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Member postings for Billy Mills

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

Thread: Stamp laser engraving or cnc cut?
24/01/2015 00:05:37


I would suggest that if this is for commercial use you go to an engraver who is very used to making exactly what you need, you will end up with crisp lettering from someone who is fully versed in the requirements to make stamps.

You might find someone with a cnc mill who can do the job, but engraving cutters are a little different and are usualy run at very high speed to produce smooth sided letters. Many signmakers offer engraving services.

A low power laser will not cut metal but they are in common use to make rubber stamps. Etching is fine for a foil but deeper etches undercut. Lasers will directly mark leather, I have engraved images and lettering into leather for many people, that's the delux option.



Thread: Workshop Lighting
27/08/2014 02:18:18

Should have said 10 bulbs at 100W which is the kind of consumption that a lot of houses - mine included- runs as a lighting load. That's at 14p per KW/Hr. So if you pay £10 per replacement bulb after changing 10 bulbs you break even at 1,000 Hours then save around £100 per 1000 Hours and don't have to replace bulbs. You do loose all that heat however..


27/08/2014 01:28:27

The thermal time constant of the bulb is dependent on filament thickness and on the operating voltage. When talking pictures with optical soundtracks were developed it was quickly found that low voltage heavy filaments produced far lower hum levels. The Stroboscopic effect is wildly misunderstood. A real stroboscope produces a very brief flash- around a microsecond. A slight ripple at 100 Hz from incandescent or florescent lights will not "freeze" rotating parts but will produce a slightly blurred image at sync rates.There is a very clear difference between a moving part and a stationary one. If your visual accuity is so low then you should not operate a machine tool.

Incandescent bulbs appear to be very simple basic devices but they are somewhat deceptive. The amount of light for the electrical power input is very low - around 2%, most of the rest being heat. Changing the voltage reduces the lifetime extremely quickly, reducing the voltage and they can last much longer than the nominal 1000 hour life. Depending on the bulb type a 1% increase can reduce bulb life by 10 to 16%. A Photoflood bulb is essentially an over voltaged bulb, it has a life of around 50 hours. Decreasing the voltage is a bit of a miser's folly, light output falls off and you spend a lot more on electricity that you save on bulbs.

If you take a 100W incandescent, over 1000 Hrs that's £140 of electricity. Although a LED replacement will cost more than a 100W incandescent it uses 20-25% of the power so say £30-35 of electricity for the same amount of light but very few replacements is a very good deal.

contrary to popular myth, LEDS do get dimmer with time, their lifetime is rated to 75% of their initial output in some standards. This depends -as you might expect- upon how hard the LED is driven. Most LEDS can be expected to reach their quoted lifetimes however it is somewhat of a scandal that many CFL's fail far short of their rated lifetimes although reliability has improved.

My workshop has it's old 5' flouro's with localized LEDS, when the LEDs can match a 58W tube then they will be swapped but at the moment the replacements seem to need a bit more work.



Edited By Billy Mills on 27/08/2014 01:31:39

Thread: Breaking Vacuum Cleaner news for Model Engineers...
23/08/2014 10:31:05

There are deliberate "features" in vacuum cleaners to limit the vacuum to reduce carpet destruction. One well known maker was sued a long time ago by an owner who had a very expensive carpet with rapidly developing bald patches. So air leaks and other devices are used to limit carpet damage. Dyson's biography also contains one other fearsome abuse that concerned him.

It is certainly true that vacuum cleaners and dust extractors are incredibly innefficient devices, It takes around a KW/hr of energy to move a few grams of dirt a few feet. That must rate as one of the least efficient process in the home. Clearly there is a great opportunity for the next step in cleaner design.

I would hope that the effects of the legislation are better than that over incandescent bulbs which had the effect of introducing more mercury in very fragile thin glass tubes into homes while the vastly better LED option was retarded by the rush into the very unsatisfactory CCF .


Thread: Vibration
13/08/2014 00:27:46

Because lead under the feet reduces the oscillation it could be a slight spindle imbalence is causing the stand to resonate. Touching various stand surfaces will show up any resonances. If it is the problem then damping pads _used in cars to stop panel resonance- will solve the issue when fitted to the right place, almost as good as a lump of wood on the back of the panel.

Lead under the feet would not alter a spindle resonance. Would have suspected the motor controller had it not been said that same effect happened with another drive. Anyway if the machine turns ok at other speeds and produces a good surface finish then it is not the spindle seriously out. Keys don't cause problems at your speeds!


Thread: Old Mill Problem (electrical) Help
19/07/2014 12:40:36

The failed resistor could be a series resistor to a bridge rectifier which would limit the switch on peak current. If one of the diodes has shorted or a contactor coil has gone low resistance then a series resistor could overheat and then go open. Compairing the contactor coil resistances would show a low resistance coil. The seperate diodes can also be checked with an ohmmeter.

Any half decent electronics engineer should be quickly able to sort out what has happened without a diagram once you can see the back of the board and look at all of the components closely. It is also possible that the resistor has died of old age and slight overdissipation over 40 years on our high mains voltage.


