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Member postings for Michael Gilligan

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

Thread: spiral spindle cutter
21/06/2018 05:45:29
Posted by john constable on 20/06/2018 23:06:52:

I'm having trouble posting a jpeg. The little paste window is popping up but it still wont let me paste....

.

Sit quietly with your beverage of choice, and read this: **LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=103028&p=1

MichaelG.

Thread: The Workshop Progress thread 2018
20/06/2018 23:06:25
Posted by mechman48 on 20/06/2018 22:19:24:

... Would I be right in guessing that the second photo is more accurate ?

Correct MichaelG

.

Thanks for the confirmation ... I like that one.

Two-tone might indeed look good.

MichaelG.

Thread: PID Controller - MEW 269 - wrong connector
20/06/2018 22:53:50
Posted by Neil Wyatt on 20/06/2018 19:28:21:

[ ... ]

Which is then point I have been making - the thermocouple wires only need to be consistent materials until they reach the 'cold junction' temperature and in the case of a furnace controller which is unlikely to use an ice bath the interposition of an XLR connector in unlikely to make any meaningful difference.

Sorry to labour the point, but to me it is very clear.

.

Thanks for replying, Neil

I am now happy that the problem is as I suspected : We were having two different conversations!

The real objection to the XLR connector and its lead is as I [hopefully] clarified in my post of 09:45:02 yesterday. ... It inevitably moves the cold junction to a point which is not monitored/normalised by the instrument.

MichaelG.

Thread: The Workshop Progress thread 2018
20/06/2018 17:54:30

Very difficult to choose, when the same 'original colour' looks so different in the two photos.

... Would I be right in guessing that the second photo is more accurate ?

MichaelG.

Thread: PID Controller - MEW 269 - wrong connector
20/06/2018 17:05:29

Apologies if people are bored with this discussion:

This thread has just dropped off the first page, so I'm bumping it in the hope that Neil will see it again, and respond.

[ I simply don't understand your point, Neil; and that leaves me uncomfortable ]

MichaelG.

Thread: Speed Controller
20/06/2018 16:21:36

For the sake of undoing two screws, it might be worth releasing the circuit board and checking what's written on the chip ... These things are always easier when we've found a datasheet.

MichaelG.

Thread: Variable transformer
20/06/2018 15:51:38
Posted by Paul White 3 on 20/06/2018 15:41:13:

... the only additional info I can give is the wire gauge of the winding, this is 23SWG ( to the best of my measurement ).

.

Possibly good for 0.75A ... so I would see how much it warms at 0.5A

**LINK**

https://en.m.wikibooks.org/wiki/Engineering_Tables/Standard_Wire_Gauge

MichaelG.

Thread: spiral spindle cutter
20/06/2018 15:12:55

To be honest, John ... I think the best bet would be to build a scaled-up copy of the Pen Wizard [probably with something other than the simple mandrel].

There is a lot of information on their website !!

... and nothing wrong in making one for your own use.

MichaelG.

Thread: Casting from 3D printing and other wichcraft stuff young folk do...
20/06/2018 15:07:28
Posted by Ady1 on 20/06/2018 14:47:18:

Is there a website?

.

Not that I can find ... but see if you can do any better;

the message came from Dr Hermes Haulage

MichaelG

Thread: Variable transformer
20/06/2018 14:10:02

A browse through currently available offerings might be a good start: **LINK**

https://uk.rs-online.com/web/c/power-supplies-transformers/transformers/variacs/?sra=p

Find something of similar weight and it will probably have a similar rating.

After that ... run some load tests and see when it starts to get warm.

MichaelG.

.

Edit: Here is a Torovolt on ebay, for comparison

https://www.ebay.ie/itm/Variable-Transformer-240V-0-6A-Cressall-Torovolt-33Y-Variac-Unused-/192484445526

and a link to Cressall's web-site: https://www.cressall.com/about-us/

Edited By Michael Gilligan on 20/06/2018 14:20:37

Thread: Casting from 3D printing and other wichcraft stuff young folk do...
20/06/2018 14:00:17
Posted by Michael Gilligan on 20/06/2018 13:25:55:

Thanks, David ... I have just sent an eMail to Sam

MichaelG.

.

... and have received a preliminary response !

