Member postings for Kiwi Bloke

It should be an easy fix. My >30-year-old Karcher HD 575 is still going strong, but has always had a problem where pulling the trigger doesn't always release more than mains-pressure water. Usually, after a few trigger-pulls, or a bit of a wait, it is fine, only to 'fail' the next time the trigger is released. Or not... Annoying. Due, I'm sure, to it not being used enough, so evaporation of the water inside leaves the solids to gum up the works. The cure is to remove, dismantle and clean the pressure-adjusting valve. A smear of silicone grease helps. Similar attention to non-return valves, as above (NDIY), might also be necessary. The pump also piddles water out from the pump body drain orifices. This is because the piston seals wear. It's all an easy fix - assuming spares are available (here, in NZ, I'm not hopeful).

The pump is easily dismantled, without worrying about oil, orientation, etc. The swashplate assembly, between pump and motor, is oil-filled, but does not have to be disturbed for pump maintenance.

Repair, don't replace!

Just thinking aloud here... I have no experience of, or knowledge about the subject, but when did that ever inhibit anyone posting to a forum?

I don't doubt the delamination phenomenon, but it seems a bit odd that a symmetrically-applied, radial compressive force causes delamination, unless there are severe axial shear forces at work. In other words, the inner layers are being squeezed, orange-pip-like, towards the open end of the horn. Perhaps the horn also needs to be constrained axially, having given the wide end a plane bearing surface, so all layers can be supported, as the radial force is applied.

Alternatively, although I'd expect high shear forces to be induced, another way of squashing down the horn may be to try drawing it down through a succession of smaller diameter dies, as in wire drawing. Perhaps many small diametrical reductions between heats might avoid delamination. I would imagine that the horn might need to be soaking in whatever heating method used for perhaps tens of minutes, to make sure it's 'cooked' all the way through.

Another way of applying surprisingly large forces is by wrapping with strips of well-stretched rubber (eg strip cut from old inner tube), perhaps several layers.

Nurse should have tucked me safely up in bed, instead of letting me play on the computer after my bed-time. Of course, JasonB is right, the pulley screws on and it's a collar that's pressed onto the spindle shaft. I was working from memory (dangerous these days) - the vertical heads have been stored away and forgotten about, for some time. Sorry for any puzzlement caused.

The anti-friction bearing mod was the subject of this thread. I'm horrified to see that four and a half years have passed since then, and I've achieved nothing useful in that time...

Edited By Kiwi Bloke on 07/08/2019 07:02:54

Barrie, just in case you were wondering, the milling spindle is removed by pressing it out, (nose first) through the pulley. Do let us all know how your project goes.

Barrie, your result looks pretty good, vastly better than what my machines will do. Yes, prev. post was directed to OP, but also as a warning to all owners.

Yes, I did mean radial play - as a result of slack sleeve bearings / bushes. Particularly annoying, because correction requires replacement, possibly custom manufacture, unless modification is considered. One forum member was intending to fit anti-friction bearings, and it's been written up in ME - ages ago. Unfortunately, it seems to require the manufacture of a smaller diameter spindle, so rigidity may be compromised. Perhaps fancy bronze/PTFE, or other 'plastic'-containing bushes are the simpler answer. One day, I'll sort mine out...

Of course, the silly pressed-on pulley design means that elimination of axial play is difficult to eliminate, but at least one can try to adjust it out...

Emco dropped the ball when they designed the milling attachment for the Unimat 3. It uses sleeve bearings, which can't be adjusted. The spindle end-float also can't be adjusted properly. The pulley is pressed onto the spindle - its position determines the end-float. It can be 'adjusted' by judicious use of press or more brutal techniques.

I have two milling attachments (don't ask...), both bought barely-used, but both have unacceptable play in the sleeve bearings, making the attachment effectively useless for milling. I would imagine that they have been like that since new and have not worn excessively. The result is as you have shown. I suggest you check your spindle for radial play.

'You get an item but it's not quite right so what do you do, use it or return it???' Good question, Tony. I suspect it depends to whom you try to return it. The people who understand that quality matters seem to be dying out - at least in the retail sector.

