Werowance attempts Kenneth Wells Traction Engine

[werowance]

found this image online that looks like the brass boiler casing butts up against the outside of the firebox and just the copper pipe goes thru the hole. guess that would make sense as that would hold the firebox end in place.

 

[Steamchick]

N.B. Silver solder melts at anything from 630C. to ~830C. depending on grade, but brass needs over 900C. I think?
Unlikely to melt brass with small blowlamps, but take care.
MOST proper boilers are made using Phosphor Bronze, not Brass. I have experienced Brass (probably with a high zinc content?) that crumbled like a biscuit after 20~25 years due to DE-ZINCIFICATION. An Electro-chemical reaction that occurs on wet brass. In this case a screw-down valve at the bottom of a gauge that never actually dried out after use. There was always a drop of water left, trapped.... Now replaced with a stainless steel valve, but I doubt I shall be around in 25 years more to be bothered by it. Your brass soldered into the "toy-equivalent" boiler will probably be OK if you DRY the boiler after use. Remove the filler, warm gently until all steam has gone, then leave the bung out and box the job in a cardboard box - that will allow moisture to permeate - in a dry cupboard or shelf. Cardboard is good, because if it has been wet you can see the water damaged cardboard at a later date. Gives a clue as to whether the storage has ben dry or wet! (There is "Engineering" in the material selection for storage as well!).
On pressure.
As the boiler appears not to have a gauge, although that enhances every model, what pressure will the safety relief valve maintain, with supply valve closed, full fire and full water? What is the DESIGN limit on the drawings? Mamod and other "toy" model makers use 15 psi for most, but some boilers are designed for 20psi Normal Working Pressure, that is NOT EXCEEDED until worst conditions. (The design withstands more than 8 times the NWP, I understand!). You tested to 150psi, (Post #17 "i pressure tested to 150 lbs") so that means NWP at less than 1/8th is a MAX NWP of 19psi to best resolution of a test gauge.... The SAFETY valve must ensure that 19psi is never exceeded. - Can you prove that with a steam test when finished? - I should adjust the SAFETY valve to "Never exceed 15psi", as that is "normal" for this sort of model in practice. What does your design drawing say?
K2

 

[Steamchick]

On the question: "i dont know if i need to cut this hole in the firebox end to fit just the boiler pipe or to fit the brass boiler casing. i know if the casing does pass thru the firebox end it wont by much but looks like it might just pass thru maybe 1/8 of an inch or so".
Well, I don't know, not having the drawings, etc.
BUT logically, if the boiler (the structure joining back axle, firebox, etc to the Smoke box, front axle, etc) goes all the way through to the back of the firebox (which the end plate drawings suggest) and uses the studs showing on the ends of the boiler (Or is it a single through stud? - as I would expect?) to make the mechanical connection, then the only thing the brass casing tube is really doing (apart from looking pretty) is carrying the flue gases past the outside of the copper boiler and to the smoke box, to vent up the chimney.
In that case the brass casing could sit on the face of the front smoke box plate, but I think it would be better if it does go through that plate and project as you say "about 1/8in beyond."
Are there not adequate dimensions on the drawing to be sure? (Size of hole versus OD of tube, or addition of lengths of parts, etc.).
K2

 

[sarel]

found this image online that looks like the brass boiler casing butts up against the outside of the firebox and just the copper pipe goes thru the hole. guess that would make sense as that would hold the firebox end in place.

View attachment 164925

The boiler moves into the firebox to go flush against the back of the firebox and be fitted through the 5.1mm hole with a nut to the rod going through the boiler centre. the filler/safety valve bung is visible in the picture through the top of the firebox showing you how deep the boiler goes in.

