Member postings for Bob Worsley

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

Thread: Upgrading from a Clarke CL300M, where to go?
01/10/2023 10:33:06

One vitally important thing to have on a larger machine is some alternative method of holding the chuck than screwed on. Either the old L fitting on an old machine or Camlock now. Yes, chucks are more expensive but swapping the chuck in 2 minutes after machining some 3" bar is nice.

Yes, a 38mm spindle bore in my book is essential.

A Norton box is useful, for changing feed rates, scarcely use mine for threading.

A rear tool post for the parting off tool is also essential.

Never used a variable speed drive, just a gearbox, works fine in my experience and nothing electronic to go wrong.

A self extracting tail stock is worth lots of money, like a lever clamp to the bed. Amazes me that there are machines that use spanners for this.

Thread: Latest ME, ELS Article
10/09/2023 09:23:54

I was interested to see that there is no feedback encoder on the lead screw, so the assumption that a step always happens is made. As a post says, will it work with 4.5tpi?

Thread: Safety
19/08/2023 10:16:42

Ah ha, yes, all these people saying they make safety a priority, so why do they then drive through a 30mph speed limit at 50mph then?

It is noticeable that since Covid NO ONE drives through our village at 30mph, no, not one, have a radar speed gun as well. And the worst offenders are now lorry drivers, particularly of the 8 wheeler dump trucks.

Dead is dead.

Thread: Evolution TCT blade
14/08/2023 10:42:07

I have used one of the Evolution metal cutting saws for years, the 255mm diameter version. When first bought was used to cut lengths of 50x20mm mild steel, whilst not quite as fast as cutting wood, wasn't much difference.

BUT!

What the saw will not do is cut rusty metal. If the metal has a layer of rust on it, in my case inside roled amd welded tube, the balde will only last for a dozen or so cuts. The flaky rust is hard and destroys the tips. If you have ever tried to oxy acetylene cut rusty steel then you will know that that doesn't work at all. If the metal just has a film of corrosion that can be removed with WD40 and wire wool then ok.

The comment about it chucking very hot chips everywhere is true! Use some sacking to catch them.

Thread: James Carson Models
11/08/2023 09:15:05

Assuming it is the same firm but LBSC had lots of good words to describe the Carson steam engines. I only have odd copies from 1920's and 30's but the Carson engines come up quite frequently.

Thread: Use of coal, oil and fossil fuels
07/08/2023 10:33:41

As CS says, is this 300% efficiency real? I asked earlier if anyone had real data they could present, none so far.

My experience of messing with aircon units is that the electricity they use to run the compressor and fans doesn't make for any great efficiency, considering the cost of buying the unit in the first place. Of course, then the grid is overloaded and get blackouts then efficiency drops to 0%.

As for water temperature, if radiators are designed for 70C then obviously going to be colder with 40C, but why not just run the water pump for 12 hours per day rather than 3 hours? Electricity obviously, but heat output per 24 hours will be the same.

04/08/2023 10:44:43

Read my way through all of this thread, what seems to be missing is some real, hard, numerical evidence that heat pumps actually work. By that I mean that the COP really is 3+, even in the middle of winter when the heating is actually needed.

I have bought several air con units from sales. These are a heat pump and are easily converted to a heating type heat pump by simply swapping the air flow through the unit, what was the cold output is now the air input etc. My measured conclusion is that the various compressors and fans take as much energy as the heat pump produces. There is a gotcha here of course, reading books on heat pumps and you finally find that if you want heat output then the air input radiator has to be at least twice the are of a similar rated cold output radiator. So these fancy heat/cool heat pumps you can buy are simply not up to scratch. There is very little heat in a cu m of air, and the air flow rate is a gale. You see these photos of ASHP installations on houses and they have a fan about 500mm in diameter, with the house wall only 100mm away. Why not bolt the ASHP to the wall 3m off the ground and facing into the wind, normally west, so the fan doesn't need to run to get quite a bit of air movement by default. Oh, sorry, looks ugly so the planning department won't allow it.

In the UK a GSHP seems a much better bet. We simply don't get sub-zero temperatures much, even a frost is a rarity. So the ground pipes only need to be 400mm or so underground and at 400mm spacing using 10mm bore pipe. The ground heat rises up from deeper down, gain from sun in winter is zero.

Keep replying, useful info.

Thread: Making an alternator that charges 'properly'
11/07/2023 10:02:21

Three phase excitation? Really? Three phase would then need three coupling transformers between the stator and rotor. Single phase excitation only needs one transformer, and at the power levels needed works ok.

Car alternators are three phase simply because a three phase machine is more efficient than single phase, got nothing to do with a smoother output, it is feeding a battery after all.

Thread: Looking for Thetford Town book by Alan Marshall
25/04/2023 16:41:36

Any progress?

A copy of the disc or book could be really useful!

Thread: Vintage Heidenhain DRO
21/04/2023 09:46:36

I had a Heidenhain DRO even older that yours, mine used a 4040 microprocessor, look to see what yours uses because it might be quite valuable. The 4004 was the very first microprocessor in 1970.

Thread: Draper Stormforce circular saw sharpener
31/03/2023 17:22:47

Saw this in the new Machine Mart catalogue but after searching still not really sure what blades it will sharpen.