There's been quite a bit of relevant discussion about these things in this forum already. If clocking the chuck taper suggests the chuck is 'out', it's a dud. The collet may also be 'out'. However, it has been pointed out that, even good-quality collets can't be relied upon to be perfectly aligned when the chuck is tightened. Applying a balanced torque (couple) to the nut may help. Collet 'pushers' are available. These are used to apply a temporary, radial force to what the collet's holding, as the nut is tightened. (Tighten a bit, clock it, tweak, tighten, rinse and repeat...)

As I understand it, these chucks were originally designed to hold cutters, not workpieces, so absolute alignment wasn't such a priority, given the short length of (most) cutters.

However, on thinking about it a bit more, the laws of thermodynamics and energy conservation have to be satisfied, and I've conveniently ignored the energy accounting. I think I'll go to bed...

Well, if no-one really understands how syphons really work, allow me my 50 cents' worth. I've skimmed the Wikipedia entry, so am now an instant expert and world authority...

The 'flying droplet' syphon is interesting. Elsewhere in the article, it's said that a syphon will work (assuming that it has been started, presumably) in a vacuum. But would the 'flying droplet' type work in vacuo? It seems to me that the discharge tube tries to empty, by gravity, just like water running out of a simk, thus reducing the pressure in the 'air chamber'. This 'sucks' up liquid in the feed tube. But this suction should only work if air pressure pushes the liquid up the feed tube, into the 'air chamber'. So, for this type of syphon, it seems to me that air pressure is needed to 'get over the hill', and gravity takes care of the flow down the discharge tube. Of course, the cohesive property of liquids helps the bulk flow in the discharge tube from breaking up and allowing air up the tube, to break the syphon. So, a combination of gravity and air pressure are required.

Does this mechanism seem a reasonable explanation for 'conventional' syphons too? ...Well, those not in vacuo, at least.

S'pose it'll be illegal in Blighty - isn't there some law against 'carrying fire aloft'? Hot air balloons must be an exception. Perhaps I'm just making this up...

If it's whisky - or indeed any other alcoholic beverage - I shall continue to use it in the manner to which I am accustomed, DIRE WARNINGS notwithstanding.

Glad you're now all geared up. My apologies, my chart in fact suggested a 55T idler, not 50T as I said. I should have gone to bed instead of posting when tired...

Cutting the thread is easy enough - don't be scared. There's plenty of info out there. It's best to ensure that the cut is made primarily by only one side of the tool, either by making a small lateral movement for each in-feed, or by feeding down the flank of the screw, by setting the topslide round by half the included angle of the thread. Take a very shallow cut first, and check the pitch is what you intended, then gently does it...

Good luck.

Brian Perkins' VW was published as a construction series in Strictly IC Magazine (USA), Robert Washburn's excellent mag. Sadly, I believe that both gentlemen are no longer with us.

40T driver. This meshes with 38T, which is keyed to 20T, both on 'first' stud. The 20T wheel lies outboard of the 38T wheel. The 20T meshes with a 50T 'idler' on the 'second' stud, which in turn meshes with 50T on the leadscrew. My chart suggests a 50T idler. You have a 55T idler, which seems OK, if it fits - obviously, the number of teeth is unimportant. The first stud is on the higher slot on the banjo, the 'second' stud on the lower slot. So your setup looks nearly there, the driver seems to be where it should be, so it's just a matter of getting the 20T and 55T into mesh.

Meshing adjustment. Slacken the banjo clamp nuts, and swing the banjo downwards, to give you 'wriggle room'. Get the mesh of the idler 55T and leadscrew 50T wheels correct, then the mesh of the 20T wheel on the 'first' stud with the idler, then swing the banjo up to get the mesh of the 38T correct with the driver and clamp the banjo. To align with the idler, the leadscrew gear will have to be spaced outboard with a spacer or small dia. gearwheel acting as a spacer (you seem to have done this).

Don't mesh the gears 'tightly', but allow a little backlash. Some advocate a strip of thin paper between gears when setting up, to ensure some clearance. Lubricate the gears. Slideway oil is good - it doesn't get flung off as readily. Lubricate the studs too.

Hope this works - working from charts and memory, and haven't checked the maths (it's getting late). I have the luxury of a gearbox, so haven't done this very much since the gearbox arrived...

Edited By Kiwi Bloke on 25/07/2019 11:25:51

Edited By Kiwi Bloke on 25/07/2019 11:27:30

Edited By Kiwi Bloke on 25/07/2019 11:31:19 (I said it was getting late...)