View attachment 164925

 

[sarel]

anyone know if the brass boiler casing passes thru the firebox casing? i have watched the videos and also re-read the instructions and im not seeing where it says if it does or not. my pipe is not metric and is just a tad different size so i dont know if i need to cut this hole in the firebox end to fit just the boiler pipe or to fit the brass boiler casing. i know if the casing does pass thru the firebox end it wont by much but looks like it might just pass thru maybe 1/8 of an inch or so by looking at some of others builds but cant tell for sure.

View attachment 164923

See page 85 of the book.

 

[werowance]

N.B. Silver solder melts at anything from 630C. to ~830C. depending on grade, but brass needs over 900C. I think?
Unlikely to melt brass with small blowlamps, but take care.
MOST proper boilers are made using Phosphor Bronze, not Brass. I have experienced Brass (probably with a high zinc content?) that crumbled like a biscuit after 20~25 years due to DE-ZINCIFICATION. An Electro-chemical reaction that occurs on wet brass. In this case a screw-down valve at the bottom of a gauge that never actually dried out after use. There was always a drop of water left, trapped.... Now replaced with a stainless steel valve, but I doubt I shall be around in 25 years more to be bothered by it. Your brass soldered into the "toy-equivalent" boiler will probably be OK if you DRY the boiler after use. Remove the filler, warm gently until all steam has gone, then leave the bung out and box the job in a cardboard box - that will allow moisture to permeate - in a dry cupboard or shelf. Cardboard is good, because if it has been wet you can see the water damaged cardboard at a later date. Gives a clue as to whether the storage has ben dry or wet! (There is "Engineering" in the material selection for storage as well!).
On pressure.
As the boiler appears not to have a gauge, although that enhances every model, what pressure will the safety relief valve maintain, with supply valve closed, full fire and full water? What is the DESIGN limit on the drawings? Mamod and other "toy" model makers use 15 psi for most, but some boilers are designed for 20psi Normal Working Pressure, that is NOT EXCEEDED until worst conditions. (The design withstands more than 8 times the NWP, I understand!). You tested to 150psi, (Post #17 "i pressure tested to 150 lbs") so that means NWP at less than 1/8th is a MAX NWP of 19psi to best resolution of a test gauge.... The SAFETY valve must ensure that 19psi is never exceeded. - Can you prove that with a steam test when finished? - I should adjust the SAFETY valve to "Never exceed 15psi", as that is "normal" for this sort of model in practice. What does your design drawing say?
K2

the plans said to test to 150 lbs. i can test again with the pop off valve in place and solder my gauge to the end of the steam pipe to do the initial setting of the pop off valve.
i am aware of dezincafication and is why i said it was brass instead of the normal bronze used but brass is what the plans call for. i used 360 brass. my main torch is a larger mapp gass torch (not the little plumbers sized you get at wall mart) and when the flame licks the top edge of the brass it does that thing where it changes color and gets extremely hot on that edge. kind of like a vortex. i dont know what thats called but i know what makes it happen and what happens if im not carefull - melted brass or over heating which did happen on the first one. so thats why on the 2nd i kept the big torch lower on the boiler itself letting the heat rise up to the brass part and then brought it on home with a smaller propane plumbers torch in the other hand to just the right temp where it flowed nicely

edit - the silver solder is 22 gauge 57% silver advertised flow temp is 1211 F or 655 C and a melt temp of 1148 F or 620 C.

 

[werowance]

See page 85 of the book.

Hi Sarel, i re-read page 85 but it really doesnt say if the brass casing goes thru the front firebox plate or just up to it. i understand the boiler bolts to the back firebox plate. it says once the boiler is bolted in place to slide the brass casing in place. (i paraphrased that) but i cant tell in the photo if it actually went thru the front firebox plate by just a little tiney bit or if it just pushed up to the outside the front firebox plate. the difference i am concerned about is the large hole that must be cut in the front firebox plate that i know the boiler goes thru but not sure if its boiler or boiler + brass casing. so knowing if its one or the other tells me what size hole to cut in the front firebox plate.

sorry, i hope that helps describe why i am asking and why i cant tell for sure.