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Post by 92220 on Dec 9, 2023 21:30:00 GMT
Those photos really show the quality and workmanship!!! Wow!!!
On the point about using steel shim for the pointer and slight concerns over rust prevention, why not use either brass or nickel silver to make the pointer? Both of these can be chemically blackened. You can even black anodise aluminium at home. There are a number or very impressive descriptions of how to home anodise, on the internet.
Bob.
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Post by 92220 on Dec 9, 2023 11:23:08 GMT
Hi Roger.
That little "gearbox" looks superb!! An amazing bit of workmanship!!! You might find this ebay listing useful for stainless wire....eBay item number:165108275621 It is stainless steel piano wire in various diameters from 0.2mm up to 8mm, so you should be able to find a size to suit your gears.
Bob.
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Post by 92220 on Dec 3, 2023 9:39:54 GMT
I have got my 7 1/4” Wren in bits for a variety of jobs. Fitting tyres to the wheels and new crank pins, plus the boiler had to come off for an “undressed” inspection. She is close on 40 years old and upon washing the oil and grease off with kerosene the paint is quite patchy in places. A question for those who have tackled a job like this, how far do you go with the strip down before painting. Mine is down to frames, cylinders, buffer beams, smoke box and saddle. Is that far enough, leaving the slidebars and motion brackets in place? What type of paint would be best, although some of the UK options might not be available here in NZ? Hi Chris. Be careful which type of kerosene you use for degreasing. If it is the sort used for oil lamps, it is likely to leave a greasy film which paint will not like! If you are stripping back to bare metal, the best solvent for degreasing is cellulose thinners. If degreasing surfaces that still have paint on them, use white spirit or turpentine substitute. White spirit is available in NZ from sales@pacer.co.nz This is their website www.pacer.co.nz/product-group/1845-white-spirits/category/404-solventsBob.
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Post by 92220 on Nov 28, 2023 10:36:19 GMT
If it can still be used for "legitimate use," then use with a gas torch is "legitimate use".
Bob.
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Post by 92220 on Nov 11, 2023 12:16:21 GMT
Lovely job Roger!!! Especially that minute 'T' tap handle on top of the cover. Blink and you might miss it, it's so small!!!
Bob.
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Post by 92220 on Oct 12, 2023 16:02:06 GMT
As Wilf says, there should be a wavy washer in place. It really works wonders. Unfortunately I had a couple of ex-Myford guys come to service my lathe. I didn't notice they hadn't replaced the wavy washer and it is a bloody pain now, with no restriction whatsoever. the dial can be spun around!! Must get a new one. RDG Tools have bought the Myford rights and apparently are making Myfords again. I must chase them for a replacement wave washer.
Bob.
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Post by 92220 on Sept 23, 2023 12:45:57 GMT
Hi Pete.
No problem. As far as the enamel goes, any paint that is designed for vehicles, should be fine on a steam loco. All vehicle paints maust be resistant to solvents, dry extremely hard but remain flexible without cracking, and also withstand high temperatures. The surface coating on a car can quite easily reach 120C on a hot sunny day, even in UK. It is not unknown for people to get quite a severe burn from coming in contact with a car body, depending on colour. The darker it is the hotter it can get, and so must be able to withstand the high temperatures
Bob.
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Post by 92220 on Sept 9, 2023 18:24:07 GMT
Hi Roger.
What a handy idea!! If the paint you are using is enamel, like Phoenix Precision, cellulose thinners will wash it out completely. Just be sure that the plastic 'bottle' is resistant.
Bob.
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Post by 92220 on Sept 3, 2023 8:16:42 GMT
Hi Pete.
I don't know what that paint is you have, but to get the best out of the coating on a working steam loco, the ideal paint is a "vehicle enamel". It should then be able to stand the higher temperatures, and cure extremely hard and flexible, but not brittle. Bob.
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Post by 92220 on Aug 25, 2023 15:06:38 GMT
I hadn't thought about it along those lines (no pun intended!!) but the boiler clothing sheets on a 9F are 16swg, and when scaled down for a 5"g loco, the clothing would be 0.0055" thick. very flimsy!! On my 9F I am making the clothing sheets from 10 and 12 thou sheets, but this is all supported with an inner shell of 0.5mm nickel silver sheet to help stop it getting bent by very light loadings.
Bob.
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Post by 92220 on Aug 24, 2023 13:48:06 GMT
Bob, What sort of lower limit would you put on size for shrink fitting? I think I will end up with about 5 1/2” inches once I have turned the wheel centres down on my Wren. Hi Chris. I've not used shrink fit for many years. I still prefer to use the strongest Loctite. On a wheel that measures exactly 5.500" dia, I would make the tyre 5.493"/5.495". That is a 2 to 5 thou interference. For fitting, the tyre needs to be heated in a domestic oven to maximum oven temp. which is likely to be 200C to 220C To ensure it has expanded the maximum, allow it to soak up heat for at least 1/2 an hour. Don't forget if you do use a shrink fit, make sure you have a machined step to act as a 'stop' to fit the ring correctly, and not at a slight angle. Bob.
