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Member postings for Mick B1

Here is a list of all the postings Mick B1 has made in our forums. Click on a thread name to jump to the thread.

Thread: Its nearly there !
25/03/2019 15:42:02
Posted by SillyOldDuffer on 25/03/2019 09:44:30:
Posted by Mick B1 on 24/03/2019 22:16:46:
Posted by Bazyle on 24/03/2019 15:51:34:

...

For those misusing their Dehursts and getting away with it because they are old fashioned solidly built - the next owner will suffer from your lack of consideration.

There was no lack of consideration, because I'd never heard any of the tales current here of the Dewhurst being unfit for this purpose, and in any case the lathe had been in use with that switch probably since the late '70s. It ran from 2000 to 2015 in my workshop with no evidence of fault in the switch. It sounded to me as if a contactor operated when the switch did, so perhaps it wasn't handling full mains voltage, but I had no reason to investigate.

Yes, but it's worth knowing that Dewhurst Switches fitted to Myford's have long been a source of trouble. I believe the main problem is they aren't designed to switch hot loads and the resulting sparks damage the contacts. I've also seen suggestions that the mechanical design isn't as good as it might be. Can anyone more knowledgeable comment?

Dave

All the same, I'm finding it hard to fit a mechanism that functioned in regular use with no maintnenance for 35+ years without fault into my definition of 'defective'.

24/03/2019 22:16:46
Posted by Bazyle on 24/03/2019 15:51:34:

...

For those misusing their Dehursts and getting away with it because they are old fashioned solidly built - the next owner will suffer from your lack of consideration.

There was no lack of consideration, because I'd never heard any of the tales current here of the Dewhurst being unfit for this purpose, and in any case the lathe had been in use with that switch probably since the late '70s. It ran from 2000 to 2015 in my workshop with no evidence of fault in the switch. It sounded to me as if a contactor operated when the switch did, so perhaps it wasn't handling full mains voltage, but I had no reason to investigate.

Thread: Completed models - just out of interest
24/03/2019 12:18:59

I hope that mine will become venerated family Holy Relics when I croak.

Like my Uncle Geoff's sandcast bronze Boulton Paul Defiant ashtray, if only I could remember where it is, or whether it's me who last had it ...

Thread: Vickers Bl 8 inch Howitzer cannon of 1917
23/03/2019 16:59:28

Outstanding. laugh

Thread: Why do we do it?
23/03/2019 06:28:57
Posted by Roger Williams 2 on 22/03/2019 18:51:27:

Silly old duffer , +1

And another. Makes me wonder how many interesting threads I've missed because the first subject didn't twang my tines...

Thread: Soba rotary table
22/03/2019 16:59:41
Posted by Ron Laden on 12/03/2019 20:00:25:

I have heard the term "rivet counters" is there such a thing as "micron chasers"..devil

I once went on a bodging course to make a Windsor chair on a pole lathe, from wood that started as a pile of fresh logs. We split, drawknifed and turned the legs, stretchers and sticks. We used spanners as the gauges for the location spigots on the turned parts.

One of the guys on the course had worked at a university lab, and he snorted at the crudeness of this: "Huh, I've worked to microns!"

Quick as a flash the instructor came back: "Yeah, and I've worked with morons!"

Bin lookin' fer a chance to use that ... laugh

Thread: Parting off tool - straight or angled.
21/03/2019 09:14:37

I've used one of these RDG blade holder for I don't know how long. It works on steel, titanium, brass, delrin or whatever I'm parting up nearly 2" diameter. I wore one out over the years and replaced it last year.

It's not always ideal, and very occasionally I've broken the blade. The only thing I can think of that's defeated it was some 2.4" OD x 1.75" ID EN8 suspension bushes I was doing for the railway - the stuff was so resistant in hollow tubes, and I couldn't stand the shrieking, ringing chatter that was making my hearing aid go into feedback loops.

