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19th Nov 2013, 01:53 PM #1Novice
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Increasing inside diameter of brass tube
Hi all,
I’m making a portable coffee machine out of brass tubing and need to increase the inside diameter of one of my tubes from 63.35 mm to 63.55mm. I don’t have a lathe and I’m not sure how I should go about this. I should add that I only need to do this for the first 20mm of a 40mm long tube.
Any help is appreciated and I may have more questions as I progress so please excuse my complete lack of knowledge when it comes to metal working.
Cheers
Rob
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19th Nov 2013, 02:23 PM #2Cba
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19th Nov 2013, 02:36 PM #3Novice
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19th Nov 2013, 03:40 PM #4Diamond Member
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I can't see how it could be done very easily( or accurately ) without a lathe.( may be wrong....lol )
Pressing a mandrel into it would require a lathe to make the mandrel first.....same problem.
A car exhaust business could expand it but it is such a small amount, they wouldn't have the control precision to do a good job and they would probably end up splitting it.
Maybe someone here with a lathe, who is local can help.
Is there a small machine shop close that would be able to do it for you? a TAFE machine shop?
Sorry, I can't be of more help.
Steve
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19th Nov 2013, 04:21 PM #5Member: Blue and white apron brigade
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Any expansion method means it should be annealed beforehand.
That means heating is several times to read heat and holding it at red heat for a couple of minutes and then letting it cool slowly in air.
With a 3.25 mm wall thickness I would just get that 0.2 mm bored out on a lathe.
A question we should ask is what is this piece doing, is it under pressure, liquid or gas, how tight does the fitting need to be?
If high accuracy or pressure sealing is not needed, another possibility is - have you already cut the 40 mm length?
If not cut a 60 mm length and then use a wooden arbor with emery cloth and work it back and forth and around and this should eventually take of the 0.2 mm. This will create rounded internal edge which can be removed by cutting 10 mm off each end.
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19th Nov 2013, 04:31 PM #6Novice
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- Sep 2010
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- Melbourne
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Thanks for all the suggestions! The piece will be slipped over another tube (63.5mm OD) and brazed in place. It wont be under pressure and precision is not really required for the brazing - I just need a gap for the braze filler to flow through. Using the arbor and emery cloth may be the easiest option and if it fails I will find someone with a lathe.
Thanks
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19th Nov 2013, 06:12 PM #7Golden Member
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19th Nov 2013, 06:21 PM #8Banned
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- Jul 2011
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G'day Rob.
Which part of Melbourne are you in? That would be a 5 minute job here. I'm north, factory in Thomastown. Work Saturdays if that helps.
Regards Phil.