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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: Urgent - opinions of lathe I am going to view/buy
13/09/2021 19:27:24

Well, how much did you pay for it?

Thread: Multimeter recommendations
12/09/2021 18:36:08

Perhaps the clamp ammeter is the way to go? No high current clearing needed, just the ability to withstand 1000V on an uninsulated wire.

Thread: Fowler Z7S Steel Boiler
12/09/2021 18:28:05

Use copper?

Copper is at a historic high price, £6,500 tonne, so will be expensive, but will also last much longer than a steel boiler IF you only use it a few times per year. Yes, there are lots of articles in ME about how to lay up a steel boiler, but it only takes one bubble in one corner to start the rust.

Up to you of course, but for such an expensive engine saving £2k on the boiler seems silly. Talk to Station Road Steam and the other model buyers if they would buy the engine with a steel boiler.

I think copper is wonderful stuff after reading up about its strengths and weaknesses.

Thread: Searching for magazine collectors
07/09/2021 16:40:57

Where abouts are you? I am trying to build up a collection and your early ones would be of interest.

TEE Publishing might be interested.

Thread: Disposal of swarf
07/09/2021 16:31:13

Seems to me that this is waste from a normal domestic household. Some have hobbies of cooking, or woodwork, or tapestry, dog and other animal waste or anything else. So the black bin takes it all, discrimination otherwise. Of course if you have 50kg then take it to the scrappy.

Our council produced a list of the only items to go in a black bin. Didn't include animal waste, sanitary products, even and old sticking plaster. These people are real dummies, how do they dispose of some paper towels covered in little Johny's sick?

Thread: Multimeter recommendations
07/09/2021 16:25:23

Buy a cheap, £3-5, one so it can bounce on the floor, do not bother with a Fluke or similar.

If you want a fixed meter, on a shelf or something in the garage, then get an LED display, LCD tend to be unreadable without being able to move it around to get the reflection just so.

Don't need more than 3.1/2 digits at which point they all use the same chip inside.

Thread: Urgent - opinions of lathe I am going to view/buy
03/09/2021 10:25:08

Imagine seeing this lathe at an auction. You can look, but not try it. Wind the screws in and out, rotate the spindle, look at the motor. But basically you will not see any hidden faults. Now consider what this lathe is like compared to a dog in an auction sale room.

I was trying to suggest things to do to establish its condition, no one has helped by saying that you can indeed look at the motor and drive, does the top of the headstock open to look at the spindle? I don't know. The things you really need to know are the state of the bed, damaged or cracked, the spindle, does it rotate easily, the carriage, does it move smoothy.

Don't forget that if the seller is an arts graduate then their knowledge of lathes will be negative, don't expect to have your questions understood, let alone answered. Go to look with a pile of cash in your pocket and a means to bring it home, found that riffling a wodge of notes does tend to change people's minds. On the other hand I have also found that screwing the price down also is foolish, you get an irritated seller. But your primary job is to establish a value to YOU, not others on the forum who last bought a machine years ago. I buy stuff on sales, usually auctions, and NOT ebay, on a regular basis. I have found that the good and the bad do even out, but that also requires you to buy on a regular basis. It is an easy price improvement to simply clean the thing. Also have other chucks so you can swap them around etc etc.

A three hour drive is just the investment you have to make to buy a machine, or anything in fact, enjoy it!

02/09/2021 18:59:27

Wow, what do you expect for £750, brand new!

Look at it. Got the 127 tooth metric gear, that is expensive. Look at the tumbler reverse gears, are the teeth still as wide as the gaps, so not worn. Screw the two chucks on, not tight, but enough to be able to pull on them to see if headstock wear. Rotate the chucks slowly and feel for any graunching, and in back gear.

Move the cross slide, press a finger tip against the slide whilst rocking the feedscrew, as you increase the amount of movement then wait until your finger tip can feel the slide moving. Finger tips are extremelty sensitive for this. Repeat on top slide, but it would normally be much less worn. Rock the carriage with the handwheel, there will be at least 10 or 20 degrees of slop, it is a gear into a rack, but feel if it is graunchy up near the headstock compared with the other end.

