Starrett hook rule No. 604R with (what is the slide item and what does it do) the number on it is No. 22C.  I'm not familiar with this kind of stuff, was in the bottom of a box lot last Saturday.

That is a drill bit sharpening gauge, for the common angle at which twist bits are ground.  You'll notice that the angled edge (on the left in your photo) has got fine increments marked on it.  That will let you confirm that you've ground both flutes evenly.  You turn the bit so the bit's cutting edge is against the attachment and note where the "center" of the bit is, then turn it so the other flute is against the attachment and confirm that your center is at the same increment.  When the bit's ground at the correct (standard) angle, the leading edge of the flute will touch the attachment over its length, falling away as you turn the bit in the direction it will turn in the drill motor/drill press.  Checking the "fall" against the increments on the rule itself will let you confirm that you've ground the two flutes consistently.

There are one-piece gauges like this; these attachments are for machinists who don't grind bits all day long.

If I didn't already own one, you've be seeing a "ping" indicating you've got a private message from me...

I think the side towards the hook is for measuring the angle of drill bits. The other end...no clue.

Mike

the picture in the starrett book shows the angle of the slide part pointing the other way,,,so yours might be ass backwards?...turn it around?...maybe you can use it both ways...no clue

Thanks, it does say drill point on the angle and it is 59 degrees.

Quote from: mikeswrenches on November 06, 2018, 04:43:17 PM
I think the side towards the hook is for measuring the angle of drill bits. The other end...no clue.

Mike

I think that's just there to signal that it's not for anything.

Maybe the slide piece is attached the wrong way.  It looks like the stop on the left holds the drill bit end and the sliding gauge should be facing down.  I have never seen one of these before.  I will have to watch for one.

Quote from: amecks on November 06, 2018, 09:07:28 PM
Maybe the slide piece is attached the wrong way.  It looks like the stop on the left holds the drill bit end and the sliding gauge should be facing down.  I have never seen one of these before.  I will have to watch for one.

No, it's just a stop rule - used for measuring from edges.   The drill bit is just held up against the bit gauge by hand pressure.  If you rested the bit against the stop, you'd have to adjust the gauge every time you brought the bit back from the grinder.