Those slots in the faceplate are there for a reason. Drill and tap four 8mm holes into the back of the job and bolt it down securely. It will move about all over the place with only one on the centre.

Is this for a riser block? ..Maybe canny working-out of bolt positions will enable you to locate them either where they need to be, or in some "dead" area where it doesn't matter – then you can bolt to the faceplate it as Hopper suggests, and (with a nod to Pete Rimmer) use a half centre to add some support the distal end whillst still allowing it to be faced.

Why not mount on centres and tap a hole off centre to use a screw as a driver. This still leaves the od clear and the part is fully supported.

I cleaned up 3 pieces of scruffy nominal 6” diameter x 4 1/2 “, in a chuck, to around 150mm x 111mm last week. Only problem was lack of swing over the cross slide🙂 . Finished sizes were not important. Tailstock support was applied when possible.

I would face in a 4 jaw independent check if I wanted the ends parallel, or between centres as PR. No problem with a faceplate, if the faceplate is skimmed (if not true) to get parallel faces, (as long as the first is true – so shimming necessary – but I would not be contemplating securing it with just one through-bolt. Method would depend on the use of the finished part after due consideration of all relevant factors -like how much of these faces actually need to be parallel, for a start.

Not a good idea IMO, plus if the bar is not cut truly square where fitted to the f/plate the faced end will not be square to the 150mm length, I believe the 4 jaw with centre support is the route to take.

Emgee

Put a piece of paper in between the faceplate and the job. (It will need a hole of course) This will greatly increase the friction between the two. Also a good idea when holding jobs in the vice for milling or shaping.

John

I would feel safer if the 8mm size could be increased to at least 12mm or better 14mm. Whatever you do, take small cuts, and as both ends will have to be faced, then use tailstock support.

Yes, I don't disagree Emgee – but it's often a matter of degree (how far out is it?) and perhaps necessity (can I hold it any other way?).

As usual, there are some 'unknowns' with a question like this that make it hard to be exact (the initial state of the material, equipment availability, what the finished design permits in terms of work holding etc). The work order is also something that will have some bearing – face the ends and then turn parallel or vice versa – which may also be dictated by the other factors.

Anyway – hopefully Robin has a few extra 'clues' to help him get to where he wants to go. I'm sure he'll figure it out!

Regards,

IanT

Usual practice for accurate work is to use a soft ctr and take a skim cut off of it then don't remove from spindle until job is complete. Alternative which I tend to use is hold a stub of steel in the 3-jaw and turn a 60deg point onto that, again don't remove until job is complete or reskim if you do have to remove it.

I think an improvement on Jasons soft headstock centre is that I have found that with cutting pressure and tailstock pressure ,the temporary centre can slowly retreat towards the head stock,despite having a newish chucks in good condition. so I reduce the diameter of the bar on the the end that goes into the chuck so that there is shoulder to stop the centre sliding in the chuck jaws. then as a further improvement I get a circular steel blank around 4 to 5 inches diameter ,drill a central hole to suit the larger diameter of the centre and weld it to the centre,positioned about 1/2 inch away from the chuck jaws so that the weld is clear of the shoulder, then drill a hole towards the o/d of the blank,to take a bolt and two nuts which then makes a driving dog for the lathe carrier to drive the work piece.By only skimming a small amount from the centre point each time it is set up ,it takes ages before the cebtre becomes too short,Advantages -a dead true centre every time,and its a lot quicker than removing an 8 inch chuck ,fitting the usual hard centre and then refitting the chuck,I use this arrangement on a Colchester, on a smaller lathe the drive disc could be a press fit or loc tighted if no welding facilties are available,