Member postings for Macolm

The field of view is very small with what are effectively small telescopes. They are good for their intended purpose, but unlikely to be suitable for most engineering tasks. The headbands with additional lenses as in the previous post are more suitable.

Edited By Macolm on 18/02/2022 21:49:07

Edited By Macolm on 18/02/2022 21:49:53

Driving out coal and nuclear generation in the UK and most of Europe has been very successful, and there is also a presumption against further gas fired generation. The monumental failure of governments has been to put in place any practicable replacement.

A parable. You quite like lettuce, and your wife is crazy about them. To have fresh lettuce every day, you plant twenty rows of twenty, a total of um er, is it 400? Enough for a newly picked lettuce every day of the year, and some spare. What could possibly spoil such a brilliant plan?

Unfortunately, this appears very close to the thinking behind our electricity system, where the average output of renewables is assumed as always available, and without practicable provision for the prolonged periods of low wind that occur.

As a comparison, consider the Crossrail project. If it opens this year, it will have been 14 years from initiation. At the start, all the technologies were available and well proven, all that was needed was detailed planning and execution. A similar timescale is proposed for the electricity grid to become CO2 emission free, but in contrast, the key storage or backup technologies are currently not proven as practicable, or are even unidentified. Over last summer there were more than 10 weeks consistently low wind generation. To cope with such a situation would require an impractical amount of storage for current technologies.

Finally, from https://www2.bmreports.com , here is current UK grid data and prices. Yesterday, the balancing cost reached £4 per kwh. Today only 53p!

Try not to mangle it! I usually manage to grip such keys in a milling vice. It will probably need an equal thickness spacer to keep the jaws parallel, or perhaps even a slightly thicker spacer to ensure gripping along the inner side of the key. Start with it really tight, once it slips off, the chances of success reduce. A vice with rounded jaws is hopeless.

Another possibility is vice-grips or a mole wrench. Again, probably needs to be the genuine article to have much chance, and again as tight as possible. Tap shaft with a copper mallet, or if not available, apply hammer via a piece of aluminium etc to avoid bruising.

Clive

Interesting find, and should be good for intended purpose. Like the ordinary low cost keyless chucks that come with portable drills, closing may be very low geared. Another possible source of quicker closing traditional keyless and locking is Metabo, the first type on the following webpage are well made, again for percusion use. Whether easy to get in the UK I don`t know. They are long though.

**LINK**

Edited By Macolm on 31/12/2021 12:52:36

Most of the annoyances of ordinary keyless chucks can be much reduced by the reverse lock type. Here is what a Rohm model looks like, I think it is 1.5mm to 13mm and is a thread mount. You can see the lock ring with release direction arrow. I made up the arbor to minimise the height, which is little more than a key type.

Operation of the locking ring is very intuitive, scarcely noticed once you are familiar with it. In fact, the chuck is sold primarily for impact use on a portable drill, but is made to a high standard, and concentricity is excellent. It does have holes for C spanner release, but this has never been necessary in ordinary use on the mill.

Note there are "reverse lock" keyless chucks. These have a ratchet that prevents loosening, released by a ring at the arbor end. Though not particularly useful on the lathe, I would not be without one on the mill. It is secure enough to grip milling cutters for spot facing, though of course not stiff enough for actual milling.

Even if it is a MK 1, if using with a VFD I would suggest a 2 pole 2800rpm motor if changing from what you have. This would get spindle up to 2000rpm or more which seems within the capability of the bearings, if somewhat noisy due to straight cut headstock gears. It is useful for small work though probably not used much. Lowest gearbox range is 22 times reduction from that, so a nominal 72rpm, and less than 20rpm available via VFD. Torque clearly is increased by 22 times relative to top speed.

As usual, there should be no switches between the motor and the VFD, so the original wiring is best discarded.

You will almost certainly find it impossible to get a bond with ordinary epoxy with any oil contamination. Petropatch now seems to be an epoxy putty - I suppose it might be formulated to work with existing oil contamination, but I doubt it. It was once akin to jointing compound, and a cloth patch. Also, there was a Bostik two component acrylic adhesive that would adhere to an oily surface, absorbing the oil. As an aside, there are epoxies that bond polythene ski sole material, so clever chemical action is possible.

