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Member postings for Brian Oldford

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

Thread: traction engine pump
14/06/2019 16:40:15

Leaky balls perhaps.

I mean leaky ball valves of course. laugh

Thread: Thomas from Hornby
13/06/2019 16:48:19

? and another.

Thread: BR Std 9F
10/06/2019 20:40:01

You may find one of the drawings in the xxSL/SW 1093 range may provide the details.

Thread: Noise Cameras
10/06/2019 09:36:08

In the case of those motorcyclists/motorists with after-market exhausts, wouldn't they simply temporarily refit the original exhaust for the MOT?

Thread: Need to drill a hole digital caliper
07/06/2019 13:41:18
Posted by SillyOldDuffer on 07/06/2019 13:39:35:

. . . . . . . .

Some stainless steels machine well, they're not all evil.

Dave

The swarf usually is!

Thread: Tyrosemiophilia
07/06/2019 13:39:40

I collect money.

The problem is I'm not very good at it.

Thread: Model aircraft pilots angry over drone laws
06/06/2019 14:00:27
Posted by Haggerleases on 06/06/2019 13:24:59:

It's one of the reasons I'm starting out in model engineering. Sold all my model aircraft stuff in a funk of annoyance and decided to plough my money into a lathe, a drilling machine and so on. Surely to God they can't legislate against that!

I wouldn't be surprises if the Whitehall Mandarins try.

Thread: Plug and Socket
06/06/2019 13:56:53

Why not a GX16 type plug and socket. Often used for microphones and ham and CB transceivers.

Thread: Myford Super 7 Bed for Power Cross Feed
06/06/2019 13:53:28

IIRC the cut-out in the bed is larger to accommodate the bevel gear that rides in the keyway. Myford may have rationalised the beds of the later PCF and non-PCF machines.

Thread: Connecting a pair of motor controllers.
05/06/2019 19:14:54
Posted by Ron Laden on 05/06/2019 11:19:14:

Thanks guys,

It would be good if the two controllers could be connected to a single potentiometer but whilst not knowing the controller circuitry I can appreciate the advice of using a dual pot to keep things seperate and safe.

Ian, yes the controllers come wired with a combined pot/switch.

Ron

Edited By Ron Laden on 05/06/2019 11:30:18

I would have thought by now you would have reverse engineered the PCB and published a full schematic by now so we could opine further. frown

Thread: Oh bugger, I told you I was ill
05/06/2019 19:08:39

Get well soon. Wentworth needs guys with your skill-sets.

Thread: mark 1 1/2 student with an inverter
05/06/2019 19:06:44

Why on earth would you want not to take advantage of the infinitely variable speed that a VFD provides when wired in the usual manner?

Thread: Connecting a pair of motor controllers.
04/06/2019 10:35:10

Now I've looked at those budget controllers I concur with SOD. Without getting them on the bench and having a poke around at the circuitry to find out exactly how the pots are connected into the gubbins it might be better to stick to two pots on a common shaft.

As these controllers are PWM devices I'm sure it could be done in the way I suggested with an Arduino but it would take a little R&D to avoid letting out any of the blue smoke.

03/06/2019 21:25:31
Posted by Ron Laden on 03/06/2019 18:48:44:

I just wonder how matched the two sides of a dual gang potentiometer are, percentage wise would they be within 5% of each other when connected to the controllers or better/worse..? I am assuming that two identical controllers would be quite close output wise but if the dual pot adjusting them is well out of balance that could be an issue.

I can live with a motor speed difference from the two controllers of around 5% possibly a bit more but not too much more.

If you need better "balance" you might consider using a couple of PWM ports on an Arduino. With care I would think you should be able to get sub 1% balance.and a whole heap more functionality should you need it.

Thread: Antikythera mechanism
03/06/2019 21:20:23
Posted by Neil Wyatt on 03/06/2019 20:54:16:

ME is one of the oldest hobby magazines on the planet, but it isn't quite that old!

N.

Although some of the contributors may be. smiley

Thread: Connecting a pair of motor controllers.
03/06/2019 09:09:26
Posted by Ron Laden on 03/06/2019 08:58:26:

Hi Stuart, yes the original pot has a switch so as you suggest the 2 wires must be the switch. I assume you can get dual gang pots which are switched..?

Ron

If you need seperate switches and can only find a pot with a single switch you could slave a two pole relay off the switch.

Thread: Just for the Record
01/06/2019 16:58:28
Posted by Colin Heseltine on 01/06/2019 09:55:38:

That chuck looks like the same one as Cowells supplied for the ME90 lathe. I have one on my Cowells lathe.

Colin

Just one step above the lever scroll 3 jaw that my kit built Flexispeed Meteor II had about 50 years ago.

Thread: Electronic Indexers - How Is Cumulative Error Avoided?
01/06/2019 09:11:30
Posted by Bazyle on 30/05/2019 18:10:34:

In practice the problem has quite a low boundary. You are only ever going to cut gears up to 200 (plus whatever the JW large wheel skeleton uses) so the number of variables is quite small. For each of those 200 you need a maximum of 200 entries, average 100, in a table telling you how many steps to take. So the memory requirement is only 200x100 off 16bit numbers. You can do the calculations in excel and blow them into an eprom (except nobody does that anymore) have a few switches on the high address lines to select the tooth count and a couple of counters take the values and do the steps. No processors needed !

Whilst seemingly a very elegant solution for its simplicity , For "awkward" divisions won't that encounter the problem of cumulative error mentioned upthread?

Thread: Colchester Lathe Factory
31/05/2019 12:06:07
Posted by DC31k on 31/05/2019 07:06:11:

Would it have been kerosene? He says 'spirit carrier', so much more likely alcohol-based. Paraffin ignited in that manner would be rather smoky.

What interests me is all the gold-coloured machines they use to make the lathes. Did they paint them up specially for the film or was every machine in the factory that colour?

The material in the spirit carrier would have been what's known in some foundries as plumbago.

It leaves a coating of graphite on the mould cavity which helps bind the surface of the sand mould and impart an improved finish to the casting. It acts as a binder to the sand and significantly reduces any erosion to the sand as the iron is flowing into the mould cavity.

Thread: Piston Ring slot
30/05/2019 21:25:54

Is the tool flexing?

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