Best steel for a chuck key

[capnahabParticipant @capnahab]

I need to make a chuck key. Not sure if it needs hardening at the business end but if I did need to harden it what would be the best type of steel to use ?.

[capnahabParticipant @capnahab]

[BazyleParticipant @bazyle]

Mild steel is adequate. We have had a thread on this before. But make it long enough so that it can be double ended to serve another chuck too, and perhaps use a hardenable steel for the cross bar so you can make that a hex for tool holder setting.

[Tony Pratt 1Participant @tonypratt1]

Yes, from experience Mild steel is fine.

Tony

[mechman48Participant @mechman48]

Mild steel would be fine; I made a spare to make setting up in a 4 jaw easier, I toughened the end up by heating up & quenching in Whale oil… yes I still have a couple of litres from my journeyman's days in the toolroom of days long gone… & for the purists, eco friendly, Green peace, PC mob please refrain from lambastations…I've had this oil since well before all this PC crap came into being, probably some of you weren't even born when I 'acquired' it… & I'm keeping it.

George.

[Tony Pratt 1Participant @tonypratt1]

Hi George,

Sorry to rain on your parade but you can't heat treat Mild steel by the method you describe

Tony

[MuzzerParticipant @muzzer]

Can't stand those chuck keys you get with used machine tools that were made by schoolboys or apprentices out of toffee mild steel. I made mine from 1045 steel (0.45% C, water or oil quenching) and it's not chewed and mangled after several years. No point going to the bother of making one and using the wrong material.

Murray

[AjohnwParticipant @ajohnw51620]

I only have problem with the new ones from the past 10-15 years or so. The ends are butt welded on and shear off. Before that they were probably hot formed and then machined. Never had one break.

If I had to make on I would use silver steel or drill rod as it's called in the USA. and not leave sharp abrupt corners down at the business end. Not like the short one in Georges shot and a longer taper than that on the large one. To be honest though the scroll in the chuck would probably strip before either of those keys broke.

If heat treated I'd go from blue to very dark straw at the end unless it was a very small hex one. In that case paler at the end. For the usual chuck sizes circa 6in and up and square keys I don't think I would heat treat – just make sure it's very precise fit in the chuck

I have seen small 4 jaws where people have obtained longer grub screws and added a knob on the end to ease setting up but I feel a longer handle is easier – more movement for tiny adjustments. But if too long and too tight the chucks can break.

John

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[Neil WyattModerator @neilwyatt]

> Whale oil… yes I still have a couple of litres from my journeyman's days in the toolroom of days long gone

As an environmentalist whose piano has ivory keys I can't exactly point the finger…

Anyway, if you can stand the smell of hot whale oil, you're welcome to it!

Neil

[AjohnwParticipant @ajohnw51620]

One of the whale oils, sperm I think, is supposed to be the ultimate tapping lubricant. Perhaps it's the male connotations. Maybe some one should try the real stuff.

I need to make a chuck key. Being mean and having what I need I will just make the business end out of silver steel and locate in a 1in deep hole in the main body, loctite and pin through it. I think it will be a lot better than the usual welded on tip types sold now. The broken tipless body of one of those should be ok for the body.

John

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[RainbowsParticipant @rainbows]

My worry with hardened keys is that it is much easier to replace a munched up key than it is to replace a munched up chuck.

[Ian S CParticipant @iansc]

Find a suitable sized high tensile bolt (metric 8.8 or better, UNF/UNC six radial dashes on the head), perhaps a second thinner bolt for the cross piece. Old Caterpillar Tractor bolts are about as high grade as you can get, another one is Unbreako cap screws.

Ian S C

[Alan RawlinsParticipant @alanrawlins60482]

I made a new chuck key out of the longer extension bar out of a socket set. I bought the bar from a car boot sale for £2.00. It turns and machines well using a fly cutter for the square end and high tensile bolt turned down for the cross bar.

I made mine a little longer to give me a bit more leverage as the ones provided with the lathe were too short, for me.

[LambtonParticipant @lambton]

Ian SC is quite right – use a suitable high tensile bolt. The steel used for these has exactly the right properties for a chuck key i.e. toughness (rather than hardness) and good resistance to torque. No heat treatment is necessary.

Mild steel would do as a temporary measure but why go to the bother of making a key from a material that is not suited to the application.

[Ian S CParticipant @iansc]

For changing chuck jaws, I use the speed wrench from my 3/8" drive socket set, or I have a fitting that fits in the battery hand drill, even quicker, use the normal key to tighten the chuck.

Ian S C

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