I came up with a new method - probably been done thousands of times but it's new to me.
Every attempt I have made using gauges etc. has to date not satisfied me so I came up with this.
Put a small diameter rod in your 4 jaw chuck (as small as it will go) clock it up as best you can get, drill a centre and give the OD a lick so the two are concentric. (I used a 3mm rod in a drill chuck/shank held by my 4 jaw).
Now move the rod out a few inches from the chuck and clock up the OD.
Once you are happy it's rotating dead true. then bring your tailstock in and measure the deflection of the shaft with your dial gauge as you engage the centre. (The thin shaft flexes front to back if your tailstock is off center.)
Adjust your tailstock until there is no deflection as the centre goes in - QED.
By rotating your centre you can check for errors in your centre, you can also check parallelism errors by using differing stick out from your tailstock (errors here are not adjustable or easy to fix - but at least you know.).
Back to front errors are adjustable, up down is generally by shimming.
I found this a lot easier than rotating dial gauges etc.
Regards,
Ken
Every attempt I have made using gauges etc. has to date not satisfied me so I came up with this.
Put a small diameter rod in your 4 jaw chuck (as small as it will go) clock it up as best you can get, drill a centre and give the OD a lick so the two are concentric. (I used a 3mm rod in a drill chuck/shank held by my 4 jaw).
Now move the rod out a few inches from the chuck and clock up the OD.
Once you are happy it's rotating dead true. then bring your tailstock in and measure the deflection of the shaft with your dial gauge as you engage the centre. (The thin shaft flexes front to back if your tailstock is off center.)
Adjust your tailstock until there is no deflection as the centre goes in - QED.
By rotating your centre you can check for errors in your centre, you can also check parallelism errors by using differing stick out from your tailstock (errors here are not adjustable or easy to fix - but at least you know.).
Back to front errors are adjustable, up down is generally by shimming.
I found this a lot easier than rotating dial gauges etc.
Regards,
Ken