Member postings for Clive Steer

There are short comings with the normal converters as RA2 points out but many wouldn't notice these. To get the best finish I'd use a 5 phase motor. I've only seen one machine with these and it was eye watering expensive.

CS

Absolutely and you could use your smallest/simplest machine such as a pillar drill to act as the idler motor. However you need to be aware that the motor may be the other side of a no-volt release and motor protection arrangement.

CS

My take on this thread is that if you want simplicity, in both installation and use, then a passive static converter is a good contender. The main components are just an auto transformer to convert 240V to 440 V which powers 2 of the 3 phase wires and a bank of capacitors to "generate" power on the 3rd phase wire. They are robust although not necessarily efficient but are very easy to fix by oneself or an ordinary electrician.

Their common failure mode is that the capacitors degrade with time but it is relatively cheap to replace a set for £50.

Adding a motor to turn it into a rotary converter improves the phase balance and provides a degree of energy storage beneficial for starting machines with direct on line motors. The downside is that the motor adds a level of noise and inefficiency. Static converters are reasonably tolerant of supply issues that some countries power distribution systems may provide.

Active 3 phase converters can be more efficient and compact but may need to be overrated to allow for DOL motor startup loads.

Converting each machine to be driven by a VFD is the most complex option. For those wishing to benefit from the variable speed they provide this is a price worth paying.

CS

I second the use of lighter fuel which I use to clean off gummy residues from clock and watch mechs before running them through the cleaning machine which uses IPA.

CS

I believe with one wheel off the ground the count will be twice that for normal two wheels moving. You only need to work out the gear ration between the wheel and the speedo takeoff which may not be an integer. I am not a Mini expert but the ratio is likely to be fixed whether a metric or Imperial speedo is fitted. In which case the metric speedo would be an 800 and the Imperial one a 1275.

To check thee calibration of the Speedo you will need a tachometer but bear in mind that if you use a car tachometer it is usually driven from the camshaft so the input is rotating at half indicated RPM.

CS

The speedo dial calibration number is turns per unit indicated. So 800 turns will make the Odometer increment by 1 unit and if the input spindle is turning at 800 rpm the Odometer will increment 1 unit in 1 minute. Also at 800 rpm the pointer will indicate 60 whether it is kilometres or miles per hour.

To match such a speedo the vehicle gearbox/wheel configuration must make the speedo input spindle rotate 800 times for the appropriate travelled distance.

Vehicles have a vast number or wheel/tyre size, gearbox and differential ratios so the range can be quite large. The vehicle designer may also wish the flex drive to the speedo to run at a specific speed for a number of reasons I'm not aware. I would imagine that a long flex drive with a number of curves would need to run slowly to prevent wear or achieve a smooth drive to thee speedo.

You don't have to physically move the vehicle to check the calibration just be able to rotate one wheel or hub assembly. You need to determine the wheel circumference to work out the number of wheel rotations that represent the unit distance the speedo indicates. Don't forget that with one of the drive wheels stationary the differential will multiply the spindle turns by 2. This gets you into the ballpark but a tyre compresses when on the road and loaded.

I believe there are similar instructions offered on various vehicle owners websites.

CS

On the Nemags the rotor is magnetised to give a reading of between 10-15% of required reading and then incrementally demagnetised to fine tune the calibration. However the range of adjustment is relatively small if the speedo is to remain accurate over its lifetime. There are quite a few hairsprings to cover the range of turns per unit distance from 560 to 1850 that Smiths speedos cover. Similarly there are quite a few worm and ratchet wheel tooth counts for Odometer to cover the same range.

A common fault with old speedometers is that the pointer arbor shaft wears where in runs in the drive spindle bearing making the drag disc run closer to the magnet causing the speedo to over read. If the wear is excessive the disc can catch on the magnet causing the pointer to "flicker".

In most cases owners take care to ensure their vehicle is appropriately lubricated but this doesn't seem to extend to the speedometer and like other types of clocks not thought about until they stop working.

CS

Hi Speedy Builder5

One thing you might like to consider is that the speedo itself may have been changed. The speedo is often swapped out if it starts to give unsteady reading for one that looks similar but not designed for that car.

