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Member postings for SillyOldDuffer

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

Thread: Milling - Turning Axis Wheels the Wrong Way
15/02/2016 18:24:43

I'm building the Jan Ridders Coffee Pot Stirling at the moment. Although my self-taught skills have improved considerably I am still in the bottom 10% of the class when it comes to finish, and I'm trying to improve.

I generally manage to put holes in the right place, turn to wanted diameters, and mill to the correct depth, more or less. The things I make usually work but the finish is poor. (This is not false modesty!)

One of my mistakes is that when starting a cut, or changing direction, I have a strong tendency to turn milling table axis controls the wrong way. This drives the cutter into metal that has to be left untouched if the object is to look good. Quite small errors can spoil an otherwise acceptable bit of work.

wheel.jpg

This picture is a close-up of the flywheel. You can see that I have crashed no less than three times into this particular spoke. It is very annoying because the other 5 are quite good, at least by my standards!

I feel like a learner driver having trouble with parallel parking again. My confusion is something to do with reversals of right-left and forward-backward movements, and ditto with my rotary table. (I usually get up-down right thank goodness!)

Is there a trick to this like "lefty loosey, righty tighty" or is it just practice, practice, practice? All hints and advice gratefully received.

Thanks,

Dave

 

Edited By SillyOldDuffer on 15/02/2016 18:26:01

Thread: Dial Indicators
13/02/2016 22:29:57
Posted by Ajohnw on 13/02/2016 19:19:13:

Shall as I understand it came into wide spread use in the world of software first and spread from there. -

I'm no expert but I always thought that the 'shall' wording was just standard commercial contract speak used to express requirements, though like John my experience is software related too.

I used to be in a team that wrote Requirements for hardware, software and services. The form was to specify essential requirements in the form "The widget shall be pink." This would be issued to industry who would reply with a compliance statement like "The widget will be pink". If the price was agreeable a contract would eventually be issued in the form "The widget must be pink." and this would be legally binding.

The purpose of this rigmarole was to allow clarity and agreement to be negotiated before finally committing to contract. The specification of a large IT system can contain thousands of individual requirements and it pays to get good agreement between customer and provider up front especially where sub-contractors are involved too.

Words become seriously important when a contract is in dispute. I once spent over two hours arguing with a supplier's lawyers about the contractual meaning of the word "all" and lost the common sense argument because poor wording in another part of the contract accidentally contradicted the usual meaning of "all".

My feeling is that chaps using machines to make real things have much more fun in their work than us poor s*ds in offices!

13/02/2016 18:18:55

One of my books contains this advice about Dial Indicators. "When using a dial indicator on a surface plate for accurate measurement of gauges and fixtures, it is quite a good plan to tap the table or plate with a hide or rubber mallet when the indicator is set and just before taking the reading. However good an indicator is being used, there is always the possibility of a certain amount of "stiction" (a modern colloquialism) in the movement, and the vibration thus set up tends to make conditions more or less uniform for each reading"

So there you have it: the cure for a sticky dial indicator is to hit it with a hammer.

By the way Sulfer has been the correct UK spelling since 1992. Please don't shoot the messenger!

12/02/2016 19:23:00
Posted by Neil Wyatt on 12/02/2016 07:22:16:

Measurement accuracy

closeness of agreement between a measured
quantity value and a true quantity value of a
measurand

Measurement precision

closeness of agreement between indications or
measured quantity values obtained by replicate
measurements on the same or similar objects
under specified conditions 2.15

Isn't that exactly what I said?

Neil

Perhaps I do understand it after all then!

It just goes to show how careful you have to be about the written word. English may be a great language but it's all too easy to trip over shades of meaning especially when words have both lay and specialist meanings. Like Energy, Force, Work, and Power for example.

You'll have to forgive me. I come from a profession where "Entity" as in "Entity Relationship Diagram" can be defined as being a "thingy"...

Regards,

Dave

11/02/2016 21:44:47
Posted by Anna 1 on 11/02/2016 20:28:37:

Hi,all.

At the risk of opening a can of worms, May I respectfully suggest that Neils analogy to

archery is not quite correct., ( and it is many years since studying metrology)

According to Collins dictionary the words Accurate and precise are interchangable.

If you hit the gold you are both accurate and precise and presumably within the tolerance you have set

If you have a cluster outside the gold you are both consistantly inaccurate and consistantly imprecise

and need to make an adjustment

If you are all over the place outside the gold with your sizing you have got a problem. And perhaps have a problem

with the machine or tool

Kind regards

Anna

 

 

Oh no, just when I thought I'd understood it!

Although Collins dictionary could be dismissed as non-technical it's harder to ignore JCGM 200:2008 which is the International Vocabulary of Metrology. I think this supports Anna rather than Neil.

