Member postings for Cornish Jack

One of the first lessons learned (the hard way!) on S&R helos was DON'T keep contact with the winch cable when you first touch down - ground or water! Wet winching in Holyhead harbour towards the end of a fairly strenuous session on the wire, I forgot! I was breathing hard, mouth open and got a static short across my teeth - amalgum fillings! Quite startling! A few years previously at Thorney Island we were tasked to liaise with the Farnborough boffins doing research on helo static discharge. The boffins were in the Littlehampton lifeboat and we did several runs to check discharge levels. they told us afterwards that the majority were in the 150-170, 000 volts range! Given that I was acting as the end of line conductor, I'm assuming that the current levels were very low.

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Bill

As I understand it, one function of petrol powered car catalytic exhausts is pollution reduction - BUT to be effective, they need to be at working temperature. Diesels, on the other hand, operate at a similar level throughout. The majority of car journeys are short distance, shopping etc. For me, the Q.E.D is obvious but not to our 'Leaders', indeed it's not ever mentioned in the various discussions. Thoughts??

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Bill

Phil - very impressive. The sort of thing I would like to do but age and incompetence rule against!. My query was a roundabout way of finding out if a sale item would be suitable for an existing collet holder.

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Bill

Thank you Jason and Emgee - " if your collets are close to these dimensions should be OK, " ,,, that's what I was after; Yet another raid on the piggy bank!

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Bill

Thank you Neil - I appreciate what you say about possible fragility but my query is actually about identification. The D1 etc. values shown on the 'net are Imperial to 3 decimal places and the items I have differ by 2 or 3 third place values. They are not marked as to type so I'm wondering if I actually have DA200s or some other type? The closeness of approximation is such as to generate a doubt but I can't find acceptable tolerances for collets and holders. Hope that makes sense - (got to be a first time for everything!!)

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Bill

I have some DA collets which were bought secondhand. Checking against the published dimensions I appear to have a partial saet of DA200s. The checked dimensions are CLOSE TO the published for that range, but not exact. What degree of tolerance should one expect for the D1, D2 and L values ? (I'm assuming the holding value will be to spec)

Any advice appreciated

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Bill

Martin X 2 - many thanks - helpful (and reassuring) It would seem that my overly tight fit is the better bet.

Tim - I quite understand the point you make but for the price paid (including delivery from China,) I could have bought half of the materials (if I was lucky) and then produced an object no more accurate than this. I could well have paid more for the super little chuck than the whole package, so no moans from me on that score.

Hollowpoint - indeed - as noted from time to time in these threads.

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Bill

Couple of pics below of some imported components for a drill spindle. Looks to be well made and needs to be assembled. Thereby lies the problem - the tolerances are 'marginal', in that one of the bearings slotted into place with finger pressure., the other is very much an interference fit. The spindle, as is, won't accept either bearing. Not sure what the fit discrepancy is but I've had the spindle in the freezer for a week or so and still not a finger pressure fit in the bearings. I can foresee jamming problems so would greatly appreciate adfvice on best practice assembly routine for spindle to second bearing and then to housing or second bearing to housing THEN spindle through both at the same time.??? Plus any action to the remaining bearing - heating (and how). Ideas very welcome!

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Bill

Michael - the Vitrex are 9", no grade that I can see. The Abrafiles are a mix, some 8", some 9"" and the only ones I can see graded are two VERY old packs of 'Coarse'

HTH

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Bill

Update on the above post. I now have the Abrafile/Vitrex to hand. There are some 20+ packs, all displaying signs of long term storage. 2 packs only of Vitrex, the rest Abrafile. Give or take a penny or so, they will cost £4.20 for a pack of three (something for the weekend, Sir?), plus postage . These will be long-term available (although at 83, 'long-term' maybe a relative value!!)

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Bill

For general info - I have bought the job lot of Abrafiles (and the Vertex copies) which were on Ebay. This was done to prevent the dreadful rip-off pricing which happened last time this product was being sought. Once I have received them I will make them available at cost plus postage in SMALL lots only. I would not expect delivery for at least 7 to 8 days.

