Member postings for CHARLES lipscombe

Can anyone supply me with a formula for calculating compression pressure from bore/stroke/compression ratio for internal combustion engines?

Chas

Thanks Oily Rag! I was right, it is an interesting bit of gear Threading up to a face is particularly interesting.

The only problem now is where to get one!

Chas

OILY RAG: The Wardson Easi-thread sounds like an interesting bit of gear. I have not been able to find any information on the internet about these. I did find a Wardson Esi-thread which is for threading sewing needles. Not a lot of use

Can anyone point me to a source of information or supply of one of these?

Chas

A very unsettling experience Tony which I am sorry to hear you went through.

The wife of a friend of mine had a similar experience some 2-3 years ago but has had no problems since and no clear cause has emerged.

I have had a lesser experience in the course of international travel, but there was a clearly identifiable cause which was a combination of extreme fatigue, lack of sleep and jet lag.

I was walking down a corridor at Manila airport which had no natural daylight and I suddenly realised that I had no idea what time it was, whereabouts in the world I was, why I was there or why I was walking down this corridor. I just kept walking and luckily I was able to piece things together quite quickly when I emerged from the corridor. That experience was quite scary enough for me albeit much less severe than yours

Chas

I'm not sure about the ease of application issue. I am currently using an acrylic paint which is sooooo easy to spray and avoid runs. The trick with acrylics in my experience is to put them on "so wet it frightens you" to avoid orange peel. In my case the paint colour is black which in all paint systems is usually the most troublesome colour to spray. This is because the carbon pigment which is almost universally used in black paints, affects flow of the paint in a way that promotes runs.

Why do I use acrylic? I am painting replica bulb horns (think Laurel & Hardy and model T fords). The product is unlikely to have contact with solvent e.g. petrol , drying to the dust and insect proof stage takes about 2 minutes and I get a gloss finish. What's not to like? It's the usual story of horses for courses.

Chas

S.O.D.

You are right on the money regarding the term Enamel, we would all be better off if this term was consigned to oblivion. Historically, the alkyd paints were so far in front of anything else when they appeared that the term enamel was not an unreasonable comparison.

Complicated? I think it all depends on your background, the other man’s technology often appears that way to the outsider. After a lifetime working as a chemist on the resins used to make paint it seems easy to me! But I really struggle with some of the articles in MEW and anything electronic baffles me completely.

Paint technology suffers from two extra complications not found in engineering i.e. meaningless terms like enamel and coach paint, and tradition.

Painting is a hot-bed of traditional ideas, often against all logic. Why would anyone would want to paint something in cellulose paint when modern paints are better in every conceivable way? Presumably because their vehicles were originally painted in cellulose and they want an original-looking finish? Modern finishes are visually indistinguishable from a first-class job in cellulose and if you can't see the difference,what is the point?

I have been retired (gratefully) for 20 years now so I am not up to date with the very latest, especially in Europe (I live in Australia). It was interesting to me that with all the fire/explosive problems of cellulose paints, they were eventually banned on emission grounds. Especially so because the acrylics use similar solvents.

Nick Clarke.

Yes always go to a specialist or risk disappointment later. Also be careful to use products from one brand. If you use one brand of paint and someone else’s thinner for example, you are giving the paint manufacturer an automatic get-out clause if anything goes wrong.

Andy Carlsen

Yes there are many different acrylics (and alkyds, and polyurethanes, and polyesters) and to me it is debatable whether for a layman it is worth acquiring more than a basic knowledge. It is enough to know that acrylics are generally excellent but normally affected by petrol while polyurethanes are just as good or better than acrylics and not affected.

Generally:

I have yet to see a water-based finish that would be suitable for the kind of items that we make.

Becoming popular in Australia amongst hobbyists for high temperature situations is Brake Caliper Paint . This requires mild stoving conditions but is high gloss, durable and as tough as old boots. It is one-pack and I would guess is a polyurethane.

Chas

The OP asked for a history of paints so hopefully this post will clarify a few things. Historically until about 1900 all paints belonged to a category called oleo-resinous varnishes. In other words they were linseed oil or similar, in which was dissolved a natural resin e.g. rosin, kauri gum etc, plus pigment and solvent. These paints dry by oxidation which means that they do not become hard enough to sand for a few weeks.These paints have two drawbacks 1. that they yellow on ageing and 2. they crack over time to produce an aligator-skin like effect that will be well-known to the restorers of vintage vehicles. Because of their tendency to darken the so-called heritage colours on victorian buildings tended to dark greens and reds, browns and also cream (where yellowing was not so obvious). They are well and truely obsolete nowadays.