Power it up if possible, how noisy is it in all speeds, but just one in high gear and one in backgear will tell you most of what you want. Are you familiar with the noise a lathe makes at 700rpm? Pretty noisy, but not ear muff noisy. Put the feeds in and out, forward and reverse, noisy?

Does the tailstock barrel move smoothly?

Look at the bed in front of the headstock, how many times has the chuck been dropped on it. The bed uses raised Vee ways, look at the state of them. Look for signs that they have hacksawed stuff off in the chuck and overshot and hit the bed. Hopefully hardened so any wear in the saddle which can be scraped out.

Just stand back and look at it, is it twisted, are the cabinet panels all straight and undented.

In the end you have got most of a lathe, two new chucks but probably not Burnerd, the cabinet is a lot of money, and making a good bench isn't so easy.

If you can run it and sounds ok then easily worth that money. If you can't run it then have to look at the pulleys and motor, have a good sniff, if burnt out then the smell lingers for ages. My guess is that it was used for turning down commutators or something like that, certainly not model engineering, hence the grubby look. Boxfords are like South Bends, good basic lathes.

Thread: Threading myth .... busted!
02/09/2021 10:04:56

Surely it depends on the size of the thread? If cutting 4tpi then the ability to put some top rake on the tool will help it cut, hence a better thread? Going straight in on a 1/4" cut is going some on a small lathe?

Thread: Ok to grease Myford feedscrews?
29/08/2021 10:54:04

Interesting. Just reading old copies of ME and around 1981 there are endless letters (remember those?) about how naff the Myford oiler is. This was a pump action type that you just push onto the nipple, not lever action. My Harrison also came with a similar oiler and never managed to get anything out of it.

In issue 3666, October 1981 there was a letter describing why these oilers are so naff. The basic reason is that they should use grease, thin grease, not oil. A grease type pump action oiler is different to an oil type pump action oiler.

The grease to use is BP Energrease PR1. This grease is almost translucent, and a sort of reddish brown colour. I am sure I had a tin of this bought decades a go but can't find it. It will settle out if just left so will need a good stir.

It would seem that the thing not to do was to use oil, in my experience it just leaks out of the gun and makes a revolting mess.

I am trying to find a modern equivalent to this grease, but the world has gone lithium based and not to sure if it is similar. Closest match so far is SKF LGMT 2 which is a mineral grease with a similar colour.

Don't really see any difference between oil or grease on a leadscrew for picking up contamination, both are sticky. But grease does seem better to lubricate things like the leadscrew end bearings, Norton box, change gears, feedscrews etc because it stays there, oils slowly run off.

Thread: MT 4 1/2
28/08/2021 10:21:29

Also used in the L5A lathe, and I haven't used mine since I bought it in 1987.

Didn't know it was called mt4.5 or that a 5C collet would fit, must lead a sheltered life!

Thread: Identifying Monel metal rivets
28/08/2021 10:17:24

Thanks for the information.

I found

https://www.rivetsonline.com/rivet-data

which gave the identification information.

Most web information are for the use of monel rivets in aluminium masts etc on boats, so there can't be any corrosion problems.

It is seriously hard work to crush end ways one of the rivets, but 3/16" is large, a steel rivet needs 5 tonnes to set it cold, doubt a vice is anywhere near that.

Thanks Bob, I also have tins of muticoloured alloy rivets,

Monel is also of use other than boiler stays, but lots of short lengths isn't so useful.

Looks like it joins the bags of titanium bolts and pop rivets as possibly useful.

27/08/2021 10:37:10

Tidying up and came across several bags of rivets. Some obviously aluminium, but some I assumed where steel, but not really magnetic. Further looking suggested they were monel.

Each of the rivets has two centre punch marks on the end, and after lots of searching this seemed to be the identifying mark for monel.

Has anyone any ideas please?

These rivets were bought many years ago in a sale and the lot consisted of many bags of these and other items plus stainless tube etc. Labels quite clearly stated they were all part of a modification kits for Harrier aircraft, just about when they were all scrapped. Steel rivets would not be a sensible item to be used, but monel in the aluminium airframe could be.

Monel is the material to use in boiler making, but not if they turned out to be cheese! Bang!

They are 3/16" diameter snap head and various lengths around 1/2" to 3/4" long. Calculating specific gravity and come out a little lighter than the monel 8.8.