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Post by 92220 on Aug 23, 2023 10:16:48 GMT
That's interesting. Looks like I had an out-of-date drawing!!! I have done some searching and have found only one photo that SEEMS to show a difference in diameters but it is not at all clear. It was, I think, an early photo where a new boiler was to be fitted. All the others I have found show the boiler and smokebox the same diameter where they meet. Just goes to show that careful research is needed when working on a scale model, and it is so easy to get things wrong when relying on memory!!!
Bob.
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Post by 92220 on Aug 21, 2023 16:06:51 GMT
There is a ring around the end of the smokebox where it joins the boiler clothing. On fullsize it is approx 2" greater than the smokebox radius, so 4" greater diameter. Scale 2" for 5" g is 0.177" (1" = 0.0885" scale). You can work out your clothing outside diameter at the smokebox end, as the smokebox diameter plus 2 x 0.177". That is the theoretical O.D. at the smokebox. Hope that helps.
Bob. Edit.
I forgot to point out that the Brit and 9F have boiler clothing diameters greater than the smokebox diameter, not smaller.
Bob.
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Post by 92220 on Aug 21, 2023 7:41:44 GMT
Would seem I'm, perhaps, a little over-cautious!!
Bob.
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Post by 92220 on Aug 20, 2023 12:56:19 GMT
Shrinking the tyres onto the wheels is good for larger size wheels but it becomes much more fiddley with smaller wheels because the tyres don't expand as much and so accurate machining becomes much more critical. The advantage of Loctite, with the right compound, is that it is considered similar to a shrink fit in engineering. Using the grubscrew, as well, is really 'belt and braces'and is just a safety feature.
I remember when the company I first worked for as an apprentice draughtsman, did some tests with Loctite Retaining Compound, back in the early 1960s (Nowadays Loctite 648) fitting a 1.1/2" ballrace into an aluminium housing, and left it 24 hours to cure. We then tried to press the ballrace out of the housing while pressing on the outer race. It would not move under a 3 tonnes load. In the end we tried it in the 10 tonne flypress. It still would not come out with just an axial loading. It ended up that the only way we could remove the bearing was to be really brutal, with the flypress, until the bearing shattered.
Bob.
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Post by 92220 on Aug 19, 2023 13:51:32 GMT
Mild steel rims on cast iron wheels are fine. The steel rims will last much longer than CI rims, before needing to be re-machined. The rims can be fitted as steel blanks and the rims machined insitu. That way they are guaranteed to run true to the wheels. They can be fitted using Loctite Retaining Compound, but also use a small, (around 3mm) socket grub-screw, half in the steel rim and half in the CI wheel, on the insides of the wheels, where they are hidden from general view. That arrangement is a bit "belt and braces", but you won't ever have problems with the rims coming loose on the wheels, in service. It
Bob.
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Post by 92220 on Aug 19, 2023 13:39:15 GMT
I served my apprenticeship at James Neil ( Eclipse ) in Sheffield , and it pains me to now see the name on products what I consider to be inferior to the original ones that I own from those days , based on experience similar to others . I believe the name is now owned by a Hong Kong consortium who have world wide interests. PS If I remember correctly , the pin chucks quoted were made on high precision 6 spindle Swiss Auto machines . Totally agree!!! Eclipse pin chucks, nowadays, are useless as far as concentricity goes. I have 2 sets, bought new, within the last 5 years and all collets run at least 10 thou eccentric!! Absolutely useless!! Bob.
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Post by 92220 on Aug 18, 2023 9:26:33 GMT
Hi Eric.
That should do well.
Bob.
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Post by 92220 on Aug 16, 2023 8:18:52 GMT
One problem with rust is that it will continue to increase even when under a coat of paint. Hoping the etch primer will kill the rust will generally not work as few etch primers will have enough acid in them to work on the rust. Another problem is that rusting will continue even when air is excluded by a coating of paint, because the rust will generate it's own 'atmosphere' under the paint. Just rubbing down rusty patches is also not a solution on it's own, because rust works it's way down into the metal and unless you take off a lot of the metal surface too, the abrasive paper will just not reach every molecule of rust. It will then be able to eventually regenerate.
Bob.
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Post by 92220 on Aug 12, 2023 21:15:53 GMT
Hi James.
Phosphoric acid is way better than Kurust. At least it was when I tried Kurust many years ago. Maybe they have changed the formula since, and made it better, but having got a small, very effective, bath of phosphoric, I'm not going to change from something I know works well.
Keep, up the good work. Your post is really interesting to follow.
Bob.
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