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Post by 92220 on Apr 27, 2020 8:33:35 GMT
Hi Roger.
If you can have a positive pressure in the garden workshop, that would help keep the dust from coming in from outside due to the suction of your spray booth fans. I fitted the largest lorry air filter I could get hold of, to the air inlet fan to my spraying shed and it works well to stop dust being drawn in around the door.
Bob.
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Post by 92220 on Apr 27, 2020 8:29:32 GMT
That is some rivet squeezer!!! I think I might make up a miniature for riveting. The sliding ram for the moving snap is a handy idea. It could be made to work over a very wide materials thickness.
Bob.
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Post by 92220 on Apr 27, 2020 8:19:10 GMT
Hi Daz.
If you have access to a decent sharp guillotine, you could do what I do. I clamp a long parallel, dead parallel to the blade, on the guillotine table, usually around 3" from the blade, using other parallels. Then, with the material I want to cut, tight against the fixed stop, I trim it into a dead parallel strip. I would then put a piece of 2mm strip/sheet/plate, against the stop and use that as the new stop to guillotine off the 2mm strip you need.
I used that method to cut all my boiler bands out of 0.008" steel shim, which I was able to buy in a 3.0 Mtr length. The idea of fitting the stop a distance away from the blade is that you have a decent area of material to hold hard against the stop without getting your fingers close to the blade. It is possible to guillotine strips that are 18+" long and only vary by about 3 thou over the full length. Cutting brass sheet should be a lot easier than steel shim too.
Bob.
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Post by 92220 on Apr 24, 2020 22:01:24 GMT
Hi Roger.
I hadn't thought of the snifter being piped to the outside when reading about it being in the smokebox. Makes sense but that wasn't how I read it.
Bob.
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Post by 92220 on Apr 24, 2020 7:59:02 GMT
Hi Gary, Of course, the other benefit we haven't mentioned is that fitting the snifting valve to the wet header keeps the cylinders up to temperature while coasting. The alternative one admits cold air to the cylinders, something you don't really want to do. The pumping action of a coasting locomotive isn't trying to reverse the flow, it's still trying to suck air out of the steam feed pipe and deliver it to the blast pipe. As long as you allow some air into the steam chest, all of that has to pass through the cylinders and out of the blast pipe. You won't get any reverse flow until you completely block the flow of air and you start to create suction. A small restriction in the snifting valve arrangement will only cause a slight braking effect, it won't reverse the flow through the blast pipe. Hmmm. In full size, locos could have quite long spells of coasting, but Swindon still didn’t put the snifters on the wet header. They researched most things pretty carefully, so I’m happy to go with their judgement on the relative benefits*. In modelling one of their products, I like to follow their design principles as closely as possible, so it would be simply wrong on a 15xx. (Other railways may have had other ideas, but they were of course, invariably wrong. “There are two ways of running a railway; the Great Western way, and the wrong way” -Anon. ) On a miniature line, I find coasting is both rare and short-lived, in fact coming to a halt in the station is about the only time it happens. Enough to suck crud into the cylinders without a snifter, that’s for sure, and the free running is valuable so as to glide to a dignified halt instead of a clunky stop, but the distance is not enough to worry about cooling the cylinders via a tiny hole. We are probably not going to agree, but my opinion is that the benefits of a snifter close to the cylinders are real and proven, while the benefits of putting it on the wet header may be true in theory but are unlikely to be borne out in practice. YMMV - Gary *I believe one of the issues is that placing the snifter on the wet header requires it to be at the top rear of the smokebox, where it is quite likely to suck in grit from the chimney. I could be wrong. Hi Gary. Also, isn't the pressure, inside the smokebox, below atmospheric, to draw the fire? A snifter inside the smokebox would therefore be working much less efficiently. I'm with you. I think a snifter near the cylinder is much more effective. Bob.
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Post by 92220 on Apr 24, 2020 7:47:08 GMT
Hi Roger.