I have one of the metal cut off saws, slow speed type, with a HSS 9" or so blade with 80-90 small teeth. Will it sharpen one of there blades? Anyone tried? It needs the blade to be indexed around one tooth at a time so each tooth gets an identical sharpen, depth, angle etc. It is this that I can't confirm or deny. Not expecting it to automatically index around, but it does need to be same depth on each tooth.

Can buy it cheaper than from MM!

Thanks.

Thread: Mitsubishi VFD question - single phase input possible?
29/03/2023 16:51:16

Possibly, use an external rectifier feeding a whole bunch of external smoothing capacitors.

The only real difference between 1ph and 3ph input is turning the volts into DC.

Thread: Assessment of an old copper boiler
21/03/2023 10:18:16

A suprisingly realistic set of comments?

One further comment I would add, and this from reading 19thC books on boiler safety, is look at the riveting. Are all the rivets in straight lines, all equally distant from the plate edges, if you can see the back then are all the heads well formed. Also the flanging, is it even all around the flange, is it tight against the plate, is it reasonably smooth with no thin sections. Again with rivetting, is it damaged from the rivetting. They are copper rivets, not brass!

If the rivets look like a dog's hind leg then what about the distance from plate edge to rivet, In the old days boiler failure was frequently caused by gouging, the appearance of cracks in plates along rivet holes, in Tee and angle iron in the corner, in the middle of plates due to temperature stress with hot steam and cold air or water.

It only takes on weak rivet to cause a leak, and that is what the 2X hydraulic test is for.

There must be multiple thousands of old boilers, before 2000 with the CE marking etc. Foolish to throw them away, even at £5/kg scrap price. Just be careful.

Thread: Finding star point
16/02/2023 19:58:24

Just wondered why you thought it was star connected? Yes, 400V, but could also be delta connected at 400V?

Look at the three leads, do they join with one or two winding wires? If one, star, if two, delta.

Thread: Grinding your own hss lathe tools. Tips & tricks?
06/02/2023 09:38:03

In my experience you will notice a definite improvement if you find yourself a grinder with 8" stones. The motor will be powerful enough to actually grind! Mostly 3ph but practice doing 230/400V converters!

Keep the gap from wheel to rest to a minimum, especially with an 8" grinder.

Use good quality white grind stones.

Get a devil stone, for cleaning the wheel in bulk, and a 1ct diamond for precision cleaning.

Thread: TIG welded copper boilers
04/12/2022 18:33:03

I have carefully read this, and anything else i can find, on TIG welded boilers, but never seen any comment on the use of mixed metals in the boiler.

A copper boiler is a single metal, copper, plus the odd gunmetal bush. But what about the use of hundreds of monel metal stays? These are metal alloys, not a pure metal. Does TIG welding work with alloys?

When welding the actual metal is melted and the two. or more parts being welded form a liquid pool which cools and freezes, so what is the end result of this pool?

With silver solder the base metal does not melt, the solder does and forms a surface coating on the base metal, and this freezes.

These are quite different. Silver solder relies on the surface tenacity between copper and solder for the joint strength. With welding the joint strength is the inside strength of the molten and then frozen pool.

The basic question is, is my professionally built TIG welded boiler ok with monel firebox stays and other parts? Why?

I am not at home to look up a book I have written by a boiler inspector in the 1870's But the repeated failure mode of steel boilers is due to grooving, where water flowing in the boiler cuts its way through the plates, bang! The worst possible place for boiler feeds is where the boiler is hot, the backhead. And where in my professional TIG welded copper boiler are the two feeds? The backhead! Whilst it is said that an injector feeds hot water, can't be that hot, don't work with a hot feed water, basic principle of operation.

Thread: Taylor Undertype Engine
21/11/2022 18:37:35

Finally, Sarik have declined to take responsibility for the drawings, offered a refund but no technical help. If these drawings are all you have to go on, no 1903 or Taylor re-working, then still no mention of copper thickness or working pressure.

Ok, I can make my own mind up, but this really isn't good enough, and Sarik should be informed in no uncertain manner.

Not Happy.

Thread: Duplex steam feed pump
01/11/2022 19:04:40

This is the Weir type pump?

Yes, LBSC did several versions of this in the 40's and 50's, can get castings from Kennions.

They look a wonderful thing to start model engineering with, much smaller, cheaper and simpler than a loco like Tich.

Thread: Taylor Undertype Engine
29/10/2022 09:36:29

Yes, but we still have the situation where neither the copper thickness or the working pressure is marked on the drawings.

Presumably this is Sarik's pigeon, the drawings need updating.

28/10/2022 18:44:44

Thanks for the response, bit surprised! Never really considered them, couldn't see the point, but saw mine at SRS and looked really interesting.

ME articles? I have just vol 8 from 1903 where I found the use of 15swg but only odds and ends from the 1971 redesign by Taylor which is why I asked about no material thickness or even working pressure from the Sarik drawings. Mind you, they are the size of a bed spread each so hard to use. Sarik haven't yet replied.

If 12swg, 2mm, still seems a bit thin for 5" diameter.

I recently bought a model which dates from 100+ years ago, so the boiler is made as the Greenly design. At the moment just considering it, but 15swg and brass tubes are not acceptable, likewise the riveted boiler. What to do?

Hi Chris, thanks for the offer but looks like I am having to stop driving. What boiler pressure did you run yours at? Did the compounding work as expected? What did you drive, it is a big boiler and just turning it over won't need too much steam!

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