Between centres boring of cylinder blocks

[kvom]

It is always worth knowing the exact ctr height of the spindle above the cross slide, mine is 3.387" so it is a simple matter for me to pack up items as required rather than trial and error. I stack up a combination of parallels, 1:2:3 blocks and feeler gauges.

In this photo, did you first use a drill in the spindle to rough it?

[Jasonb]

That one had a cast in core so no need to drill first.

I often use the same method for crankshaft bearings and do drill them first, often apply a little pressure with teh tailstock to reduce risk of pushing the casting out of position

[Chipswitheverything]

Hi Jason, with ref. your query about the angle of the cutting bit in the Geo. Thomas design.  In the text, GHT suggests 40 degrees, to give 16 thou a turn.  Also, when the bar is first made, put it up between centres and lightly skim the area in the vicinity of the cutter, so that the mike readings, bar bottom to cutter tip,  can be made over a true running part of the diameter.
  Great photos of the substantial component set ups, by the way, Jason ....      Dave  ( not Andy! )

[Jasonb]

Sorry Dave I was mixing uou up with CHIPmaster

[sbwhart]

Hi

I think the best way to bore the cylinders for my loco is between centres in the lathe. The bore by the way will be 1 3/16".

Has anyone made a between centres boring bar? one with micro adjustment?

Any help here will be appreciated.

Cheers

Rich

Bit late with this one, No micro adjust but:- I used a clock with a flat stylus on a magnetic base on the bar and zeroed on the tip of the tool to give a reading of tool adjustment worked fine could control cut to 0.05 mm or better.








Cheers
Stew

Hope this helps

[Firebird]

Hi

Thanks to one and all 

Cheers

Rich

[Tennessee Whiskey]

I know I'm a bit late, however, I was watching a Keith Fenner video and saw these sleeves for a tool bit in a boring bar. Maybe a bit pricey, but, unless you can broach a square hole or just want to use a round bit only, these seem to do both with the added feature of pretty precise adjustments .

https://www.mscdirect.com/product/details/82432204

Cletus

[Jasonb]

I just drill a hole to the across corners size of the square tool bit, the grub screw bears on the flat surface of the tool bit so it won't rotate

[Firebird]

Hi

Thanks Cletus and Jason.

I have 2 chunks of cast iron now so I'll be looking into making a boring bar shortly.

Cheers

Rich