Member postings for Jerry Wray

The numbers quoted for viscosity do have meaning. I have carried out many thousands of viscosity measurements by many differnt methods over the past fifty years. You can look-up the meanings of the various SAE figures on the web.

There is whole body of instructional and disputational text on viscometry which makes this a subject for the academic. However the practical applications are relatively simple in industry where robustness of method and results are subject to time constraints. One such example is in the varnish kitchen where the viscosity of the varnish being 'cooked' can change whilst the measurement is being done.

The basic and simplest methods are measurements of flow rate, that is the time taken for a specified volume to flow, for example, through a specific sized hole. The apparatus used is generally a so called flow-cup. You can visualise these methods by imagining punching as hole in a bucket, filling the bucket with the liquid in question and timing how long the bucket takes to empty. For comparative purposes the temperature need to be known for each measurement. The results are reported as so many seconds at the test temperature. There are legion of cups in use, in the gravure printing industry the Zahn cups ( small bucket on a stick) are most favoured, in the car painting business in the US the Ford No. 4 cup held sway, and in the UK the BS.B4 cup, nominally equivalent to the Ford 4, in practice these could only be compared when one or other had a conversion factor applied.

Of course this sort of method only works well for Newtonian liquids. ( search Google for an explanation of Newtonian!) Non-Newtonian materials gels, thixotropes, dilatants, semi-fluids, foodstuffs, etc. etc. have to be tested in different ways often by methods which involve rotation of a paddle in the liquid and measuring the amount a spring is either stretched or compresessed. The classic instrument for this is the Brookfield Viscometer.

Jerry

Robin,

I have exactly the same bandsaw on which I cut metals quite happily for small jobs, using a metal grade blade, but I also have a metal bandsaw which I use for major cuttting work.

But 35 quid for a blade! Have you tried Tuffsaws? Lots of MEs use him.

**LINK**

Not only are his blades excellent quality but he is a fount of knowledge. He is very helpful and will make blades to taste very quickly. On occasion he has given me overnight service. Try him!

Jerry

If you look into the general world in which we in the UK have to operate I think you might find that the words 'should' and 'must' are equavalent and that any atempt to differentiate them will eventually lead you an appearance in front of a man or woman garbed in a wig and red coat sitting in judgement on you where formality is the order of the day, where every word you utter is written down and being told to justify yourself.

Jerry

I should endorse Clive's comment about WD40. This and other similar products are not simple lubricants. They leave a deposit on the surface, which is part of how they function. Although this is only a thin film it is such that anything which is built to close tolerances will be sufficiently affected as to cause problems, in some cases leading to jamming.

Jeryy

Having recently retired after more years in the technology side of the UK paiint industry than I care to count I always read the posts about paint and related subjects with interest.

We should all realise that anything that occurred in the UK industry up to about 1980 is unlikely now to be reproducible today. The majority of the industry has gone the same route as engineering, the money men took over and took command of the techmical side. Since the work at the bench had no obvious value more and more has been imported and many skils disappeared. (end of rant). Both US and Continental European practice has been at variance with that of the UK.

Unfortunately computeised colour matching is dependendant on the characteristics of the colouring pigments that it has been fed and will attempt to match any colour it is presented with with what it knows about and has available. Some mixing schemes will operate on only 7 pigment bases and nearly all on 12 0r less.

Ol' Fred who made the colour in 1924 (post grouping) that you are trying to match when presented with a colour to match from the customer may well have sent his lad to the dry colour stores for a particular shade that he knows will give that shade or its particular undertone. He might have made fifty gallons as a first batch and used just a few ounces of the special to get the effect he wants. No way could anybody then or perhaps even now discovere what particular special Joe had used. That way led to madness of course, the paint maker down the track may have old Joe with his own colour matching ideas. See Mark Ps post.

Just a final word about RAL colours and other standards. BS381C was the first standard across the Commonwealth for Industrial colours, RAL was not heard of in Britain until the late 1960s. When first used here much effort was expended trying to achieve the colour values printed on the back of the master patterns until it was realised that only certain German companies actually achieved those coordinates. France had a different scheme - AFNOR.

Jerry

With reference to your fifth paragraph Shakespeare had a phrase which is relevant even today concerning smells,sweets, and roses.

