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Member postings for duncan webster

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

Thread: gents unipolar slave clock
14/11/2018 20:46:20

Thanks Jon, I'll change it to 60ms.

Martin, I live close to Liverpool, and have stood next to their shortt free pendulum going 'how does that work then?' Next time I'm in L'pool I'll visit again. The new museum on the Albert Dock is not really worth a special trip, apart from a carriage from the Liverpool Overhead Railway and of course Lion from the L&M there is nothing of interest.

Thread: Do I need a hole in sintered bronze bearings
14/11/2018 19:13:55

Glacier DU is ptfe. Chap in our club has oilite axle bearings on his loco with feed holes through the shell. It has lasted for many years, although I agree this probably isn't that many hours. ML7 countershaft bearings were oilite I think, and they last for ever.

Thread: gents unipolar slave clock
14/11/2018 19:08:51

Anyone know how long the pulse should be for one of these? I've got it going with a 240mA pulse 50ms long every 30 sec. It will work on shorter, but it sort of feels better at 50ms. In reality I don't suppose it matters, but it would be nice to know. I've tried Google and got nowhere

Edited By duncan webster on 14/11/2018 19:09:41

Thread: Yorkshire Steam Wagon Drawings ???
13/11/2018 11:24:44

Try Leeds industrial museum

**LINK**

Thread: Thread cutting again
09/11/2018 21:44:51

Why not grind a tool from a bit of HSS. Make the plug first and use it as a gauge. I've done it loads of times so it can't be difficult.

Thread: Solution found to the World's biggest problem . . .
09/11/2018 21:30:49
Posted by Howard Lewis on 08/11/2018 21:44:42:

Not sure that HSE would approve of damaged/worn items being repaired or modified and repurposed.

Plus think of the effect on refuse tip employees!

But it would be kinder to the environment if we all did.

Howard

The HSE would have nothing to say provided that the operation was carried out safely and the finished product was safe to use, neither of which sounds unreasonable to me. The problem is not H&S or the HSE, it is (often highly paid)people who are not prepared to exercise their judgement and just want to stop the job.

Thread: Learning CAD with Alibre Atom3D
07/11/2018 23:38:35

Thanks, tied up with hospital visits for next couple of days, I'll get back to it at weekend

Edited By duncan webster on 07/11/2018 23:38:44

Thread: Fireworks Ban
07/11/2018 22:39:24

Having had a dog who was absolutely terrified of fireworks I'd be in favour of limiting sale to 2 weeks end October/early November. As it is around here every minor celebration seems to be the excuse for pyrotechnics.

Thread: Learning CAD with Alibre Atom3D
07/11/2018 22:21:44
Posted by duncan webster on 06/11/2018 19:37:13:

Apologies if this has already been answered, but I don't fancy trawling through all the posts. I realise that working on my laptop is not as handy as on the desktop where I have 2 screens, it means I can sit in the same room as SWMBO. If I download to laptop can I also download to desktop, or move it at some date in the future?

It really is time I got out of a 2D world.

So I've made a start by reading the instructions (what a weird idea, not like me at all). My laptop has Intel(R) HD Graphics 620 . According to the interweb this is DirectX 9 compatible, but is not a separate graphics card. Should I stick to the desktop?

Thread: Small Hex Fastenings
07/11/2018 15:42:27
Posted by JasonB on 06/11/2018 13:20:48:
Posted by duncan webster on 06/11/2018 12:39:32:

4mm A/F on M3 looks silly, I bought some and never used them. It it were a 5 BA bolt with a 6 BA head it would be 0.193 AF which is near enough 5mm. 5BA nut is 0.221" near enough the same as M3 which is 5.5mm

Suppose it depends on what you are modeling.