It defines:

Measurement accuracy

closeness of agreement between a measured
quantity value and a true quantity value of a
measurand

NOTE 1 The concept ‘measurement accuracy’ is not a
quantity and is not given a numerical quantity value. A
measurement is said to be more accurate when it offers a
smaller measurement error.
NOTE 2 The term “measurement accuracy” should not
be used for measurement trueness and the term
measurement precision should not be used for ‘meas-
urement accuracy’, which, however, is related to both
these concepts.
NOTE 3 ‘Measurement accuracy’ is sometimes under-
stood as closeness of agreement between measured
quantity values that are being attributed to the measurand.

and

Measurement precision

closeness of agreement between indications or
measured quantity values obtained by replicate
measurements on the same or similar objects
under specified conditions 2.15

NOTE 1 Measurement precision is usually expressed
numerically by measures of imprecision, such as standard
deviation, variance, or coefficient of variation under the
specified conditions of measurement.

This history and practice of metrology is a fascinating Anna : I'm amazed Neil hasn't asked you for an article (yet)!

Regards,

Dave

 

Edited By SillyOldDuffer on 11/02/2016 21:45:30

Thread: Home workshop org gone?
10/02/2016 21:37:55
Posted by here again on 07/02/2016 08:25:44:
I keep getting' problems with certificate'
As far as I can see its because some org or other doesnt approve of AVG , maybe because itsfree? Dont know whether to use or not

AVG won't cause certificate problems. It's OK to use it.

If only one site is causing certificate errors then the fault is at their end. Don't trust the site until they fix the problem.

If you are getting certificate errors from many different websites then a common cause is that your computer's internal clock is wrong, probably because the BIOS battery is dying. Although the clock should be automatically corrected by an internet time server there will be a period during which strange and confusing things happen.  The clock goes wrong again when the machine is switched off.

Regards,

Dave

Edited By SillyOldDuffer on 10/02/2016 21:39:35

Thread: Use of domestic room as a workshop
09/02/2016 20:47:29

My sister found swarf in her lasagne at a do I was hosting. Now the whole family carefully inspect everything cooked by me.

I have a garage workshop separated from the kitchen by a utility room. Swarf gets out despite mats and regular sweeping. You can make domestic mess even worse with bad luck or stupidity. The black dust caused by me cutting through a hard block of cast iron with an angle grinder went all through the house.

My bedroom workshop is excellent for clean lightweight hobbies but they aren't as much fun as metal mangling!

Thread: Small easy project
09/02/2016 20:06:51

Very nice! I wonder how many people will be inspired to make their own?

Thread: Daft question (maybe)
09/02/2016 18:28:10

Well, these people seem to have some good stuff...

Seriously though, modern machine tools have largely displaced the type of lathe most useful to hobbyists. We have good reason to be grateful to anyone prepared to cater for our needs. And of course many of us have benefited from the ready availability of classic tools made redundant in Schools, Colleges and Industry by progress in mainstream manufacturing. Buyer beware though, some of these classic tools are lemons!

My feeling is that "China bashing" simply discourages and confuses newcomers to the hobby. By all means buy second hand If you know what you're doing, but please don't put new friends off by rubbishing the alternative. Comparing a high-end industrial machine picked up in good condition for a fraction of its original cost with a tool designed to be affordable in the hobby market is hardly fair.

Far Eastern lathes and mills may not be the best possible but they are certainly "value for money". Whether they are also "Fit for Purpose" depends on what you want one for.

My own experience with Chinese tools has been positive - they've been nowhere near as bad as I was led to expect by the critics. All of them worked out of the box, all of them benefited from some fettling, and all of them have shortcomings. But I've learned a lot by using them and have had no reason to regret my purchases.

Enjoy!

Dave

Thread: Small easy project
07/02/2016 21:08:57

Thanks Lars_G and Hollowpoint. Much to my surprise given the Japanese origin I think Hollowpoint has nailed it!

Wikipedia says that the British bought 150,000 Arisaka rifles in 1914 and used them mostly for training. "The 6.5×50mm round was subsequently produced in Britain by the Kynoch company and was officially adopted for British service as the .256-inch (6.5 mm) caliber Mk II in 1917."

I think this example of Trench Art probably came from a Training Camp. I now doubt it was made in the front-line as I'd previously believed.

The item works well as a pen-knife and although easy to make must have been a desirable novelty. I wonder if the Swedish examples were manufactured by Mora and how many other nationalities have produced them?

