PGK's 1" Minnie

Due to my failed attempt at soldering a Minnie boiler I can not add any thing which would help, but I am watching with great interest and have great respect for your determination, I have as a reminder 3 failed smoke boxes on my shelf, became very proficiant at flagging the plates towards the end.

I do think that if I was to try again I would avoid the higher temperature solder and try to solder it all with the 55.

Julian, Brian,

Thanks, guys. I figure there must be other novices out there who should gain from my learning curve and errors and there's no doubt that this process takes some learned technique. I've also got some 38% silver solder to get to play with which should be fun.

I hadn't thought of using NaOH for washing ..just been using H2SO4 and plain water rinses and it has needed a second dunk in a stronger solution to shift some of the old flux so will try NaOH iin the process.

For a novice i think it has to be multistage soldering. I'm getting even more respect for anyone who can turn these parts around, repack them and carry on soldering a different side without exhausting all that flux - and I'm layering that on as heavily as i can.

Brian, Were i to make another firebox then i reckon that cutting some of the vermiculite bricks into bits that fit between the faces and rivets outside and wiring them to insulate could help..as indeed was a piece inside and perhaps give one a chance with these torches to get the heat in.

Hi pgk pgk,

I'm following your progress with great interest.

Please keep up the narrative, there are probably dozens of boilers out there waiting to be completed.

The Minnie shown in my avatar, is built around a commercial boiler bought from Reeves in the early 70's when I was struggling just as you are. My intention, however, is to complete the boiler that was started way back.

I had managed to silver-solder the barrel, wrapper (C24), pump-pad and thickening pads with some help at night-school, but then failed miserably when I attempted the firebox on my own. I was following Mr Mason's instructions including a hearth made from an oil barrel using coke (the fuel derived from coal) for refractory material . I just kept exhausting the flux, which I think was Thessco F, because I was just too slow at getting heat into the components and not helped by the torch blowing out without warning. I remember that the instructions included turning the firebox over and doing both plates at one setting, more easily said than done.

Julian mentions an important point, in that the recommendation is for the firebox to be left open at the back so that that when the boiler is assembled it gives access to the stays for silver-soldering from inside with propane. I had enough trouble with the flame going out when just wafting it around in the hearth, let alone inside a closed firebox.

I've now completed a lot of test pieces, albeit small ones, so my next big event will be the firebox wrapper and tube-plate, when I can drum up the enthusiasm.

Regards

Phil

Edited By CotswoldsPhil on 07/05/2016 10:32:57

Phil,

I've just been back through the book and unless I'm being my usual dense self I read it as soldering both firebox ends in one go..although it took me two. I can see the logic of leaving the firehole plate off until the stays are in - now!

And that leaves fear that one gets near the end and hits yet another failure. I sorta think i should have started with my instinct to make three of everything for two spare goes - my usual construction approach has more scrap under the bench than in the job At least i kept all the formers instead of re-purposing them

I've also experienced the torch going out... too close to the job for enough air. it'd be nice if there was way of getting the needed heat with a tighter flame one could focus. I usually light up a small canned blowlamp and have it running on the bench for a quick relight - just in case. I learned that the first solder day!

I think i made the point elsewhere that I was game to attempt upto three boilers before giving up and abandoning minnie because for me this is nothing about actually owning minnie..it's about the learning curve of techniques needed to make this sort of stuff. Buying a commercial boiler might be cheaper but defeats the point (for me)..although if it comes to No3 I might just drive a heap of components to Julian's place , wave a bottle of whisky and shout for help

(If you've got the tubeplate former then the plate is quite quick to make. As i mentioned earlier a full size ?timber wrapper former might be a good idea - made to the shape of the plate corners for a really good fit. You still need the firehole plate bolted in place to have everything square even if not soldering it )

pgk

Hello, pgk

I have been following your thread with much interest so please keep posting your progress. As has been mentioned before, by Neil and others, this forum is missing a "like" button but back-slapping posts do little to enhance the thread and that leaves little in the way of showing our appreciation of someone's efforts.

I will be undertaking my own boiler construction ( a 5" gauge Britannia) sometime in the next year or so and am grateful that you are willing to share your failures as well as your successes. When starting out on this road, one cannot have too much advice or information and I am learning something each time you post.

So, quite simply, thanks for sharing,

Steve

HI pgk, I can't weld, brazen or solder, at sometime I hope to make a small traction engine, and I want to build a boiler for it. It is not the running of the engine but the challenge in building I hope to master.

I read this thread and was going to say enjoy it , which is wrong I don't enjoy your expensive learning opertunities, but I respect you writing up your build .

Keep up with he good work

Thanks for the comments, guys. I apologise for no new updates here.. hopefully in a few days. I was topping field edges with the tractor and all the twisting to reverse into difficult bits stirred up my back problems. Crawling and sitting is OK but standing, bent over machinery, will be a bit longer.

A few days of cortisone tabs and I'm back to it. Little to report since this is just a remake of parts... barrel and throatplate almost finished, pads being done. I plan to play with 38% for the pump pad sweating.

I plan to break up the solder jobs into smaller units.. so inside barrel first. Only question i have there is whether anyone has used solder foil for the larger pad to get it properly into the joint?

Edited By pgk pgk on 19/05/2016 09:35:32

For large areas I just put a few centre punch marks which raise a small burr around the indent which seems enough to give the gap required.

