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Member postings for John Haine

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

Thread: Sewage dumping
24/10/2021 16:26:22

IIRC, the proposed amendment resulted from a petition. People power? Next you'll be claiming we live in a democracy...

Thread: Selection of AC transformer for Align Power Feed
23/10/2021 11:43:28

Power factor.

23/10/2021 09:37:26

110V x 1A = 110 VA, 150VA should be plenty.

Thread: Advice from the photographers.
22/10/2021 19:31:01

Considering the hassle and potential difficulty you might consider just applying money to the problem and sending the slides off to a company that does this.





Thread: Lathe query.
22/10/2021 13:01:51
Posted by Rod Renshaw on 21/10/2021 17:37:48:

Welcome Paul

All good advice above, but if you should be unfamiliar with working with it, please be aware that 415v will kill the unwary.

240v sometimes gives you a second chance but 415v is not forgiving

Apologies if you know all this.


Quite true. But the most likely scenario is that one touches a live conductor while another part of you is earthed. Nominally mains neutral is at earth potential and relative to neutral "live" is 230V. But relative to neutral each line of a "415V" 3-phase supply is ALSO at 230V. The 3 phase is 415V phase-phase voltage. So touching one of the phase wires from a safety point of view is no more dangerous (which isn't to say that it's safe!). If you connect yourself phase to phase of course it would be a different matter.

Whatever, whether 1-phase or 3-phase, mains electricity is dangerous and should be treated with respect!

Thread: warco 220
22/10/2021 09:02:43

As I said, based on experience, take t/s off lathe and lathe off stand, 2 people can move reasonably easily.

21/10/2021 13:58:18

When I sold mine I unbolted it from its bench (wood), removed the tailstock, then the buyer and I managed to get it into the back of his estate car. I sold the bench with it.

Thread: Spacing of buttons for making involute cutters
21/10/2021 11:54:11

Indeed, but quick calcs using Mike Cox's formulas says that for a 20 tooth 20* PA gear the mod would be 1.7542mm. You can choose 3 of button diameter, PA, teeth or mod, but not all at once alas.

Thread: From where I might be able to source some 1300 micron (1.3mm) mild steel sheet?
21/10/2021 11:41:39
Posted by not done it yet on 21/10/2021 10:45:50:
Posted by John Haine on 21/10/2021 09:48:17:

If you look at the earlier part of the thread the magnetic properties are pretty irrelevant as long as it is magnetic enough to work as some sort of latch. And lamination iron even at 50 Hz is well under 1mm thick.

Edited By John Haine on 21/10/2021 09:49:25

I would expect laminations to be thin to reduce eddy currents within the assembly?

Again, if you look back, he's using a neodymium magnet so there are no eddy currents except transient when the latch closes or opens.

21/10/2021 09:48:17

If you look at the earlier part of the thread the magnetic properties are pretty irrelevant as long as it is magnetic enough to work as some sort of latch.  And lamination iron even at 50 Hz is well under 1mm thick.

Edited By John Haine on 21/10/2021 09:49:25

Thread: Spacing of buttons for making involute cutters
21/10/2021 08:51:14

Actually this raises an interesting point. Since all the gears in a clock famously rotate only one way, it shouldn't be necessary to machine a symmetrical profile on each tooth. The other side could for example just be a buttress to give reasonable tooth strength. Then you need to assemble the gears the right way round to make sure the teeth mesh on their "right" sides.

21/10/2021 07:24:38

Because you only have to get one feed right.

Thread: Britan Lathe - New Lathe Day
20/10/2021 17:36:17

That now seems to be a retail park!

Thread: Spacing of buttons for making involute cutters
20/10/2021 10:00:14

A good find that, DC. I have tried a somewhat similar approach where one selects a starting point as given by "Mike's Workshop" method (which essentially matches the curvature of the involute at the pitch point), then perturbs the centre and radius of the circle by a small amount and evaluates the maximum error. If this is less than the last time, preserve the values and perturb again. Continue like this, possibly reducing the perturbation each time, until the error is less than a preset limit or no better solution can be found after a set number of iterations.

Edited By John Haine on 20/10/2021 10:04:54

Thread: From where I might be able to source some 1300 micron (1.3mm) mild steel sheet?
19/10/2021 21:22:12
Posted by John Smith 47 on 19/10/2021 21:16:50:

...Though in this modern age, why the heck manufacturers continue to make it so darned complicated is totally beyond me. Also those tolerances are jaw-droppingly imprecise. For 18 gauge steel sheet it appears to be +/- over 8%! You have to wonder how the heck does anybody in manufacturing industry manages fabricate any useful products out of that mess! Bonkers.

It's called "engineering" John. Designing within the constraints of materials and components that can be sourced at an appropriate price.

19/10/2021 19:46:49

Why does it have to be 1.3mm? Part of the art of design is to use easily available standard components and materials as far as possible.

Thread: Reproduction ivory look hand grips
18/10/2021 09:33:23
Posted by Simon Johnson 2 on 14/10/2021 16:23:50:

I'm intrigued by the potato in vinigar method, any more information on it anyone?

I think it's not vinegar but glacial acetic acid which is much nastier stuff. Other sources suggest soaking in sulphuric acid then boiling in the same, but someone who tried it said he just ended up with a sour soft boiled spud. Glacial acetic would make sense as it extracts water and also turns cellulose into cellulose acetate ("celluloid". Also could be done with nitric but that is cellulose nitrate which is highly inflammable. As always, Google is your friend.

Thread: Super 7 questions
16/10/2021 17:56:59

Regarding the link belts question, the original S7 uses I think "A" section but the big bore "Z" section which are actually smaller in width. Important to get the right ones, A section link belts on Z section pulleys slip. There are also link belts with links moulded from flexible plastic without reinforcement - I bought one of those from RDG and it was quite unsuitable, stretched like anything and slipped badly. Finished up with a Gates red belt made of some sort of fibre sections bought from RS.

Thread: Load reactors for VFDs
16/10/2021 14:33:44

I think that the motor is more likely to generate spikes itself rather than the VFD. I think that spikes will occur because of leakage inductance in the motor windings, which might overstress the VFD semis or the motor insulation, or both. Adding series inductance would surely make spikes worse as in effect it's adding leakage inductance? It might be possible to mitigate spikes with some small shunt capacitors (suppressions caps) provided you get them with a high working voltage. Before trying this do you have a 'scope to see if there are any spikes in the first place?

Thread: Reproduction ivory look hand grips
14/10/2021 13:27:19

Apparently you can pickle a peeled potato in glacial acetic acid to make a substitute. I've never tried it though.

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