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Member postings for Kiwi Bloke

Here is a list of all the postings Kiwi Bloke has made in our forums. Click on a thread name to jump to the thread.

Thread: Stroboscopic effect
29/06/2020 07:29:02

I have set up a strobe to look at a spinning lathe because I'm a curious person (in all senses...). It requires a conscious effort of will not to stick something into the spinning bits 'just to see'. However, I'm willful (again, in all senses).

I assume the strobe frequency was stable, but could not test it properly. It passed some half-arsed tests I subjected it to. What surprised me was the Super 7's spindle could be seen apparently rotating back and forth a little, at a frequency of perhaps a couple of Hz. So there appeared to be a 'torsional vibration'. Was it real? Due to elasticity of the drive belts? Was mains frequency fluctuations to blame? Does anyone care? But it was a pretty experiment...

There are some very pretty videos of Paul Horn micro boring bars in operation, where one side of the work-piece has been cut away, so one can see the inside from the outside (makes sense?) The frame rate, or strobe illumination has been synchronised to the spindle, so it appears as if the tool is magically removing metal. Fascinating!

Thread: The fit of tapers
29/06/2020 07:07:59
Posted by Nicholas Farr on 28/06/2020 16:54:25:

Hi, referring to Paul Kemp's post above, I've known of machines that have gears on very shallow tapers without keys or pins grubs screws etc. They have to be fitted by extremely high pressure oil between the gear and shaft while being pressed home. The oil expands the gear by a few microns while the oil is pumped into a hole down the centre of the shaft and out to the joint line, no galling occurs, but of course accuracy of both parts has to be very good and the oil pressure has to be released before the pushing on pressure they can only be removed (without cutting them) by the reverse proceedure.

Regards Nick.

Edited By Nicholas Farr on 28/06/2020 16:56:58

This technique is also sometimes used to fit high-precision anti-friction bearings, eg on lathes. The inner race can thereby be increased in diameter to achieve the radial clearance desired (which I assume is none - or less, ie pre-load).

Thread: ER32 frustration
29/06/2020 06:47:12

Posted by pgk pgk on 29/06/2020 06:36:53:

...pushing the collet inwards to align things, ...

If you can push the collet inwards, relative to the ring, it's not engaged with the retention lip in the ring. Is that possibly the problem? I hesitate to suggest this, because I would assume that you already know how to use the thing. Some posters on this forum, however, seem not to.

Thread: Reamer type
29/06/2020 06:42:00

Adjustable reamers of this type are sometimes sold as sets with both 'straight' and 'helically cut' blades. For some reason, adjustable reamers command silly prices second-hand (even if looking well beaten-up) here in NZ. Unpleasant to use, in my limited experience. If anyone can offer advice about how to sharpen the blades (properly), I'd be grateful...

I bought a beautiful Hilger & Watts (IIRC) micrometer water level in UK in the late 90's (?) for very little money. It was considered merely a curio then, so I suppose laser levels had already taken over. Or, perhaps, prevision levels, autocollimators, etc. One day, perhaps I'll use mine, but for what?

Thread: Camshaft
24/06/2020 10:02:11

Good grief! Either it's the result of some pretty fancy materials development, or it's been designed to fail just outside its warranty period. I suspect the latter...

Thread: COMPAQ Bore Gauge
23/06/2020 12:13:27

Bother! Too late to edit my post. It's 'Compac', isn't it? Compaq made computers, PDAs, etc.

23/06/2020 10:26:31

Howard, can you put up a pic of your Compaq device? I have a beautiful, complete, Compaq (dial) bore comparator set, but it will take some finding (I'm 'between workshops' and much equipment is stored away in boxes). Mine is for larger bores, but there may be parts of interest in common. If yours looks similar, I'll organize a search party to find mine and measure whatever you're interested in.

Edited By Kiwi Bloke on 23/06/2020 10:29:13

Thread: CAD for a Chromebook
15/06/2020 12:06:21

Pete, did you replace the Chromebook's firmware (as in MrChromebox) and use GalliumOS, or did you keep ChromeOS? If you didn't junk ChromeOS, why not? When I did the Mr Chromebox firmware re-write, I wondered whether I was wise to lose ChromeOS, although it seemed a useless OS to me. If you have a good reason to keep it, I'd be interested to know.

Thread: Interpreting these bearing blue patterns
15/06/2020 11:57:29

choochoo_baloo, I've PMed you.

Thread: Brush motor repair
15/06/2020 06:19:10

We had an Henry when in UK, but left it there in 2005, fearing that it would not be possible to clean it well enough to satisfy bio-security checks at the border, when we moved our stuff here (NZ). He was much missed. IIRC, Henry cost us 90 quid. I saw one a few years later, in the local branch of a national chain of DIY stores; price $600, which translates to about 300 quid at today's rate. Possibly only(!) 250 quid then. How is such a rip-off possible? They're still available here, but I don't know the current inflated price. A few SEBO models are available here, at about twice the UK price, but at least they are the full-power jobs, not EU limp-wristed versions. I'll investigate importing a pattern motor for the Dyson. I expect freight will cost more than the motor, but it'll still be cheaper than Kiwi prices...

14/06/2020 11:29:07

Well, this thread has had 774 views, so someone might still be interested to know what happened...