Thread: Steel Prices
13/08/2021 09:52:41

Try your local auction, things come in metal cases and I have found that the steal sheets are worth more than the contents.

Network stuff uses BNC connectors by the million, some brass, some zinc, worth the effort of pulling them off.

Just like 2004 or so when the last commodity price leap happened, never really came down either.

Thread: Drill powered nibblers - buying advice sought.
01/08/2021 09:46:57

Awful things, I bought a Bosch one, flog it to you if you want.

What is wrong? Well, they use a circular punch and die to cut in any direction so the swarf consists of millions of horseshoe shaped bits of metal, which get in the soles of your shoes.

Thread: Digital CNC phase converter build
20/07/2021 20:03:53

This is an interesting thread, lots of opportunity for the magic blue smoke to leave!

What is a split phase 480V AC supply? It seems to be from posts that it is two 240V supplies but independant of each other so you do actually get 480V live to live? Where on earth does it come from? This arrangement of two supplies that can be used live to live seems to be an American thing, 110V to 220V.

Talking about 30kW output, have you costed a 30kW transformer? Might be a long way towards the 3ph install cost.

Don't forget that the only way to convert single to three, or multiple, phase is by using energy storage devices, capacitance, inductance or inertia, and inertia is the cheapest.

Seems to me that buying a diesel generator is much the simplest solution, something about 60kW is about £4k secondhand. Again, be aware of the synchronous reactance which is what makes a 10kW generator power only a 5kW load. For the plasma cutter you don't need AC, since it works internally from a DC bus. Similarly for 400V 3ph VFDs, they all seem to use an internal DC bus and the AC doesn't do anything.

A 100A 400V 3ph supply is about 24kW, seem to be beyond that?

Thread: Blown Bricks : Advice please !
11/07/2021 19:38:00

There is a 20 year old estate in the village, and lots of the bricks are spalling. But only on the walls, none on the houses. These are engineering bricks so unlikely to be softer than the mortar.

Having watched the problem develop over the years, something useful from a dog walk, I think it is the damp getting in the wall. But, we have had hardly any frosty days for years, not this winter, and the bricks still spall so not certain of the reason. The worst affected bricks are the ones on their sides at the top of the wall.

Provided the wall is a brick thick then unlikely to be a safety issue? Just leave them.

Thread: Tooling Auction
05/07/2021 10:15:43

I do wonder if these questions are to make sure the person actually exists?

How many auctions have you bid on and next time the self same stuff is still there.

Thread: GigaFactory
05/07/2021 10:11:23

Something that might be of interest, about the battery management chips used in lithium batteries. They use security pass codes to stop you replacing dead cells.

So it would appear that if you want to repair these battery packs, then only the manufacturer or agent can do it. Otherwise it looks like the battery won't talk to the car, or computer, and both are useless.

All because of safety?

Never really worked out why lead acid batteries aren't used. Yes, heavier, but most cars only have one person in them so the additional weight isn't really important. They are an established technology, can be easily recycled, and can get one cell to match the ampere hours demand of the car, not hundreds of cells in series and parallel.

Thread: What RCD NVR for a workshop?
03/07/2021 11:02:34

Slight complication if you use inverters to run three phase motors from single phase, you must use the Type B ( as far as I can remember) type of RCD.

The RCD works by measuring the imbalance in the current in the live and neutral wires, the problem comes when there is a DC current also in the wires, this saturates the inductor and it will never trip. Hence no safety. Some other devices also put a DC load on the mains, but it is the inverter that is the big problem with model engineers. There is discussion about the old practice of using half wave rectification in TV sets, but they didn't have RCDs then, just the ELCB, earth leakage circuit breaker, no where near as good.

Never ever run a high current load through an extension lead just for the hell of it! If you forget to FULLY unwind it then you will get one hell of a surprise as it explodes. Always fully unwind extension leads for loads over just a 100W or so. The reason? The wound extension lead is a transformer or choke winding, and forcing current through it causes it to heat due to the magnetisation and hysteresis losses as in any inductor. Added to this you are adding in some extra resistance, but more importantly lots of synchronous impedance which will effectively stop the welder working as it should. The welder uses a variable choke to introduce synchronous impedance into the output winding to limit the current.

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