Boring copper tube problems

[nigel jones 5Participant @nigeljones5]

I frequently have to bore holes in large bore ( 3 to 6&quot copper tube. I use a stepper drill and then a boring head to go to 1.5". Thing is I am having great difficulty in achieving this as the mill simply doesn't have quite enough torque. My mill is the X2 500w brushed motor. I converted it to belt drive which made things a lot worse as it ups the head speed! I reworked the pulleys to give the lowest gearing I could but the machine still stalls easily. Obvious solution is a bigger mill but I haven't seen anything second hand between mine and a full size Bridgeport type which I simply don't have space for – are there any cutters which would make lighter work of cutting/boring copper using an indexible boring head? I already use milk but it doesn't make much difference.

[nigel jones 5Participant @nigeljones5]

[Neil LickfoldParticipant @neillickfold44316]

Very sharp tools, small cuts.

[Nick_GParticipant @nick_g]

Posted by fizzy on 19/04/2017 19:55:55:

but I haven't seen anything second hand between mine and a full size Bridgeport type which I simply don't have space for –

.

**LINK**

**LINK**

I have one of the Boxford ones which has a much smaller foot print than a Bridgeport. – I could measure it for you if needed.

But that one is IMHO over priced for what they normally go for.

Nick

[Simon CollierParticipant @simoncollier74340]

This is my Springbok boiler on the table of my SX3. My friends thought I was mad; they simply chain drill and file. I think some use a hole saw.

[egaParticipant @ega]

Rotabroach?

[WorkshopPeteParticipant @workshoppete]

Mini Rotabroach I have them up 1 1/2" and the hole is dead size with very little power can be used in a battery drill no need for a mill.

[Ady1Participant @ady1]

A lathe with backgear?

A lathe is a mill on its back with a fabulously thick column

Edited By Ady1 on 20/04/2017 00:43:36

[JasonBModerator @jasonb]

I think Nick has the answer if the mill is stalling then you need to reduce the load. You can't reduce the dia so the only other option is to reduce the depth of cut, may take a bit longer making more cuts but you will get there in the end.

[MWParticipant @mw27036]

I would also use a much sharper HSS tool than the typical carbide brazed boring bar, they're normally far too blunt for the job.

Michael W

[KWILParticipant @kwil]

The problem with the Boxford VM30 is that it is limited height (ie daylight) once you have a vice and boring head in there. OK for the smaller jobs, if a little noisy with the head gearing.

Hence I added a Bridgeport with a raising ring to the machine tool inventory.

Chain drilling and then boring to final size is quite easy.

Edited By KWIL on 20/04/2017 10:08:42

[HopperParticipant @hopper]

Posted by Michael-w on 20/04/2017 09:15:23:

I would also use a much sharper HSS tool than the typical carbide brazed boring bar, they're normally far too blunt for the job.

Michael W

^^^^ +1 on this. Copper is sticky stuff to machine. A HSS toolbit with a razor sharp honed edge with plenty of top rake works well and plenty of cutting oil to help stop the copper sticking to the toolbit and adding massive drag to the rotation.

[Roderick JenkinsParticipant @roderickjenkins93242]

I've been using ccgt inserts to machine some copper boiler bits – seems to work very well. Perhaps you can find a holder for your boring head to take this type of insert.

Rod

[Nick_GParticipant @nick_g]

Posted by KWIL on 20/04/2017 10:05:04:

The problem with the Boxford VM30 is that it is limited height (ie daylight) once you have a vice and boring head in there. OK for the smaller jobs, if a little noisy with the head gearing.

.

I take your point that it is a a little short on headroom for a machine of it's size. Gears on mine are very quiet though.

Nick

[SillyOldDufferModerator @sillyoldduffer]

Posted by fizzy on 19/04/2017 19:55:55:

…

I reworked the pulleys to give the lowest gearing I could but the machine still stalls easily.

…

I already use milk but it doesn't make much difference.

Hi Fizzy,

I've tuned into the mill stalling part of the story. Perhaps copper, of which I know little, really is that sticky, but I'm suspicious that it's stalling a boring head rather than tearing.

Can you describe your pulley set-up in more detail please? I'm wondering if the ratios are still too high.

As to milk and copper, I'd never heard of that before. On the web someone said "lots of milk", though. I think he means flood rather than dribble if that helps.

Dave

[JasonBModerator @jasonb]

Full fat milk for best results. Don't think I would want to flood too much as if you don't clean it all up the workshop will soon stink. I jast dab a bit on with a brush.

[Michael GilliganParticipant @michaelgilligan61133]

Are you people seriously advocating the use of Milk [as sometimes used in Tea & on CornFlakes]

… I seem to recall "milk" being a colloquial term for 'soluble cutting oil mixed with water'.

MichaelG.

.

Edit: … and I've just found this

http://mamaflinter.tripod.com/id10.html

Edited By Michael Gilligan on 20/04/2017 15:01:59

[MikelkieParticipant @mikelkie]

I've used cream mixed with meths 50/50 on copper turning with exilent results… a tip from the late Arthur Presscot.

[JasonBModerator @jasonb]

Yes COW milk Michael and bacon fat for metal spinning.

[Martin ConnellyParticipant @martinconnelly55370]

I've found rendered pig fat in the form of lard the best lube for rise and fall brass door hinges. I tried all sorts of other thing before lard but none worked as well.

Martin C

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Mikelkie on 20/04/2017 15:54:00:

I've used cream mixed with meths 50/50 on copper turning with exilent results…

.

Thanks for the confirmation, Mike [and Jason]

MichaelG.

[nigel jones 5Participant @nigeljones5]

Thankjs one and all…I cant make the cuts any finer at one thou per cut, I cant reduce the gearing amy lower and although the milk helps the stench is terrible next day…more torque me thinks

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