Micro-surgery delivered the two ends of the broken armature winding into a position where they could be slipped into a small-diameter ferrule, with a third wire added, to make contact with the commutator. The wires were bent over as they exited the ferrule and cropped. The ferrule was crimped, the joint was soldered - for electrical integrity - and epoxy was dribbled around and heat-cured, to ensure electrical insulation and in the hope that no movement would take place. The third wire was connected to the commutator, crimped and soldered. That took a couple of patient hours, and a lot of impatient expletives.

Going around the commutator, measuring the resistance at between diametrically-opposed commutator bars showed consistent resistance, except for one position. It turned out to be a loose commutator-winding connection, so it was re-crimped and soldered. Opposite and adjacent resistances all consistent, and no continuity to the armature's body. Yippee!

So the motor was reassembled, correcting some distortion of the flimsy frame caused by use of a bearing puller. Apply mains (with a soft-starter in circuit - because I could). Motor ran up to speed without drama, but when at full speed, the impressive 'ring of fire' around the commutator was present, as before. Bad words. I assume something in the winding moves under centrifugal force, either breaking a widing or shorting to 'earth', or there's an earth leakage I didn't find at low-voltage testing.

New motor required. Pity...

Edited By Kiwi Bloke on 14/06/2020 11:29:54

Thread: Interpreting these bearing blue patterns
14/06/2020 10:57:12

I don't think that you can interpret these blue 'prints' because of two problems. Firstly, the 'blobby' appearance of the blue suggests that the bearing surfaces are contaminated - probably with oil. Get the journals and shells clean and dry, before applying blue. The blue film on the spindle looks thin enough. It should transfer to the high spots on the bearing shells almost as if it's dry - certainly without blobs or signs of flowing. Secondly, 3 thou is a lot of movement. This means that the spindle can rattle around when trying to get a print of the blue, so you are unlikely to get meaningful results. I suggest you start by taking out a shim (or two), so the bearing clearance is as small as possible, whilst allowing the spindle to be turned.

If the spindle surfaces are truly round (let's assume they are, to minimise complication at this stage), and the spindle's journals have been evenly blued, you should turn the spindle only about 1/8 turn, otherwise there will be more smearing than necessary, making interpretation difficult.

When you can get a repeatable blue print, you can start trying to make sense of it. No-one said it's quick...

Answer to questions 4 & 5 is 'yes'. I think we can be sure of this, even at this stage.

Shim removal will certainly be required, because you're going to scrape this, aren't you? - if only to find out how it's done, and 3 thou vertical play is excessive, even before scraping. Get a shim out, then start to fettle the bearings.

Edited By Kiwi Bloke on 14/06/2020 11:03:01

Thread: Copper tube bending
09/06/2020 06:45:16

Just a thought. If the pipe is really clean inside, you'll probably get some lead effectively soldering itself to the inside of the pipe. I don't suppose that matters, unless you are going to want to silver-solder lead-contaminated parts of the pipe at a later stage.

Thread: tom senior
09/06/2020 06:39:19

Here's a link to the Denford Forum. Loads of interesting stuff, including manuals and drawings for Tom Senior machines. **LINK**

I'll leave you to find your way to the Tom Senior stuff - finding it will likely involve numerous interesting distractions...

Thread: Keeping Nozzles Clean
08/06/2020 11:19:38

Is it just me, or have others started to read Neil's posting and wondered whether they were accidentally on a medical forum?

Time for me to go to bed, I think...

Thread: Plastic and Paper Models
05/06/2020 08:25:20

Beautiful work!

Sad to see that Wingnut Wings is closing.

Thread: Covid19 - Overseas Subscriptions
04/06/2020 22:40:50

Thanks Neil; email coming. I can't even begin to imagine the difficulties you and the rest of the crew must be facing, trying to keep the ship afloat. Difficult times...

Thread: How can I seal this oil sight glass?
04/06/2020 22:32:56

I think you'll find that the brass piece is externally threaded, and screws into the CI body of the gearbox. The 'slots' are there for a driver ( best made, with a pilot to fit the bore ). The chromed ring probably therefore screws onto an extension of the threads, trapping the glass between the two. Be careful when attacking the chromed part - it's likely to be brass, so easily marred.

Hylomar is a good sealant, if subsequent disassembly is required, but pretty much any low-strength oil-resisting sealant will do here. Loctite 567 Hydraulic Sealant (assuming the number is current) is a great sealant for drain plugs and any union which relies on the threads for sealing. It sets, but is easy to undo. I wouldn't use it on the chromed ring, however - that needs to be easily undone.

Thread: Covid19 - Overseas Subscriptions
04/06/2020 11:41:26

Can we have an update please?

What is the solution for us overseas subscribers who want complete runs of the paper magazines so that we can get them professionally bound? Nothing received here in NZ (where international post seems to be received OK) for ages. Will there be stocks of the missing back issues available from MTM?

Thread: Brush motor repair
03/06/2020 10:56:44

Andrew - thanks, I hadn't heard of SEBO. A quick search reveals the model selling for about 310 GBP in John Lewis is magically NZ$1200 - about 600GBP - here. We get ripped off like this all the time. That's why repair becomes 'do or die'. I guess, for similar reasons, the local recycling (joke in NZ) centre doesn't have skips containing any Dysons - otherwise it's a good idea Chris. Luckily, it's not all gloom in NZ. We have only one active (known) case of Covid-19. Unfortunately, the economy is now wrecked, and the national debt is ridiculous. The government is throwing money around, all over the place, with no apparent idea of what it's supposed to do. Guess who will pay.

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