The advantage of Abrafile, as against any of the others is the small diameter fixing pins which allow the blade to be started in the middle of a sheet with minimum material loss.

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Bill

Just received the following **LINK**

11 days for delivery and, at the price, appears to be extraordinarily good value. Had a quick look and it all looks good - the bearings spin sweetly, the chuck is a little jewel and the drive pulley looks to be standard. Don't know whether the "only one left" is 'click-bait' but seems a reasonable bet, price-wise.

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Bill

More a matter of the last week or so, watching the start of 37 million quids worth of trying to modify Nature - or, to be precise, the North Norfolk coast. The antics of the accompanying twin-hulled tow craft are quite amazing. one hopes the results will help to avoid a repeat of the 2013 'excitement' !!

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Bill

Samsaranda - mixing mercury and aircraft was always tricky ! The Britannia you mentioned was a complete write-off - no possible way of tracing all the little globules. Can't remember which, but I seem to remember that at least one of my operational types had mercury triggered crash switches. Post retirement, I worked part-time in a watch and clock shop for a friend. He informed me one morning that he had dropped and broken a stick barometer the previous evening and had swept the resultant mess into the rubbish bin. I did an online search and showed him the results - he was suitably impressed!!

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Bill

Very impressive machine with an equally impressive range of accessories and modifications available. Unfortunately, UK buyers suffer the usual cost problem of U,S, of A imports. I recently had a mantel clock repaired by a local c hap whose main workshop machine was a 'long bed' Sherline and he swore by it. When I first considered it, a big plus was the company's on-line manuals of methods of operation - very informative.

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Bill

I am confused! ... not an unusual condition

I remember Chernobyl but NOT any radiation fears in the UK . Given the normal geostrophic wind patterns of generally West to East I wouldn't have expected any major pollution. The pollution scare which DID register was the Windscale/ Sellafield explosion which caused very specific problems with Welsh sheep for some considerable time afterwards., plus a general concern expressed by our European, particularly Scandinavian, neighbours.

Chernobyl was indeed horrible but one memory remains immovable - the military helicopter crews who VOLUNTARILY flew and hovered over the site dumping concrete to try to contain it, knowing it was a death sentence. How does anyone do that? The ultimate in heroism. R I P

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Bill

Varies between 'gloating' and 'despairing'

The gloating bit comes from remembering the time when the only modifying tool I could afford was a Stanley knife, to having (almost) every machine tool I've ever wanted.

The despair comes from realising I lack the skill to do anything useful with them and the workshop is too overcrowded for comfort, anyway.

Sod's Law is immutable!

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Bill

Thanks, Joe

Ask me another on sport ... equally rubbish at that!!

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Bill

Joe -

.-. --- -... . .-. - --.---.. .-. .--. ..

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Bill

My original posting was looking for comments or a reasoned rebuttal (which I was totally incapable of providing) in a forum with many well qualified to do so. Pity it didn't happen!

However back to the source and this was posted :-

"

Quote:

Originally Posted by Haraka

As a kid I thought I had invented a similar type of system,but it required the geared intervention of an interrupter plate that blocked magnetism .....That was after my attempt to square the circle. (which also went down in flames) .

I also had the same idea as a kid, what is interesting is that I was in college before I finally found an answer to where the 'hidden loss' was that would keep it from working given lossless mechanical perfection, probably not exact but close enough:

Any material that can block magnetism will have induced eddy currents that will create a drag, hence the action of moving the interrupter plate requires more energy than it would if not in a magnetic field.

Even though I knew it would not work I asked various science teachers what the flaw was and none had an answer other than it would not work. I figure out the answer on my own while taking some long forgotten course.

One of the reasons that the 'inventors' of free energy devices get as far as they do is that they rely on the classic "show me why it wont work" (other than conservation of energy of course) rather than proving it will work.

As to Steorn, I believe they may have genuinely thought it was real, my theory on why it failed outside demos is that they were unknowingly tapping energy from the slightly unbalanced magnetic fields of a nearby high tension transmission line. "

Thanks to MurphyWasRight

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Bill