Turning and drilling phosphor bronze ......... help !

[DAPPH]

My £ 200 ish electric pond suction cleaner died after only three sessions the dam thing managed to get water up inside the controls and shorted out the circuit board. I've had a refund instead of a replacement cleaner , as I've found out that they are very very unreliable and many die because of water ingress to the contrils .

So I've now purchased a sludge /leaf cleaning head /hood that uses the venturi principle to suck up crud off the pond liner and expel it through a rigid pipe . This hood fits on to a power washer.
I have to make my own female attachmetn/adaptor as my power washer is not the run of the mill screw on ones it's a KEW 150 bar Alto fitting that is similar to an air line quick release spigot end.

I want to make an insert/strengthener out of phosphor bronze alloy ( PBA ) so it won't rust ,it will be soldered /sweated in place to strengthen a thin walled brass threaded 19 tpi pipe that is going to be screwed into some die cast aluminum . I have this brass gas pipe fitting .
trying to turn the 19 tpi on my lathe is a bit nightmarish as the thread counter won't automatically run true , so all the threading passes would have to be run manually from a right hand carriage stop .
I can try that later when i have some scrap metal to practice on i certainly won't be using PBA for the first trial because of the high cost of the PBA

I now have a 150 mm long 35 mm dia slug of the PBA , I will eventually cut the strengthener insert off at 40 mm long and am looking for some info on cutting speed & rpm for the lathe .
I'd also like advice of the cutting speeds to bore centrally on the lathe with a drill a 5 mm dia through hole with part of that hole being drilled to 11.8 mm dia .

On top of this insert I'll be fitting a PBA capture device for the Kew's high pressure hose spigot end .
This time the strengthener thread and affixing hole in the capture device will be made by hand with a tap & die set in 19 tip 1/4 " gas thread so I can screw it on and off as needed .

Now come the risky bit.
For this capture device I turning up a 32 mm dia part x 43 mm long part that I want to drill two chords through the bar at 2.5 mm dia & also chain drill & file / cut out a 10 mm across the axis x 2.5 mm wide slot in the piece just below these two other holes .
What sort of cutting speeds /rpm are needed for these secondary holes>

Over the whole project , can any of you guys give me a few pointers where I should extra careful and why ?

 

[optima21]

in my limited experience with phosphor bronze, I've found that if it heats up when drilling, it can bind on the drill bits until the eventually jam, or small drill bits can break. the drills an cutting oil will be fine on steel though, this might not be an issue with free cutting phosphor bronze though. I'd normally use slightly slower speeds than I would for steel, and you can use the same tools for phosphor bronze that you can for steel.

 

[Wendelspanswick]

What lathe have you got?
From memory, on my Colchester Student, you use any numbered marker on the thread indicator for odd numbered threads although I might have got that ass about face.

 

[DAPPH]

My lathe is a British made Sphere 28 inch between centres back gear screw cutting lathe ..very similar to the Atlas 10F, it has the same head stock , carriage ,r stock . apron ,cross slide and compound slide with a few differences . But it's basically the same stuff. I have a of the original tooling as well but no milling attachment as that was sold two days before I discovered the lathe was for sale
It was made approx 1942/3 and used in making torpedo fuses . Purchased brand new unused from a War Office release sale in Feb 1946 by a submarine munitions engineering officer .It passed to his son on his demise and was sold to me just over a year ago when the son downsized nd moved into sheltered accommodation .
I have the original manual of operations ( MOLO ) it gives a list of threads that have to be manually cut by setting an end stop to the RH of the carriage & picking up the thread dial on 1 when it is at the stop . You then have to start the lathe & be sure you have the lathe in back gear mode so it is as slow as possible ( A variable speed motor would be ideal for this lathe but is a tad expansive to set up at present . )

The 1/2 " gas thread is one of these specials at 19 tpi , the various change gears that are a standard set can't give you that rate of feed . Evidently you used to be able to get hold of a set of gear change wheels from Atlas ( They ceased all production around 1994 ? ) that took in all the non standard threads , but I'm told by the old timer machinists I know in the USA that they were very very expensive and are now like the proverbial rocking horse muck .

So I bit the bullet and turned up the PBA to the required diameter s.. it was not long before it got grabbed by the tool and wrenched out the three jaw chuck. I put that down to me not taking the slop out of the cross slide . I have a good 5.6 mm free play , everytime I wind it back , I have to take it at least 1/2 " out . So that when I go in for the next cut it is actually being pushed into the work and not free sliding in to grab it out of control .

Any way I managed to get burnt on a couple of long bits of swarf .. didn't realise it would have got that hot as it hadn't changed colour much .

I changed the cutter to a 3.5 mm wide parting tool and took the metal off in strips rather than doing an inch traverse in one go .. That solved the long swarf problem and also kept the temperature down but I still had to drop the piece in a bucket of cold water several times when I wanted to handle / measure it as it was still too hot for even a pair of riggers gloves . This is one of the interesting problems of turning on an imperial lathe when all your measuring tools are metric.

