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Post by Roger on Oct 24, 2019 18:56:07 GMT
Instead of machining the flange, could you counterbore the holes and secure the assembly with cap head screws or countersink them? You certainly could, but I'd prefer to make it more prototypical really and keep the nuts and studs.
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Post by Oily Rag on Oct 24, 2019 20:59:07 GMT
Crikey indeed! When I consider the number of opportunities available to cock this up it seems miraculous that it is at this almost finished state. My tired brain would have made an unrecoverable mistake long before this point. Else my trembling fingers would have allowed it to drop onto a hard surface...
Impressive just doesn't cover it... Jim S
Thanks Jim, Having a reliable machine is absolutely vital, no missed steps or significant backlash can be tolerated when it's such a thin section. You do have to be ultra cautious with the setups, especially since there's no usable reference on the axis you can use. Without an externally available reference it's hard to register one operation with the next. It's also only symmetrical about one axis and it's easy to confuse which way round it is. That's because the boiler is tapered and so is the base of the skirt. You have to accept that it might go horribly wrong until it's finished the last cut, so I won't tempt fate just yet. It's just doing what I hope is the finishing pass on the inside of the rim and that's another few hours to get the kind of finish I'm looking for. At least if it does go wrong, the programs and strategy have now been proved, so it's not quite so bad if I need to start again. To quote David Pye
‘ simply any kind of technique or apparatus, in which the quality of the result is not predetermined, but depends on judgment, dexterity and care which the maker exercises as he works. The essential idea is that the quality of the result is continually at risk during the process of making; and so I shall call this kind of workmanship “The workmanship of risk”: an uncouth phrase, but at least descriptive.’
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Post by simplyloco on Oct 24, 2019 21:15:51 GMT
To quote David Pye
‘ simply any kind of technique or apparatus, in which the quality of the result is not predetermined, but depends on judgment, dexterity and care which the maker exercises as he works. The essential idea is that the quality of the result is continually at risk during the process of making; and so I shall call this kind of workmanship “The workmanship of risk”: an uncouth phrase, but at least descriptive.’ To Quote John Barrett
"Conversely, through knowledge, skill and application, the outcome can be predicted with some accuracy..."
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Post by delaplume on Oct 24, 2019 21:47:58 GMT
At Bridgnorth we had an hydraulic tester to which the body was bolted down and the pressure raised by integrated hand pump.........Adjustment of the top nut was instigated until the valve just leaked a small trace of water at the pressure. required....... A measurement between the body face and the underside of the bridge piece was recorded and the pipes machined to that length and fitted...With the valve aasy. now bolted back on the loco and steam raised the safeties were given a final check and the loco released back into traffic.... PS}---- In this photo the tubes are actually missing but you can see where they would be...
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Post by Roger on Oct 24, 2019 22:00:54 GMT
At Bridgnorth we had an hydraulic tester to which the body was bolted down and the pressure raised by integrated hand pump.........Adjustment of the top nut was instigated until the valve just leaked a small trace of water at the pressure. required....... A measurement between the body face and the underside of the bridge piece was recorded and the pipes machined to that length and fitted...With the valve aasy. now bolted back on the loco and steam raised the safeties were given a final check and the loco released back into traffic.... ibb.co/nRYjG2tPS}---- In this photo the tubes are actually missing but you can see where they would be... That's certainly something I could replicate. I've added threaded holes to the inlets to the safety valves inside for just such circumstances, although I wasn't sure I'd ever use them. At the time I didn't have a hydraulic test rig and pump, but I do now. Maybe it's worth having a play. I could at least see if they are water tight.
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Post by terrier060 on Oct 24, 2019 22:46:22 GMT
Hi Roger As you know I have been out of circulation due to Jan's illness. She has been in hospital over two months now.
I have just been looking at your safety valves and bonnet. A work of art, and making me even more nervous about tackling the base of the chimney and dome on the Terriers.
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Post by Roger on Oct 24, 2019 22:56:24 GMT
Hi Roger As you know I have been out of circulation due to Jan's illness. She has been in hospital over two months now. I have just been looking at your safety valves and bonnet. A work of art, and making me even more nervous about tackling the base of the chimney and dome on the Terriers. Hi Ed, You must be at your wits end, it's such a worry. You'll be fine, just work out all the moves before hand and I'm sure you'll be fine. These things are a bit daunting to start with, but if you break it down into small steps it becomes manageable. Make sure you can find your way back to reference points and that you can reach everywhere. Check and double check the entry points and how much each cut is going to take. When you start, look at the G-code and only step when you're sure it's sensible. If you don't understand something about a path it's generated, stop and figure out what it's doing before running it. Always start with a very much reduced feed and be ready to pause and re-assess if it doesn't sound happy or it doesn't look like it's going to do the right thing. I'm very cautious when starting a new operation, it's easy to make a mistake so it's worth taking the time to convince yourself everything is as it should be before running continuously. Once it's started, you can ramp up the feed rate and test the water to see how happy it seems. There's no magic to it really, just a bit of care and cautious skepticism!
