Brit Progress: Boiler Plates

[Deleted]

The 5/8" reamer arrived from RDG today (less than a fiver!) so I couldn't avoid doing the combustion chamber any more!
There's quite a saga to this. I thought I would line bore the water tube holes with my new boring head. Big mistake as the photos hopefully will show. I landed up 'doing it by hand' if you'll forgive the expression. I propose to file off the tube ends when it is brazed up, or should I prepare them first? They are quite snug at the moment!


I don't have a 39/64"drill, so I drilled out the top and bottom holes at 14mm using a step drill, supported on a stout wooden beam: it's probably a better method as the step drill doesn't make triangular holes in soft plate!


Took me a while to set this up using a long boring tool fitted with an insert. That front face is not vertical.


Wasn't going too well on the first hole, so when I looked I found that the insert had virtually departed the holder! The button screw was dead tight, and when I replaced the insert the socket head stripped inside 'cos it's a crap rubbish item.


Resorted to hand methods: 12" round file and a brass sizing bar slightly tapered on one end, finished off each hole with the new reamer. Took half the time that it took to set up the line boring!

[simonwass]

Doesn't really matter either way if you finish the tubes before or after silversoldering. Left long you get more heat into them so could get better penetration. For the same reason you should always leave stays long then trim once complete, a short stay doesn't get hot as quick.
A tip for your tubes, make them a loose fit and put 3 dings on each end when assembled using a blunt chisel, this makes 3 small contact points to hold them secure and allows the silversolder to flow all around.

[Deleted]

Thanks Simon. My dilemma is that LBSC in his words and music advocates 'tight' tube fits and deep countersinks. I suspect this stems from the days when brazing fillets held the tube in place rather than the deep penetration one gets with modern silver solders. Or have I got it wrong?
JB

[brozier]

If you are Silver Soldering you need clearance to match your selected solder as it varies between grades.

For 55 Johnson-Mathey states :
"The optimum joint gap for this filler metal at brazing temperature is normally 0.05-0.15mm."

See
www.jm-metaljoining.com/products-pages.asp?pageid=60§ionid=3

So I used 0.1mm all round and a countersink on each side of the plate. TO get this I drilled to size and opened out with files.

I practiced the tube joints on some scrap to understand what I was doing.


See here for more info....
homepage.ntlworld.com/bryan.rozier//silver_soldering/Silver_Soldering.html

That combustion chamber looks pretty complicated. I think I'd do the cross tubes last as they obscure the smoke tube joints. I haven't made one like this though so might be worth asking someone who has ... Baggo?

Cheers
Bryan

[simonwass]

I suppose on the face of it a tight tube with deep countersink would give a similar contact area to making a parallel rattle fit. Might use a bit more silversolder filling the countersink but not much more. File the usual handful of nic's around the hole to let a fillet form on back side. If you are feeling confident, use silverflo24 (or similar) to assemble the cross tubes and tubeplate, get it right and you'll not have trouble later if you disturb the join and get a leak, you'll be into radweld or loctite 290 territory then hoping to get it to seal.

[Deleted]

Thanks for all the advice everyone. I now have all the components made ready for the big heat! I'm going under the knife tomorrow, just a day case, but if I don't come back you know where there is a half built Brit for sale!

Someone said the other day that the boiler was complicated: after doing the stays this afternoon and looking at the thing I'm inclined to agree!

[Deleted]

Had a rivetting time today after resting up for a while! Here is a start on the firebox assembly: doorplate, throatplate and centre stay all in place.


Interior view


If you haven't rivetted boxy sections like this before you will need a stake or two (not the gambling variety, tut, tut.)

A bit of angle iron that jams under the vice jaws and therefore doesn't move too much


And a vertical stake to do the girder stays. It's only unhardened silver steel 5/16" and is perfectly adequate. Centre drill to the size of the rivet head, and whack a suitable ball into it to make the rough shape and bingo!


Outer stays tomorrow, they might be a bit more tricky.....
JB

[redmog]

Excellent Photographs.

What nice quality photographs JB.
Is your workshop well illuminated or are they flash?
It's shaping up very nicely.
I hope you have a spare pair of hand to take the photos of the
'Big Heat'.
I'll be expecting to see that.

