This little shop job has been hanging around since June last year when I discovered that several of the adjustable micro spray heads on my automatic watering systems for the garden hanging baskets and green house had blown off due to variations in water pressure whilst the supply lines were soft empty then suddenly getting flushed through with sun heated water .
My first attempt at solving the problem was to buy some 150 mtrs of new special for the purpose 1/4 OD thick walled micro irrigation tubing. Well , it worked for a while then the problem returned with a vengeance this year when the year old tube had age hardened and set into the expanded form of last years summer.
I must have had 14 or more of the spray heads fly off when I reset them up on the timers in March 2015 & turned the systems on .
Initially I tried to turn some 1/4 bore copper gas tube into sleeves , the idea being that I could slide a sleeve over every joint and it would therefore hold the tube to the correct diameter on the threaded parts . Trying to turn 3/4 " lengths of the gas pipe into square faced ends with a slight lead in was fraught with disasters . Most of the time the cutting tools ripped into the thin walled copper and tore it in half .
I resorted to using a hand hack saw to cut the tubes and still found that facing and counter boring was wrecking things due to the copper tearing , deforming or sliding around in the chuck 3 & 4 jaw chucks . Tightening things up more saw the thin tube wall collapse or rip off at the chuck again.
So I ordered a metric collet set for an M4 taper only to find that when they arrived that I'd made a typo and should have selected an M3 set instead.
It took several emails and a few more weeks for me to get the new set after sending the incorrect ones back & having to pay a handling charge plus the difference in price between the sets.
T day I did a few trial runs using band saw cut 3/4 inch lengths of tube , the collet set using an 8 mm OD collet , the QCTP with a facing tool & a precision 1/4 center point that gave the faced ends a slight clean internal champher . Well it works exceedingly well as I found that if I could have a smidgeon of water line tube protruding from the sleeve , once I'd screwed the spray head in , the protrusion of rubber took the form of the champhered internal end thus making an even better seal and stronger grip.
I'm not sure if it is a wise thing for me to try to use a long stock tube and try to part off the 3/4 lengths after facing and making the internal champhers , then when I've got my target of another 54 pieces done , face and champher the unfinished ends . OR .... If I'm better off doing it like I've already done things
.... advice on this using thin wall copper tube would be much appreciated .
I've used copper tube for the sleeves because it was available and also because I hope the expansion factors will also help squeeze the rubber water tube to the threads of the spray head in hot weather .
Here are a few pictures of what I'm on about.
One thing I did have to do was make a sliding shoe that could be fastened to the back & forth sliding fence on the band saw , just a simple letter " L " out of some spare 5 mm thin ply and a bit of 1x 1 " waste wood . So that as I pushed the tube under very careful control into the band saw blade I could hold it perfectly still to stop it sliding about or rotating. This in turn prevented the band\saw blade grabbing the soft copper as it had done when I tried to cut the tube without the shoe & just using the fence as the guide . It also allowed me to get very similar sized lengths without me resorting to measuring which is a bit of a bonus as I have a total of 74 sleeves to make at the end of the exercise .
