Member postings for John McNamara

A DTI mounted on the right height mag base wins by a mile for me. after eyeballing the rings for a rough setting.
The whole process should only take a minute or two to get it within a thou. less than that can be a fiddle maybe a bit more.

I keep one on the lathe at the ready.

In Australia Ajax powder is easy to get.

**LINK**

In the UK "Mumsnet" Well I never!
**LINK**

Anyway there will be something sort of powder in the supermarket for aluminium pots apart from Scotchbrite,
Scotchbright should have a warning label, "Use it on glass at your peril" I know,...... an apprentice used it to clean some brand new laminated glass windows on a job one day. They all had to be replaced every one was badly scratched.
Not a good day at all. cost a fortune. You wont find it in our house.

Regards
John

Hot soapy water is always a good start it removes oil, grease, dirt and loose rust. Used on one part at a time, Followed by a kitchen sponge and bare hands applying Ajax household cleaning powder to the corroded parts, (No Scotch bright pads they contain carborundum powder, very scratchy). Its up to you to avoid rounding edges. the sponge or the hands will not provide a solid backing for the powder making it a gentle process.

After a couple of minutes check the progress by drying the part and inspecting it. if its heavily rusted then stronger methods will have to be used but often this process is enough. You may have to repeat it several times. as you work on the harder spots.

Once completed rinse in hot water then thorough drying with a cloth, do not leave any water on the part or you will get rust spots. Paper towels work well then oil the part to stop new rust forming.

It works for me.

Regards
John

Yes! it is an Engineering instrument.

"Optical tooling" is a special branch of metrology

**LINK**

Hilger and Watts is one of the best makers.

Regards
John

Hi

I have clutch reverse on my lathe and use it when threading in Metric to reverse the carriage, the imperial thread dial indicator does not work with metric.

If I was setting up another lathe I would look into a VFD to provide the reversing function, they can be set to speed up or slow down over a specific time, you can also set the maximum reverse speed. Less likely to undo a screwed chuck. if you gently ramp the speed up.

And variable speed for general work as well. you will still have to change belts for high torque loads in particular but a lot less often.

change

Regards
John

It appears we have the full gambit of opinion regarding Bitcoins.
I am in the "Negative" cohort
Think I will mosey down to the workshop and make some nice metal chips.

Over the years there have been many so called hot investment Ideas. Some have been very successful. Others have fallen by the wayside to languish in oblivion. Yes with the benefit if hindsight we can muse over fish that got away. A pointless exercise in my view.

On the other hand we can be proactive and manage our affairs in such a way that our investments are more likely to survive in a downturn overall and that the cost of individual failures is ameliorated. This is why I posted a link in my previous post to an internationally cited and applauded paper on diversification as a means of reducing portfolio risk.

A properly considered trading plan takes a fair amount of time and research, there are numerous books on the subject they all start off with making up a list of available resources and goals.

In the past people like Peter Lynch suggested that a portfolio should be divided into maybe 8 - 10 parts.
**LINK**

His work was done when markets were conducted by calling prices across a room. Now that markets are conducted electronically transactions are almost made instantly. New research indicates that Diversification needs to be much greater, maybe 50 or more holdings, see the paper I posted previously or google portfolio diversification. The cost of buying and selling is now a fraction of what it used to be making it possible to make small purchases.

Beginners tend to concentrate on individual investment ideas, and ignore the attached risk of capital loss for doing so if the price drops. even doubling up in a falling market. One must remember it is impossible to pick the top or the bottom of a market. Another golden rule, "the trend is your friend" until it fails!

Experienced investors look for a more balanced approach they spread their risk and diversify over many asset classes. They have a plan and they stick to it.

All the above is just my personal view, I have been Investing in the stock market since the mid 70's.

Regards
John

Edited By John McNamara on 06/11/2017 03:57:48

Edited By John McNamara on 06/11/2017 03:58:51

Is "Investing" sic, in Bitcoins a wise place to place your hard earned savings?

Well that is a matter of opinion and no doubt many have made a handsome profit. Will the trend continue forever! The current Bitcoin chart is trending up into hyperbolic, the price is being driven by herd mentality, sooner or later there will be a pull back, and it can be a hard one, a 50% retracement is quite common.

Have a look at the gold price history chart link below, notice the hard and prolonged pullbacks.

**LINK**

Gold is another good example of how markets are driven by animal spirits a phrase used by John Maynard Keynes and later Professor Robert Shiller at Yale University to describe how markets behave.

**LINK**

Is Bitcoin any different from any other market? I would argue no, but that is just a personal view, in the end every individual investor has to decide what sort of risk is acceptable to them.

As far as bitcoin is concerned I will pass. I don't like the chart.
And more importantly I do not understand it, and this is another personal golden rule, never invest in something you do not fully understand.

If you must invest in Bitcoin what percentage of your assets will you be prepared to risk?
For those that may be interested the following paper from the Tasmanian School of Economics may be of interest, It discusses diversification as a means of reducing the impact of drawdown (When an individual investment fails)

**LINK**

Another golden rule...... Diversify

Regards
John

Tall trees don't grow forever.

Hi James

We live in interesting times, If you have not visited the following sites you may find them very informative, I selected these sites in no particular order, because they all are skilled metal machinists. You will need to browse through the videos to find milling specific topics covered, There are many others, but these are a good start.

Books are great for learning the technical details of machining, video on the other hand is an ideal medium for learning the hands on skills needed.

