Member postings for John ATTLEE

Bob,

Clive has reminded me of what I have forgotten from my days at Smiths Industries many moons ago. He is absolutely right on what he says about Nemags etc and the RPM with one exception. It may be that different hairsprings were fitted. However, my recollection is that calibration was achieved by altering the magnetism of the mechanism so that there was more or less drag pulling the needle around.

I think that you can put a pointer on the speedo cable and count the number of rotations of the road wheel to get one of the pointer (after taking into account any effect of the diff).

I will note Mike Flannery for my own purposes.

John

Bob,

A corrector gear box can be fitted between two speedo cables and Speedy cables or Thomas Richfield could advise or you could make one yourself. Suitable range of small gear available from RS. You could put a different scale on the speedo but be very careful not to interfere with the needle. The only problem is that the odometer will not read correctly and I always find that a pain. Don't worry about the MOT as there is no requirement for it to be calibrated. However, it does have to read correctly within certain percentages and it is a pain if it does not.

Speedy Cables can probably make the ododmeter read correctly. They can also zero the mileage if you have no confidence that anything like the correct mileage is being shown. It is quite fun to know how many miles YOU have driven it the vehicle in total, especially if you have overhauled it.

John

Dear Margaret,

I have made an M14 x 1.5 mm flange nut for you. If it does not fit then you probably need a 9/16 UNF nut as discussed. If you PM me your address I can pop the nut in First class post tomorrow morning.

John

Dear Margaret,

I will have 9/16th dia FULL nuts but I think that they will be BSF. I may also have a 9/16th UNF tap. I will check what I have got later this afternoon or tomorrow morning. Don't despair!

John

Justin, it looks as if the plate is secured to a wooden block by wood screws which I would have thought is nowhere near rigid enough. I can understand why you have done it that way. Others might be able to suggest how to mill a relative large (relative to its thickness) plate. I would clamp it in multiple places but expect it not to be completely flat. Perhaps soldering it to a heavier plate /block or using a suitable adhesive that would come apart with heat. Both techniques would have a parallelism problem wrt to its base.

John

Thank you Roger!

It was the ortho snap but I did not understand the effect that it would have.

Many thanks,

John

Dear All,

Help! I have managed to get my Turbocad stuck on orthagonal so I cannot draw a line at an angle however hard I try. I cant switch it off! Any hints please!

John

Yes, it was great. Especially good was the earth moving equipment being allowed to really work.

John

Dear All, in answer to Tom Pratt, I would agree that i was being a bit sanctimonious and i might even be a bit hypocritical because I am not that PC myself. However, I would push back on the twit bit!

In answer to Bob, nearly all my engineering activities either directly or indirectly supports the REME Museum which is a registered charity.

Recently I made an accessory drive pulley wheel for my 190 ton Scammell Contractor. The blank was 230 mm dia and 125 long it weighed 40 Kgs when I started. The Contractor is used to transport REME Museum owned heavy armoured vehicles to steam and military vehicle shows around the country in order that the maximum number of people can enjoy and understand them.

I have been undertaking a longer term project on the REME Museum's Conqueror ARV. Amongst other things I have rebuilt the Meteor M120 petrol engine that is basically an automotive version of the Merlin engine. I had to make an extensive range of tooling to do this. Note that the tank does not belong to me and I cover all the costs of the engineering work.

I am pleased to say the Conqueror performed well at the recent Capel military vehicle show and large numbers of the public enjoyed seeing it.

I really enjoy this forum even if we josh each other a bit. I do rather larger work than models at the moment but the tips and advice are invaluable.

If anyone needs access to a slightly larger lathe or milling machine, I am near Portsmouth.

John

Personally, I would prefer to use what modest skills and facilities I enjoy to benefit society!

John

Surely a mains voltage system uses Earth Electrical Bonding and Automatic Disconnection of Supply. A critical feature of any installation is that ALL metalwork is electrically bonded and thus it is all at the same potential. Writing this has given me a horrible thought, my little Atlas lathe is plugged in via a three pin plug. Have I separately bonded it to the metalwork of the ISO container? If I have not, I certainly will in order to avoid precisely the problem that Samsaranda describes.