Chris

[Deleted]

Hi Chris.
Tripod, decent Fuji Camera (6900 Zoom, several years old) and lots of strip lighting. Flash doesn't normally deal with metal surfaces very well. Most of these exposures are at around 1/15 of a second, but I use the two second delay so there is no chance of any camera shake.

regarding the 'Big Heat', I don't know anybody who wants to stand in front of a 40kw burner for twenty minutes.......
JB

[drumkilbo]

All very interesting and informative JB, and as Chris says, beautifully illustrated too. Thanks for going to the bother of posting it all.

Ian.

[Deleted]

Outer stays rivetted on, and found to be much too high, forcing the firebox out of the bottom of the boiler! Lots of bashing and swearing to reduce the height! It was all made to the instructions, but when I looked on the drawing, two key wrapper dimensions differed from 'As Drawn' by an eighth of an inch! I don't normally take dims off the paper, but on this occasion I should have! GRRRR!

Rear view of 'amended' stays! They will be fettled up later for a better fit against the wrapper.


Trial fit with dummy foundation ring part. I seem to have made the inner firebox a bit small so it looks like I will be using a 3/8" ring on the outer faces! The backhead is sitting on the outer firehole flange, just to check that I have the correct angle (or nearly...)


View down the sharp end: everything seems to be in the right place!


Big Heat next!

[steam4ian]

G'day JB

Your last picture shows a lapped joint for the longitudinal seam on the barrel. Is that allowed in UK?

Regards
Ian

[Deleted]

Hi Ian. Yes, if it is an established design then it is OK so long as I put some bushes in strategic places. There are lots of Brits running around and they haven't blown up yet......
JB

[drjohn]

Oct 13, 2009 21:02:07 GMT steam4ian said:

G'day JB

Your last picture shows a lapped joint for the longitudinal seam on the barrel. Is that allowed in UK?

Regards
Ian

Is this inferring that the country around Adelaide has better standards for boiler safety ? Hmmmm!? P'raps someone ought to inform the AMBSC or whoever certified the boiler I got from there!


And JB - there always has to be a first! ;D ;D ;D

DJ

Actually, I'm very impressed if the boiler is as good as the pictures proclaim - fingers crossed for your big heat!

[steam4ian]

G'day all

Better standards?

Historically lap joints have not been admitted, see UK model boiler making liturature, Harris, Evans, LBSC etc. Acceptable joints historically have been butt and strap and a housed coppersmiths joint.
It would be good if lap joints were reconsidered, however some testing to destruction would be a necessary basis before departing from traditional wisdom.

The AMBSC "appear" to have ignored testing to destruction of test boilers with butt jointed ends when writing the subminiature code. The tube burst whilst the silver soldered butt ends stayed secure. So the AMBSC may err on the side of caution.

DJ it is a pity some sod thought he could palm off to what he percieved as a third world country a third rate boiler.

JB's work is most inspiring; I look forward to his onging exploits.

THANK YOU JB.

Regards
Ian

[ausdan]

have removed my post, as it does nothing to support this excellent thread...sorry JB

I plan to do something similar when I start to build my boiler, thanks for efforts JB

[drjohn]

Oct 15, 2009 10:25:51 GMT ausdan said:

Dr J u need to get over it mate .

DJ, thats what can happen when you buy unseen? its a gamble, you lost....move on

Its getting really old to hear you continually slagging off about a the AMBSC and our boiler inspectors, the way you wallow on you think that every boiler ever made in the last 20ys is the same as yours.

if I end the post with three of these everything will be fine

Hi Ausden - if I had been a rookie and the boiler had blown up in my face and that of 20 kids, would it still be ok to "move on"

Get lost!

As safety conscious model enthusiasts, we cannot let such cr*p just "move on". Ok you're obviously an Ozzy called Dan, but you are too shy to publish any details about yourself on your profile. So continue to hide behind anonymity if that's what you want. But don't "move on" from potentially lethal Sh*t made in OZ by "experts"

DJ - no smileys - what's the point?

[Deleted]

Can I have my 'informative and inspirational' thread back please?
Thanks
JB

[drjohn]

Sorry JB

[spamcanman]

JB, there was a Britannia boiler in the same stage of yours but soldered at the Midlands show plus the rolling chassis again in the same advanced build as yours I had to do a double take on the builder to see if it was you, I took some pictures with my phone I'll see if I can get them on here.