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Member postings for MW

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

Thread: Crap vee blocks and "Oxford Precision"?
26/06/2017 10:50:12

I honestly believe the bad vee block video and they should never have said that it would be ground on all surfaces to within 0.001".

The roughness of the surface isn't an absolute indication if something has been ground or not, it may only point to how coarse the grit used to grind it was.

Also, how can he be sure that the pin he is resting on it is also as accurate? Is he not imposing an undue amount of leverage and tilting up one side of the pin using the indicator? 

His indicator holder should have a heavy base as well like steel or iron, in order to provide the most stability, rather than float around like a jelly on springs. 

Michael W

Edited By Michael-w on 26/06/2017 10:58:16

Thread: Harold Hall's Advanced Grinding Rest
26/06/2017 09:39:58

To have put his own time and effort into making his website with most of his projects on it, which is virtually free to use, really shows his dedication to this hobby.

Michael W

Edited By Michael-w on 26/06/2017 09:40:24

Thread: Workshop Ventilation.
25/06/2017 12:27:49
Posted by mechman48 on 25/06/2017 12:13:57:

My converted garage/workshop is insulated with Celotex in studding panels on the walls behind OSB, the roof space has space blanket loft insulation, there are Celotex panels glued to the insulated roll panel main door, the entry door also has a Celotex panel glued to it so it is pretty well insulated.

George.

I know the very ones, I think I have a few pieces in the loft but I know they've got stacks of them at wickes, I got my earlier dimensions wrong, it's 5x4x1.8m in size, so for the roof, i'll probably need around 20m in total, taking a little off for the purlin gaps inbetween.

Michael W

Edited By Michael-w on 25/06/2017 12:28:37

25/06/2017 12:15:26

Yes it appears I have already talked about this, so I must get myself checked out for early onset dementia. Sorry for that blunder, but it's worth asking twice because I think I've already got some more concrete ideas and suggestions than I had the first time round.

A reversible fan doesn't look like a good prospect so that'll go firmly in the dump.

The type of roof tiles I use are black armourglass ones, and they're quite expensive so I think I'll keep those for now.

Roof insulation sounds like a great idea but trying to get that approved will be something else, if I could quietly do it I would but it's a big area to do and I don't think i'll be able to sneak that many foam panels and planks without someone taking notice.

Would I need some kind of special outdoor vent if I had one facing the outside to draw air in? I take it would need to be better protected from the elements and bugs?

Michael W

 

Edited By Michael-w on 25/06/2017 12:16:26

Thread: What Did You Do Today (2017)
24/06/2017 21:15:27
Posted by martin perman on 23/06/2017 19:39:36:

I then went to Hitchin to get a tow bar fitted to my recently purchased Subaru Forester, I've always fitted all my tow bars but wasn't keen about taking the complete rear end off of the car.

Martin P

I think I might know which place it is, on the indust. estate. Could've stopped by! cheeky

Michael W

Thread: Workshop Ventilation.
24/06/2017 19:11:16
Posted by Mark P. on 24/06/2017 19:07:59:
As my workshop is my garage I open the front doors,the side door and the window thereby creating a through draft.
Mark P.

One of the biggest downsides I have is the lack of a through draft, all my windows are at the front, and my original idea was to put another one at the back,(I even have two spare windows!!!crying 2) but I got that idea thoroughly rejected for security reasons. So this fan business is the only shot I've got going at the moment!

Michael W

Edited By Michael-w on 24/06/2017 19:12:46

24/06/2017 19:09:11
Posted by Andrew Holdaway on 24/06/2017 19:07:11:

Michael, Reversing a fan motor will give you some air movement, but nowhere near as much as when it is spinning in the correct direction. You will have to change the impeller over as well.

Far better to turn the whole fan around if possible.

Andy

Yeah I just realized that and when picturing the impellor moving in my mind, saw that it wouldn't get much air through, so I'll scrap that idea.

and mounting on the front of the building looks like a possibility, perhaps with an extra guard over the top of it to stop a build up of flies? 

Michael W

Edited By Michael-w on 24/06/2017 19:13:40

24/06/2017 18:54:00

Hi,

As we all know it's a scorching summer and we brits don't take readily to too much heat.

