thinking that what you have is a remnant that the hobby smith was using as a tool.  That sure would be handy for forming forks or as a stake for bowls.  You could even use it as a top tool to fuller or vein your stock.

Thanks for the ideas.

shape of it almost makes me think of a bead breaker for tires of some sort.   interesting item though

It is made from the end of a pavement breaker jack hammer bit.

I thought it might an old treadle for a press or something.