Try search for oily surface adhesives. I found ThreeBond 1217M, but there should be others. Be prepared for a shock when you see some of the prices!

If your lathe can be used in reverse, mounting the screw from inside a threaded sleeve allows the excess to be parted off. I have an interal grooving tool that works for this. I just hold it in a three jaw chuck, which is adequate for most purposes.

Edited By Macolm on 13/12/2021 17:33:33

Edited By Macolm on 13/12/2021 17:34:17

I should mention that the implementation shown suffers from the deficiency that there is a considerable bending moment at the junction of stud and clamp body. It was originally intended to buttress it here with a large diameter threaded sleeve, say M10 inside and about 20mm fine outside for the clamping wheel thread. This was not done because no suitable combination of tap/die/bolt was found. Despite this, it has so far been satisfactory.

For drilling I mostly use the mill/drill these days, it avoids careful marking out. By adding a threaded spacer and T nut, this type of clamp can be fitted and secured in a T slot. I normally clamp the metal together with a piece of scrap MDF.

Edited By Macolm on 22/11/2021 11:09:44

I have had good results joining polyurethane by making a knife-edge bit for a soldering iron. Hold the heated iron fixed for example in a vice, apply cut ends of belt to opposite sides, then slide them together off the edge, and hold till set. This avoids exposing the melted PU to air. If necessary, trim flash with a scalpel.

One problem that is rarely mentioned, but which I have found troublesome, is vignetting. This is the fall off in brightness towards the corners, which is an intrinsic feature of lenses, even an "anti-vignetting" lens. It is due to some of the ray bundle being increasingly obscured off axis within the lens itself.

In practice, better cameras do not suffer much from the effect, it is not immediately noticed in a photo. However, when a slide or print is copied using a camera, there is now two lots of vignetting, and the effect does become more noticeable. Correction using software may be a possibility.

On the other hand, a scanner should provide constant sensitivity across the entire field, and certainly I have has good results scanning my slide and negative collection. It does need a high resolution scanner to cope with the small image size. I have an older Epson scanner which can be loaded with eight slides, each individually adjusted, then all of them (slowly) scanned.

Incidentally, for a pretty dire result, try projecting slides and photographing the screen - three lots of vignetting.

People are not taking this seriously! To consolidate the confusion, what if the small circle rolls inside the large one?

Edited By Macolm on 11/10/2021 14:07:49

None of the explanations seemed instantly self evident. Here is my attempt.

I have used PTFE plumbing tape for similar thread stiffening. You can vary the number of turns within reason for adjustment, it lasts quite well, and is quick and easy to replace.

Re CCGT v OCGT

This is trickier than it looks. The CCGT 60% plus efficiency only applies over a amall optimum operating range, and the start up time during which nothing is generated is of the order of an hour. Fine when used for baseload, but the achieved efficiency will be much less when used for load following to make up for the random variability of renewables. CCGT has become the remaining main provider for this.

Windows seems to be able to change the boot order in the UEFI BIOS and I have previously had problems with that, but in this case boot order remained as previously set up. The DVD is highest to allow for potential disaster recovery, but the problem stayed the same when the faulty cable was moved to a non bootable drive. I don’t seem to have an option to stop boot order being changed or I would have it set.

Of late, Windows updates are a cause of many problems, often due to defaults being restored such as back to “auto”, followed by loosing a carefully set up workaround.

Thank you for your suggestions. I am pretty confident of the adequacy of the hardware - that is unless there is a failure. Having replaced the defective SATA cable, the computer has operated properly since.

When that cable was faulty, the BIOS POST (power on self test) did appear to be successful as indicated by a short beep, and which presumably included test of the SATA interface. But thereafter there was no data communication with the Windows SSD or for that matter any other drive as indicated by a complete absence of any HDD LED activity. I suppose it could be due to a coding error in this particular BIOS version. Certainly the boot sector was not damaged, since start up was immediate with the new cable.

Thanks for the inputs, and indeed an M.2 drive does disable a particular SATA connection.

The puzzle to me is that while all the SATA ports proved to be working properly, the use of a defective cable on one port prevented the computer from being able to boot into Windows via a different port.