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Post by Roger on Apr 10, 2014 13:01:15 GMT
For your notes Roger, you need quite a lot of microns clearance, otherwise the silver solder won't flow through. Thanks, I've noted that I need at least 20 of the little critters all round. |
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Post by ejparrott on Apr 10, 2014 15:35:17 GMT
more like 75 to 100...
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Post by Roger on Apr 10, 2014 17:42:50 GMT
Ah, the 20microns clearance was my interpretation of Julian's comment 'a couple of thou' which I took to be on the diameter. So are we looking at 75-100 microns difference on the diameter? (3-4thou) |
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Post by ejparrott on Apr 10, 2014 21:03:39 GMT
I aim for a 4 thou clearance in a joint interface
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Post by Roger on Apr 10, 2014 22:30:15 GMT
I aim for a 4 thou clearance in a joint interface Duly noted, thanks for that. |
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jma1009
Elder Statesman
Posts: 5,922
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Post by jma1009 on Apr 16, 2014 7:54:48 GMT
Flickr has changed their set up yet again so cant upload a pic, but there's a link here www.model-engineer.co.uk/sites/7/images/member_albums/84404/512913.jpgnot the best pic im afraid but ive silver soldered the 2 injector steam valve bushes in place (can just be seen behind the dome bush) and drilled 79 other holes for bushes and stays and nearly ready to silver solder the girder stays to the outer wrapper. the front foundation ring to inner firebox tubeplate will also get done at the same time plus the throatplate stays. this is the one heat up i always get nervous about as there is a lot to do quickly and no margin for error. however once done, the rest of the boiler is pretty much plain sailing and not so tricky. obviously all big holes for bushes such as blow down valves and check valves must be done before fitting the inner firebox and tube assembly. i like to fit the front foundation ring to the throatplate very early on (it was the first joint to be done, with high melting point stuff). having it in position i find considerably simplifies lining up the inner firebox and girder stays. however it does mean that it must be silver soldered to the inner firebox tubeplate at the same time as silver soldering the girder stays to the outer wrapper as there is no way of cleaning the joint or knowing it is clean subsequently if done as a separate stage. whether this is the best method i dont know, but it's what ive always done! cheers, julian |
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Post by GWR 101 on Apr 16, 2014 8:29:19 GMT
Julian. must say I am most impressed, must remember to show it to the other half who reckons we cant multi-task !!, looks like training in juggling whilst riding a unicycle would come in handy. Regards Paul
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Post by Deleted on Apr 16, 2014 8:37:14 GMT
very nice Julian....great work as per usual.... well you have convinced me.. I shall have a go at my own boiler even if it is a bit of a handful for a first timer....hope you can deal with the constant requests for advice that this will mean though...  Impressive work.. Pete |
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Post by Roger on Apr 16, 2014 11:38:47 GMT
Looking good Julian. Do you ever add one or two stays in the side to hold things together? It just occurs to me that they have to be there later so one or two could be used at an earlier stage of the build.
Flickr still works if you do this....
Click on the photo
Click on the Share icon
Then click on the Drawing Pin icon
Hold down the CTRL key then dab the C key to copy the static link that's already highlighted
Go to your post where you want the link, hold down the CTRL key and press V
You won't see your picture, it will just be a long link, but when you post it, the link will appear.
I can see why they've made the changes. You'll notice that when the photo is finally displayed, it gives your name and Flickr a mention which is what they want.
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Post by Deleted on Apr 16, 2014 19:42:47 GMT
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jma1009
Elder Statesman
Posts: 5,922
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Post by jma1009 on Apr 17, 2014 8:59:44 GMT
thanks paul pete and roger!
the club boiler inspector cast his eagle eye over the silver soldering of the tubes, firebox tubeplate, inner wrapper etc yesterday so can go ahead with the heat up referred to in yesterday's post.
ive made up a load of rings of silver solder from silverflo 55 rod that are a tight fit on the 1/8" copper rivets that will be the throatplate stays. these rings will get fitted on the stays in the water space against the firebox tubeplate, and should flash through when heated from inside the firebox same as the tubes did. it is virtually impossible with propane to add silver solder to the inside of the firebox if heat is applied inside.
ive re-arranged the throatplate stays from the martin evans design and added 3 extra stays. he was a bit stingy with the throatplate stays for my liking. there is also a problem with don young's 7.25"g terrier NEWPORT design with the throatplate stays where there is a huge unsupported area. (in fullsize there are palm stays that link the tubeplate to the bottom of the barrel).
