Purpose of odd 2-jaw chuck?

[Cannonmn]

6” dia, maybe 4” deep, jaws maintain V profile for about 2” down into this Union chuck.

What was original purpose please?

 

[JST]

Does it have one screw with teo opposite sections? or two screws? can't tell, probably does not matter.

No definite reading on the purpose. But it would be just the thing for chucking up pieces of rod to make bushings..... pop it in, drill, next..... probably for roughing, since the concentricity would not be perfect. Any similar purpose, where a shank needed to be chucked quickly and decently.

 

[gbent]

It would be just the thing to hold square stock to do end work.

 

[Rob F.]

Not sure of original intent but I would use it for square stock. I have a project right now where I am forging some posts of 1 1/4 hot rolled square into newel posts for hand railing and guard railings. Bottom of post is upset on the end to about 1 3/4 sq and will have a round bar drilled into the end. The round needs to be set into the floor to anchor the post. I do this in the lathe with 4 jaw and cat head in the steady. Face end square and drill hole. This little chuck would be perfect for jobs like that.

Gbent types faster, beat me to it

 

[sfriedberg]

2-jaw chucks were more common when rough castings were more common. Just from the title, before seeing the picture, I expected to see a chuck with slip/replaceable jaws, which would have been a standard thing. Jaws would have been customized for the job, allowing either symmetric or asymmetric parts.

 

[john.k]

Several brands of 2 jaw are listed in my 1970s machine catalogs......I wouldnt be surprised if Pratt Burnerd still sell them.....At one time twist drill chucks were 2 jaw too.....with a single lh/rh screw tightening .........The attraction of 2 jaw was lower price than 3.

 

[Spinit]

6” dia, maybe 4” deep, jaws maintain V profile for about 2” down into this Union chuck.

What was original purpose please?

I have never seen this kind of chuck before. It seems it would be something which does not get used much once the three jaw chuck shows up. With the v shape in the jaws it seems it is something you may use when you do not have a collet chucker. That might mean there would be a few different v sizes to accommodate a range of diameter ranges. Just guessing.

 

[DDoug]

...and now for the next question:
Is it in any kind of usable shape ?

Accuracy ?

 

[Rob F.]

...and now for the next question:
Is it in any kind of usable shape ?

Accuracy ?

If he wants to sell it I know it is good enough to do the forgings I am doing. Jaw threads look OK in the pic.

 

[jims]

I have a power two jaw chuck that uses a drawbar to open and close jaws. I think it is about a 6 inch chuck.

 

[thermite]

If he wants to sell it I know it is good enough to do the forgings I am doing. Jaw threads look OK in the pic.

Castings and forgings is wot these did, the screw-operated ones. No clear bore to the spindle. Plumbing fittings, many of their taskings were.

Not hard to make new screws.

My one is scroll-operated, Hardinge, 6", 2 piece jaws, std blanks. Those can also pass long bar stock.

Making a new scroll is a non-trivial exercise.

 

[Cannonmn]

Thx for info. This one is old but screw threads etc in new condition, appears little to un-used. Closing is via one offset screw with opposite threads on either end. Thru hole looks like 1” dia. Or less. Offset Closing screw has male square-Drive on each end.

 

[thermite]

Thx for info. This one is old but screw threads etc in new condition, appears little to un-used. Closing is via one offset screw with opposite threads on either end. Thru hole looks like 1” dia. Or less. Offset Closing screw has male square-Drive on each end.

You don't much want one of these for general-purpose work. Nor even those with two-piece jaws, as I have.

Basically, they were "tooled" for volume production, same part, over and over. With the jaws carved to fit, the part need not be round, not even symmetrical.

All that work went to POWER checks, first on manuals, including turret/capstan, then onto CNC, ages and ages ago.

 

[DDoug]

Odd that this one doesn't have removable top jaws.

 

[M.B. Naegle]

I've got one that came out of a shop doing motor armature work. One less jaw in the way at the expense of accuracy, so good for quick and simple jobs.

 

[Dumpster_diving]

I have one similar, but without the spindle thread backing plate. Instead just a cylindrical spigot at the back about 1" diameter. I speculated it would serve well for holding large taps in a large tailstock (4-5 MT)...but YMMV.

 

[Frank Ford]

Mine gets a fair amount of use holding 3/4" square acrylic when I'm making my crank handles:

 

[thermite]

Odd that this one doesn't have removable top jaws.

Few did, back in their heyday.

Taller ones that you see here, yes. Specialized from the factory for plumbing fittings, pipe, this, that, or.. wotever.

 

[DDoug]

Few did, back in their heyday.

Taller ones that you see here, yes. Specialized from the factory for plumbing fittings, pipe, this, that, or.. wotever.

Yes, I know of a local shop that still uses them, and has the Low
melting alloy set up (Kirksite ?) in a room with fixtures for making
the custom jaws.

Do allot of castings, so can quickly make up a set as needed.

 

[John Dunn]

I worked in automotive engine rebuilding shops decades ago and there was an old / unused thing under the bench from decades earlier. 1/3 hp motor driving a slow gear reduction with a chuck like this on the output side. It was for driving Reamers (with various size square drive shanks) when fitting bushings before they went to Sunnen honing equipment.