It's not the name that's important. Don't get hung up and put form before function.

When I was involved in boat building the blade quides on the bandsaws, Wadkin, Startrite, Record etc. were all lignum vitae. I still have a small stash ready for when I next need something as hard bur self lubricating.

Jerry

Thanks Bazyle and JasonB,

I have a very worn 6mm shank End Mills which I will try to grind into a (hopefully) suitable form to act as a tap. I also have some files which was my father's which he used to use to cut large Whitworth threads for earth moving machinery. I just need to dig them out, from his toolboxes (not from the earth).

Good job I am now retired.

Jerry

Tracy were my first thought. If I consider for example a 6mm shank 20 tpi is 1.27 mm pitch (25.4/20 ). I don't know if this i sufficiently accurate as a 6mm collet has an internal thread of almost an inch.

Jerry

I need to clean-up some threads in screwed shank collets and end mills.

I believe these threads are Whitworth form of 20 tpi with diameters equal to the shank, either imperial or metric THe tread form and pitch are the same for both.

Harold Hall's Metalworkers Data Book confirms these dimensions.

Can some one advise me where I can obtain taps and dies to these sizes. I have tried the usual sources.

Thanks

Jerry

Thanks for the link Michael, but that doesn't tell me anything. Its just a sales blurb, I would need to see an explanation of the chemistry before I used any unknown composition where high temperatures and naked flames are anticipated. The missing information of course is the composition of the binder.

The mention of Zircon above implied that the posters had actual experience. Zircon in that link is merely being used as a trade name (registered or otherwise). Zircon as we well know is a gemstone.

I am not doubting the claims made but surely the performance relies on the conversion of the Zircon into zirconia at high temperatures.

Jerry

Can someone tell me what they mean by 'zircon paint' and where and from whom it might be obtained?

What are its particular characteristics?

Jerry

I know this is cheeky on this site but does anyone know whether the Model Engine Maker (MEM) site is down?

I have not been able to connect since Monday pm.

Any news please.

Jerry

A note about the regs. pointed to above. The relevant word is 'spirits'

In the end its all about taxation. A consideration may be the source of the ethanol. If you are being supplied with ethanol from somebody's dutiable source, that's to say on which duty has not been paid, then you could be in trouble.

Meths and it's synonyms are supplied with a denaturant . In the past methanol, hence the methies you would find on .the park benches. It was quite straightforward to distil that off.

Nowadays other denaturants are in common use, including 'Bitrex' (look it up on the web) which makes the beverage undrinkable. Removing this is almost impossible and its presence is almost undetectable unless you try to drink it..

Once denatured and duty paid then OK. See the shelves of the 'sheds'. Remove the denaturant then trouble ensues.

Jerry

Some of you on here will know of my obsession s about coolant (metal working fluids). No mention gets ignored by me.

Has anyone tried through tool coolant?

Jerry

Just a follow on about the HSE myth busters.

If you are really interested in the sorts of accidents that do occur subscribe to the prosecutions listing, you can get a daily listing and/or a summary; these do name 'and shame' and give a summary of the evidence produces in court. As everyone here will appreciate machine guarding features in most cases.

A further resource provided by the same organisation, and considerably larger but less detailed is the enforcement database. This shows both Prohibition Notices and Improvement Notices. From this you can see how many any particular company or Industry has been issued with.

You might be surprised at the names (no individuals, only businesses) which appear from time to time. Of course this reflects HSE's inspection regime. **LINK**

Jerry

I bow to your greater knowledge.

Jerry

I bow to your greater knowledge.

Jerry

Oh No! Not van de Waals forces! There has been much correspondence amongst physicist disputing the existence of these. Perhaps we should all back-off until we have read the latest research papers, Then we might be able to take a view.

For the uninitiated these forces have been in dispute for at least forty years.

Jerry

If anyone has a technique for completely removing the layer of oil from metals I would be pleased to hear it. I have tried to remove the last mono-molecular layer when I worked on food and pharmaceutical packaging, but without success.

Any tips, the nearest we have come is washing in toluene followed by ultrasonics , using water borne and solvent borne methods. Unfortunately the water miscible systems involve wetting agents which themselves leave behind a film.

Jerry