Pratt & Whitney rifling machine

[DiscoDan]

I ran across this on eBay today. Never seen one before.

Pratt & Whitney Sine Bar Rifling Machine (#209) | eBay

Find many great new & used options and get the best deals for Pratt & Whitney Sine Bar Rifling Machine (#209) at the best online prices at eBay! Free shipping for many products!

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[francist]

And a beautiful piece of casting work on the pivoting arm to boot!

 

[markba633csi]

I declare I have no idea what that does

 

[Karl_T]

I happen to have the pull broaches for this machine. These were used during WWII to make 30 cal rifle barrels by the thousand.

 

[seasicksteve]

I declare I have no idea what that does

It is used to establish the internal features of a rifled barrel. It sets the rate of twist and uses a single point broach to cut rifling A well made and sought after machine

 

[pontiac428]

What does the sine bar do?

 

[seasicksteve]

What does the sine bar do?

The sine bar works like a taper attachment, but in this case it makes the head rotate. The sine bar is used to adjust the rate of twist by adjusting the speed at which the head rotates relative to the carriage that moves the cutter. Hopefully makes sense

 

[pontiac428]

So the rotation of the head is driven by a rack gear- or a linear to rotating cam/dog plate- at a variable cross (sin) angle, or something like that? I take it it's a push-only system, too?

I'll never touch enough barrels to pay for getting that guy running. I wonder if there's even any interest in it when all of the competition is already using a push-pull button setup on numeric control. I see lots of push broached pistol barrels, though, there it's common practice.

 

[Provincial]

Here is a YouTube posting showing the machine in action.

 

[francist]

Great video! Some seriously primitive engineering but brilliant none the less. Thanks for posting that

-frank