Member postings for Mark Rand

Running Hardinge lathe, Beaver milling machine, J&S 1400 surface grinder and Wolf pedestal grinder over the last 12 years or so, all fed by a single VFD/inverter. Initially Danfoss, later Teco. with DOL starting, plug reversing, dual speed motor and multiple machines operating at the same times.

Oh, and there isn't an issue with unbalanced loads. Inverters are constant voltage supplies, not constant current. I do have a neutral generating transformer, but in fact none of my machines and virtually no industrial machines need a 3ph 5 wire supply.

Edited By Mark Rand on 11/10/2022 18:11:11

Because your camera is not rotating the image to the direction you see, it's only changing the metadata which goes with the image. Sloppy, lazy programming.

Open the photo in something like Paint, rotate it clockwise then rotate it anti clockwise. Then save it. It will write the metadata to suit the way the image is displayed on the screen.

Note, if you're afflicted with a mackintosh device, you'll have to find a similar, but different solution.

Edited By Mark Rand on 11/10/2022 16:13:38

£25,000 per ton is good value????

Edited By Mark Rand on 11/10/2022 11:42:45

^^^^^

That isn't the case from my experience.

Two things:-

1. Inverters are generally more than happy driving multiple and variable loads with downstream switching. The output stages of a computer UPS, a solar/battery inverter or a modern welding set are almost identical in design to those in a motor drive VFD.
2. Having started my career at a manufacturer of large rotating electrical machines, I've often wondered if a rotary converter with a wound rotor (synchronous machine) wouldn't do a far better job than the common 'induction motor with capacitors' arrangement. It'd need an exciter and governor setup, but that's not difficult and it would have far better voltage and phase angle regulation.

Edited By Mark Rand on 10/10/2022 17:29:27

I've been running my workshop with a single inverter for the last 12 years. Pedestal grinder, drill sharpener, Hardinge lathe, Beaver milling machine and J&S surface grinder. The original was an old Danfoss 23kVA monster that I got for £10, the current one is a Teco Speecon modified by Drives Direct to have a voltage doubler inside and sold as a '7.5hp digital converter'. It's quiet, efficient and completely reliable with DOL starting, plug reversing and multiple motors on multiple machines.

I have two additions to it to improve things.
1) A sinewave filter from REO to eliminate motor noise and any possibility of electrical noise.
2) A star to star transformer acting as a neutral generating transformer so I can run any 240V devices built into machines (5 wire three phase instead of 4 wire three phase). This isn't actually neccessary for any of the machines, but I already had it.

Inverter output stages and protection have improved unrecognisably over the last 40 years, when most of the horror stories and urban myths date from. The worries about inverter outputs and protection not being capable of handling multiple loads and switching are just not relevant any more.

Edited By Mark Rand on 09/10/2022 10:30:44

I was one of several thousand 'synergies' that GE claimed as a reason for their takeover of Alstom Power (Ex ABB-Alstom Power, Ex Alstom Power, Ex GEC-Alstom, Ex GEC Turbine Generators, Ex EE AEI, etc.).

At least I got my redundancy pay for being synergistic...

Beware of apparently bent gibs. They can bend a surprising amount due to uneven temperature through them. I had a pair of gibs for the shaper seem to have well over half a thou of bend and I scraped it out. Next day the bend was the other way... I realised that they had had a day for the temperature to normalse.

After that I kept them chocked up so that air could circulate around them and used a fan to make sure that it did when I wasn't working on them. No more issues with gibs flapping about.

Not with a day to look after a stand and another to actually see everything else!

All those electrons going to landfill...

Report the item unless it's strictly a business to business listing.

Ebay's terms indicate that prices should be VAT inclusive for retail sales.

I was supposed to be doing some welding in the shed today but... Got the covid booster in one arm and flu jab in the other yesterday. Got the shivers last night and slept most of today. First time I've had a reaction to any vaccination.

With the rotary table sat on your knees .

Make another scraper blade with a smaller radius. This'll make it easier and more accurate to do small cuts when trying to even out the coverage in the later passes.

Actually, the comments about SORN aren't 100% correct. My Triumph TSS was taken off the road before this SORN nonsense came in. It's still off the road and doesn't need SORN.

The sharp edge needed isn't the angle of the cutting edge, it's the lack of any flat on the edge whatsoever. If you can see the edge, it isn't sharp. My test, after lapping a blade is to gently push it along a thumbnail. It should remove a scraping off the top of the nail rather than sliding along it.

A Workmate can be useful when hand scraping because it's lower than the bench and you can stand on the step of it when the work is still too tall. The work needs to end up close to waist height.

You should find that the blue on the surface plate gets thinner as you go along. Don't add more blue each time, just roll it out to make sure it's even. As the work gets closer to flat, the thinner blue comes into its own.

Did my medical (diabetic) license renewal a few weeks ago, also online. The replacement license arrived 5 days later. Three days after that, I got a letter saying that they'd keep me informed about the progress of my renewal.

Would now be a good time to consider moving to TIG for welding? Needs more dexterity and coordination than gas welding but I find that it does everything I need up to the thicknesses that need arc welding.

I'm a bit confused by the above. I took VR at 58 at the end of 2016, but I've got 42 full years of full contributions. Even if I paid for the empty years between 2017 and next year, it would make no difference to my pension.

Isn't that why the full sized rails have two conductors across each joint on each rail as well as the fishplates?