Member postings for Andrew Tinsley

Sounds as though it might simply be an earth leakage trip having tripped in the consumer unit for the workshop. Worth a quick check.

Andrew.

Like Martin, I have been meaning to make one for many years! I will now get stuck in, thanks Bernard!

Andrew.

I used the Ebay search engine for Loctite 243 and I clicked on one of the first few items. I shall take a bit more care in future. I must admit I didn't spot the fraud for a couple of days!

Andrew.

Sorry Michael and all, I should have said Loctite 243 threadlocker. I got the Locttlf version. I didn't realise the spelling wasn't Loctite for a couple of days!

Andrew.

Turns out that the Loctite 243 that I purchased from Ebay is a FAKE, I am trying to work out how one registers a complaint to Ebay, but cannot see how to do so. Anyone know how to do this?

Andrew,

Just purchased some Loctite 254. It is in a bilingual container (English / Chinese and it says made in China.

Is this just more offshore manufacturing or is the product dubious? Certainly looks like a Loctite container.

Andrew.

The Arc set is out of stock, more is the pity as I would like to buy a set.

Andrew.

Strangely enough, I do use carbon steel tooling on my watchmakers lathe. The reasons? Well I find it difficult to find small cross section HSS and I have a lot of carbon steel, small cross section blanks, that came with the lathe.

The carbon steel tooling lasts a long time between sharpening (presumably as cuts are small), it is easy to get the edge back using a stone, when it does need sharpening. It also produces a better finish than my odd HSS tool.

If someone had told me forty years ago that I would be using carbon steel tooling, I would have laughed in his face!

Andrew.

I have been lucky buying second hand reamers. Most have been good to excellent with only a few being no good. I suspect I may have been lucky. I only use machine reamers if possible and then only with a floating reamer holder. Doing it like that has always given me good holes. Before using the floating holder, it didn't always work out too well.

I only use hand reamers if I really have to. My technique must be very poor as the results are usually poor as well !

Andrew.

I would be interested in the answer, I have a slightly bent long series drill. I have tried several ways to straighten it and failed. At the moment it is awaiting conversion to a normal jobber length!

I suspect it is hardly worth the effort depending on the cost of a replacement.

Andrew.

I purchased a 4 jaw independent, slim, Myford threaded chuck from Rotagrip, maybe 5 years ago, so they may not yet be extinct.

I don't know of any current 3 jaw chuck with a Myford thread. I have an Arc 3 jaw Chinese chuck. I believe they are made by Sanou but marked Arc. My Arc /  Sanou chuck was quite a revelation. The quality and finish were far better than anyone could expect from its modest price. Maybe not up to Burnerd  standards, but not far off.

Andrew.

Edited By Andrew Tinsley on 26/01/2021 18:47:24

I suggest that you do the experiment yourself, you might well be surprised at what you find! No point in arguing the toss when you can actually do the taper turning and measure the result,. I did and was very surprised I could not measure any meaningful convex shape. This was on an MT2 taper.

Andrew.

Hello Old Mart,

What is quoted above is quite correct. What your Smart and Brown extract doesn't say, is how big the convex error is.

GHT did the measurements and showed conclusively that the errors are minute, even if the tool height is out by a fair amount. The Smart and Brown manual is an example of this old chestnut being repeated down the ages with no body bothering to check it in practice.

After reading GHT's comment a few years ago, I repeated his experiment and could not measure any difference in the taper for a tool height error of I think +- 5 thou. It was a long time ago!

Andrew.

I seem to remember that G H Thomas experimented with varying tool heights when turning Morse Tapers. I think his conclusion was "take the proverbial pinch of salt" about getting the tool height dead centre. .

Having the tool off centre by a few thou, didn't alter the taper within his measurement capability.. I think he said that it was a bit of an old wives tale, passed down from one book / article, to the next.

Andrew

It is pretty obvious that my ideas of a safety critical calculation is miles away from what is understood by model engineering boiler makers.

I agree with Phil 's comments above, the so called calculations are simply trivial or non existent. If I had realised this in the first place, I would not have posted.

It would appear that most things are decided by past practice and no real calculations are involved. In a past life I was responsible for some safety critical calculations on nuclear reactor pressure vessels and I was expecting a derated version of this type of calculation. My apologies for misunderstanding the context of safety calculations in model boilers.

Thanks everyone,

Andrew.

Hello Brian H,

The UK link you give does not give the basis of the required calculations and KN Harris' book, although an excellent one, gives no information on the required calculations either.

I will peruse the Australian code with interest, something that I have not done. Thanks Duncan too.

Andrew.

Hi Peter,

The shadow graph hasn't passed. I have one in my workshop and for jobs like this, you can't beat it!

Andrew.

None of the books on model boilers give any indication of how to calculate the strength of the shell. Even the older ones going back to Greenly's time, don't give such calculations.

Also never seen a published boiler design that gives the calculations.I suspect that the calculations are simple minded ones coupled with using "normal good practice".

Doing a proper strength calculation on a model boiler isn't trivial and I am not too sure that many boiler inspectors would be able to follow the maths anyway.

Please tell me if any books or designs do have the calculations, it would be interesting to see.

Andrew.

I have made quite a few copper boilers, some to my own design. Never had a problem certifying them until this latest one. The boiler is for a 3.5" gauge Quarry Hunslet. Looking at a couple of published designs, show them to be very similar (as perhaps one might expect)

I have now been asked to provide boiler safety calculations, which is quite reasonable. However to do a proper stress calculation for the complete boiler looks as though it could turn int quite a complex exercise, if done correctly.

Can anyone point me to what is required and how straightforward or otherwise these calculations are?

I am quite relaxed about the results, as comparing my designs to published ones. I always err on the safe side and my boilers are probably stronger than most.

Andrew.

Hello SOD

The digital height gauge that I repaired was just out of guarantee Mitutoyo. So you think digital height gauges are more reliable than mechanical ones? I don't! I have also had complete failures of two expensive digital calipers, again just outside guarantee period.

My mechanical Kanon height gauge is going strong after almost 50 years, as are several mechanical vernier calipers of good manufacture, again getting on for 50 years of age. I bet a pound to a penny that most electronic measuring kit won't last that long.

Andrew.