I ended up turning a 13.8 mm dia at one end of a 42 mm long piece , left a 5 mm web in the middle and then turned the other end down for threading in 12 mm .It was about this time that I decided to use the hand die to thread the spigot to 12 mm ,thinking it would be easier and less likely to suffer accidental damage .
Before I turned the ends I gently bored a 5 mm hole right through the piece using a special cutting oil lub/cooler spray and using a resharpened drill I'd ground bit to a slightly flatter angle . The PBA came out in tiny slivers as I was feeding the drill in so evenly & slow . A snail would have done it faster . It was a hole success so to speak .

The 13.8 mm end was a slight hand push fit slid into a bored out 1/2" gas union that I'd cut one of the threaded ends off & soldered in . This was then left to cool naturally & undisturbed so as to not get any crystallization in the solder as it has 150 bar trying to push it out .

After lunch I started to use a hand die to put the 12 mm thread on the phosphor bronze spigot & found it impossible to get it started at the correct threading diameter. So I put the part inn the lathe and gave it a decent lead in for threading.
Despite the lead in it was still difficult to get the thread going for it seemed to grip the die at every opportunity even though I was using the special cutting spray . I was only able to turn less than a 12 th of a circle on each cutting stroke before having to back off and remove the burr. Anything greater resulted in it binding up and causing the part to rotate in the protective copper sleeve as it was in the vice. Three 10 minute sessions later I took the die off , inverted it and then took the thread down to the shoulder of the part over the next 15 minutes.
My arms ached like mad , plus the dreaded backache decided to pay a nasty visit yet again.
I had an hour of being laid flat on my back and then attacked the job again , this time I tapped a 13 mm thread in some mild steel that Ii turned up to make the pressure hose nozzle capture device .. ( I decided in the end that using PBA for the capture device was too risky and too bloody expensive) /
It was then all screwed together and I set up the cleaning hood & power washer .. it works fantastic , took out about 16 cubic feet of water in a matter of just a few minutes plus no end of sludge , weed , new & old part decayed oak leaves from the pond .

Today I modified things a bit to enable me to attach a five foot long old sea fishing rod butt as a long reach handle so I can reach across the pond and get the bottom without having to bend my spine much .. Joy Oh Joy , yet again , it works perfectly and didn't give me much back pain either.

 

[carbon]

Can you upload a picture of the connector on the hose you have as there could possibly be an adaptor available for it. The thread on the inlet of the sludge sucker should be 3/8" bsp if that helps.

If the hose end is 8mm in diameter it may not be available as a socket yet. Male ends are, which doesn't help

 

[DAPPH]

Thanks Carbon ,
Yes the thread is a 19 tpi 3/8 BSP thread ... a total pain to try and get something meaty in metal that I could bore out or adapt without some a serious weak point showing up , that's why I went the phosphor bronze route as it is as strong as steel eveidently .

Coke can size reference view



The brass connector spigot .. i think its 11.8 mm max dia .



The cheats way of getting the spigot retained in the capture device .. it would have been quite difficult to replicate the angled holes and slot in the trigger/handle of the washer so that the jaws open up as the retainer wires are pushed forward into the slot to allow them to open . Had I a milling machine it wouldn't have been a problem .




Inside the venturi area .. the jet at 150 bar is so powerful that about five inches up from the jet it has actually pierced the plastic discharge hose wall . Looks like I'll have to slide some sort of shaped thin stainless steel sleeve in to take over this damaged impact point .





The high pressure line spigot end .. the stainless steel safety pin type thing locates in the dirty looking grove when it is all set up in the capture head.

 

[carbon]

Thanks, it looks like the 8mm coupling, they measure them on the end, not the larger diameter. I've found with these suckers its better to replace the flexible outlet hose with a rigid pipe a couple of feet long, as its possible for the jet to make a hole in the side of the flexible hose when running at higher pressures / flow rates.

 

[DAPPH]

Funny you should say that about the hole appearing, I commented about that in the info for the fourth picture , was your rigid pipe..... plastic waste pipe or aluminium ?

 

[carbon]

Sorry should put my glasses on more before replying. They are usually supplied like yours with the flexible hose, but I've threaded some thin wall aluminium tube and added it.

 

[DAPPH]

Hi Chris ,
I've been off line for a few days getting my computers re set up & sorted with Ubuntu .

Thanks for the reply . My cleaning hood came without any tube .
I'm hoping to visit a Wickes store soon and will see if there is any thin stainless steel hand rail or aluminium etc. that might be adaptable to fit over the end of the plastic adapter ........ once I've shaped it a little on my pipe bender with it full of set candle wax to stop it collapsing or splitting the walls .

 

[carbon]

I used about a metre of thin walled aluminium tube, threaded the end and used that in place of the supplied hose fitting. Then added the hose on the end of that. Only down side of doing that is it now takes up a bit more room when transporting it.

 

[DAPPH]

Thanks , as the current plastic outlet pipe set up has a slight dog leg and the puncture point is about seven inches up from the bottom of the outlet pipe on this dog leg , I'm thinking of making a 350 mm or so long pipe with a slight dog leg at the seven inch up point to take the initial force of the jet, perhaps actually giving it a bit of a turn through 70 or so degrees to take the plastic pipe away quicker at the upper end & cable tying the pipes to the home made handle for support .