I believe the Mini were fitted with a Smiths Nemag speedo. On the speedo dial, either at the bottom or above the Odometer digits, there are the type number and calibration value. The type number will be something like SN618/90 and a calibration number like 1376.

The calibration number represents the input shaft RPM needed for the speedo to indicate 60 mph or the equivalent KPH. You can probably ask a Mini forum which type should be fitted.

A Nemag speedo has two separate mechanisms that need to be correct. The pointer and the Odometer. The Odometer is corrected by changing a worm gear as was shown in the link. However the pointer requires a hairspring change which is slightly more complicated.

For the most knowledgeable advice I would recommend contacting Mike Flannery of Flannery Speedometer Repairs.

CS

I'm not absolutely certain but I believe the latest Newall scales have the electronics that drives the inductive position sensing circuit incorporated into the scale head so they now output the more common quadrature signal that is used by glass and magnetic scales.

Earlier Newall DRO's had analogue electronics in the scale and the digital conversion was performed in the readout head which resulted in a complex and unique interface.

The Newall method of position sensing is similar in some respects to a Linear Voltage Displacement Transducer (LVDT).

CS

My experience is that the generic Chinese readout head products are of good quality and value for money. However the accuracy and repeatability of a DRO system is mainly down to the quality of the scales and the rigidity of their fixing to the machine. Devising and making a suitable mounting arrangement may be difficult for a beginner especially fitting one to an old machine not designed for a DRO.

Where long scales are needed I use glass scales as they are in aluminium cases but for short scales and certainly where space is restricted I use the magnetic scales. Also magnetic scales are good if you are uncertain about the amount of travel needed as the magnetic scale "tape" can be cut to any length required and if cut too short the tape is quite cheap.

Glass scales lengths are usually quoted as being overall length rather than movement range which is less so allowance must be made plus 20mm extra margin.

As has already been mentioned the fixing brackets supplied with most Chinese scales are inadequate but suitable brackets/clamps/shafts etc can be purchased from say PlanetCNC to build a suitable fixing arrangement.

It is difficult to be specific as each machine has its own challenges so it might pay to use the Blue Peter method of using wood, cardboard and glue to make a mock up before final purchase. It is even quite cheap to purchase lengths of 20x30 mm extruded Ali tube to mimic glass scales.

Although the readout bars are quite good they don't provide the extra functions often needed on mills.

CS

You don't need a DRO to make accurate parts. However I feel the DRO's on my machines help me ensure I'm more likely to get parts right first time than when using the usual methods. Whether they are worth it depends on how valuable you feel your time is. Even if it is a hobby it should be enjoyable and there is probably nothing more frustrating than have to make a part again because of a simple measurement error. Even more so if that part is one from a set of castings.

I find making an in situ diameter measurement on a lathe the most difficult and frustrating as the carriage or tailstock often prevent a clear view of digital calipers. With a DRO I measure the first cut and then calibrate the DRO for that tool. This ideal for multiple parts as they all come out the same diameter but you have to ensure you get the first one the right diameter.

Using the DRO on a mill to spot mark multiple hole locations for latter drilling is particularly valuable and reduces silly errors.

CS

Taking Baz and Daves point about info search would the ME site be able to support "wiki" pages on certain repeat subjects such as motors, VFDs, index tooling, work holding etc.

CS

From the pictures there appears to be a relay connected on the mains side of the transformer but the pictures don't show clearly what wires are connected to it. Also I can't see the relay coil which may be slugged to allow operation on AC. The relay may form part of a latching/protection circuit in the vent of a welded electrode.

I'm struggling to determine if the device is AC operated essentially oscillating at 50Hz or DC with some form of rectifier on the secondary side of the transformer which I can't see in any of the pictures.

Anyway I think it is rather like a 50Hz buzzer. The coils on the other assembly somehow retracting the electrode from the workpiece creating the spark. As the mains cycle goes through zero the retraction is released allowing the electrode to drop down and make contact with the workpiece and the process is repeated.

From the info the electrode appears to be a brass tube which allows water to flush arc debris from the gap by gravity feed from a header tank but there may also be a degree of pumping as the electrode vibrates.

I've made similar simple eroders but these have used DC but it will work with AC.

CS

Andrew.

Further study of the sales pamphlet suggests it has a motor feed for the electrode which may simply be a dc motor controlled by the arc voltage.

