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rmcphearson
02-02-2010, 05:33 PM
I bought an old Cushman 4 jaw off fleabay and it requires a chuck key bigger than 1/4", smaller than 5/16". The i.d. of the socket is about .290 across the flats. Is there such thing as a 9/32 key?

I may make one from a hardened pin but I don't have a mill so it will not be a quick and easy job for me.

Regards,
Roland

JCHannum
02-02-2010, 06:00 PM
Chuck keys do not necessarily follow any dimension standard. To make it more complicated, they are often tapered to boot. It is a good learning project for file work.

digr
02-02-2010, 06:49 PM
I built this one (http://www.shopfloortalk.com/forums/showthread.php?t=10734) and didn't have a mill yet. Used a side grinder with a cut off wheel.

Mcgyver
02-02-2010, 08:38 PM
I may make one from a hardened pin but I don't have a mill so it will not be a quick and easy job for me.


as a general principal, make the part you want wear soft....better to have the key get messed up over time rather than the chuck...I'd make the key from mild steel.

its an easy job to file a square section on the end of a round bar of mild steel

Ken_Shea
02-02-2010, 08:58 PM
Or turn a piece about the right size then beat it into the chuck key hole with a big hammer, wiggling it from time to time so it don't get stuck, kinda like broaching in reverse.

Just kidding, just kidding :D

Doozer
02-02-2010, 09:03 PM
That's a good way to break a pinion or worse.

--Doozer

Ken_Shea
02-02-2010, 09:14 PM
That's a good way to break a pinion or worse.

--Doozer

Hard to believe any one could take that seriously Doozer, especially with the "Just kidding, just kidding :D"
at the end.

Doozer
02-02-2010, 09:30 PM
Sorry, as soon as I read about hammering........my eyes totally glanced over the "just kidding" part. Sorry bout that.
--Doozer

Ken_Shea
02-02-2010, 09:35 PM
Sorry, as soon as I read about hammering........my eyes totally glanced over the "just kidding" part. Sorry bout that.
--Doozer

HaHa, yeah, it was meant to be like that, almost didn't put the just kidding part to see what the replies would be but didn't want to appear dumber then I really am :D

Doozer
02-02-2010, 09:43 PM
It's sorta like walking down the sidewalk and seeing a car accident happening, and you miss the $20 bill just laying on the sidewalk.
--Doozer

wooleybooger
02-02-2010, 10:24 PM
is it a square key or hex? square keys are easy. measure diagonally (top rt to bottom left) in the screw and turn a piece to that dia. not much filing left to do and it leaves nice rounded corners.

Ken_Shea
02-02-2010, 10:26 PM
is it a square key or hex? square keys are easy. measure diagonally (top rt to bottom left) in the screw and turn a piece to that dia. not much filing left to do and it leaves nice rounded corners.

An excellent simple solution!

rmcphearson
02-02-2010, 10:55 PM
I already made a crude one of mild steel with a grinder. It's not going to hold up. One reason I got the 4 jaw is so I can bear down without damaging a scroll.


is it a square key or hex? square keys are easy. measure diagonally (top rt to bottom left) in the screw and turn a piece to that dia. not much filing left to do and it leaves nice rounded corners.
Square. I measured and turned down, as stated above, a hardened roller from an old hydrostat. I'm turning the flats on the lathe but its slow going.

Thanks,
Roland

kendall
02-03-2010, 02:43 AM
Sorry, as soon as I read about hammering........my eyes totally glanced over the "just kidding" part. Sorry bout that.
--Doozer

Used to be a guy at work who ALWAYS went on about people using a hammer with broaching sets (was there for 6 yrs, and never saw anyone do it, and no-one ever had as far as I could determine)
Every time he came in for a broaching set I'd hand him a 4lb mini-maul with it, which would set him off every single time.

Ken

keelan
02-03-2010, 03:07 AM
There's this toole that ye olde timers kept in their toolbox. It would work well to help you manufacture or modify a key to fit. It is difficult to describe, but I will try my best... It consists of the wood of a no certain hardwood tree, carved into a teardrop or cylindrical shape. A hole is introduced into the hardwood with the utmost care. Into this hole is ensconced a fragment of iron, with sufficient quantities of carbon diffused into it to cause it to be hard when properly treated. Across this shard of iron are cut many a tooth, the sharpness of which allows them to cut metal. A process of heating and cooling the piece is applied, causing it to become most tenuous under the strain of daily work.

I've heard there are some makers still producing these whimsical devices. Nichols, Sons & Co. of the new world, and Bahco, Brothers & Co. of the northern territories of the old world and well known among those interested.