Method of fitting/retaining boiler within the mainframes

[colm57]

I could really do with some some advice on this please.

  I have now finished my boiler for my 3.5" Black V Loco "Doris" I have set it in between the main frames to see the fit. i have to say that i am completely baffled as to how to secure it so it doesn't move. I can only imagine that its screwed into the Smokebox and secured between the mainframes but could still move up and down within them. Under the boiler is the ash-pan which is held in place by a pin and a bracket to the boiler so i suppose it could should sit on that, but to me that doesn't seem very substantial. 

 I have looked at some other ideas whereby the boiler has apiece of angle either side of the firebox and rests angle on the mainframe.

I would most grateful to you guys for any advice or pictures to help me

Regards

Malc

[ettingtonliam]

The usual method is a short length of brass angle fixed to the side of the firebox, at a level where it can sit on the top of the frames. Another piece of angle, screwed to the frame acts to stop the angle fixed to the boiler from lifting. If the boiler is fixed to the smokebox, when it expands it can slide on the top of the frame at the firebox end.

[colm57]

Thanks for your speedy reply. I understand your explanation perfectly and it would be simple and effective. Can`t thank you enough.

Regards

Malc

[millman]

Piece of angle fixed to sides of outer wrapper and resting on top of frames is a popular way of restraining boiler, another popular method as used on the Polly range of locos is a piece of square bar used as a frame stay positioned so that the front of the foundation ring sits on it

[miken]

Nov 2, 2024 22:38:33 GMT ettingtonliam said:

The usual method is a short length of brass angle fixed to the side of the firebox, at a level where it can sit on the top of the frames. Another piece of angle, screwed to the frame acts to stop the angle fixed to the boiler from lifting. If the boiler is fixed to the smokebox, when it expands it can slide on the top of the frame at the firebox end.

The above is the method I use. I would add that I secure the brass angle to the sides of the boiler using bronze screws caulked all round with soft solder.

[Jim Woods]

Sometimes LBSC just let's the foundation ring sit on the top of the horn blocks. Princess Marina and Netta are like that

Jim

[brucevoelkerding]

Millman - with Regards to the Polly method, what holds the Boiler down on the Stretcher? Does the Cab prevent the Boiler from being lifted ?

Jim - I have the set of 3-1/2" gauge Netta Drawings. You are correct, on Sheet 6 you can see the Boiler Foundation Ring sitting on the Horn Block. This does imply the Smokebox Saddle must not be located until the Boiler is fabricated. Another interesting Concept on the Netta drawings, sheet 8, are qty 2 Links (one on each side of the Boiler). These Links are 1/16" x 1/4" Section with a 3/32" Hole at one End and a 1/8" Hole at the other End on 3/4" Centers. The 3/32" Hole is riveted on the outside to the 1/4" deep exposed bottom edge on the Inner Firebox. The 1/8" Hole accepts a 5BA Screw which is threaded into the Ash Pan (thickening Pad provided). The Ash Pan is rigidly fastened to the Frames. Dumping the Fire is done with a hinged Portion of the Grate. The Back of the Ash Pan is open. There is really no way to remove Ash from the Portion of the Ash Pan ahead of the Trailing Axle shown on the Drawings.

I am constructing a "second Generation" Netta, the LNER Q6. Since the Fire Box is longer, I am slightly decreasing the depth of the Foundation Ring so it has a nominal Clearance over the Horn Blocks. I have Holes in the Frames to mount a Block on each side of the Frame to support the Foundation Ring. These will be machined to height after the Boiler is in Place. I am strongly leaning towards using the Cab to hold the Boiler down. The Ash Pan requires a "Tunnel" (open at the bottom) to clear the Trailing Axle. The Ash Pan has both bottom Surfaces Completely OPEN. They will be closed with a flanged Bottom Plate, removal by pulling 2 Pins. I have convinced myself that the Grate can be installed up thru the rear Ash Pan Opening.

[millman]

Brucevoelkerding, the only thing holding the boiler down is gravity! The cab will prevent it lifting so will the blowdown through the side of the frame, also the plumbing will help hold it in place. I have had my Polly tipped right over hanging in mid air by the buffer beams and everything stays where it should and when you consider how many Pollys are running I have never heard of any problems regarding boilers moving on the stay.

[brucevoelkerding]

on my 7-1/2" gauge American style Atlantic the Grate is made in 2 pieces. The Split Line is on the centerline of the Locomotive. Due to the American design of Bar Frames, the Ash Pan Segments simply pull horizontally out of each Side of the Locomotive. (note the Ash Pan is not as deep as a prototypical one where it would drop down inside the Trailing Truck) The qty 2 Segments are held together with 1/4" (maybe 5/16") dia Rods running crosswise from the inside of one Ash Pan Segment to the inside of the other Ash Pan Segment. They are located close to the Top of the Ash Pan. Both ends of these 2 Rods are tapped 10-32 and I use Soc Head Cap Screws thru the Ash Pan Sides into the Rods to hold it all together. A loose piece of plain flat Sheet Metal lies in the bottom of the Ash Pan to prevent hot Coals slipping thru the Split of the Ash Pan. The Rods act as Supports for the Grate Sections which are set in position thru the Fire Hole.

With a Screw on each End of the Rod it is no Problem removing one Screw from each Rod. I do put a slight Smear of Anti-Seize on the Screws once a Year.

[brucevoelkerding]

Senility is creeping in ! I was replying to a Thread on Model Engineer Forum and posted it here by Mistake.

[David]

Neither of my locos have any fixing at the firebox end. One has the foundation ring sitting on the frames, the other has it sitting on the rear hornblocks. Every other loco I know in our club is the same, but I don't know that many of them to that level of detail.