Thread: One Man and His Lathe
16/07/2014 12:48:14

Like the idea, but once Lathes have been covered can we have some more interesting machines? There is the metrology world, water and air cutting, press tooling, wire EDM, watchmaking and the optical world all of which have processes and methods that we can learn from and can take model engineering forwards,

If we have to stick to rotating machining then how about looking at the innards of modern machining systems- even a Britan has some very useful features ( such as the tool rest) which a lot of readers might find interesting.


Thread: Anti Corrosion for Electromechanical Things....
10/07/2014 21:54:41

It is helpful when using dessicators to include a colour change indicator in the bag to check the seal effectiveness. I don't see the issue with sealing up an Ampex, you use the appropriate bag or as Martin has said make one. As Muzzer has found out it is a waste of effort NOT to seal a bag with dessicator, hardly difficult to predict. A very effective bag seal can be made using 3M 467 transfer adhesive in 1" strips if you can't heat seal. But many shipping grade single and double sided tapes dry out and become useless within a few months.

VTR's are not quite the same as Machine Tools, you cannot spray oil or wax all over. Would suggest that the people at WWW. BATC.ORG.UK would be a very good souce of info if you are not already a member.


09/07/2014 14:11:36

If you have to...use a conformal coating -aerosol or dip- a product proven to be compatible with electronic components on the boards. If you have to dry out electronics use IPA but watch out for some capacitor types especially polystyrene, don't use a product intended for petrol engines. I would not apply anything to the mechanics at all other than the reccomended lubricants.

However VTR's should not be exposed to corrosive /dusty conditions if you want it to continue working, it begs the question WHY ?

If it is long term storage then silica gell desicators and a plastic container- even a bag- is better than nothing. If there is corrosion already then it is too late but dessication will minimise further corrosion.

WD40's formulation varies in different places and at different times, but it is simular to white spirit, light mineral oil and a perfume, that is what they declaired in the UK in a MDS some years back. So you cannot say with certainty that this liquid is long term safe on copper/tin/lead/aluminium/plastic but it will remove specialised lubricants from bearings that have very small amounts of lubricants.


Thread: Infra Red Tacho
05/07/2014 19:47:42

Nearly all inkjet blacks are dyes, they charge a lot more for pigments! . In the original article MEW115p53 the author said that in his experience that Aluminium, steel and cast iron don't seem to be particuarly reflective so he used Humbrol white paint and black paint 1.e. the inverse problem!. Most reflective sensors have a sharp peak in their output when the reflector distance is changed so a simple control is to vary the target/ sensor distance.

Because reflective sensors are exposed to ambient light they often have visible light filtering built in, they often work around 900nM where many dye blacks are light greys and the optical filter is "black" plastic. There are a lot better sensors than the now obsolete SYCR102 which has a very slow detector.

Worth trying changing the sensor distance in any reflective sensor application.


Thread: florida tools shops?
22/06/2014 02:41:53

Those US wood stores are places of Wonder to a wood starved Englishman. I Just hope that the Bugs get beaten soon. Not much wrong with Harbourfreight excepting that we don't have them in the UK. Like Machine Mart but much bigger range of everything and very low prices eg a set of 7 metric nut drivers for $7.00 and loads of tools that never make it over here. Your problem will be your weight allowance, SWMBO detection and trying not to say "I do not believe it" as you fill a trolley.


Thread: studs
22/06/2014 02:24:51


Yes "Procedures in Experimental Physics" is virtually identical. That was where I learned more that I was taught elsewhere....... There are some outstanding chapters, for ME's the last two chapters sum up a lot of basic machining and design technique. In many ways the contents are still very useful, although electronics has produced a lot more active devices, Physics and working different materials has only grown -not altered.

Although a pre WW2 book they were very clever people, there is a description of a vacuum thermopile which reliably detects starlight for example. In the 50 years since reading this book ( and the Amateur Scientist) that stuff has been very valuable.

The Holzapeffel volumes are also gems, although I would agree that the verbosity may be a barrier to the short fused. I would love to see a much fuller account of the Portsmouth Block Works. Brunel Snr and Maudsley combined ( the tangental turning tool was produced for the mass production of wooden pulley blocks, it was in wood and metal turning forms, one version used a hollow bit - a tube - for grooving pulleys, circa 1800. As this was the first production line - i.e specialised tooling, sub dividing the work and sequential progression with fully interchangable parts with relativly unskilled labour, they considered simplified cutter sharpening- hence the tangental tool. Way way before cars and meat cutting in Chicago)

The revision notes have some of the more interesting material. I have vols 1,2 &3 as a Tee reprint and 4 & 5 as a Dover edition. I spend quite a bit of time every year in the US so have quite a few Dover reprints as well as lots of treasure from second hand bookshops.

John and Michael, I just have to agree with almost everything you say, People who have gone before knew their stuff very well, there are some brilliant books from 50-200 years back that are now almost forgotten traces of the Engineers and Scientists that got us where we are. Looking at their work can often give new insights into today's problems and give us an understanding of methods and fundamentals. For people on small budgets that's a big point, technique becomes even more important.