2" whit nut is 1.38D

Standard M3 nut is 1.83D

6BA hex on 126" 5 BA thread is 1.54D

5BA hex on 5BA thread is 1.75D

4mm hex on M3 is 1.33D

I know which one is closersmile p

Edited By JasonB on 06/11/2018 13:22:33

If prototype is pre WW2 the nuts will be to BS190, and 2" bsw would be 3.15" AF, which is 1.585D, 1.5" BSW is 2.4" A/F, 1.6D. Post war were to BS 1082, one size down. Even then 1.5" BSW would be 2.22" A/F, 1.48D

Thread: Learning CAD with Alibre Atom3D
06/11/2018 19:57:33

Thanks David, I'll get on with it in next few days

06/11/2018 19:37:13

Apologies if this has already been answered, but I don't fancy trawling through all the posts. I realise that working on my laptop is not as handy as on the desktop where I have 2 screens, it means I can sit in the same room as SWMBO. If I download to laptop can I also download to desktop, or move it at some date in the future?

It really is time I got out of a 2D world.

Thread: Small Hex Fastenings
06/11/2018 12:39:32

4mm A/F on M3 looks silly, I bought some and never used them. It it were a 5 BA bolt with a 6 BA head it would be 0.193 AF which is near enough 5mm. 5BA nut is 0.221" near enough the same as M3 which is 5.5mm

Thread: An alternative to parting-off
05/11/2018 10:18:36

Just had a look at the Aldi advert. It says 0.7 to 2.4 m/sec blade speed. This is 138 to 470 ft/min which seems a bit fast for cutting steel

Thread: MEW Stepper Power Cross Feed stops
03/11/2018 22:39:25

I used microswitches and relay for end of travel and stop switches on my mill table drive. Seemed better to rely on hardware for something that has got to work or it gets expensive. Arduino takes care of speed and ramps. Might not be applicable to your situation but send me a pm if interested

Thread: Spindle design
30/10/2018 18:07:09

Having had a quick look for belleville/wavy info I've realised just what a spindly bearing the OP is proposing, 6mm ID, 10mm OD, 3mm thick. He won't find a suitable spring I think. In fact for a 6mm shaft the hole in the spring needs to be say 8mm minimum, the only one I can find is 15.5 OD, 10.5 ID (EPL4 or 5) which means a 625 bearing perhaps, 5*16*5 or next step up 16.5OD, 11.5 ID and a 606ZZ.

This is all making it a lot bigger, so perhaps not feasible after all

For a unidirectional load the outer (stationary) member does not need to be a tight fit, but it won't do any harm as long as it's not too tight. The inner (rotating) does need to be tightish, so as I said before if you are adjusting via the inner you need to get it just right, too slack and you get movement between inner and shaft which causes it to get slacker over time, too tight and you can't adjust it. If you don't believe me read the manufacturer's bumph sheets.

30/10/2018 11:07:24

To amplify Kiwi Bloke's comments, you need a reasonable preload to resist forward loading, the actual spring rate doesn't matter. Disc springs are a good alternative, but I have the impression they are stiffer than wave washers, so you need to be more accurate in machining axial lengths. Again as someone says you can stack them up \/\/ which reduces the overall rate and gives wider tolerance

29/10/2018 20:15:12

sorry it's a bit rubbish, not a lot of time this week. The 6*10*3 is 6mm ID, 10mm OD, 3mm thick, not as you've drawn it. I've also drawn the front bearing wrong but that doesn't matter. The important bit is that you make the housing so that the front bearing takes the axial load as per your original sketch, the rear bearing is trapped hard up axially between the step on the spindle and the pulley/spacer arrangemnent. You arrange the lengths so that when the rear bearing is pulled up tight the wavy washer is preloaded by the right amount. Look in bearing manufacturer's guff about what the right amount is, it is usually more than you'd think. Or give them a ring, they are usually very helpful even if they realise you're only buying one. If the wavy washer overlaps the inner, add another spacer as bottom sketchwavy washer (small).jpg

Thread: Gargoyle Velocite oil.
29/10/2018 11:50:29

Gargoyle is now part oif Mobil, so any Mobil stockist should be able to sort it out

Thread: Myford Super 7 Tailstock Micrometer Dial
29/10/2018 09:26:17

It appears to be screwed in, on the parts list there is a reference to part # 11855, the S7 parts list refers to A2114 but they could be the same or very similar. No dobt I'll be able to improvise, or I could take the easy option of 300 divisions (thous) and a calculator!

Edited By duncan webster on 29/10/2018 09:26:42

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