Is there such a thing as an ‘external reamer’?

[DiogenesIIParticipant @diogenesii]

Forgive the truly appalling 'fag-packet' sketch.. ..I hope there's enough information for a man of your experience to see what I'm driving at, and how it might be made to work – something I've been pondering for my own ends..

The bracket / block should just clear the cross-slide body, I think it will be okay as something to bring the slide to a stop against. rather than crash into with abandon..

..I'm rather assuming that your lathe has a pair of bolt holes in the lower front of the saddle?

[Tony Pratt 1Participant @tonypratt1]

Trouble with driving a screw driven slide against a stop is that you can easily ‘overcome’ the stop so losing repeatability

Tony

[Anonymous]

A UK supplier, although still not cheap:

Hollow End Mill

Andrew

[Tony Pratt 1Participant @tonypratt1]

So Robin Graham, was this ever sorted?

Tony

[John ReeseParticipant @johnreese12848]

I am not sure if anything was sorted out.

An approach that was not mentioned is adapting a dial indicator to the cross slide. Many machinists use a magnetic back dial indicator to make saddle or cross slide travel repeatable.

[JasonBModerator @jasonb]

But why use a dial indicator when the lathe already has a DRO?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Andrew Johnston on 01/09/2021 09:37:33:

A UK supplier, although still not cheap:

Hollow End Mill

Andrew

.

Those look useful, Andrew …

“For machining outside diameters such as lugs and recesses in castings. Size range available in imperial and metric from 3/32" to 1" and 3.00 to 21.00 mm”
[these being the bore sizes, I note]

… but I have two questions [one simple, and one perhaps pedantic]

1. Are they intended to simply be held in a collet by the outside diameter ?
2. Being end-cutting … Do they really qualify as ‘external reamers’ ?

MichaelG.

Edited By Michael Gilligan on 02/10/2021 08:16:16

[Anonymous]

Posted by Michael Gilligan on 02/10/2021 08:13:36:

1. Are they intended to simply be held in a collet by the outside diameter ?
2. Being end-cutting … Do they really qualify as ‘external reamers’ ?

1. No idea

2. A machine reamer cuts on the leading chamfer, not the flutes, so essentially end cutting

Andrew

[Michael GilliganParticipant @michaelgilligan61133]

[Robin GrahamParticipant @robingraham42208]

Posted by Tony Pratt 1 on 30/09/2021 12:01:46:

So Robin Graham, was this ever sorted?

Tony

Apologies for failing to report back on this. What happened was that I found that the repeatability of the QCTP was indeed much better that I had supposed as you suggested – perhaps not half a thou, but good enough. So I ended up turning in the normal way, with the aid of the DRO and a bed-mounted carriage stop.

This topic has had over 50 replies and I can't acknowledge every contribution individually, but I have read and been informed by every one – my thanks to all who have replied.

Robin.

[Author]

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