Thanks for that explanation. I've always wondered how they worked and what sort of accuracy they could give. When I want to locate a flat surface like the fixed face on the machine vice, I have a piece of 3/8"" dia mild steel bar permanently fitted into a collet that goes into the spindle nose. I turned the end down to 0.250" dia on the mill so that the bar would be running dead concentric. To find the face of something I use a Rizla cigarette paper (no I don't smoke!) which is exactly 0.001" thick, and JUST trap it between the 0.250" bar and the face I am locating. Then it is just a case of moving the table 0.126" to get dead centre. Interestingly I found that even moving the table a tenth of a thou on the DRO could trap or release the cigarette paper so I reckon that is more than accurate enough for anything I can do, and it's quick and easy to use.
Bob.
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Post by 92220 on Apr 23, 2020 17:04:33 GMT
Hi Roger. That's interesting! I've never had a wobbler because I use a dial centre finder, which suits my needs, but I've often wondered what goes into making a wobbler. How accurate is it at finding the centre or is it just a way of finding the vertical surface of a hole or part?
Bob.
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Post by 92220 on Apr 19, 2020 18:48:51 GMT
..........and I chucked it away, thinking the milk had gone off!!!!
Bob.
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Post by 92220 on Apr 18, 2020 10:17:04 GMT
Hi Kerrin.
I wasn't sure of the reason for diluted acid being more aggressive, so googled it. Here is the answer:- This promotes attack by the acid. ... In case of weaker acids, the dissociation increases with dilution, which means that as more and more water is added, more hydrogen ions will be generated. By and large, dilute sulfuric acid is more harmful than concentrated sulfuric acid.
Bob.
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Post by 92220 on Apr 17, 2020 8:33:39 GMT
Hi Kerrin.
If you want a copper plating on mild steel without electrolysis , you can use a copper sulphate solution with a small amount of sulphuric acid in it. When I was a trainee draughtsman, doing my workshop training, we used the copper sulphate solution to check whether a piece of metal was mild steel or stainless. The mild steel always came out copper coated and the stainless stayed self colour. You don't need much sulphuric to make it work. From what Steve has said, citric acid might also work, instead of sulphuric acid. The plating is not as resistant to rubbing off as electro-plated is though.
Hi Steve.
The citric acid trick is handy to know. I use a dilute phosphoric acid bath for most of my mild steel parts, . It coats the steel with a coating of iron phosphate which kills rust and also prevents it coming back. It also provides an ideal surface for painting. If anyone wants to use phosphoric acid, it is available on ebay quite cheap. It also needs to be diluted to around 15% acid to water. I'm not sure of the chemistry, but diluting the acid makes it work much stronger on rust. A 10 minute soak will usually clean up most rusty parts. Actually, if I want the phosphate coating to REALLY stick, I sand blast the steel part and then ALLOW it to rust, then pop it in the phosphoric. The converted rust helps the phosphate to adhere well to the surface, and not rub off,because, like the rust, it becomes almost part of the metal surface crystals.
Bob.
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Post by 92220 on Apr 16, 2020 18:07:52 GMT
Hi Steve.
Lovely job!! I'm pleased to see you will be removing the zinc coating. While zinc plating is good at preventing rust, it also prevents paint from adhering well. Even etch primer doesn't help much. There are etch primers made specifically for use on galvanised steel, but even they don't adhere as well as on plain steel or brass. The only way to guarantee paint sticks to galvanised is to actually 'weather' it outside for 24 months. Not really a suitable idea for model engineering projects!!
Bob.
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Post by 92220 on Apr 15, 2020 8:32:53 GMT
He was a super guy! As everyone says...he will be sorely missed in the model engineering world. He helped me massively. He had never got hold of a 9f valve gear drawing, so I sent him a copy. He spent ages going through it and checking all the dimensions of the full size. He then corrected where necessary, and then reduced it all to 5" gauge so that all I had to do was transfer his dimensions to my working drawings. A really sad loss to us all.
Bob.
