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Post by runner42 on Feb 4, 2015 7:11:38 GMT
A bit of an update, but no pictures until later as the boiler is still in the pickle I like to leave it in there as long as possible. I have managed to silver solder the 18 rod stays in the crown in place of the girder stay. If you look again at my drawing at the beginning of the thread the rod stays in the crown has to be drilled pretty accurately to avoid inferring with the longitudinal stays between the smokebox tubeplate and the backhead. Also the cross stays in the crown need to lie between the longitudinal stays and the regulator actuating rod. With a hand power drill this was a bit of a challenge for me. I have managed a good fillet of silver solder around the rod stays on the outside of the outer wrapper and inside the crown of the smokebox. However, penetration between the wrappers is not good, this is because I went for a tight fit of the rod stays to prevent them moving during the silver soldering process. I need to take advice of this lack of penetration. I could attempt to place silver solder rings in between the wrappers but this is going to be very difficult.
Brian |
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steam4ian
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Post by steam4ian on Feb 4, 2015 8:10:13 GMT
Brian
You may be jumping the gun, anyway let's hope so.
Leave it to the BI to assess.
If you do have to add solder try the silver solder paste from Cuppalloys or JM rather than trying to put rings around the stays. you can squirt the past into position.
Ian
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Post by Shawki Shlemon on Feb 4, 2015 8:55:59 GMT
for what is worth , I always use loose fit or clearance hole for stays / bushes and tubes , I stand corrected but it is commonsense that there must be a space for silver solder to flow . Here is the bad news , if its passed and then leaks on hydro test then the job is 10 times worst . It is easier to fix now than later .
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Post by runner42 on Feb 4, 2015 22:12:33 GMT
Here is the photographs. An experienced SASMEE colleague told me that the penetration occurs at almost the molecular level that silver solder will penetrate even though there is no apparent gap, in fact the capillary action is greater the smaller the gap. Obviously an engineered gap will result in a nice visible fillet on the opposite side indicating that penetration has occurred.
But isn't the practice to apply silver solder to both sides giving the appearance that penetration has occurred?
Brian |
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Post by runner42 on Feb 5, 2015 6:05:38 GMT
Sorry brian, but that is absolute cobblers. The solder hasnt penetrated. There is no strength in those crown stays. Cheers Paul Paul, I don't want to prolong the debate it's a fruitless exercise because there is a question mark on the penetration of the crown stays. It may have penetrated or conversely say due to contamination not occurred. But in defence of my SASMEE colleague he has produced test pieces with varying gaps and found through cross sectioning that penetration has occurred where the gap is almost non-existent. The common practice is to engineer a gap of around 0.004" to ensure that penetration does occur and form a nice fillet on the other side. It's more of a providing confidence that penetration has occurred and removing the question mark not one of increased structural strength.
I am unsure that you saying that there is no strength in the crown stays is an overstatement. If you look at the fillet formed by the silver solder it extends nearly an 1/8" up the stay and similar distance out on the wrapper. If I compare this to a nutted and comsol soldered stay I would say that it is equal in terms of structural strength.
But I am not accepting the status quo, I am taking Ian's advice of doing nothing until I speak with the BI on Tuesday.
Brian
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Post by runner42 on Feb 5, 2015 6:11:08 GMT
So that I don't fall into the same trap and extend the problem on the side stays if I use a No 11 drill (0.1910") to open up the holes and using a 3/16" stay will this give me a better result?
Brian |
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Post by Shawki Shlemon on Feb 5, 2015 8:57:17 GMT
As far as I am concerned right or wrong I only apply solder from one side only , a slight penetration on the other side , not necessary a complete fillet indicates ( a complete fillet is great ) healthy penetration . To fix a non penetrated joint , clean , apply plenty of flux on both sides and heat on the side one require penetration , in this case an oxy will be ideal to use on . For 3/16 stay a clear hole drilled with no 11 or 10 will be ideal in my opinion . As Ian says wait to see your BI .
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steam4ian
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Post by steam4ian on Feb 5, 2015 20:57:49 GMT
Brian
Have you got that boroscope camera from Jaycar working yet?
It would be helpful to you, the BI and ourselves to see what it can show you. There is penetration with some of the joints. As the SASMEE expert says you only need a microscopic penetration between copper and copper. Arguably a microscopic penetration is better than a thick portion of solder which is weaker than copper.
If the boiler were mine I would leave it in the pickle. Citric acid is not so strong it will eat it away but it will stop the copper in any crevices in joints oxidising.
Regards
Ian
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jma1009
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Post by jma1009 on Feb 5, 2015 22:08:34 GMT
hi brian,
a few points...
paul1979 is quite correct as is Shawki.
why are the sides of your foundation ring in 2 parts? the foundation ring provides a very important function in transferring the load on the inner wrapper to the bottom of the outer wrapper. i would regard a 2 part foundation ring side piece as a potential source of weakness unless very well silver soldered together, plus a major departure from the published design. i mill out my foundation ring pieces from much larger copper bar.
cheers,
julian
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Post by runner42 on Feb 5, 2015 22:16:11 GMT
To fix a non penetrated joint , clean , apply plenty of flux on both sides and heat on the side one require penetration , in this case an oxy will be ideal to use on . I think that you have focussed on the problem of apparent non-penetration. I normally heat on the opposite side to where the silver solder is applied, remembering Julian's advice of drawing the silver solder flow to the hottest part. In this instance I applied the heat to the same side as the silver solder and when I saw that the heat had melted the silver solder stopped the process. However that may have been premature and the inside of the wrappers just didn't reach the required temperature. Using propane only may be insufficient and that a higher local temperature is required.
