What is this sine bar accessory?

[GeneT45]

The attached photo is from a friend, it's a sine-bar that his father made, with a mysterious tooling plate and some pins ("stubs"). Can anyone identify the use of the plate and stubs?

Here's what he had to say:
"
The stubs are not attached by the cap screws.
They are set in bores like the upper right.
Not really sure what the cap screws are for.
They do not fit the threads in the plate.
The stubs are threaded across to be attached to the bar.
The longer stub can be installed on the bar so it will pivot on the plate. That's how I originally found it. I suppose for horizontal angles. Maybe the use a parallel to make the reference surface?
"
TIA,
GsT

 

[mmcmdl]

Almost looks like a " stain " on the flat plate where the bar was/could have mounted . Other than that would be a WAG .

 

[benmychree]

What would lead you to believe that the plate and sine bar are associated with each other?

 

[GeneT45]

What would lead you to believe that the plate and sine bar are associated with each other?

Well, as @mmcmdl pointed out, there's a mark on the plate that seems to indicate that they sat against each other, and the 'peg' hole on the plate seems to correspond with the location of one of the pins on the sine bar.

GsT

 

[extropic]

Because neither pin seems to protrude from either side of the bar, I don't see how the peg hole "corresponds" with the sine bar.

How are the other two pegs attached to the plate? Pressed in or easily removable?

I think the plate might be a type of mini pallet to fixture small parts. What is the spacing between the two pegs?

You should ask "KURPAN".

 

[GeneT45]

Because neither pin seems to protrude from either side of the bar, I don't see how the peg hole "corresponds" with the sine bar.

How are the other two pegs attached to the plate? Pressed in or easily removable?

I think the plate might be a type of mini pallet to fixture small parts. What is the spacing between the two pegs?

You should ask "KURPAN".

The pegs in the plate are cross-drilled and threaded and can replace the pegs on the sine bar.
I think the pegs are a snug sliding fit, but I'll have to ask. Same with the spacing.
Kurpan is my friend's (and his father's) last name.

GsT

 

[mmcmdl]

Well, as @mmcmdl pointed out, there's a mark on the plate that seems to indicate that they sat against each other, and the 'peg' hole on the plate seems to correspond with the location of one of the pins on the sine bar.

So don't quote me here , but yes . being a machinist / toolmaker made tool , this had a purpose . They go together I would think . The one stud is longer to fit into the hole and can be screwed in . The other stud is always a known distance which would be the hippopotimus . He had a use for this and made it up on his spare time on the shop floor possibly . I made up larger 45 and 30 degree sine bars for the BP slots when I did the woodwork down the basement 40 years ago . If I go thru my boxes , I have multiple sine bars of all shapes and sizes that I've made over the years .

Some don't realize that the pin distance doesn't mean a hill of beans with sine bars . we make them to suit the job . If you know 1 side , either the hippo or the x or y , you know your angle . I would keep these 2 together , they are a pair of tooling definately made to go together . I still have quite a few of my elders tools like this as well as my special job jigs . Keep them , and use them . I know I'd be happy if I knew someone was using my tools 50/100 years down the road .