Member postings for duncan webster

when I worked in high vacuum field, all ally forgings were sealed by putting them in an evacuated chamber and letting them outgas for a bit, then a bucket of resin, was posted in through an airlock and the forgings immersed, then let the air in slowly, fish them out and let it harden. I doubt the resin would stand steam temperature. This is all a long time ago, so might be not quite right

I've had just as much trouble with iron castings as with gunmetal with porosity. I put a thin sleeve made from cored bronze in my latest, although I doubt they would have leaked like Furious Fowler's, just a bit of porosity at one end of the bore spoiling the finish

that didn't take long, on it's way

Having a clear out at the ME club I've found an original set of instructions. If anyone wants it send me a pm with your email and delivery address and it's your for the cost of postage

To develop Dave Halford's suggestion, you could put a canister of silica gel in the airline, or you can actually get bottles of dry compressed air, although this could be expensive. On my 2 locos with cast iron cylinders I've just put a lot of oil through after running, they haven't run for some years now (too heavy to manhandle, or I'm getting decrepit) but they still turn over.

When I was still in the day job we used to make large stainless containment boxes which had radiused corners (makes them easier to clean). Instead of trying to form the corners they had a square cut away, the sides folded round and then a made from solid hemisphere chopped into 4 welded in and dressed off. You wouldn't have seen the join. I the link some loco firebox end plates have been done the same way

Edited By duncan webster on 03/10/2023 23:37:05

Sorry, I meant this Hooker, expert on superchargers and jet engines. Well worth a read, Title Not Much of an Engineer available via Amazon in both paperback and Kindle. The paperback is significantly cheaper.

I did say it wasn't a serious suggestion!

This is not a serious suggestion, but I've just re-read Hooker's autobiography where he mentions shedding of Karman vortices as a cause of vibration, so I thought I'd throw it in to add to the confusion.

That's pretty much what mine is, but I think I remember using a thyristor instead of a transistor so once triggered it keeps on blaring away until you disconnect the battery. having a little local difficulty retrieving it from the ex club member who has it at his house, will send in the heavy mob soon!

I put a few banana plug/sockets in the loop to keep lengths manageable, you need a surprisingly long bit to go through a lot of models

Thanks, understood

If you don't have access to the email address on your account here, you should change it before Thursday or you may be locked out.

you might understand this, I don't. Explain please

The problem is club stands where there are lots of valuable models. Quite a few reported instances of things like Stuart Turner Models disappearing, easily slipped into a bag whilst the steward is chatting to an interested onlooker, and then practically untraceable, sold on ebay a few months later where they will fetch Several hundreds of pounds. Perhaps we should engrave a postcode onto our models if we want to display them, but having a frame number on your pushbike doesn't stop it getting pinched. Mine was lifted out of a back garden when #2 son couldn't be bothered locking it up.

And yes, the low life will steal anything

Edited By duncan webster on 02/10/2023 17:55:07

I meant it would take the thief some time. Having resistors in line is potentially better as you say, but a lot of plugs /sockets if each model on display had it's own

The problem with learning from videos is that a lot of them are just plain wrong, some are dangerous. For a complete beginner, the SMEE courses are a good start, but not cheap, especially as they are held in London. When I were a lad you could go to night school and learn about machine tools, but since successive governments have decided that making things is not the thing to do school and tech college workshops have been disposed of. You might be very lucky and find a course near you, but I'm not holding my breath

LHSparey books are a good start and anything by Stan Bray, Neil Wyatt etc. The Sparey one is a bit long in the tooth and won't cover tip tools, but real men use High Speed Steel (dons tin hat and heads for shelter!)

Don't use 3 in 1, that definitely goes gummy over time

Edited By duncan webster on 01/10/2023 23:26:44

But that would take a fair bit of time, so unless the stewards area sleep the simple method is a lot better than nothing, provided it reacts to a cut wire.

well blow me down! I was so troubled by this that I had to do some sums. I took a pendulum with a bob 10 units in mass suspended 10 units from a hinge and then slid a 1 unit mass down the rod in 1 unit increments. Lo and behold the Equivalent Length starts at 10, goes down to 9.76 at 5 units, then back up to 10. the distance to the cg starts at 9.09 and goes up steadily to 10

If anyone wants to repeat the exercise, according to wikipedia the Equivalent Length is (m*d^2+M*D^2)/(m*d+M*D), using the same nomenclature as before. You're never too old to learn something! If it wasn't such a pain to import an image I'd paste it in

Edited By duncan webster on 01/10/2023 21:55:16

I think the alarm relies on a plug holding a N/C switch open, pull out the plug, the switch closes and the alarm sounds. The wire could be string. Not how I'd do it

According to my very old little book provided by United Steel Companies, EN58M is Austenitic Cr-Ni, so should be non magnetic. The M doesn't mean magnetic

But he isn't adding mass, he's moving existing mass down (unless I've completely misunderstood what Joe wrote

However, if I screw the large adjuster nut DOWN (away from pivot, towards bob), so the cg goes down. Not like adding pennies to Big Ben. if m is the little mass and its distance is d, M is bob mass and its distance is D,

distance of cg from hinge = (m*d +M*D)/(m+M) which increases as d increases

so if someone cuts the wire you won't know?