The danger is that a damaged electrical flex, say, could make a machine become live and then we grasp it firmly and good night. If it is permanently bonded to earth potential then the fuse, MCB or RCD will trip and all will be well.

John

On a Meteor / Merlin the rotor turns at, I think, 3 times camshaft speed. I suspect that this is in order to give enough energy for the coil. The points camshaft and rotor arm are geared to rotate at camshaft speed. I don't know if this is relevant without a pic of the mag in question.

John

Dear All,

I use a regular industrial supplier but I buy whole lengths unless I want a lens, eg 200 mm dia 17 mm long. Last Nov I bought a 10' length of 27mm ENIA Pb for £44 + VAT.

In April I bought a lens dia 200 X 17 lg and it was £23 + VAT.

I bought a length of 36 mm hex and thought that it would last the rest of my life but I am using it up quite fast!

John

I also think that Jelly's idea is a great one and solves a problem for me. On my Denham lathe, the travel on the tailstock is only about 1.25 inches for some reason. This means that I often have to take several bites to make a deep hole and I have suffered from poor productivity so far as drilling is concerned. I frequently have to drill more than 1" dia.

Also where I have a large dia workpiece, sometimes that carriage will not clear the chuck jaws and thus I cannot get it out of the way. The DRO reader does not help. Thus the tailstock is not close enough to the work piece. I do have a 3 MT extension but it is obviously not a desirable set-up.

I don't use QCTPs but I have indexable tool holders mounted in square blocks so the tool height is always correct. The block is secured by a single 5/8 stud and there are four tapped holes on the top of the compound slide.

I think that I would go for a square block bored out to 3 MT to hold the drill and with a male 3 MT end. Obviously it would be made by holding the tool with the male 3 MT mounted in the chuck and the female 3 MT bored and reamed. I would provide some means of extracting / ejecting the drill. The height will always be correct.

To set up, I would plug the male 3MT into the tailstock and then clamp the block (by two studs) to the top of the compound slide on the carriage. Zero the X axis on the DRO and I would be good to go.

I cant wait to do it!

John

Dear All,

I would go along with what everyone has said. I would just add that on a tank like a Centurion or Conqueror, the road wheel hubs are filled right up with grease AND the lips of the seal face outwards. This is entirely consistent with what has been posted. The intent here is to ensure that little or nothing, including water, can get IN because there is no space available. Regular greasing would tend to push any muck out.

John

I fitted a standard Chinese DRO system from a well known dealer near Guildford to my ancient Victoria Elliot U2 milling machine. Scales on all three axes. It absolutely transformed the machine. It makes the machine far more accurate and productive.

To test it, using the PCD function, I centre drilled 6 holes on a 1" PCD on two separate pieces of 5/16 ally alloy plate. Drilled through with 5/16 drill. Made up 6 off 5/16 dowels which were a light push fit in the holes. All six would push into place whichever way I assembled the two plates. That was good enough for me!

John

Given the very small number of people who would have the necessary, skill, experience and willingness to do the job, I think that they are wise to concentrate on finding someone first and then consider what 'tickets' might be needed.

John

It looks just a little bit later than mine which is a U2. Your vertical head looks much more robust than mine. What does the hand wheel on the vertical head do?

If you put a DRO on it, you will massively increase its productivity and you will find that you use the machine more. Best to have it on all three axes.

John

Peter,

I purchased a Vertex BS1 and I am pleased with it. It did not come with a chuck but I knew that and was happy with that. It was about £500 with VAT.

I have made a set of 12 DP change gears for my Denham Lathe. I also made a 127 hole plate in order to make a 127 tooth gear wheel for my lathe.

Make sure that you want a dividing head rather than an indexing head that can do 2,3,4,6and 12 divisions. The Vertex BS1 can do indexing as well for speed.

John

By my calculations, 20 watts continuously would cost about £1 per week. I think that I will try a 20 watt heater this winter and see if it can protect my bigger lathe.

PS How do I attach a photo to a post?

John