To ER is human but ER collets could be divine

In case there is any confusion.

Adding a backplate for a chuck will involve two registers.

One will be register that locates the backplate to the Mandrel of the lathe. The back of the register recess needs to be perpendicular ("square" ) to the ID off the backplate register to ensure that the bacfkplate runs as true as possible, and as repeatably, as possible, to the axis of the Mandrel. .

The second register is that the O D needs to be turned to provide an accurate register for the chuck destined to be fitted to that backplate.

It is essential that the chuck is located accurately along the lathe axis, not an angle to it.

So the backplate needs to be faced so that the chuck is located both radially and axially.

A prefinished backplate should have the register meeting these conditions, so that it only needs the OD to be machined to size, and faced.

Howard

Well that's cleared things up then!

Peter,

Thanks for the info on Peatol Machine Tools - I saw this yesterday but of course there was no one around to ask about supply and price. A US modellers site claims this to be very accurate on a Sherline!

This adaptor looks to be the solution; The idea of registering a chuck to a backplate looks interesting but I'm unsure about my skill level and right now, the time it would probably take me.

As to importing - I sometimes buy Sherline components direct from the US - found a site that will list them on eBay and ship through eBays' international shipping. You still pay the UK taxes - import duties and VAT - but not any US ones. Shipping comes out reasonable (not cheap but acceptable).

I can find ER20 with M14*1.5 on ebay, but I'm after ER16 as I already have the collets. I'm not desperate enough to but another set! I'll keep my eyes open on ebay for an old faceplate and fit a flange mounted one

Thanks for the suggestions