Regards,

Dave

07/02/2016 12:41:08

img_5035.jpgOn the subject of trench art can anyone identify the cartridge this penknife is made from? It was given to my grandmother by her brother who was killed in France in 1918. I expected it to be a British .303 but the dimensions are all wrong. Nor is it the standard German calibre. A friend who knows a bit about guns thought it might be Italian except that their bullets were rounded rather than sharp tipped. And I can't think where my relative would have got hold of Italian ammunition during WW1.

img_5033.jpgimg_5034.jpg

Dimensions are approximate!

trenchart.jpg

Thanks in anticipation,

Dave

Thread: Taper turning. (offset attachment)
06/02/2016 19:41:52
Posted by Russell Eberhardt on 05/02/2016 16:19:17:

I don't know what is so difficult about resetting the tailstock. I just adjust mine so that a razor blade held between the centre points sits at right angles to the bed.

Russell.

Hi Russell,

Much depends on the lathe I think. It was easy enough to get the razor blade right on my old mini-lathe until the adjusters were tightened to fix the setting. At the last moment the tail-stock would describe a small figure of eight around the headstock axis. Getting it spot on could be quite a fiddle!

As to cause, the innards of my tail-stock were a bit rough from new and I suspect more expensive lathes might develop similar symptoms if damaged or worn.

Dave

Thread: Bending steel
06/02/2016 18:56:29

Closer inspection reveals that the wire globe is made from two hemispheres bolted together. I'm entirely ignorant about such work, but couldn't you rough out a half-sphere template from stacked discs of wood and bend the wire around nails banged strategically into it?

You can buy old-style filament bulbs in the UK for decorative purposes. I can't remember where I saw some on sale recently but it may have been B&Q or Maplins. But they're on the web too, LINK .

Regards,

Dave

Thread: Anyone know more about these modules?
06/02/2016 18:22:34

As they are so cheap it might be worth buying one in the hope that the underlying chip is marked and its datasheet can be looked up.

The functions available through the interface may be more comprehensive than you expect. For example, this TI chip uses an IC2 serial interface to adjust lots of parameters so that the charger can be optimised for particular batteries.

Please let us know how you get on. It looks like an interesting module.

Cheers,

Dave

Thread: Checking runout
05/02/2016 19:43:37
Posted by Roderick Jenkins on 04/02/2016 21:27:49:

Hence the inverted commas. Irony (see what I did there?) doesn't seem to work very well over the intenetsad

I believe he gets one brief mention in Genesis but Ray Winstone managed to make a meal out of him in the film Noah. Mackay managed to construct a whole poem around him **LINK**

Rod

Mea Culpa Rod. It seems that it's not only our American friends who don't get irony!

I think the Mackay of the poem must also be the author of one of my favourite books - "Extraordinary Popular Delusions and the Madness of Crowds". I like the works of the "real" Tubal Cain too.

Cheers,

Dave

Thread: Small easy project
04/02/2016 20:34:52

It's clearly a Model Engineer's notion of the perfect wedding ring. I claim my prize please!

Thread: Checking runout
04/02/2016 20:28:44
Posted by Roderick Jenkins on 03/02/2016 11:48:08:
Posted by Brian Hutchings on 03/02/2016 10:21:11:

I never realised that Tubal Cain was American!

He's an imposter surprise. The "real" Tubal Cain, the well respected writer for ME (and EIM, dare I mention it?) was Tom Walshaw, a Brit.

Rod

Sorry to be a pedant but Tubal Cain is in the Bible: he's the first metalworker.

Thread: Miniature tools
29/01/2016 19:29:31

Very nice! Pics like this make it obvious that I need more practice though. Perhaps a lot more...

Congratulations on the bronze,

Dave

Thread: Old PC Linux
29/01/2016 19:12:29
Posted by Russell Eberhardt on 29/01/2016 09:17:53:
Posted by SillyOldDuffer on 28/01/2016 20:40:45:Here's a fuller comparison between Ubuntu and Mint.

I think you'll fiind that comparison is a bit out of date now.

Russell.

Hi Russell,

I'm sure you're right as it's a couple of years old. It was the most recent comparison I could find on the web (using duckduckgo). Are you able to provide a link to a more modern one?

Ta,

Dave

28/01/2016 20:40:45
Posted by clivel on 27/01/2016 21:47:22:

Being based on Ubuntu, Mint offers all the advantages of Ubuntu, but as "An Other" mentioned has a much friendlier use interface, one that will immediately be familiar to anyone who has used Windows XP.

With respect, the statement that Mint has a "much friendlier user interface" than Ubuntu is more a matter of opinion than of fact. The Unity desktop is certainly different, but it works well and has advantages. Here's a fuller comparison between Ubuntu and Mint.

Although I happen to prefer Ubuntu and Unity I wouldn't knock Mint. Mint is definitely good news if you like things to be familiar.

Cheers,

Dave

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