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1018 cold rolled lathe chuck key

umahunter

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#1
Was gonna make up a extra chuck key outta some spare cold rolled was wondering if heating up to red hot then oil quenching would add some durability any thoughts? ??
 

scwhite

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#3
Was gonna make up a extra chuck key outta some spare cold rolled was wondering if heating up to red hot then oil quenching would add some durability any thoughts? ??
Not enough carbon
You will be better off to go to a steel supplier and order you some 4140 and make you one
You can buy it 29 to 30 RC . It will machine easy enough . And is still hard enough .
Or just go it tractor Supply and buy a Grade 8
Bolt . Machine you one out of that .
 

Tozguy

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#6
I have been using some key stock because it has a very good fit and nice square corners. It is standing up well but then I don't torque my chucks or D1-4 cams all that hard. The round corners and loose fit of the OEM chuck key were too sloppy for my liking.
 

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scwhite

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#7
I have been using some key stock because it has a very good fit and nice square corners. It is standing up well but then I don't torque my chucks or D1-4 cams all that hard. The round corners and loose fit of the OEM chuck key were too sloppy for my liking.
Yes yes should not be to hard to make
 

Tozguy

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#8
Last edited:

darkzero

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#10
Yep I have used a 3/8 drive extension to
Works good
I used to do the same on the cam locks for my lathe. But on my lathe the came locks are 10mm square & 3/8" extension is pretty loose. I now use a 10mm drain plug socket. I prefer to use a ratchet & extension over the stock chuck type key.
 

Tozguy

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#12
I used to do the same on the cam locks for my lathe. But on my lathe the came locks are 10mm square & 3/8" extension is pretty loose. I now use a 10mm drain plug socket. I prefer to use a ratchet & extension over the stock chuck type key.
This is what happens to a cam lock if you use a poor fitting wrench
IMG_0082.JPG
 

darkzero

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#13
This is what happens to a cam lock if you use a poor fitting wrench
View attachment 231877
Ouch! That's what I was afraid of happeneing when I was using the 3/8" ratchet extension on my cam locks. I didn't imagine it could get that bad though. I'm glad I switched out to using the proper size 10mm square drain plug socket. Thanks for sharing!

To clarify, I stated earlier that I didn't like using the stock chuck type key that came with my lathe for the cam locks. Nothing against using that type of key, I just didn't like the one that came with my lathe. I was too lazy to make a new better key & is why I use what I use but I like it.
 

umahunter

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#14
Ok is there a formula to figure out what size circle I need to come out with a square the right size I thought I mesured right but I came out way undersized once I milled down a square with square corners I must have mesure wrong some how ???
 

Tozguy

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#15
Uma, I would look at the square as two right angled triangles joined along their hypotenuses.
Measure the width of the socket and use 45 deg. trig functions to calculate the hypotenuse.

If you measured the socket diagonally there is a chance of coming out too small when the inside corners are rounded.
 
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Tozguy

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#16
DZ, ever since I mangled a cam lock I have been using a better fitting softer wrench. Granted it may have been a defective cam lock (too soft) and lack of experience on my part but I feel better using a tool that should give before the cam lock does. Key stock seems to fit the bill perfectly.

IMG_0168.JPG
 

bobshobby

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#17
Not enough carbon
You will be better off to go to a steel supplier and order you some 4140 and make you one
You can buy it 29 to 30 RC . It will machine easy enough . And is still hard enough .
Or just go it tractor Supply and buy a Grade 8
Bolt . Machine you one out of that .

Salvaged second hand grade 8 bolts are great for making parts that require that extra bit of toughness. Also old car / truck drive axles, coil and leaf springs are really good, sometimes may need annealing before machining, then re-hardening as required.Although usually ok with carbide tip tools. These parts are usually available at auto mechanic shops free.
 

Jonno_G

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#18
Ok is there a formula to figure out what size circle I need to come out with a square the right size I thought I mesured right but I came out way undersized once I milled down a square with square corners I must have mesure wrong some how ???
Yes, there is.

If you know your dimension across the flats (say 10mm for instance) then Pythagoras theorem (a^2 + b^2 = c^2) tells you that your diagonal will be 14.14mm, so you need to start with at least 15mm round stock to get a 10mm square.

Cheers,... Jon.

Sent from my Lenovo YT3-X50F using Tapatalk
 

T Bredehoft

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#19
The diagonal of a square is 1.414 times the side. The side of a square is .707 times the diagonal. These numbers have been in my head for over 30 years.
 

umahunter

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#22
So I need to make a wrench with side that are .3125 and mesures on the diagonal .4200 but the corners aren't perfectly square so the diagonal might not be totally accurate
 

Catcam

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#24
Ok is there a formula to figure out what size circle I need to come out with a square the right size I thought I measured right but I came out way undersized once I milled down a square with square corners I must have mesure wrong some how ???
Hi,
to get the circle diameter you need to get a certain square machined out of it, simply divide the diameter by the square root of 2 (1.414) gives the perfect size, but if you don't mind a chamfer on the corners you can get a bigger square out of the round shaft.

Alternatively instead of dividing by 1.414 multiply the diameter by its reciprocal, that is multiply by 0.7071 to give the same answer.
works for any circle to give the included square.
 

bfd

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#25
you don't want to have too sharp of corners on your key. the socket may not have good sharp corners and the key will not fit bill
 

umahunter

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#26
Well I got a chance to make a body had to stop and make a vise clamp to use got me to thinking should I use regular cold rolled for a handle or should that be hardened aswell 20170507_022854.jpg
 

darkzero

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#27
Handle doesn't need to be hardened, don't even need to harden the entire body either, just the square end will be perfectly fine.