Member postings for Mike Poole

My wife needs a bigger bag than that.

Mike

+1 for being tiring to use, when I was a pretty powerful mid 30s and spent a day with a Bosch breaker that was like the Kango Jason mentions, I was knackered the next day. My last adventure with concrete breaking was with a cheapy Screwfix SDS machine, it did the job I needed to do, it was far easier than the lump hammer that I started the job with.

Mike

Some times filter components can fail with a flash bang and smoke, the equipment can keep working without the filter being operational but will now be putting noise onto the mains supply. A failed capacitor can be hard to spot as the only damage may be a crack that is not easy to see.

Mike

The Red Kites in South Oxfordshire are becoming a nuisance, reports from people in our village are appearing of al fresco diners coming under attack, one woman reported having a slice of pizza taken which she was taking a bite from. The village duck population has virtually disappeared, a sheep had its udder and tongue devoured by kites. They seem to have developed a taste for small live animals which is beyond a diet of carrion. People in the village are feeding them because they are spectacular when the swoop into the garden and this is probably a factor in an exploding population since they were reintroduced to the Chilterns over 20 years ago. I can sit in the pub garden and easily count 15 of them circling over the village, it has been suggested that garden feeding is giving them an easy food supply which is increasing the population beyond the natural supply of carrion would support. I spent a day with a sheep farmer in Devon and crows were his pet hate, as a sheep with a full fleece can fall over and not be able to get back to its feet the crows will take an easy meal of the sheep’s eyes, the sheep mutilated by the kites was probably a faller and may or may not have been dead when the kites started their meal. I have seen one or two kites that have been killed on the road as they feast on large road kill like badgers and deer, they can probably just collect a rabbit and devour at their leisure in a safe place.
Mike

Edited By Mike Poole on 28/06/2023 11:43:37

The morse taper is designed as a self holding taper but still requires a drawbar for milling applications. I find the self releasing property of all tapers designed for milling to be a good idea. I think the Morse taper was designed for drilling and lathe tailstocks are frequently used for drilling so a morse tailstock became common. With an adapter sleeve morse tapers can be used with an R8 spindle. One thing I really hate is hitting spindles to release tapers so if a morse taper spindle is not fitted with an ejector system I would seriously consider adding one.

Mike

You have spoiled my day Lee, luckily you didn’t provide a picture but a 70 year old in a short skirt is something I wouldn’t wish to see but my imagination is quite good even in cases where I wish it wasn’t. I will have to move swiftly on to something engineering that is interesting.

Mike

Roger, the situation you have found yourself in is a perfect example of what can go wrong when an installation does not properly address the control of electrical emissions. Very often a noisy VFD will not be a problem until a piece of equipment that is sensitive to noise is operated in range of the noise source. You may have unwittingly bought a noisy VFD, a sensitive DRO and a wiring installation that does not meet the requirements to control emissions. Input and output filters are often omitted from drives to keep cost down but the filters are usually available as separate components. The incoming mains filter can help to reduce the noise fed back into the wiring system but emissions radiated from the drive can be usefully screened with a metal enclosure. The braid of an SY type cable is primarily a mechanical protection and other types of cable will have copper braid screen and maybe a copper foil layer in addition, CY is a cable with better electrical screening. The reason they make all this stuff and have recommended earthing strategies is because you are not the first to run in to trouble and I doubt the last. Much research has gone into the practical methods of emission control and it is worth following the recommendations. An industrial Ethernet installation in a car body welding shop has extensive earthing requirements and checking compliance was a part of the buy off process. Mains noise brought our factory to a halt for 15 hours and cost a lot of money, although we did not prove it conclusively we strongly suspected that a large VFD was the source of our problem.

Mike

Edited By Mike Poole on 23/06/2023 10:19:18

You, as are many others are using the control panel that is intended for commissioning and service functions as the main means of control. The control of he VFD should be from a properly installed panel with robust buttons and a quality potentiometer if required.