So my workshop is a 5mx5m Building, double glazed windows, 50cm thick walls and 19mm thick roof, with tar shingle tiles. I was thinking, "is it hot in here or is it just me?" so I wanted to establish whether it really was just me. So I put a cheap thermometer on the wall after a morning of perusing the local D.I.Y store. And I regularly get temperatures of 35C on a sunny afternoon. I recon the outside is more like 27C.

So something clearly is going on here. The question mark is over how it's fixed, and in order to fix we have to spend pennies, and we want to make sure we get it right, so that we don't have a "2 steps forward, 1 step back" scenario on our hands.

So I started looking at how proper ventilation with a wall fan, rather than a cheap small static 2x2" hole with guards on both sides of the walls which i'm almost certain isn't good enough.

So I probably went overkill when I started to begin with, looking at fans from machine-mart which topped £200, I'm not questioning their top notch quality and airflow rate but it's probably intended for more like a factory scenario rather than a medium sized outbuilding and I'm a little unsettled by the price tag cheeky​.

So I found these £35 ones on ebay, to which I could probably fit a louvre type, wall grille to the exterior, with a bug net attached of course.

Fan:

**LINK**

Outer Wall grille:

**LINK**

Reversing Switch:

**LINK** perhaps there is some way I could perminently reverse the polarity of the motor myself?

So the theory goes, I attach one to the back wall to draw air out, and one at the front to draw air in, now it would have to change the direction of spin in order to do this, so I would need some way of changing it, i'm quite open minded about how that can be done.

simply turning it around and mounting it the other way around, would look pretty odd but I suppose it's doable and removes the associated risk of tricky electrical installation.

So would this help enormously or have I just created some "hot air" idea? wink

The only other thing I can think of doing would be adding a layer of foam roof insulation and sandwiched between the original planks and some new ones. This would slow the time it takes for it to heat up.

But I haven't had this idea approved by the powers that be and might take some convincing, insulating the walls now is out of the question i'm afraid, I should've done it on construction and now my space is totally filled up and removing it all would be too much bother.

Thank you for listening, I expect with most of us using an outer space for this we have a lot of experience to hear on here!

Michael W

Thread: Bevel gears on ebay
24/06/2017 12:48:40

This might make it a bit easier for people to respond...

**LINK**

Michael W

Thread: Which Chuck?
23/06/2017 11:35:55
Posted by Lee Goulding on 22/06/2017 12:32:03:

ok thanks for that any reason above the other you would choose that

Price point is very good, especially for vertex given their gear isn't really cheap, normally you can expect a high price. More or less always over £100 for a set of parallels or vise or chuck etc..

My chuck is a standard HBM 5" 3 jaw, maybe sometimes it's just a case of the "lucky Winchester" (99% are useless and 1% are fantastic). But mine regularly holds a decently round bar to 0.02-0.03mm at chuck point, or 5mm out or so.

I would consider Vertex to hold a better name than HBM, mainly because they normally give you anything you buy with an inspection certificate. (hand written as well, which slightly helps in the unlikely case of a refund required, because it means someone at least had to pass their eyes over it.) 

I would also say I speak from experience with vertex whereas I've never used pratt/Bernard or a TOS device, although I have seen TOS chucks on much bigger lathes.

Michael W

Edited By Michael-w on 23/06/2017 11:45:10

22/06/2017 12:12:50

Vertex one would probably suit my purposes.

Michael W

Thread: "Vintage" CNC
18/06/2017 08:47:00

If you want to get really old school look at the cam operated auto-lathes, nothing but an electric motor turning a central shaft, the rest is mechanics, amazing really.

start at about 0:40 if you want to see the tools working. 

Michael W

Edited By Michael-w on 18/06/2017 08:51:22

Thread: Lunokhod
17/06/2017 20:36:31

PLA is a lot stronger than I thought it would be.

Michael W

Thread: Brown-out Protector project.
13/06/2017 10:09:16

Well, I'm glad to see that this has generated some discussion at least, which is what this is all about.

Michael W

13/06/2017 09:39:13
Posted by Clive India on 13/06/2017 09:12:33:
Posted by Michael-w on 10/06/2017 12:42:35:

Hi,

This came up in a recent EPE magazine, a brownout protector for induction motors..