Zero top rake is again not ideal for anything except CZ121 and suchlike, but for most materials - as long as you keep the tool well into the work - it cuts accurately and cleanly.

One problem I have had is the the last couple of blades I've bought have had side rake on the top surface, which deflects the cut and produces a concave surface on the cutoff face of the workpiece. Just touching the top with the bench grinder to take off that rake seems to have resolved that.

I've use blade-type partoff tools with carbide inserts and they're better in some ways, but relatively expensive and give you another item to maintain stocks of. The HSS blades are of course regrindable and leave you more self-sufficient. I don't wanna be sitting there stroking me chin and trying to decide which of a range of tools to be using for parting-off.

Thread: I want one!
19/03/2019 15:48:50

Mouse has got to be eating something. Probably the bird food.

How big a mouse to tidy spanners?

Thread: Toolroom lathe?
19/03/2019 09:07:47

I'd say a toolroom machine is probably better defined by the capabilities of its user to extract performance from it than any branding or advertising.

Edited By Mick B1 on 19/03/2019 09:08:19

18/03/2019 11:30:55

A screwcutting gearbox is a seriously desirable feature if random threading work on diameters too big to use a die or tap is likely to arise.

I have a Warco WM250V which I very much like - but I do occasional volunteer machining for a steam railway and (more) occasionally amongst that a screwcutting requirement arises - and that means a lot of faffing time setting up a gear train and returning the lathe to standard afterwards, plus careful thought sequencing the ops to isolate the screwcutting so I don't have to use power feed whilst the thread's set up, because most thread pitches also give a completely unacceptable turning feed rate. So if you're often going to thread multiple sizes bigger than, say, 1/2" or so, I'd think such a gearbox is pretty much essential.

I know some lathes are described as 'toolroom', but as a turner on and off since 1975 I can't say I really know what that means. Maybe geared handwheels so as to be able easily to position tooltips accurately within tenths? Excellent concentricity from all chucks and collets, parallelism, mild and even wear on all slides and ways would also be important - an alleged 'toolroom' lathe that's been casually set up or harshly used might not deliver what it once said in the advertising.

I can certainly turn within a few tenths on diameter and a few thou on lengths on my Warco, and so far the vertical slide's met all my milling needs too. There are lots of folk who swear by Myford 7s, and I've seen those in a few toolrooms, too, alongside other 'ordinary' lathes that've clearly been well looked after. If you can get a long bed variant with a gearbox in good nick - and are confident enough to recognise what's what and what's not - and are prepared to afford it - maybe that's what you want.

Even after 40+ years engineering at varying levels of engagement, I think it's very difficult to know in advance what'll work best, even for myself, never mind anyone else! I still sometimes get surprised about what I can do, and what I can't.

Thread: Its nearly there !
17/03/2019 22:10:51

I see all the comments about Dewhurst switches - how did I get away with using mine to start and stop my Speed 10 many thousands of times over 15 years without a hint of a problem?

Thread: Why do both power hacksaws and bandsaws exist?
17/03/2019 17:34:54

At least some and maybe all of the power hacksaws I've seen had a hydraulic(?) mechanism to lift the blade on the backstroke so a not to drag it over the work.

The blades were always much wider and thicker than standard hand hacksaw blades. Once worn out, the all-hard-HSS type tended to be cut up, bound with tape and ground sharp as box cutters.

Thread: Cold Blue
17/03/2019 15:39:05

The best I found was G96 gun bluing paste. Wash everything in very hot detergent water and apply the paste whilst metal's still hot to the touch. Small paintbrush works quite well. Wash off thoroughly and oil up lightly. Wear rubber gloves throughout.

There's also KoldBlak. I found that worked, but less well, and more faffing.

 

Edited By Mick B1 on 17/03/2019 15:39:45

Thread: Its nearly there !
17/03/2019 15:25:54

What's up with my eyesight? I think it looks pretty good, and I can only see the faintest mismatch. laugh

Thing I'd wanna do it put in a leadscrew clutch and handwheel dial, like my old Speed 10 had. Good for milling in the vertical slide, and dialing off exact facing lengths, with halfnuts engaged and without disconnecting the geartrain.