Edited By Kiwi Bloke on 25/07/2019 11:38:37

Walk into Comwell Tools or Buck and Hickman. Branches throughout UK. Both have web sites. 'Burrs' finds the things within the sites.

After all that there has been written about threading calculations, confusion persists. The dissenters are correct. Perhaps gear trains and their calculation confuses people. Although Pete and Duncan have already explained, and not wishing to steal their thunder, let's look at it another, possibly simpler, way.

Say you have a lathe with an 8 TPI leadscrew. Each leadscrew revolution moves the carriage 1/8", or 25.4 X 1/8 mm. Multiplying top and bottom by 5, to get the calculation into whole numbers, gives 127/40 mm. So, in order to cut, say, a 1mm pitch, the leadscrew must revolve 1 / (127/40) = 40/127 revs. This must, of course, happen each spindle revolution. This is where the changewheels come in, but we don't need to bother with that complexity. The problem is closing the half-nuts at the right spindle and leadscrew relationship. The point is that 40/127 is inconvenient because the smallest whole number that can be used to multiply this fraction by, in order to get a whole-number result, is 127. Only then will the leadscrew and spindle be correctly synchronised. So, the suggested method would work if one had a 127 tooth pinion on the thread dial indicator...

Edited By Kiwi Bloke on 25/07/2019 10:02:20

Clive. 'I suspect that your stiff "General" brand edge finder was intended to be used with the light line method rather than the kick off method.' Well, of course, it could be used this way, and perhaps it should be, as it's the most sensitive method. But my point was that the manufacturer's instructions are as I quoted, and they seem bizzarre. I'd be interested to know whether anyone has used General's method.

'Mentioning GHT reminds me that his analysis of how the things operate is wrong. Nothing to do with tilt. Just a matter of generating enough force between probe and ball for it to drive sideways along the surface. Once its moved a fraction off axis centrifugal force takes over and it flies.' I don't remember GHT's explanation. I'm not sure that I understand what you mean by 'enough force between probe and ball for it to drive sideways along the surface.' I may have misinterpreted what you meant, but, to avoid confusion, the probe's ball or cylinder does not drive itself along the surface it is contacting, as a result of friction at this interface. The sideways force is generated by asymmetric forces between the chuck and the ball end of the probe sitting in the chuck, once axial alignment is lost. Experiment confirms that the tip of the probe is driven sideways, from the chuck, but doesn't pull (or push) itself sideways. If centrifugal force deflects the probe, things may have got rather hairy. Better to arrange things so the probe doesn't whirl free, if possible.

May I suggest that the above extract from the boiler regs is published regularly in ME? Whilst I would expect boiler inspectors to know this, how many builders would know to first pressurise their newly-built boiler this way? Not me, certainly - although I'm not into steam.

Here's another twist. From an estate sale, I got a 'General' (General Hardware Mfg. Co., Inc., USA) 'Universal Wiggler and Center Finder'. It's of the spring chuck / collet / multiple probes type in appearance, but is intended to be used differently.

Its instructions state: 'Insert the large ball of attachment into spring chuck. With the spindle turning, make the ball run true by holding any blunt object against it. Apply a thin coating of layout blue on the ball and feed the work up to it until the blue is barely wiped.' Note, layout blue is specified. I suppose you're supposed to use a small brush, and ensure the probe is not deflected. No alternative method of use is given.

The chuck can be tightened, but, even at its slackest, it holds the probe fairly stiffly and 'roughly', and it's not suitable for use with the usual wiggler kick-off technique. How one is supposed to get the ball to 'run true' accurately, by the suggested method, is beyond me, but, since the thing is surplus to my requirements, I've never bothered to try seriously. I find it difficult to believe that this method is used, if for no other reason that one needs to be able to have a very good, close-up view of the probe in action. Anyone ever come across this method in use?

I have a flaky memory of GHT commenting on a 'stiff' wiggler that didn't kick-off consistently. He considered it useless, until someone pointed out to him that it was not supposed to kick-off. Memory thinks one was supposed to look for disappearing light between probe and work, so the probe had to be set running true, as above. Could be mistaken - memory nearly full, and stuff is being dumped to retain a little capacity...

The 'General' set also contains a cranked 'probe', intended to hold an indicator, which can be held stiffly enough by tightening the chuck. Perhaps those sets containing such a 'probe' are intended to be used as above, and not to 'kick-off'.