J

sweating the pump pad with 24% was easy enough on such a small part.. with 38% it was a real doddle. I then machined it accurately to square dimensions...but brain-farted to the wrong square dimensions and had the pleasure of making a second one - Doh!. The pads were cut/shaped and bent as before and rivetted with plenty of thickish ht5 then left overnight to thoroughly dry... that's a step i was a bit quick over before..fully dry is definitely better. I'd also stuck a length of 55% to one long edge of each pad with flux.

Tonight I scraped away the vast excess and popped it back in the jar then set up my hearth and tools (pics for other novices)..can blowlamp as relight source, welding gloves, something to move hot stuff with, spare rods and flux jar.

The barrel angled for access without the solder pieces able to fall away and lots of insulation.

It's first real use of 55%..very easy to get to temp and the placed solder shows when it's all hot enough. Visibility down the barrel is limited and my experience showed by adding way more solder than needed so it ran through the large pad and the small pad and pooled. Quite apart from wasted expense it was a pain to file off. the outside isn't an issue using a belt sander but the inside had to be done by hand..my dremel sanding drums just kept spinning on their mandrel.

But at least we have a solid first (repeat) step. The pump pad has now been added and I'm waiting on it's flux to dry. With the benefit of hindsight I think I could have soldered that in the same session but I'd rather not be making a third boiler next week (but watch this space!)

You don't need to wait for the flux to dry, mix - apply - solder no need to wait.

J

Where I've laid a piece of solder along a seam prior to heating and left the flux wet then I;ve had the solder peice dislodged by the extra bubbling/steam. I'm not quite confident (yet) at judging matters for just applying by solder rod.

Hi pgk pgk,

For my limited experiments (so far) and taking on board what I have read elsewhere, I use a soft flame to first warm the work and dry the flux (driving off the water). Where I've placed bits of solder which get displaced, I just push them back with a pointed implement or, if it's just one, hold it in place whilst the steam escapes. Once the flux is dry, wind up the heat and get on with the soldering.

Regards

Phil

Edited By CotswoldsPhil on 23/05/2016 09:25:30

Phil.

Yes I've done that before with little bits and I'm sure in the rght hands it's never a problem. At the mo' I'm playing super-cautious after the failures and ths way the piece of solder wire is firmly 'glued' to the proud edge one is filling...not that it means one can assume it'll stay there....

It gets pretty hot even with welding gloves on and poking at bits with a long rod is obviously less accurate than close work..

No, I hadn't given up...just summer is busy here but cold weather is coming.

It was a batcave. I cleaned and serviced the woodburner and found 7 mummified bats in it and one free flying in the shed the next night (I'd left the airvents open this time)..so today's job was a bat-proof chimney cowl.

As to the minnie boiler - I'm making a new firebox as much for practice as the first one isn't too pretty - albeit likely functional - and it makes me realise how much more pedantic and accurate one needs to be with bashing these shapes. But nothing essentially different with mark1 to report.

I can already see boiler No3 on the horizon but I need to plod through and make all my mistakes here first

Today I fluxed and rivetted up No2 barrel,throatplate and wrapper and brazed it. This definately takes practice! With less panic and excitement I think I've succeeded but once again forgot to specifically dob a bit on each rivet. I don't think that'll matter since the only loose fit rivet got soldered from flow between the sheets and all the others are through a solidly soldered overlap. It's mucky looking with silver solder excesses in places which will make work cleaning up later (when all the soldering is done).I will tidy the barrel inside before more work there.

So i'm about where i was with the first set pics last year and looking forwards to moving on. I used 38% silver for this session. Once it's pickled and flux cleaned off I may post a pic.

That should be a really good hearth. I love using the skamolex blocks, just putting two in an L-shape and laying the 'target' along the join reduces heat up time by half.

Neil

Help please - I have a problem.

I cleaned up the brazed tube/throatplate/wrapper and rechecked. Prior to soldering it was all pretty darned square when rivetted (unless I blundered when checking) but now I have the throatplate free edge running away from square to the barrel by 1/16th" over it's 1&15/16th" length and that of course throws my parallel back edges of the wrapper out by the same angle. I'd also left the wrapper sides longer than needed with intention to trim level with the throatplate after soldering.

Problems therefore are that it's all very annealed and soft after soldering so filing or milling really needs support. Best I've come up with would be to make a timber block to fill the wrapper and then clamp in a vice - unless there's a simpler way? I don't think any of my vices can clamp one side of the wrapper with the edge to be trimmed accessible.

The other problem is that i need to try and square it all up. I think the throatplate angulation has to be left alone and i don't think that matters? It's the sides and back. The only real reference is the front of the barrel (sit it one a flat surface) and finding a way of scribing a line parallel to that along the back (now top) edge of the wrapper (without a 10" height guage) - which at least runs away so there's 'spare'. Once that is square then the bottom of the throatplate and wrapper can be finished at right angles to the back.

I think i've figured it out. I have a 6" angle plate. total length to back of wrapper is 9&5/8" so cut a length of bar to 3&5/8, sit it on the angle plate and touch off with a cutter. (my mill has enough throat) then with a wrapper filling wooden block made up i can mill off the back of the wrapper to an accurate 9&5/8" with the barrel vertical in that angle plate. Once i have that new reference and the block i can clamp the wrapper in the mill vice (back edge against the angle plate) and skim off the bottom of the wrapper level with throatplate...?

messy woodwork needed.

If you want to scribe the 9.625" then just cut a block of wood and drill a hole for a scriber at that height, may be a whole lot easier to just file down to the scribed line.