MichaelG.

20/06/2018 13:25:55

Thanks, David ... I have just sent an eMail to Sam

MichaelG.

Thread: spiral spindle cutter
20/06/2018 12:11:18

I've just spotted an interesting-looking upgrade to the RouterLathe: **LINK**

http://www.notjustround.com/Tools.html

MichaelG.

20/06/2018 11:29:38
Posted by Hopper on 20/06/2018 10:29:24:

That looks like it would suit the OP's needs better than jury-rigging a model engineer's lathe. Does it have a brand name?

.

Yes ... probably several, but the one most of us mentioned was the Trend RouterLathe.

[see p1 of this thread]

MichaelG.

Edited By Michael Gilligan on 20/06/2018 11:30:10

Thread: Cataract lathe by Hardinge Bros
19/06/2018 18:50:14

Sorry, I can't help Keith

But I'm bumping this thread to stop it dropping off the bottom of the page.

They do look delightful machines: **LINK**

http://www.lathes.co.uk/cataract/

Some photos of what you have would be interesting.

MichaelG.

.

Before you ask how to post images:

https://www.model-engineer.co.uk/forums/postings.asp?th=103028&p=1

Edited By Michael Gilligan on 19/06/2018 18:52:23

Thread: PID Controller - MEW 269 - wrong connector
19/06/2018 09:45:02

As we are now well into p3 and still struggling ... I would just like to re-state the issue:

  • The Schematic Fig.2 [not Fig.1] shows the Thermocouple correctly connected to terminals 9 & 10 of the PID Controller.
  • The controller will treat those terminals as the reference junction[s], and will presumably have a local correction device to normalise it to a 'cold junction'. .... Please see the Wikipedia page for a picture of how this is done on a Fluke meter.
  • Chris Gabel has, for convenience, added an extension lead of 'thin gauge stranded wire' and an XLR connector, which moves the actual cold reference junction 'outside' his ABS box.
  • The temperature at the controller's 'cold junction' correction point is therefore not tied to that of the actual cold junction.
  • If the extension lead had simply been made of thermocouple extension wire and a matched plug and socket, this invitation to error would not exist.

MichaelG.

.

https://en.wikipedia.org/wiki/Thermocouple#/media/File:Cold_Junction_Compensation_with_Thermistor_to_measure_the_junction_temperature..jpg

Edited By Michael Gilligan on 19/06/2018 09:47:53

19/06/2018 08:45:52
Posted by Neil Wyatt on 19/06/2018 08:21:30:

Indeed, it proves my point exactly.

Neil

.

Then could you please explain your point [either here or privately], because we appear to be having different conversations.

MichaelG.

.

Edit: I am particularly keen to understand why you made this obvious but irrelevant statement:

"If you connect the two wires at both ends, you won't have any voltage to measure..."

Edited By Michael Gilligan on 19/06/2018 09:08:17

18/06/2018 22:46:39
Posted by DrDave on 18/06/2018 22:39:15:

... The Wikipedia entry on thermocouples (or that referenced byMichael Gillian on p1) gives a good overview.

Ducks and awaits incoming criticism!

.

We are, I'm sure, in agreement !!

MichaelG.

Edited By Michael Gilligan on 18/06/2018 23:00:55

18/06/2018 22:41:17
Posted by Neil Wyatt on 18/06/2018 22:17:55:

Actually the 'cold junction' is almost a myth.

usually it's drawn as the inner part of the special connector.

If you connect the two wires at both ends, you won't have any voltage to measure...

.

dont know Perhaps this is a more helpful diagram:

**LINK**

http://enacademic.com/pictures/enwiki/84/Thermocouple_circuit.svg

MichaelG.

Thread: spiral spindle cutter
18/06/2018 21:33:03

John,

I've just been browsing around, and found this page: **LINK**

https://stusshed.com/tag/beall/

The first couple of pictures are another [perhaps the original?] routerlathe-style device ... but then it gets more interesting: Maybe sufficient to get your inventive streak going.

MichaelG.

.

Edit: Here is Beall's website: 

http://www.bealltool.com/products/penwizard/penwiz.php

Where you will find detailed instructions and some excellent photographs angel

Edited By Michael Gilligan on 18/06/2018 21:41:20

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