**LINK**

**LINK**

**LINK**

**LINK**

Regards
John

Criticism is water off a ducks back to me, My real concern is that the top end of town in particular and the media in general are at best disinterested in the applied engineering art, unless it has some sensational twist that can be made use of in their agendas. 3D printing is a good example, and the suggestion that those terrible plastic guns will get into the hands of miscreants or terrorists who of course have a lot more sense and by nefarious means find it much easier and far cheaper to locate the real metal equivalents that actually work. But most of the time its just the China bashing story that prevails, the end result is little risk capital is available for Engineering.

Regards
J

Edited By John McNamara on 27/10/2017 08:03:27

If only the media would notice us engineering related souls at all in a positive way. All we hear is doom, gloom and the China syndrome.

Given the length of screw travel I wonder if the larger one is a small chain breaker.

Hi Collin

I was thinking along the lines of a plastic tube probably double walled that had a series of electromagnets wound within it. If they were energized in order starting at the bottom, would small particles of material be propelled along the tube?

After I posted this question I did a little research: In the past I have seen a number of videos of DIY versions of so called rail guns, these however usually use sliding contacts and rather large capacitor banks to store enough energy to propel a projectile. Some appear to be quite dangerous. This is certainly not my intention here, I only want to move material at safe speeds.

I then stumbled upon what are called coilguns, these do not use sliding contacts they are more like a stack of solenoids see the link below.

**LINK**

From that link the following paragraph on non ferromagnetic projectiles

"Some designs have non-ferromagnetic projectiles, of materials such as aluminum or copper, with the armature of the projectile acting as an electromagnet with internal current induced by pulses of the acceleration coils." They are inducing eddy currents in the material.

So maybe there is a way to move non ferrous material slowly.

To be absolutely clear I have no interest and will not participate in any conversation about moving anything but swarf, waste or any other low speed material moving use.

I wonder if this is already done in industry?

Regards
J

Looks like part of an old insulated terminal to me

I prefer MDF or hardboard coated with a couple of thick coats of one pack semi gloss clear urethane. By thick I mean poured on then brushed smooth using as much as the surface can carry without running off.

It works really well in three days it is very hard and durable.

Edited By John McNamara on 25/10/2017 04:45:13

Repulsion or attraction does it matter? the main thing there a force, the question is how can we use that force to move the swarf particles?

Picking up non ferrous swarf, can it be done with eddy currents?

I have been thinking on the question posed by Norman Valentine

"Can you make a special one for me, I turn a lot of aluminium and it would be really useful."

I remembered I had seen a video of scrap metal being separated using this quite commonly used industrial process.

The following link points to various examples.

**LINK**

A good DIY example
**LINK**

OK so how do we make a hand tool that that uses the principle?

Some sort of moving magnetic field.
Or moving fields? maybe using electromagnets that pass the swarf along a tube? with a sort of peristaltic action. I guess it would be limited to nicely chip broken swarf not the annoying birds nests Aluminium in particular sometimes produces when turned.

I know this is a way out concept! A perfect test of the diverse skills that are available on this forum.

Any thoughts?

Regards
John

Tool owners ghosts.

Recently I purchased a box of about 50 rusty toolmakers callipers and dividers in an estate auction, while brown with fine rust they were made from good quality steel, I thought that with a little care they could be brought back from the neglect they had suffered.

So i set to cleaning and polishing them. One by one they were washed the rust rubbed back and polished. The steel was indeed of good quality and they started to gleam.

After I had done a few, names and initials started to appear. Apart the manufacturers names there were the names and initials of previous owners, sometimes scratched on sometimes carefully engraved or punched. While not the first time I have thought on names found on tools this box with so many names moved me to think on what was being revealed on the bench. The tools themselves were of various ages some late 20th century a few maybe early twentieth century one probably 1850's there sitting on the bench were tools that represented well over 100 years of Engineering progress, and there for all to see were the names still not forgotten as long as the tools are passed on to the next generation as these tools had been.

These are not the only named tools in my workshop there are many others. now that I have been awakened to thinking on this there every time I see a name on the tools I use daily I wonder what its owner was like.

Then there are also special tools highly prized, like the first Micrometer I bought as a lad paying a good part of my wage for it. The tools I used in my teens a few of which I still have. Or the Dial indicator given to me by my late uncle in law, a fine Engineer, I use it daily. Each tool has a character of its own some work better than others for a specific job. They become old friends always ready to help solve a specific problem.

I will not keep most of the 50 tools in the box, now they have been brought back to life I can pass them on to good homes. their spirits have to continue.

Regards
John

Yep a 40 taper spindle is the way to go, the tooling is cheap enough from Asia new, there is also a steady supply available second hand, there are several variations see this link **LINK**

Or this thread
**LINK**

Older tooling will probably have a 5/8" imperial thread newer tooling may be metric, so you will need two draw bars I am trying to focus on metric tooling In case I ever find a cheap CNC mill that I can refurbish..

My current mill is a Shizuoka VHRG **LINK** When I got it it was black with grime it had been neglected. The is a fair amount of wear so I have to coax it to get reasonable accuracy from it. Where it shines is in the amount of metal I can remove without it complaining or vibrating, this is where heavy old machines win easily against lighter imports. both the vertical and horizontal spindles are 40 taper.

Regards
John

Edited By John McNamara on 22/10/2017 06:00:10