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Post by 92220 on Apr 14, 2020 9:50:00 GMT
Hi Roger. Are you offering to make lamps or LED/battery packs? (tongue in cheek!) If so I would be interested in 4 LED/battery packs. My lamps are slightly different, but I think, will have slightly larger internal volume. As far as a switch goes on your lamps....does your handle swivel? If so, could you incorporate switching in the swivel action? Bob. Hi Bob, I'll probably get a PCB made, which will mean I'll have dozens of the things. Whether they would fit your lamps is another matter. When I've got the dimensions finalised, I'll send you a drawing of the PCB plus parts so you can see if it's any good. I don't think I can easily use the top as a switch actuator. If I fit one it will probably be accessed through the rear door or out the bottom. At the moment though, the bottom is closed and the access is through the back. That's not to say that I couldn't make other styles of PCB that could all go through as one batch. Hi Roger. Brilliant! Thank you. It would be interesting to see how the 2 lamp internal sizes compare. My comment was very 'tongue in cheek', but if you are making a number of battery packs surplus to your requirements. I would be happy to buy 4 off you when available. The forth one would be for the water gauge lamp. Bob.
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Post by 92220 on Apr 14, 2020 9:41:23 GMT
Hi Malcolm.
Yes my liners are cast iron. That doesn't make too much difference. Almost any metal can be honed. I used to work as a design draughtsman at Delapena Honing Equipment Ltd. The trick is to use the right lubricant. They supply a special lubricant at exorbitant prices, for honing. All it is is EP gear oil thinned with a small amount of white spirit to bring it down to a viscosity something around car engine oil or around S.A.E.30 oil. It's not critical. The other trick is when the hone or workpiece is rotating, swivel it from side to side continually. That way you will produce microscopic 'cross-hatching' on the bore and the crosshatch marks hold the oil and keep everything well lubricated.
Interestingly, Delapena invented induction heating back in the late 1960s, to heat steel parts for heat-treatment. Their induction heating side was bought up by an American company called Raydyne, and they invented the microwave oven. We saw the very first one which was invented in the Raydyne U.K. works. It was the size of an American style fridge (about 6' high x 3' wide x 2' deep) and the actual oven was the size of a shoe box!
Bob.
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Post by 92220 on Apr 13, 2020 18:06:13 GMT
Hi Malcolm.
Reading up about your finish reaming of the bores, reminded me of how I did mine. I pressed the liners into the cylinders, as full-size (though they shrink fit them). I then found a local honing company who was prepared to hone the valve and cylinder bores professionally, to within 0.0001" on diameter!! for their basic hourly rate. Yes, it cost me quite a bit, but was well worth it as I would never have managed to get the surface finish they did. I just had to allow them 2 thou material to remove with honing....and the bores are dead parallel - no tapering.
Bob.
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Post by 92220 on Apr 13, 2020 17:30:40 GMT
Hi Roger.
Are you offering to make lamps or LED/battery packs? (tongue in cheek!) If so I would be interested in 4 LED/battery packs. My lamps are slightly different, but I think, will have slightly larger internal volume.
As far as a switch goes on your lamps....does your handle swivel? If so, could you incorporate switching in the swivel action?
Bob.
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Post by 92220 on Apr 13, 2020 8:29:15 GMT
I have some 2500 grit emery and I have seen 3000 grit paper on Ebay.
Bob. EDIT. That first photo of Keith's, showing the lamp and 'innerds', at first I thought that lamp was fullsize, 'till I realised it was a mini battery pack beside it. The dirty coating of the lamp looks perfect for a 'weathered' lamp!!
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Post by 92220 on Apr 13, 2020 8:22:26 GMT
Super detail Mike. I really like the slightly bent hook. A1 job!! Sorry about the pun. Should have said Class 7 !!
Bob.
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Post by 92220 on Apr 12, 2020 8:26:29 GMT
Unfortunately that would be an even greater precedent, Brian. You can't have the government turning a 'blind eye' to people breaking the law, however trivial. They had to provide the extension because they, themselves, have banned people from leaving home for non essential trips.
Bob.
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Post by 92220 on Apr 10, 2020 8:12:40 GMT
Hi Guys and Gals.
This is not strictly in the right place, but I posted it here because more people are likely to see it.
If your car is due for an MOT while this coronavirus crisis is with us, the Government has given a 6 month extension to all MOTs that expire AFTER March 30th this year, so most have no need to worry about getting it done. This is an excerpt from the Gov website:-
Guidance
Coronavirus: MOTs due from 30 March 2020
Your car, van or motorcycle’s MOT expiry date will be extended by 6 months if it’s due on or after 30 March 2020 - but you must keep your vehicle safe to drive.
Bob.
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