Boring bar holders for lathe

[DTR]

Morning All,

Apologies in advance for the silly question. How does this style of boring bar holder work?

http://www.arceurotrade.co.uk/Catalogue/Machines-Accessories/Lathe-Accessories/Tool-Posts/Model-200-Boring-Bar-Holder-2

(this is just an example, I'm not looking to buy one)

The clamping studs are offset so they do not bear directly onto  the bar (or sleeve). They're also not squeezing a split block together. Is there some kind of hidden bush bearing against the bar, similar to a split cotter?

Thanks

[crueby]

In the pictures, it looks like the split sleeves to the left are slid into the holes, the boring bar inside them, and the screws squeeze the sleeves down around the bars. That way you are not marking up the bar from the screws.

[Jo]

There is no split in the main block: Which implies they are dependent on some sort of cotter arrangement for clamping on the sleeve.

It would be much simpler if the sides were split. However if they are not made in steel  and are small they would have been in danger of the screws pulling out of the ali... 

Jo

[Brian Rupnow]

I have that type of boring bar holder. The capscrews pass right thru the block into threaded half round pieces that are pulled up when you tighten the capscrews, squeezing the boring tool between these half round threaded pieces and the main bore thru the block.---Brian

[DTR]

I have that type of boring bar holder. The capscrews pass right thru the block into threaded half round pieces that are pulled up when you tighten the capscrews, squeezing the boring tool between these half round threaded pieces and the main bore thru the block.---Brian

Makes sense, thanks.