cutting a square end on a round shaft?

[pgk pgkParticipant @pgkpgk17461]

Other optons include starting with a square bar…no reason a. Chuck key shaft is round..makes any thinner flat indexing a doddle.

Heat it and beat it i.e forge the end

Drill the round shaft and inset a piece of square rounded at one end and pinned, glued etc. Useful if wanting a hardened tip?

[Howard LewisParticipant @howardlewis46836]

For anyone dubious about holding an End Mill in a three jaw chuck; think on this!

In 1958, my chain smoking Turning Instructor showed me his cigarette lighter.

"Made that on nights during the war"

"But you were on lathes, and it is rectangular,"

"Clamp the job in the Toolpost and put an end mill in the chuck"

He was nearing retirement and had been making his living on piecework, so knew a thing or two!

Make a block or pillar, to fit between the underside of the jaw and the lathe bed, to set it horizontal. A simple turning and facing job ) )

The starting point is the end of the bar being turned down to just less than the corner to corner dimension. That puts the required corner relief in place before you start filing the flats.

I am assuming that a newbie may very well not have a Mill.

If one is available, then use a Stevenson square collet block, or having made it, set the first flat vertical with a square, to mill the second and repeat for subsequent flats.

HTH

Howard

[martin perman 1Participant @martinperman1]

For the ultimate toy in your workshop you could buy a WERA Profilator which can turn squares, triangles, octagons and other external shapes, the only thing its not good at is turning round, will set you back several thousands but is fun to watch.

Martin Perman

[jon hill 3Participant @jonhill3]

In the end I set up the vertical slide with milling vice and put an end mill into a suitable collet on the head stock. I judged the parallel sides with a square although I was a little bit out so I finished it off with a file.

I like the Viatnamese guys Idea of using hex nuts. Given a similar problem I think I would bore out some square block and superglue the bar in. Then carry out and not critical turning such as stepping the shaft.

[Bill PhinnParticipant @billphinn90025]

Posted by SillyOldDuffer on 13/06/2022 16:17:53:

Posted by Andrew Johnston on 13/06/2022 15:51:45:

A few tens of thou, not a few tenths.

Andrew

Is there a difference? Oh dear …

I had to think about it too.

English usage is to blame for being slow to catch up with decimalization; "a few dozen" sounds natural: "a few tens" doesn't – yet.

[HopperParticipant @hopper]

To use the try square method successfully, hold the stock of the square firmly against the flat on the job and look at the gap between the long blade of the square and the cross slide table, as shown in the pic i posted earlier. Any error is greatly exaggerated by the length of the square blade compared with doing it the other way round and looking for a gap on the very small milled flat.

[Graham StoppaniParticipant @grahamstoppani46499]

On the subject of round to square, this video may be of interest.

[JasonBModerator @jasonb]

Another way to make the use of a tri-square easier if the flats are quite small is to clamp something to the rod, such as a Vee block. I saw this tip in a book

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, when I needed to make the imperial drawbar for my mini mill, although I didn't see the need to make the top exactly the same size as the metric one that came with the mill, I still put a square on it for a spanner. As has been said though, I used a Stevenson's square with a collet and just clamped it in my vice on the milling machine table, calculated how much to cut off each quarter and the job was done, then just popped in in my mini lathe to take a small cut to round off the corners slightly.

Regards Nick.

[Anonymous]

Posted by SillyOldDuffer on 13/06/2022 16:17:53:

Is there a difference?

Two orders of magnitude.

Andrew

[Grizzly bearParticipant @grizzlybear]

Weld a piece of square onto a piece of round!

Is that cheating?

Bear…….

[Perko7Participant @perko7]

Friend of mine has an angle grinder fitted with a piece to attach to the toolpost. Sets it at the right height for the size of square needed, chucks the round bar in the 3-jaw and rotates it 90 degrees at a time by hand using suitable markings he added to the chuck backplate lined up with a corresponding mark on the headstock then locks into position with the back gear. Turn on the grinder and traverse across the piece to the depth you need. As others have said, 100% or even 98% accuracy not really necessary for a chuck key.

[Nigel Graham 2Participant @nigelgraham2]

Going back to calculating the diagonal of a square of side S, it's simpler if you remember the formula

D = S.sqr-rt 2

or just

D = 1.414S.

-which you can write on the margin of your conversion-tables, Zeus Book or wherever is your workshop's store of come-in-handy numbers and nifty equations; saves doing those longer sums given earlier.

(Their derivation is the same – good old Pythagoras!)

'

Though at a tangent (!) another tip… Using a calculator to find the area of a circle given its diameter.

Don't halve it just so you can use the radius formula you learnt at school, unless it is a very simple number anyway. Use the diameter instead

A = pi.D^2 / 4.

This shakes out to 0.7854.D^2; simple to recall because if you look at the conventional calculator keypad, you see those digits form a neat clockwise square in the top corner….

'

Perko's mate's tip might be quick "machining"…. quick enough to give the rest of the day to clean all that horrible grit off the poor lathe!

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