Centering square bar in 4-jaw chuck

[I.M. OUTAHEREParticipant @i-m-outahere]

Posted by Carl Wilson 4 on 05/01/2017 11:55:31:
OK. I'm maybe being a bit thick here. It's been a long and gruelling week so far.

If the square bar is running true, how can it then not be centred?

My first thought was exactly the same !

There are that many videos on YouTube about this it isn't funny , try some of these channels as watching it being done is easier than trying to explain in text.

Abom79

Keith fenner

Mrpete222

Joe pieczynski

[Carl Wilson 4Participant @carlwilson4]

Interesting stuff this. I'm just thinking about a few possibilities here. One is, if the application requires the level of precision we are talking about here then why would you choose to use black bar or similar, which is bound to be far from perfect? I assume we are talking about long lengths here. Second, a very short piece of square bar is highly unlikely to be bent by any significant amount.

Thirdly, there is no reason to suppose that a piece of round bar of similar length and quality to the square stuff we are talking about wouldn't be bent either.

[HopperParticipant @hopper]

So a bit more detail from the OP on what is trying to be achieved would be helpful.

If it is something special and you want square bar that is really square and to dimension and straight, you could try using a length of key steel.

[larry PhelanParticipant @larryphelan54019]

Get a copy of a book called "Simple workshop devices"by Tubal Cain.

There is a picture on the cover that is so simple that it will make you cry ! it struck him dumb !!

The idea was by Mike Chrisp.

[Author]

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