Cellulose paints appeared around 1900 and are fast-drying, have high gloss and are reasonably durable. The explosive properties of the guncotton used to make them and the extreme fire hazard of cellulose paints meant that the paint manufacturers heaved a sigh of relief when alternatives became available and promptly dropped cellulose paints from their lists.

In 1930 paints were placed on the market where the natural resins in oleoresinous paints were replaced by a synthetic resin (alkyd paints). These had excellent colour stability, durability and were cheap. Therefore they replaced the oloeresinous paints almost overnight. These paints were universally used from 1930 up until about 1960 and still have a big use today. It is worth noting that they are only partially synthetic because they still use Linseed or similar oils in their chemistry

The alkyd paints because of their hardness and high gloss were given the trade name enamels in a reference to vitreous enamels. The word enamel in a paint context is misleading and still causes confusion when used for some modern paints. It is a term best forgotten!

Around 1960 many types of paint became popular in place of the universally used alkyd.

Acrylic paints were popular for a time and use what is essentially perspex dissolved in solvent. They are the modern equivalent of nitrocellulose without the hazards and give high gloss and very good durability. They require powerful solvents and can be quite expensive.

The 2-pack isocyanates give a performance previously unobtainable in terms of gloss retention, colour retention and durability. Their toxicity is a problem. Safety precautions should be followed rigidly with these paints but the risk is possibly quite low for most people. As with other toxins, individual susceptibility is a major factor and you might be more-or-less immune. On the other hand you might be ultra-susceptible and you won't know this until it is too late (this is why some people smoke cigarettes heavily to a ripe old age while other smokers succumb to cancer in their 30's).

Through the 1980's to about 2000 polyester paints were widely used for cars etc. These are alkyd paints where the chemistry of the base resin has been modified to replace linseed oil. Thus they are fully synthetic but need precise application conditions to succeed and as far as I know they are not sold for retail purposes.

Of late there have been major efforts made to move to water-based systems for ecological reasons. Except for some industrial applications which again are carried out under closely controlled conditions (and the very popular latex house paints which are a different animal),these are not much cop in my experience for hobby or retail use.

If I was finishing a model I would use an alkyd paint or a 2-pack isocyanate depending on how the model was to be used.

Anyone care to comment?

Chas

A bit off-topic but tip I picked up from another post - use a Stevenson's collet block mounted in a 4-jaw chuck. The amount of time and trouble this idea has saved me is incredible. It is also a lot cheaper than some of the alternative collet holding devices out there

Chas

Thanks Jason, I had not followed the linked subject as far as I thought I had. In practice the point angle of a spotting deal does not seem to matter much except for hard materials. This is something of a relief for me as I became aware of spotting drills through the forum some time ago and thinking I was being smart, I ordered ones with a 120 degree angle (which seem to work very well).

Do you re-sharpen your spotting drills? Presumably this would need a good deal of accuracy, better than off-hand grinding ?

Chas

A very informative set of replies which I intend to make use of. Thanks guys!

Just one question: Why would you use a centre drill with a 142 deg angle? My own centre drills are 120 degree which is more-or-less the angle of the drill tip.

I think it would be hard to find a more genuine and helpful bloke than Ketan anywhere. In my experience the goods he sells represent good value for money and are carefully chosen to be suitable for our hobby. Obviously many others share this opinion or his business would not have thrived as it has.

Nowadays I usually buy what are obviously ARC items from Ausee here in Australia, simply because that way I avoid horrendous postal charges from the UK. I would be interested to know what the link is between Ausee and ARC.

Re the forum: I am a self-taught machinist and have found a number of postings here which taken together have greatly helped me expand my limited skills. +1 for Larry Phelans comments above, and I hope Ketan draws strength from that

My thanks to everyone who replied. As usual there is not a simple answer, it depends on quality of material, foundry technique etc. It does seem however that for the small castings we use in model engineering it is less likely to be a problem than with large industrial components where uneven cooling stresses are more likely.

I found S.O.D.'s comments particularly interesting (as usual!) especially regarding sash weights. These were often recommended as a source of cast iron for modellers in days gone by. I have personally encountered all known defects of cast iron in a single sash weight. Avoid like the plague!