I may be able to work out the circuit if pictures of the internal are available as I've made similar devices in the past.

CS

Andrew

Watton Electronics of 24 Hyde Way, Welwyn Garden City, AL7 3AR made a product called

"Arc-out" which appears to have been a simple spark erosion device possibly using a simple relaxation oscillator arrangement and probably a solenoid actuated electrode to break the arc.

I found a site dawa.de site that had a PDF of the sales pamphlet.

CS

Hats off to you Steve.

Anyone who builds a car from a kit or otherwise is to be admired as when you think you have done 90% there is still 90% still to do. It takes a serious level of determination to get out of a comfy chair in the winter to put the hours in.

I second your comments about VFD's

CS

Andy

No need to eat humble pie as all part of the learning curve.

I have no experience of the BLDC motor and controller shown in your first link and at face value it may be OK. This will probably be shipped directly from China.

I have bought and used the Jack BLDC motor and controller and one marketed as a Tansew. Both of these were from UK stockists. Both of these were well made but I thought the Jack one the best but the UK ones are more expensive but you know what you are paying with no extra "handling/duty " payment surprises.

The Brushed motor and controller in your second link I have no experience of but I wanted brushless because they are quieter and the electronics provides servo speed control. Also the Jack type controllers comes plug and play so only the mechanics to sort out.

Although the brushed motor appears to have a UK stockist, I believe, this is an agent or accommodation address as right at the bottom of the listing it shows a Chinese address. I have found this recently in many eBay listings with the same product sold at different prices and by apparently different UK sellers. However on closer study they all appeared to come from the same Chinese supplier.

On a recently bought BLDC motor the apparent seller was 20 miles from me but it took over 3 weeks for it to arrive so beware. In this case I should have read his feedback comments as someone had had a similar experience. Luckily it turned out OK and the motor was of good quality and value for money.

If you live anywhere near Hastings by all means come and have a look at my Pultra set up or we could arrange video conference session.

CS

Although being Gas approved is required for Domestic installations this may not be the case for industrial installations. With domestic there are only a few makers of boilers with integrated burner controllers which are submitted for testing and approval and approval may require spares to be available.

I believe there are no rules governing who can instal a domestic boiler. However the installation must be inspected and signed off before it can be fired up. So I believe you can instal a boiler and connect it to your central heating pipework and instal the gas pipe from the boiler to the gas supply but not connect it. I'm not sure if you need to be approved to turn off the gas and remove an existing installation. You may be permitted to turn off the supply, as I would have thought that necessary for safety but disconnection is debatable.

However if you do your own installation, and the instructions on how to do this are clearly stated in the installation manual, you may find it difficult to get a Gas Approved engineer to sign it off or their fee may be high.

Industrial systems are more likely to be built using components and since they can be so varied in their construction that the rules may be different. Provided you follow recommended practice, document what you are doing and any justifications for variance then this may be sufficient to show competence.

I would have thought that there is no safety implication with the ignition electrode as a failure in this component is allowed for in the fail safe burner control strategy. So provided an exact copy is made, bearing in mind that replacement parts for old systems may no longer be available, then this may be acceptable.

Since the charring unit may be installed in "factory" the factory inspector may need to know and also the company insurance.

CS

To investigate the aerodynamics of a particular pendulum rod and bob weight design I would keep the Q low by maintaining the desired shape of the bob but reduce its weight. Reduced Q provides a faster loss of amplitude enabling any aerodynamic tweaks to be evaluated more rapidly.

Interference drag is a problem in aircraft where the wing meets the fuselage and root fairings are a common solution. In this instance this is where the pendulum rod meets the bob and a fairing may be beneficial.

CS

The Jack motor and controller is not classed as a domestic product so should be installed by a competent person familiar with electrically safety issues.

In my view a safety improvement can be made by ensuring all metal parts are earthed via supplementary bonding conductors that are visible for routine checking.

The connectors are electrically rated for high voltage but have additional protective "boots" to prevent live conductive parts being touched by the standard 3 mm diameter test rod that simulates a small electrical screwdriver.

A supplementary plastic cover will provide a second level of protection.

The control/setting buttons use small micro-switches so if the plastic membrane cracks direct contact to high voltage is unlikely.

CS