Mike

The Dickson QCTP to my mind did not scale well to the Myford size, the large versions I have used have not had a rigidity problem but the one on my Myford which is a genuine Dickson is not a rock of Gibraltar. The ML7 topslide is not the most rigid either, paying attention to the topslide overhang helps but if heavy cuts are required then putting Myford top slides and QCTPs to one side and mounting a single tool Gibraltar tool post will maximise tool rigidity.

Mike

An alert driver may be quick enough to save an engine or in Steve’s case notice a deteriorating trend as the filter became clogged with the disintegrating belt. To the trained eye a gauge could be most useful, indeed if had one fitted to the Trident I may have hunted down the faulty filter but I don’t know if the failure was a slow build up or a dramatic failure, I suspect it was a slow process so a good chance it could have avoided the blow up. The rod failures allowed the pistons to just kiss the head which explained the ticking noise. The tow home was exciting, lane 3 of the M40 overtaking everything. Two Tridents and 3 people with a short tow rope requires intense concentration, I was knackered when I got home.

Mike

Backlash is a fact of life for any screw thread. Numerical Control and then Computer Numerical Control demanded backlash free screws and the popular solution is recirculating ball screws, hydraulic rams were also used on some machines and robots. Backlash eliminators were fitted to some mills to enable climb milling to be used. The crude split nut solution is not overly satisfactory as the screw usually wears unevenly so will have tight or loose areas. Other more complex solutions are available. Even expensive machines where great care is taken to fit screws and nuts will eventually succumb to wear and our friend backlash will appear. I am surprised or even amazed that you have zero backlash on your hobbymat, does it have something like Delrin nuts? Or some other solution.

Mike

The trouble with oil pressure gauges is they will show wide variations and still be operating normally, it will require the driver to understand what is normal behaviour and not panic when the needle drops with hot oil and idling speed. Manufacturers don’t normally fit them as they would get worried people on the phone all the time. A performance engine with an informed driver can make good use of an oil pressure gauge but probably best not to let Joe Public see what is going on.

Mike

Oil pressure lights are also known as the it’s too late light.

Mike

My T150V Trident wrecked 2 rods and needed the crank regrinding when an oil filter disintegrated and blocked the gauze filter from the oil tank. I think I could still rebuild a Trident engine in a darkened room.

Mike

Are we in the plastic age now?

I am not a religious person but I think the hijacking of religious occasions by commercial interests is very poor. I think last Friday was national fish and chip day and once again I think fish on Friday is a religious event, perhaps more so for members of the Catholic religion.

Mike

It seems lever handles were banned on outside doors because bears have learned to operate them. It’s possible Yogi might not be “smarter than the average bear”.
Mike

Edited By Mike Poole on 05/06/2023 10:36:20

DC31k raises an interesting point about the mechanical brake conflicting with the ramp down. I think the mechanical brake was useful because just switching the motor off could result in a long slow down as there could be a lot of inertia in the drive train and the job mass. I have used a Colchester with a mechanical brake and I tended to use it for a quite aggressive stop if I just wanted to take a measurement. The ability to program a short ramp down would tend to negate the usefulness of the mechanical brake so I think I would tend to favour a short ramp down and forget the mechanical braking system.

Mike

The braking resistor is switched in when the voltage on the DC link of the VFD rises too high because the slow down ramp timer is set too short. Program a conservative ramp time and the resistor may not be necessary. A fault is usually generated if the DC link voltage goes too high. A big job with a four jaw chuck fitted can result in a mass that is beyond the VFD to control even with the resistor fitted in which case the ramp down time will need to be increased until the machine can be slowed without creating a DCLink fault.

Mike

I think a blacksmith would upset the point where the bend is required to supply the material on the outside of the bend and then square everything up after bending. If you are after a bend that is very accurate the cut and shut is probably the most straightforward procedure, it could save some years of learning the craft of a blacksmith.

Mike