Thread: Why do both power hacksaws and bandsaws exist?
17/03/2019 12:11:23

As a youngster, I laughed the first time I saw a power hacksaw. I'd seen and operated bandsaws before, and the power hacksaw looked just like a mechanised version of a human sawing arm, as old-fashioned as some piece of Victorian agricultural machinery.

Of course, then I knew little of cost/reliability/floorspace exchange curves, and I guess I'd quite like one now - except I haven't really the space even for that.

Looking at t'internet, it seems that circular cutoff saws are more-or-less superseding them.

Thread: Will we be able to see Asteroid 2019 EA2 when it passes earth on March 22nd.
17/03/2019 10:50:57

Thanks, Neil,

Don't think I'll be getting out my Celestron 6 then - not for that one, anyway.smiley

16/03/2019 19:18:02
Posted by Bandersnatch on 16/03/2019 17:31:53:

Martin, I would guess that what matters is angular speed relative to the observer ..... and If my ageing brain were up to it I could probably estimate it from the numbers you give. As it is, I think I'd need to leave that to someone else.

Edited By Bandersnatch on 16/03/2019 17:32:40

Hmmm.. looks like my 'blink and you'll miss it' is wide of the mark. Doing a rough angular velocity calc. it looks like it'll take about 133 sec. to travel 1 degree at that distance (which is a guess as halfway, isn't it?), so in binos with a 7 degree field, it'll cross it in about 15 1/2 minutes.

I read somewhen in my distant youth that the 200 inch Palomar scope could just about see St.Paul's if it was on the Moon. That's very roughly in the size range of this space rock, so unless an isolated rock in space is a lot more conspicuous (will it be in sunlight in a night sky?), it doesn't look as if the binos have much chance.

Neil knows about this stuff - whass 'e fink?

16/03/2019 17:29:33
Posted by martin perman on 16/03/2019 16:45:54:

I would assume it would need a serious telescope to see it, if it passed half way that will be 119,000 miles away from earth travelling at 25 kilometers a second, 90000 kilometers an hour\56250 miles an hour.

Martin P

That's about 625 times its own length every second.

Blink and you'll miss it, I should think.

Thread: Hardened Silver Steel Shattered - How to Avoid?
15/03/2019 09:22:32

I made this little cutter to slice out the radiused groove for the cascabel ring on my carronade. It was turned, then offhand ground. I used a butane blowlamp to heat the tooth tips bright red and quenched in the grinder's diptank. On the second attempt when I held the red heat for half-a-minute or so, it worked - the teeth resisted filing. Then I polished the end face and played the blowlamp on it carefully with pauses between quick heating passes until I saw the light straw oxide, then quenched again and finished the tooth surfaces with an India oilstone.

OK, so it only had <10 mm3 of EN1A to remove, but the teeth are still hard and the shank fileable. It's about 11mm. diameter, plain silver steel.

cascabelring2.jpg

Edited By Mick B1 on 15/03/2019 09:25:20

Thread: Capstan query
14/03/2019 12:56:33

The answer, as with many other questions about machinery, is that it depends on what ya wanna do.

If you're going to make your own fasteners for models, or you're making something that needs quantities of identical or similar parts that'll be tedious and time-consuming to make on a standard centre lathe, then you should keep it. Generally, capstans are so much better than centre lathes for repetition work, and the ones I've used were so straightforward to set up, that the quantity break for worthwhile employment of a capstan can sometimes be less than a dozen.

Of course you'll need some tooling that may cost - a couple of roller boxes, Coventry dieheads and reversing tapholders.

I remember seeing a You Tube of somebody's build of a W32 IC engine, and I felt a bit pale at the thought of all those pushrods, followers, rocker adjusters, gudgeon pins, bushes, yada yada yada ... A little capstan would be dandy if you were gonna take on summat like that.

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