Brian.
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Post by runner42 on Feb 5, 2015 22:24:45 GMT
Brian Have you got that boroscope camera from Jaycar working yet? It would be helpful to you, the BI and ourselves to see what it can show you. There is penetration with some of the joints. As the SASMEE expert says you only need a microscopic penetration between copper and copper. Arguably a microscopic penetration is better than a thick portion of solder which is weaker than copper. If the boiler were mine I would leave it in the pickle. Citric acid is not so strong it will eat it away but it will stop the copper in any crevices in joints oxidising. Regards Ian Ian,
no I haven't received the boroscope camera, I ordered last Saturday, it should be here by today they say 5 working days. Yes some of the stays has penetration. I don't know if Allan will be there on Tuesday I understand he has been holidaying in Spain.
Brian
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Post by Jim on Feb 5, 2015 23:31:01 GMT
Brian, If you are looking at boosting your heating source you might look at oxy propane. I assume you already have a BBQ propane cylinder but if not they be easily obtained and it is now possible to buy your own D sized Oxygen cylinder which you own outright and refill on a swap and go basis.
The oxy propane will do all the heating on your boiler and is in my view more gentle than oxy acetylene. Oxy propane can be used for bronze brazing structures like the frame for a ride on car.
Just a suggestion/
Jim
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Post by runner42 on Feb 6, 2015 4:58:47 GMT
Hi Jim.
thanks for that, I had already earmarked your thread in my IE favourites when you talked about getting the oxy-propane outfit last year.
Brian |
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Post by runner42 on Feb 6, 2015 5:34:51 GMT
Well they say that a week is a long time in politics, but a few hours is a long time in boiler making.
I am pleased to say that I have cracked it, well almost. At Shawki's suggestion I have managed to get penetration in the crown stays by applying flux to both sides of the wrapper and the applying heat between the wrappers. As expected the silver solder was pulled through to the hottest part (a fundamental tenant of successful silver soldering). Obviously applying heat between the wrappers because it is at the backhead end only is going to have a temperature gradient across the wrapper so the farthest stays are not going to receive as much heat. It's in the pickle but what I can see at the moment is a couldn't be better fillet around the nearest with a gradual reduction but still visible penetration on the stays closest to the barrel. I won't post the photographs until Sunday.
Ian, received the boroscope camera this morning and I have used it with some success to see crown stays. What I think is required is for additional illumination because the LED lights produce a small ambient lighting but reflects off the copper giving a gruesome look to the inside. Here is a picture of the farthest three crown stays on the LHS before I did the rework.
Brian
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steam4ian
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Post by steam4ian on Feb 6, 2015 11:02:28 GMT
Brian
I took picture with my camera of the firebox tube plate form between two tubes.
I will not post it because it looks I have up-skirted a dark skinned lady with silver/white nickers.
Remember the strength is not in the fillet but in the copper to copper joint between the stay and the sheet provided by a small amount of silver solder. it is not a weld but soldered joint.
Ian
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Post by runner42 on Feb 7, 2015 1:46:38 GMT
Hi Brian, The stay in the foreground is what you are after, the one behind it, is not. If you can pull the solder through on all of them, you are back in business. Out of interest what type of solder are you using? Cheers Paul I am using www.boc.com.au/shop/en/au-boc-industrial-store/silver-brazing-alloys/boc-prosilver-45t-cd-free-brazing The code requires that we provide and retain all the invoices of materiel purchases that are used in the construction of the boiler and that these are from bona fide suppliers.
Brian
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Post by runner42 on Feb 7, 2015 1:56:23 GMT
Brian I took picture with my camera of the firebox tube plate form between two tubes. I will not post it because it looks I have up-skirted a dark skinned lady with silver/white nickers. Remember the strength is not in the fillet but in the copper to copper joint between the stay and the sheet provided by a small amount of silver solder. it is not a weld but soldered joint. Ian Ian that's the very reason you should post the photograph, red bloodied MEs with a vivid imagination can see ladies' delights in almost anything.
Brian
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Post by runner42 on Feb 8, 2015 7:04:53 GMT
If you expecting the boroscope pictures, I have done my dash and in the doghouse. The boroscope requires to be connected to a USB host and the PC is in the study which necessitates bringing the boiler indoors which I did but didn't ensure that it was completely free from occluded spaces containing used citric acid. This wasn't the case and green stains were on the carpet so until SWMBO has settled down I have to limit picture taking to the shed.
Without overdoing it this is a representative sample of penetration. The photograph could be better and have a greater depth of field but it shows what's required.
Brian
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Post by Shawki Shlemon on Feb 8, 2015 9:25:57 GMT
I don't think these stays will leak . well done .
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steam4ian
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Post by steam4ian on Feb 8, 2015 11:47:02 GMT
Brian
I am with Shawki, great work. you must have had it really hot.
Meanwhile I will try and think of how to get copper stains out of the carpet. Sulphuric acid perhaps?
What colour was the carpet meant to be?
Regards
Ian
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