What is this?

[jmarkwolf]

Owner calls it a "Bridgeport tap plate". 10in diameter, 7/8in thick.

Nothing with that name pops up in Google.

 

[Ulma Doctor]

it appears to be a shop made clamping fixture.
the maker went to a lot of trouble, but didn't get the hole spacing quite right

 

[extropic]

Mount it on your mill table and use screws and/or small bar clamps to hold a work piece that you prefer not to hold in a vise.

IMO, the maker should have left a clear (no holes) rim around the outer edge to facilitate traming the head. If it's hardened and ground, I'd think it a useful piece of tooling.

 

[darkzero]

Looks like it would be very useful for a rotary table.

 

[ch2co]

I can't really see if those holes are tapped or not. Would make more sense if they were threaded.

 

[dlane]

Got any extras?.

 

[Glenn Brooks]

Naw, it's a waffle maker. Flip the lid down and plug it in. Watch the golden brown dough push out the sides when done. We had one just like it when I was kid.

 

[markba633csi]

Good one, Glenn. The hole spacing looks pretty good to me, compensating for the fact the photo wasn't taken straight on..
MS

 

[Ulma Doctor]

Good one, Glenn. The hole spacing looks pretty good to me, compensating for the fact the photo wasn't taken straight on..
MS

if you the outermost holes, the left side of the picture, the holes are farther from the OD than on the right side.
on the last row -vertically, the alignment issue on the right side it's very apparent

 

[markba633csi]

Hmmm...well you may be right Mike, however there is a chamfer around the edge and if the holes are threaded, the shadows off the starting threads can be misleading.
Also compare the apparent size of the two cutaways- considerable optical distortion in the picture. So it's hard to say how much error. I'm sure there is some, I doubt it was drilled on a CNC machine.
"Guess the amount of error and win a prize!" A brand-new arc welder!
MS