.....

I occasionally notice lights flickering in my house, but I presume this is due to an intermittent drop rather than a full-on brownout so to speak. Which I have no memory of ever occurring.

Michael W

Yes, I think it's a waste of time - a project without a need. But then, sitting with your bum on a little truck behind a tiny steam locomotive looks like that to some people?

I would agree, the likelihood of it happening in my circumstances is pretty slim, unless there's a huge shift in energy demand.

I will probably make it as a project out of sheer interest and maybe put it to the test, but i'm not going to rig up my equipment to it. An electrical reactor would be more useful in the case of a V.F.D maybe, and result in slightly smoother control.

Michael W

13/06/2017 09:33:53
Posted by Martin Kyte on 13/06/2017 08:44:30:

So a new zero input voltage to a motor results in a near infinite current?

Sounds like a very strange version of ohms law?

regards Martin

I think you're missing the point, the voltage isn't near zero, it's just less than what the motor needs to run It doesn't happen to all motors, just that induction motors will draw to compensate under load. This is from the wiki on brownouts..

"Commutated electric motors, such as universal motors, will run at reduced speed or reduced torque. Depending on the motor design, no harm may occur. However, under load, the motor may draw more current due to the reduced back-EMF developed at the lower armature speed. Unless the motor has ample cooling capacity, it may eventually overheat and burn out.

An induction motor will draw more current to compensate for the decreased voltage, which may lead to overheating and burnout. If a substantial part of a grid's load is electric motors, reducing voltage may not actually reduce load and can result in damage to customers' equipment."

if you still don't believe neither me, nor that, then the E.P.E article or a quick google of brownout + motor, is the reason why i'm saying this, if that can't change your mind then you're beyond help. Simply put theres a lot of literature from experts and unfortunate motor owners in remote areas who support this view. 

Edited By Michael-w on 13/06/2017 09:35:38

Thread: Model Engineers Workshop Lost The Plot
12/06/2017 14:18:20
Posted by clivel on 11/06/2017 01:01:37:
 

Besides which even the expensive £15 an issue peer reviewed professional journals sometimes get it wrong. viz. the 1997 article in the prestigious medical journal "The Lancet" which erroneously linked MMR vaccinations to autism and single handedly triggered a major reoccurrence of some not too insignificant childhood diseases.

 

Clive

And the almost slavish anti-vaccination cult it would create, or at least lend a lot of credit to. Add to that autism having a lot of fluff around how it is diagnosed anyway(in all but the most severe cases at least), would almost be as valid as saying that taking cough medicine predisposes you to an interest in classical music.

Michael W

Edited By Michael-w on 12/06/2017 14:21:24

Thread: Model Engineer awarded Queen's Birthday honour
12/06/2017 13:55:02
Posted by SillyOldDuffer on 12/06/2017 12:06:13:
Posted by Hopper on 12/06/2017 11:16:24:

...

Oh, well, what do you expect in a country that still does not have a national standard gauge railway with various states still sticking largely to their individual colonial gauges?

They obviously have fond memories of the mother country:

Lol, well obviously not bad enough to refuse an award from them though.

Michael W

Thread: Model Engineers Workshop Lost The Plot
11/06/2017 07:29:12
Posted by XD 351 on 11/06/2017 07:02:00:

that MEW is a magazine that is edited by a fellow model engineer not a professional editorial team .

Ian .

Or a very good reminder that were all human, who would grudge somebody this when we all make mistakes and a pretty harmless one at that?

Michael W

Thread: Brown-out Protector project.
10/06/2017 22:10:13
Low voltage does damage motors which is caused by an increased draw in amperage. See this "The amount of power the motor draws has a rough correlation to the voltage 2current (amps). Thus, when voltage gets low, the current must increase to provide the same amount of power. An increase in current is a danger to the motor only if that current exceeds the motor's nameplate current rating. When amps go above the nameplate rating, heat begins to build up in the motor. Without a timely correction, this heat will damage the motor. The more heat and the longer the exposure to it, the more damage to the motor.

Edited By Michael-w on 10/06/2017 22:12:08

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