Damaged lathe chuck key

[Dell]

Hi all and a happy new year
I needed to use my Pultra four jaw chuck for a job as I am in the process of making a die filer because I have trouble holding a needle file due to gout in my hands, anyway in the process I managed to destroy the chuck key , the square is only 5/32”, so I have to make a new one, I have been looking for some EN19T steel and it seems no body stocks it in the smaller sizes , I have made a temporary one out of silver steel for now but I don’t really trust it not to shear, someone on another forum suggested he makes them out of socket head cap screws ( I never thought of that ) anyway my question is can I use the HSS endmills I already have or do I have to use carbide.?
Thanks Dell

 

[brightspark]

ive never had any bother turning down or drilling high tensile bolts with hss tools or drills slow ish speed and using cutting compound

 

[Dell]

Thanks brightspark
that saves me having to buy any as I have never had the need for them.

 

[My Old Landy]

As Brightspark, I don't have any carbide milling cutters and have machined many bolts etc to suit various projects.

 

[Agroshield]

If you are tightening it enough for it to shear, you are doing something wrong.

If you made the projecting square part longer, it will twist (fail in torsion) and you will see the spiral long before it actually fails in shear.

I have many cheap helical allen keys on which I have proved the concept.

 

[Dell]

If you are tightening it enough for it to shear, you are doing something wrong.

If you made the projecting square part longer, it will twist (fail in torsion) and you will see the spiral long before it actually fails in shear.

I have many cheap helical allen keys on which I have proved the concept.

Not being used to using a four jaw chuck, perhaps I am tightening a bit to much, when dialling in I loosen the opposing jaw but then even though I have loosened the opposite it still takes a lot of force to tighten the one near me.

 

[not done it yet]

Not being used to using a four jaw chuck, perhaps I am tightening a bit to much, when dialling in I loosen the opposing jaw but then even though I have loosened the opposite it still takes a lot of force to tighten the one near me.

Slacken the other two by a tiny amount each - the part may be gripped on a more narrow point, than the full diameter?

 

[Turbo]

Old allen keys make great material for lathe chuck keys.

 

[Dell]

Well I have made a couple of lathe chuck keys for my Pultra four jaw chuck out of HT socket head cap bolts and happy with the finished product, my problem was or is that I started off using the crosslide but the finish was rubbish ( more like a super fine thread than a smooth finish) I tried using indexable carbide and HSS steel but no better, tried altering speed up and down, I ended up using the hand graver as I got a much better finish , I know I only have a small Pultra instrument lathe but I should be able to get a decent finish I must admit I very rarely use the crosslide because most of what I make for antique clocks is small and I much prefer using the graver, what am I doing wrong?
Dell

 

[ranchero]

what am I doing wrong?

nothing that will work