# Cutting a slot in copper pipe



## DavidJHolmes (1 Jan 2017)

Anybody any ideas on the best and safest way to do this?

I have a piece of 28mm copper pipe about 6" long and need a 3 or 4 mm slot cut end to end. It needs to look good as it will end up being polished and would also need to be straight to work with another piece it fits over with a bit of a key on it.

I thought about the table saw using some wood to in-case it completely and slotting it that way but Google has mixed reviews and I don't fancy breaking my table saw. I don't have a band saw, although I would need to cut it upright then perhaps making it harder? I do have a cheapy router table. I also have a CNC that very slowly and begrudgingly will cut aluminium at mega shallow depths, is copper softer than aluminium? This also seems a lot of work for a slot that perhaps I'm missing a dead easy method.

Thanks in advance.


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## paulm (1 Jan 2017)

Angle grinder would cut it in a couple of minutes, or a dremel or multi-tool probably.

To keep it neat would have to rig up some kind of straight edge or timber batten arrangement I guess ?


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## Eric The Viking (1 Jan 2017)

Dremel: make a jig to hold it square to the pipe and to let one or t'other slide along. a 4mm slot would be one slit and then trimming off one side. 

I'd probably use reasonably coarse emery cloth stuck to or wrapped round something like a tongue depressor (oversized beech "lolly stick") to clean off the burr, as copper filings gum up normal files pretty well, and anyway I assume you want the edges of the cut to stay nicely parallel. 

I've been known to make copper sheet by slitting large bore plumbing pipe and, with annealing, bending/hammering it out flat. 28mm gives around 86mm width, which is a useful size. Probably an expensive way to do it, but you use what you have available. 

Copper machines fairly well and doesn't gum up like aluminium, but it also anneals (goes soft) with heating. You can't harden it like steel, but it goes brittle readily with work-hardening. I think it's probably too hard to cut safely with a woodworking blade (that doesn't mean nobody's tried it though).


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## kevinlightfoot (1 Jan 2017)

Could you cut it with a router I have cut slots in alluminium before quite easily.Copper is very soft and is easily cut with hss.


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## DavidJHolmes (2 Jan 2017)

I think I'm going to try the CNC as I can hold it to the table easier than making a jig. If that fails I will try making a jig. The only thing with the angle grinder and rotary tool is they are quite tricky to keep secure and level. I have a day to mess around so I'll give it a whirl! Thanks for the replies


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## Lons (2 Jan 2017)

I'd take an oversize bit of thin ply or MDF and fix a wood block full length, I'd screw the pipe (longer than required so the screw holes can be cut off), to the block from the back using self tappers then cut the slot on the router table using a TCT slitting cutter. probably the simplest jig you can make. If you want even more control or more solid screw fixing, shove a dowel up the inside of the pipe.

You could do a similar thing using the tablesaw and just cut through the baseboard int the pipe, just make sure the screws are out of the way.


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## DavidJHolmes (2 Jan 2017)

Lons":3433bgbz said:


> You could do a similar thing using the tablesaw and just cut through the baseboard int the pipe, just make sure the screws are out of the way.



Does it not damage the saw or blade? Google seemed pretty mixed.


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## Lons (2 Jan 2017)

I've cut copper sheet and aluminium on mine and no noticeable effect on the blade though I do keep an old 64 tooth for that purpose these days.

Copper pipe is pretty thin walled and I wouldn't thing a short length of pipe would do much damage tbh

Another way to cut it would be clamped in a cut off saw though same blade questions.


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## Sheffield Tony (2 Jan 2017)

A 6" slot in a 28mm pipe .. hacksaw & patience is definitely the safe way. Clamp into the channel of a bit of steel angle to make a straight guide if needed.


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## graduate_owner (2 Jan 2017)

Could you drill it out as in cutting mortices, then clean up with a file? A new file would do the job quicker than one that has been used on steel. Or, do you know someone with a milling machine?


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## DavidJHolmes (2 Jan 2017)

Sadly it didn't get attempted today! Other things... :roll: 

I do know someone with a mill however it takes ages for them to get stuff done (think months).

Options I had thought and wasn't sure about have been suggested so I have quite a few options. I've a good 3ft length of pipe I've salvaged so have a few tries! Thanks guys.


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## DavidJHolmes (3 Jan 2017)

Well I managed it. It cuts far better than aluminium! CNC did it a treat. Only issue is that the clamps cause the pipe to spread as its cut through making it hard to get the correct cut width. I ended up with a 5mm
slot but I'm going to have another go 









Only


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## Eric The Viking (3 Jan 2017)

Neat!


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## AndyT (3 Jan 2017)

I think I would put that bit in the vice and give it a gentle squeeze before I started again - unless the pipe needs to stay perfectly round.

Maybe you'd get a tighter slot if you leave the ends in place, make a stopped cut, then saw off the ends?


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## Northern woodworm (3 Jan 2017)

In general aluminium is easier to machine than copper: copper tends to be more abrasive blunting the tools a lot faster and has a tendency to snatch clogging or breaking tools with little notice. However with copper the difficulty is related to how hard or soft it is.

For slot cutting the pipe safely and neatly I would be tempted to use an oscillating multitool: you should be able to run one along a straight wooden edge pretty easily.


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## DavidJHolmes (3 Jan 2017)

AndyT":5y14v56g said:


> I think I would put that bit in the vice and give it a gentle squeeze before I started again - unless the pipe needs to stay perfectly round.
> 
> Maybe you'd get a tighter slot if you leave the ends in place, make a stopped cut, then saw off the ends?



I'm going to try that on my next attempt. I wouldn't want to squeeze the pipe I need it to stay round, although it will fit into a circular slot/cut out at one end so should be ok. 



Northern woodworm":5y14v56g said:


> In general aluminium is easier to machine than copper: copper tends to be more abrasive blunting the tools a lot faster and has a tendency to snatch clogging or breaking tools with little notice. However with copper the difficulty is related to how hard or soft it is.
> 
> For slot cutting the pipe safely and neatly I would be tempted to use an oscillating multitool: you should be able to run one along a straight wooden edge pretty easily.



I only took 1/10th of a MM at a time. Not sure if I'm taking enough off at once to cause any clogging etc...


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## disco_monkey79 (2 Feb 2017)

I know I'm late to the party, and that you've already completed the task (and very neatly too!), but I've done similar using one of these:

http://www.frost.co.uk/professional-she ... blade.html

It doesn't give an absolutely perfectly straight cut, as your hand inevitably wanders a little, but it doesn't deform the tube like, say, aviation shears. As others have already mentioned, slicing and unrolling pipe can yield some usable pieces.


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