Best wishes, Chas

In a recent thread concerning painting cast iron, Andrew Johnston mentioned the seasoning of cast iron. Rather than hijack that thread I have started this one to try and find out a bit more about this subject.

Certainly it used to be fervently believed that seasoning castings made from cast iron was necessary to relieve stresses and avoid distortion after machining. There were many ideas on exactly how to do this, some of doubtful merit including urinating on it.

If seasoning was ever necessary, was this because of the grades of CI available at the time, and possibly their method of production? Therefore not necessary now?

Does Andrew or anyone else ever season CI castings, i.e.is seasoning relevant nowadays? Especially for the size of castings we are likely to encounter in model-making activities.

If it is relevant, what sort of temperature/time cycles are we talking about?

Chas

Larry Phelan: Could you please supply details (sketch?) of the craftsman lathes clamps for preventing the chuck from unscrewing in reverse?

I have this problem on my Taiwanese lathe maybe because it sees and has seen a lot of use and I frequently change between 3 and 4-jaw chucks. The 3-jaw is due for replacement when "we get out the other side" of corona virus but even so I would like to have a positive lock.

Chas

It will be interesting to see if the F1 race in Melbourne goes ahead next week. I am sure it will because of the money involved and money is always the main deciding factor. It would mean the entire Ferrari entourage from close to the corona hotspot in Northern Italy will enter Australia without quarantine restrictions.

We have also had a case of a doctor who had been overseas, had flu-like symptoms and went to work treating 70 patients. He is now confirmed as having corona virus.The government have quarantined all 70 patients.

Am I optimistic that corona virus will be contained - what do you think?

To Mark Rand:

I would cheerfully bare my bum in public if I thought that would convince anyone to think instead of blindly accepting what they hear from "experts".

Unfortunately Mark's post is typical of the response of many climate change believers - denigration and insult of anyone who has an alternative point of view.

Maybe Mark follows the common belief that all scientists are to be trusted. After a lifetime as a scientist I can assure him they are not all purely disinterested men of science. As Paul Whitley said "it is very hard to get a man to tell the truth when his paycheck depends on it". If you want proof of this just look at standard ,legal practice where the defence and the prosecution field "experts" with opinions that suit their respective employers.

I repeat my assertion to Mark that it would be well-nigh impossible to get a university grant to discredit global warming - not for any logical reason, but because universities tend to be populated by radicals pushing their latest cause.

Chas

I have deep reservations about much that is said and reported on global warming. The current and often left-wing attitude to anyone that does not believe in global warming is that you are not just wrong, you are bad as well. Just try getting university grant these days to produce evidence against global warming. On the other hand you could easily be forced out of your university job because you hold the "wrong" views

As a confirmed cynic I note that while there is great attention paid to saving the planet through getting rid of items like plastic cups but total silence on the destruction of the amazon forest and the indonesian/borneo rainforests. The amazon is said to produce 16% of the worlds oxygen - worth bothering about? Or is this aspect of global warming just too difficult to deal with?

A look at the world atlas reveals the whole global warming hoax - there are much bigger land areas in the north of the planet than in most of the areas now popular for human habitation. If the planet does warm to any great extent the human population will just migrate to what are currently the frozen north parts of the planet.

Chas

Villiers were quite keen users of their own thread forms. Their later, larger carburetters incorporate a whole range of different standard threads e.g. BSF, BA, BSC as well as their own threads.

Chas

I tap quite a lot of stainless but restrict myself to 303 and 304 grades which are much easier to tap than 316.

What I have found is that HQS taps from the Tap and Die Co cut stainless very well, just as they are advertised to do. However they seem to be some form of carbon steel and do not cut for long before they go blunt. I have now abandoned these and gone to HSS only.

For tapping I use Trefolex for general purpose tapping, in the possibly mistaken belief that this is what everyone else uses. For screw-cutting in the lathe I use an American product, Tap Magic which works just as well as Trefolex but has the added advantage that being transparent it makes it easier to see what is going on.

I am surprised that people find WD 40 suitable for tapping, I would have thought that its constituents of Paraffin and fish oil would not provide enough lubrication, except for Aluminium.

Following on from SOD's posting, there is a"Hybrid" way of holding work using collets that I learned from another thread some time ago. If you buy a Stevensons' collet block from ARC Trading, you can mount this in a 4-Jaw chuck and use collets to hold the work. This dodge has saved me hours when mounting repetitive jobs to run true.

Just one of the many things I have learned from the forum

Usual disclaimer re Arc Trading, Chas