.

I would imagine that 70mm is a bit to much in length for a 10mm bar anyway irrespective of the bars length. You may JUST get away with a solid carbide bar of that size which are usually a little longer and will enable you to grip it in the toolpost. But they ain't cheap. .eg. http://www.ebay.co.uk/itm/10mm-Solid-carbide-boring-bar-C10M-SCLCR06-carbide-shank-takes-CCMT-06-inserts-/371313481049?hash=item5674021559 (unless you stumble across a bargain)

Is it possible to somehow arrange the cylinder to be held upon the lathe saddle.? That way you could 'line bore' it.

Regards, Nick

Edited By Nick_G on 22/09/2015 00:07:25

As Nick says a 10mm bar is a bit thin. though you don't need to have all that length in the toolpost, just the two screws nearest the chuck will hold it

You could remove the toolpost and make a clamp to hold the bar to the topslide.

If its the supplied 4-way toolpost then one way I have used stiffer bars is to use the slot in the toolpost as a "vee" block. Thats a 28mm bar, about 150mm long cylinder and the setup is very rigid

Or between centres boring bar with work fixed to cross slide

Edited By JasonB on 22/09/2015 07:48:33

You don't have to have the toll across the full width of the toolpost, as long as it is held securely just post another 10mmm out and don't take huge cuts.

Neil

Hi David,

I had a similar job where my boring bar was too short to machine the hole. My tool holder will hold 16mm wide bars but my 16mm diameter boring bar was too short and would probably flex if it was any longer. The solution was to use a 25mm diameter boring bar and machine flats on the end to fit into the tool holder. You could do something similar by using a 12 or 16mm dia boring bar and machine flats to fit your tool holder. Check to ensure that the cutter tip remains at the correct height.

Paul.