cheers,
julian
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jma1009
Elder Statesman
Posts: 5,922
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Post by jma1009 on Apr 17, 2014 16:51:00 GMT
the major awkward heat up just completed this afternoon. bit tired what with the heat and fumes so trying to follow what to do with Flickr will have to wait another day... in the meantime here's some links to a few pics... www.model-engineer.co.uk/sites/7/images/member_albums/84404/513252.jpgwww.model-engineer.co.uk/sites/7/images/member_albums/84404/513253.jpgi havent cleaned anything up yet or done any tittivating so the pics are as the boiler came out of the sulphiric acid and then a quick scrub in hot soapy water. there is one corner of the front foundation ring which needs touching up. there are also quite a few unsightly runs of silver solder but im not bothered about those. you can hopefully see in the first pic how the silver solder rings have flashed around the rivet heads on the firebox tubeplate from the water space. the boiler was propped up upside down with the firebox outer wrapper sticking out to do the crownstays to outer wrapper with 2 blocks along each side. some heavy firebricks plus smaller bits of thermalite blocks were put inside the firebox to hold everything down. heat was applied from underneath, the silver solder already having been added in strips inside. as a bit of a belt and braces i then fed in quite a bit more silver solder than was probably necessary, but i would rather do this than have defective girder stay joints. the side blocks of thermalite were then pushed back, the heavy firebricks removed from the inside and top of the firebox leaving the smaller bits of thermalite covering/protecting the ends of the tubes. then heat up inside firebox till the silver solder flashed through and around the rivet heads of the stays. then rather awkward heating up of the foundation ring from outside - in fact it was already hot enough and the silver solder was applied and did the foundation ring to inner firebox tubeplate joint (apart from the bit i couldnt see properly!). at the same time there was a slight diversion when my clipboard of data sheets on the workshop wall caught fire and had to be flung outside through the open door! then silver solder added to the ends of the stays protruding through the throatplate. 15 mins start to finish, but probably took a good 2 hours to flux up, apply the rings of silver solder to the stays, work out how i was going to plonk the boiler and how to arrange the thermalite blocks etc. anyway that's the awkward bit done. big sigh of relief that the inner firebox isnt wonky and the girder stays are ok and all but a small bit of the front foundation ring. i might fit the smokebox tubeplate and check valve bushes next rather than do the rest of the firebox stays. i could also probably do with changing my pickle as it's getting a bit dirty and green/blue having now used the same pickle for 1.5 boilers! cheers, julian |
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Post by Deleted on Apr 17, 2014 17:25:18 GMT
looking great Julian... now here's a question that is important to me and would make me feel happier about doing my own. You mentioned the front foundation ring needs touching up and I can see which part you are referring to in your picture,BTW the tube joints look first class.. so my question is ' is it ok to reheat sections that haven't flowed as expected for a boiler? I'm guessing it is from what you have said and I do it myself on the parts that I've been making and know that it's a reasonably straight forward thing to do but for some reason I was under the impression that the joint had to be perfect first time for boilers, not sure where i got that idea from? If I have this wrong and I suspect that this is the case reading about your build then I'm feeling a lot more confident about doing my boiler... in fact an awful lot more confident... Pete |
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Post by Roger on Apr 17, 2014 17:26:25 GMT
That looks as solid as a rock, what a nice job. I'll be so pleased if mine comes out half as good as that.
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jma1009
Elder Statesman
Posts: 5,922
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Post by jma1009 on Apr 17, 2014 18:36:01 GMT
hi pete,
there is no reason whatsoever why small bits cant be 're-done' or 'touched up'. as per the description of what happened re the rivets on my first boiler many moons ago this is not at all unusual, and in the general panic and heating up and difficulty of seeing absolutely everything clearly is perhaps to be expected. the more active fluxes such as tenacity 4A and thessco F have quite an aggressive 'cleaning' effect. the above small corner of the foundation ring will get touched up when the adjacent left hand side foundation ring is fitted and silver soldered together with the stays on that side of the boiler, and i will add plenty of flux both sides of that corner beforehand and it will get longer than normal in fresh pickle beforehand too. it is always a bit annoying when you miss a bit, but this was the most awkward set up and heat up on the whole boiler.
hope that is of some re-assurance!
i think ive read every description of boiler making in the last 65 years in ME, and one usually finds somewhere the magic phrase 'inspect carefully and attend to any bits that have been missed'!
cheers,
julian
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Post by Deleted on Apr 17, 2014 18:43:42 GMT
Thanks for the info Julian.... one final question for tonight...when reheating would I be right in thinking that you heat all of the boiler in general to avoid stress elsewhere while concentrating on the section that needs work?
cheers
Pete
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Post by ejparrott on Apr 17, 2014 19:04:10 GMT
Yes, you must bring the whole up to temperature evenly, although only the area you are working on needs to go the full way. Random numbers, the joint area needs 700degrees, the barrel could be 400 for example, you certainly don't want to try it with the barrel remaining at room, especially with the larger assemblies and particularly once the front tubeplate goes in.
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Post by GWR 101 on Apr 17, 2014 19:07:18 GMT
Julian, as always it looks superb, I am trying to convince myself to take the plunge and order the parts to make a boiler for my current build. I have no illusions that it is as easy as you make it look but I bet the sense of achievement on a job well done is some satisfaction for the effort and stress involved. Paul
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jma1009
Elder Statesman
Posts: 5,922
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Post by jma1009 on Apr 17, 2014 21:34:08 GMT
hi pete,
yes, as Ed has said you need to bring everything up to heat (generally) to avoid localised stressing of joints. this is par for the course with propane, but somewhat problematic i understand with oxy-acetylene.
hi paul,
i was a bit p-ssed off that all my data sheets got incinerated this afternoon! i should have put them somewhere safe! all my enlarged zeuss tables plus tapping sizes for all types of threads went up in flames! the sense of achievement doesnt really arise till all is finished and you pump the damn thing up with the gauge attached! till then it is a state of nervous apprehension and worry - but probably not so bad as pete will feel when he machines up his expensive cylinder castings! for us amateurs i think that sense of nervous apprehension is what gets the adrenalin flowing and makes us want to do these daft things instead of playing golf or watching the TV!
cheers,
julian
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Post by Deleted on Apr 17, 2014 22:36:29 GMT
Hi JULIAN-------PM your address to me and I'll send you some replacement ZEUS tables ( in A4 ) to you........
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