Cutting a large internal hole

Hi guys - son is using a warco 240 lathe to make motorcycle fork nut caps - is there a quicker way to make a large internal rather than using the boring tool and taking 0.3 mm cuts from the centre - not sure how else to describe this - one is a 47 mm internal and the other a 30mm wide and around 10mm deep

drill to the biggest drill you have, then bore with a boring tool. Minimum overhang, you should be able to take bigger cuts than 0.3

You could try grinding up a HSS toolbit (say 6 - 8 mm sq ) to make a knife tool.

Mount it in the toolpost along the axis of the lathe, with 12 -15 mm protrusion

(Check that it will not hit the vice jaws! )

Having made a central hole with a drill, or drills at least as big as the toolbit proceed to take a series of cuts along the axis of the lathe.

The tool should be be more rigid than a long boring bar, and so should withstand deeper cuts, say 0.5 - 0.6 mm ,to rough out the bore. The boring tool can then be used to finish the bore, and to face the innner end.

Howard

Good quality starrett holes saws can be bought for £5-£8ish, just make a hole 5mm less than the finished size, then finish with a boring bar.

Gavin, you should be able to take larger cuts than o.3mm as already stated but to be honest that is not a great deal of material to open out to.

Patience is a virtue.

For those suggesting holesaws or warning about boring into the chuck jaws I think these caps have a blind bore that fits over the nut to cover it rather than a through hole.

As said you should be able to take more than 0.3mm cuts, set the boring bar, even a long one so it only projects a few mm more than the 10mm depth of recess from the tolpost..

I'm trying to work out what other kind of hole there is...

That's not a big hole, and in aluminium most likely, unless its for a Harley. 0.5 cuts should be fine unless you are using a tiny boring bar.

I imagine your tongue is in your cheek; however, I took the OP to mean blind hole.

this is the fork cap - thanks all for the replies