HSS Boring bars?

[Jasonb]

So is that 5 times the long series pilot drill dia or 5 times the final drills dia? 6" between outer faces so that 24times the length of the 1/4" pilot or 8 times the 3/4" finished dia well actually to fit the supplied bearings 0.752" so special size reamer would have been needed

J

PS its extruded angle

[Jo]

Hi Rod,

Remind me did I invite you down to visit my workshop? If not I apologise  you are more than welcome (and bring your good lady  ) 

As someone said to me once: it is not the equipment you own that matters but the equipment that your friends own that they are happy to let you to use when you visit them  .

Jo

[Jo]

So is that 5 times the long series pilot drill dia or 5 times the final drills dia? 6" between outer faces so that 24times the length of the 1/4" pilot or 8 times the 3/4" finished dia well actually to fit the supplied bearings 0.752" so special size reamer would have been needed

Most of us step up the diameter of the drill, the advantage of doing this is that it bring the misalignments of smaller drills back with in acceptable limits. I can only go by my English historical guides that suggest that as you increase the diameter of the drilling/boring  hole the error is reduced until at a depth of 5 times the diameter of the cutting drill. But what do I know

Everything has what they call an acceptable tolerance  for Mr silky it is being able to bore accurately to  0.002mm with a crappy carbide bit. But I was pleased to find out yesterday that my Colchester having her new scale is proving to be just as accurate as Mr Silky  

Maybe I need to find a name for my Colchester that reflects my enduring love and respect for her

Jo

[Don1966]

Well since every one is showing their boring tool, I guess I can show mine. Interesting conversation you two are having Jo.

Don

[Allen Smithee]

Maybe I need to find a name for my Colchester that reflects my enduring love and respect for her

Big Bertha? Hattie?   

On tolerances - as an engineer I agree that holding tight tolerances is a sign of high-quality manufacturing, but requiring tight tolerances is often a sign of low-quality engineering...

AS

[gerritv]

This site has an excellent description of making your own German-style boring bars including a description of the required geometry.
http://www.metallmodellbau.de/Herstellung_Ausdrehstahl.php

[rotorhead]

Hi Jo,

I have a Colchester Master 6 1/2" Round Head circa 67, she is a beauty, and wouldn't think of her as oversized or overbearing...

I have made some changes to her personality in the 20 years we've been married, she has responded with alacrity and accuracy...

I call her Colly, as though she was a Collie(Sheep Dog), faithful friend....

Apologies to the OP for straying...