21/06/2014 21:48:31

Should have mentioned Holtzapffel's Turning and mechanical manipulation- all five volumes. Has an enormous amount of material including tangential turning tools ( nearly 200 years old) and early leadscrews.

Could not find "Modern Physical Laboratory Practice" J Strong online ( it is John Strong not CL Stong- my mistake. )


21/06/2014 20:49:00


Have you ever seen this? **LINK** There is enough here to keep one occupied for a few years. Although a bit OT for some, others might get a lot out of this work.

I first read this book as a sixth former, it has since become very expensive so after looking at MichaelG's reccomendation I had a look for my "fave" and found it for free! . Stong produced the "Amateur Scientist" section of Scientific American magazine for very many years. He also produced a very good book on Lab practice which is very much more detailed on glassworking, optical work and many other topics including kinematic design. I have a copy but will see if I can find it online.


Thread: WD40 alternative - any good?
13/06/2014 20:59:37

If you want to know the formulation of something like WD40 you can always look at the Material Data Sheet.

An old sheet described it as white spirit, light oil and an oderiser. It is interesting that the current sheet uses different terms but I don't think that it has changed much.

WD40 often gets used as a cutting lube however a few people mix up their own from white spirit and multigrade oil. Much less volatile than light oil some kinds of which can quickly evaporate.


11/06/2014 21:24:27

Rollie's Dad's method **LINK** uses a bar that does not have to be dead straight ( just round) and can be used on an unpowered machine using just an indicator and a bit of arithmetic. You can also check the vertical alignment of the spindle axis to the saddle travel with the same general set up.

Clive makes a very good point about tubes and bars, for the same weight a tube of say 3 or 4 times the diameter of a solid rod will be very much stiffer, perhaps we tend to associate test bars with being solid.

Hugh, sent you a Message.


Thread: What Electronic Projects are you working On
08/06/2014 17:50:30

There was an Aircrash Investigation show on the Air France Airbus into the Atlantic on a few days ago. This was a very carefully designed aircraft and the crew were especially trained to fly the aircraft using sidestick controllers.

They flew through some weather that iced the pitot tubes, one of the pilots misread the instruments and pulled the sidestick hard back. The aircraft stalled at 33,000 ft. The co pilot then applied nose down on his side but the first pilot still held the stick hard back which negated the second stick input. The aircraft fell into the sea, everyone died.

Had the controllers been mechanical or had some feedback it would have been obvious what the first pilot had done, the incident would not have happened.

So Bluetooth and car designers?


08/06/2014 01:02:48


I think you need to SEE a Student 1800 and try to pick it up, even better use it for a while. The facing test is not that unknown but the bar test is far simpler because it relates the bed axis to the spindle axis. It is also far closer to most user's turning needs and is easy to do and well understood. The Colchester's have far stiffer beds than you are used to, leveling has a different order of magnitude effect ( as described in an earlier post) so headstock alignment also has a different significance.

Your Emco might like sitting on a concrete slab.


PS I followed Tony Griffith's Buying advice and got a Student 1800 so can speak from experience.

Edited By Billy Mills on 08/06/2014 01:07:20

Thread: What Electronic Projects are you working On
07/06/2014 22:18:58


You need to wash it. Electrolube used to make a very good water based flux remover in aerosol cans called Safewash which had an attatched brush. We used to clean up pcb and monitor chassis/pcb's without issues although LOPT's were not cleaned because the focus assembly is not hermetic. Providing that you can compleatly rinse and dry -if you know what you are doing- you can wash clean almost any electronic equipment that is water safe. Washing should remove trace lubes on rotary switches and mechanical parts so remove or relube.

For cleaning at home warm water and washing up detergent works well, Would not want to wash any LCD displays or non sealed relays however, too many layers, nooks and cranies to drain.

Back in the days of rental tv some service departments used to dunk the insides of tv's in ultrasonic cleaners that used an innert liquid. The liquid was demonstrated on Tomorrow's World by lowering a working TV into the liquid. Most U/S cleaners were run with water and detergents for equipment cleaning, very much cheaper.

Was amused to read about valve amplifiers and their wonderful sound!!!!! well back in the day... I had holiday jobs in the electro-music industry when I was a kid. Used to fix Hammonds, Vox, Marshall, Fender, CopyCat et al.... The main design principle used in most equipment was that you could not make it any cheaper. They got away with it because amplifiers ony ever worked on one signal source so the intermodulation, limited bandwidth and resonances were not apparent, only part of the "instrument" sound. Made a bit of money cutting Hammonds in half- called "splitting" and adding pedal sustain and other effects.


Thread: What did you do today? (2014)
07/06/2014 13:33:43

Some old Austins had the battery under the passenger seat, there was a rotary switch mounted on one battery post which was a very good way of stopping the uninitiated.

A reason for the " all windows down and unlocked car" is hot climates. It is better to open up the car before you have to get inside- even for a few seconds- when the temp is 40C.


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