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jma1009
Elder Statesman
Posts: 5,913
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Post by jma1009 on Oct 24, 2019 23:28:46 GMT
Hi Ed,
I don't think you ought to be too worried as the Terrier chimney base can be solid internally with a plain hole through it, or stepped. The dome base isn't that much different and doesn't need the room internally that Roger's requires on his 15XX example. You could turn the external side elevation to both then finish the end elevation and matching in with files, which is what I have always done.
Hi Roger,
A clear side and end profile pic of your safety valve cover would assist me.
As a bit of an aside, does anyone have any news on Bob Youldon? Bob assisted us greatly with the 15XX chimney drawings, which were of the 56XX type.
Cheers, Julian
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Gary L
Elder Statesman
Posts: 1,208
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Post by Gary L on Oct 24, 2019 23:50:19 GMT
[snip] I've filed those parts and it's much better, but I think it's going to foul the outer nuts that hold the flange in place. 20191024_155746 by Timothy Froud, on Flickr This is what it looks like with bolts simulating the nuts on the flange. It's about 1mm too high really... [Snip] Hi Roger Beautiful work, you have excelled yourself! However you might want to consider soldering an upstand rim around that safety valve base. You can see it fullsize on some of your SVR photos. Its function is to deflect 'sideways' steam from the valve orifices upwards, to discourage condensed water from leaking down the boiler from around the base of the safety valve cover, which is unsightly, or seeping into the insulation under the cladding which isn't good when it is steel sheet. It isn't an issue with an LBSC-type safety valve, which are very crude by comparison, but some people find it troublesome with scale-type valves like yours. Hope this helps Gary
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Post by Roger on Oct 25, 2019 7:52:34 GMT
Hi Roger, A clear side and end profile pic of your safety valve cover would assist me. As a bit of an aside, does anyone have any news on Bob Youldon? Bob assisted us greatly with the 15XX chimney drawings, which were of the 56XX type. Cheers, Julian Hi Julian, These are the two views of the 3D model scaled from the Works Drawings. The machining paths are derived directly from this, so this is what the finished item looks like too. If you look at the bonnet without the shoulders it looks quite a bit different. Bonnet side view by Timothy Froud, on Flickr Bonnet front view by Timothy Froud, on Flickr
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Post by Roger on Oct 25, 2019 7:55:11 GMT
[snip] I've filed those parts and it's much better, but I think it's going to foul the outer nuts that hold the flange in place. 20191024_155746 by Timothy Froud, on Flickr This is what it looks like with bolts simulating the nuts on the flange. It's about 1mm too high really... [Snip] Hi Roger Beautiful work, you have excelled yourself! However you might want to consider soldering an upstand rim around that safety valve base. You can see it fullsize on some of your SVR photos. Its function is to deflect 'sideways' steam from the valve orifices upwards, to discourage condensed water from leaking down the boiler from around the base of the safety valve cover, which is unsightly, or seeping into the insulation under the cladding which isn't good when it is steel sheet. It isn't an issue with an LBSC-type safety valve, which are very crude by comparison, but some people find it troublesome with scale-type valves like yours. Hope this helps Gary Hi Gary, Pault is of the same opinion and I can see why that may well be a problem. I'll take a look at what I can fit in over that central boss. I don't know if it needs to be soldered in, maybe just a close fitting sleeve would suffice?
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Post by delaplume on Oct 25, 2019 15:30:18 GMT
Hi Gary, Like this ?? Roger, You can see one of those tubes I mentioned marked "LF"....
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Post by ettingtonliam on Oct 25, 2019 17:17:00 GMT
Alan What do you think the chances are of persuading Roger to repeat the safety valve cover exercise but in a profile to suit 'Bear'?
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Post by steamer5 on Oct 25, 2019 21:11:36 GMT
Hi Alan, That’s a neat picture. I’m guessing that the tool being used is a seat cutting or refinishing tool? Any idea?
