Cutting a large internal hole

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Cutting a large internal hole

This topic has 10 replies, 9 voices, and was last updated 26 April 2020 at 19:21 by Gavin Mclean.

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25 April 2020 at 16:54 #467025
Gavin Mclean
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@gavinmclean68552
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
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25 April 2020 at 16:54 #10186
Gavin Mclean
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@gavinmclean68552
25 April 2020 at 17:00 #467028
old Al
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@oldal
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
25 April 2020 at 17:09 #467031
Howard Lewis
Participant
@howardlewis46836
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
25 April 2020 at 17:57 #467044
Pete.
Participant
@pete-2
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.
25 April 2020 at 18:50 #467051
Bob Rodgerson
Participant
@bobrodgerson97362
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.
25 April 2020 at 19:19 #467061
JasonB
Moderator
@jasonb
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..
25 April 2020 at 20:31 #467081
John Haine
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@johnhaine32865
I'm trying to work out what other kind of hole there is…
25 April 2020 at 21:08 #467092
old mart
Participant
@oldmart
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.
26 April 2020 at 14:07 #467193
ega
Participant
@ega
Posted by John Haine on 25/04/2020 20:31:00:

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

I imagine your tongue is in your cheek; however, I took the OP to mean blind hole.
26 April 2020 at 19:21 #467276
Gavin Mclean
Participant
@gavinmclean68552
this is the fork cap – thanks all for the replies
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