Cheers Kerrin
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Post by Roger on Oct 25, 2019 22:33:17 GMT
There's no way I'm going to try to hold the Safety Valve and Top Feed assembly in the 4-jaw, that's just asking for trouble and would take ages to get it true. Instead, here's a fixture that holds it firmly using the four M3 tapped holes for the pillars. 20191025_202330 by Timothy Froud, on Flickr Even with that, it took a fair bit of tapping with a mallet and clocking up the face to get it within 5 microns. Clocking the diameter is easy using the Grip-Tru chuck though. I've ground up a HSS tool for this because there's no way to avoid the clack bodies and the tubes. I've annealed and bent the feed tubes as far as I need and no more since they've got to go back afterwards. They'll need annealing again to do that. Here I'm making a note of the absolute maximum diameter I can go to when I'm at the full 1mm depth of cut. 20191025_224522 by Timothy Froud, on Flickr This is setting the middle diameter and face so they're just about to touch. The exact moment is found with it running and then the zero is finely set in X and Z 20191025_224543 by Timothy Froud, on Flickr I took 50 micron cuts to start with to get a feel for it, then went to 0.1mm cuts until 1mm was removed from the face. The tool was razor sharp with a little radius put on the end with a stone. That was a little bit fiddly, and required concentration to not overshoot the limits or take too big a cut. Not difficult really, but there's plenty of room for disaster! I'll do a couple of measurements before taking it out tomorrow. It's too late to do much with is now and I'm tired. 20191025_232005 by Timothy Froud, on Flickr
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Gary L
Elder Statesman
Posts: 1,208
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Post by Gary L on Oct 26, 2019 0:19:17 GMT
Hi Roger Beautiful work, you have excelled yourself! However you might want to consider soldering an upstand rim around that safety valve base. You can see it fullsize on some of your SVR photos. Its function is to deflect 'sideways' steam from the valve orifices upwards, to discourage condensed water from leaking down the boiler from around the base of the safety valve cover, which is unsightly, or seeping into the insulation under the cladding which isn't good when it is steel sheet. It isn't an issue with an LBSC-type safety valve, which are very crude by comparison, but some people find it troublesome with scale-type valves like yours. Hope this helps Gary Hi Gary, Pault is of the same opinion and I can see why that may well be a problem. I'll take a look at what I can fit in over that central boss. I don't know if it needs to be soldered in, maybe just a close fitting sleeve would suffice? Hi Roger Many thanks to Delaplume; his photo shows the upstand perfectly. My Paddington casting doesn't have the upstand rim, so I will definitely silver-solder one on before I start machining it. (The Polly casting for their 2251 does, but too late!) Not much use to you of course. The rim needs to go inside the bosses for the clack valves, so it would either take the form of a thin ring sitting on top of the topmost 'step' of the base as it were, or else perhaps two half-circles, attached to the sides of the 'step', in between the clack bosses. A lot will depend on how much clearance you have inside the bonnet. Either way, I would think it needs to be soldered (not necessarily silver-soldered in a retro-fit) for security and to make sure it holds water. My assumption is that it collects some condensate when the safeties blow into a cold bonnet, which boils off rapidly with boiler heat. I haven't studied it in action, but have seen some results of its absence. (I think Swindon referred to it as a deflector, suggesting that watertightness is not the main requirement, but I'm guessing it is helpful.) Hope this helps Gary
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Post by delaplume on Oct 26, 2019 2:35:43 GMT
Alan What do you think the chances are of persuading Roger to repeat the safety valve cover exercise but in a profile to suit 'Bear'? Pretty slim I would imagine........He's got enough on his plate at the moment, what with this 15xx, his own job ----- and something called "A family" ....more's the pity...... However all is not lost as The Bear's safety valve unit is / was from a Star ---- and later on a Castle... I used the Peter Riche 5" Castle drawings for the mounting ring fitted on my boiler but I've yet to produce the actual valve body itself... For a while I had a 2nd grade bonnet casting from Polly which looked identical to those 3D drawings apart from the base-line which was almost horizontal......Alas, in a moment of Club friendship I donated it to a very needy Manor....
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Post by delaplume on Oct 26, 2019 2:44:08 GMT
Hi Alan, That’s a neat picture. I’m guessing that the tool being used is a seat cutting or refinishing tool? Any idea? Cheers Kerrin Hi Kerrin, Yes, that's quite correct----The valve seat is just being skimmed to regain a good seal ...........A quick glance at the rusty nuts and bolts tells you that the main body hasn't been removed so this will probably have been on an engine that was currently in service....
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Post by Roger on Oct 26, 2019 7:12:55 GMT
Hi Gary, Pault is of the same opinion and I can see why that may well be a problem. I'll take a look at what I can fit in over that central boss. I don't know if it needs to be soldered in, maybe just a close fitting sleeve would suffice? Hi Roger Many thanks to Delaplume; his photo shows the upstand perfectly. My Paddington casting doesn't have the upstand rim, so I will definitely silver-solder one on before I start machining it. (The Polly casting for their 2251 does, but too late!) Not much use to you of course. The rim needs to go inside the bosses for the clack valves, so it would either take the form of a thin ring sitting on top of the topmost 'step' of the base as it were, or else perhaps two half-circles, attached to the sides of the 'step', in between the clack bosses. A lot will depend on how much clearance you have inside the bonnet. Either way, I would think it needs to be soldered (not necessarily silver-soldered in a retro-fit) for security and to make sure it holds water. My assumption is that it collects some condensate when the safeties blow into a cold bonnet, which boils off rapidly with boiler heat. I haven't studied it in action, but have seen some results of its absence. (I think Swindon referred to it as a deflector, suggesting that watertightness is not the main requirement, but I'm guessing it is helpful.) Hope this helps Gary Thanks Gary, that makes sense. Getting a seal is a pain though, I would prefer to just have a shield that fitted closely for choice, but that might not be ideal. I'dd chew it over.
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Post by steamer5 on Oct 26, 2019 8:51:37 GMT
Hi Roger, You are a brave lad! That looks like a butt clenching job! Result, great ..... well done!
Alan, Thanks for the info, I guess that as you say it’s being done on the boiler so the amount being removed will be small, I wonder if it’s just lapping of the seat?
Cheers Kerrin
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