Model Boat Mayhem

Please login or register.

Login with username, password and session length.
Pages: 1 [2] 3   Go Down

Author Topic: A few steam questions  (Read 1556 times)

derekwarner

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,321
  • Location: Wollongong Australia
Re: A few steam questions
« Reply #25 on: May 27, 2020, 12:02:26 AM »

belli......You will find Citric Acid at more competitive price/quantity from Home Brew stores  O0 ..... Derek

[You may need to increase the concentration above the recommended value]


https://nationalhomebrew.com.au/wine/national-home-brew-citric-acid-100g


'For acid bathing of copper and ceramic saddles, dissolve 5g in one litre of cold water and soak for 24 hours'
Logged
Derek Warner

Honorary Secretary [Retired]
Illawarra Live Steamers Co-op
Australia
www.ils.org.au

Jerry C

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 1,136
  • Location: Caernarfon, North Wales.
Re: A few steam questions
« Reply #26 on: May 27, 2020, 05:34:16 AM »

When I made my first boiler I ordered a kilo of citric acid. Got a funny look off the postman.
Jerry.

frazer heslop

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 245
  • Location: Durham
Re: A few steam questions
« Reply #27 on: May 27, 2020, 03:15:32 PM »

I used to buy Scalecleen by the stone from the States its a form of citric acid and works far better. Check the spelling not my strong point.

No luxury digi thingy ma bobs this end just a ciggy paper and count the turns :} .I used to make a living fixing tool makers oops moments and they always blame the machine but the fault codes never lie %) 
cheers
Logged

frazer heslop

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 245
  • Location: Durham
Re: A few steam questions
« Reply #28 on: May 27, 2020, 08:03:51 PM »

This is a small wobbler I made for a 12inch Puffer.
Its still waiting for the hull
Have you seen Les Propers Youtube he has some nice small boats and steam plants
https://www.youtube.com/watch?v=9rcorLIJVdU
https://www.youtube.com/watch?v=EURne7s7u-8
Logged

belli

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 35
  • Model Boat Mayhem is Great!
  • Location: New York (the other one)
Re: A few steam questions
« Reply #29 on: May 27, 2020, 10:15:59 PM »

I mailed Leslie to get a copy of his book but regrettably wasn't able to.  I do like his little boats but they might be a trifle small for me, shaping the hulls would also be a bit time consuming and quite difficult to get symmetrical if you were impatient like me.  I think if vac-formed or molded hulls were available, that would be better for me.

I also have the building of Clyde puffer on the list, they were really what I found first and the French Mini-Vap 50's.  I have the Boxer Clyde Puffer in CAD, ready for laserin' but haven't got to it.  It might make a suitable hull for a simple steam plant as it could be built in a few hours if you had all the material to hand.  There is a nice read here: https://www.modelboats.co.uk/news/article/puffin/525     of a fellow that did exactly that.  It wouldn't take long to put something  like that together.


I did buy JohnTom's Clyde Puffer in CAD and was terribly disappointed.   I work with CAD a lot and what I received really was of no value.  Taking some images that you have found on-line, feeding them thru a photo to CAD converter really doesn't cut the mustard. 


Regrettably things at work are starting to tick upwards, I will be busy for the next two weeks but will endeavour to spent a little time finishing off some engines and making a start on some boilers.  My favourite non-ferrous supplier will be re-opening on Monday, they do allow me to go and pick through the off-cuts.  You still pay 'full' price but at least I can get smaller pieces.  The flywheels of these three engines were machined from 11/2" hex bar as that is what I had....

Keep building Frazer, more photos and sketches please.

Logged

frazer heslop

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 245
  • Location: Durham
Re: A few steam questions
« Reply #30 on: May 27, 2020, 10:56:20 PM »

There is some drawings on the net for a Clyde Puffer named Vital Spark I think this is what Les based his boat on
Good luck with the engines
cheers
Logged

belli

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 35
  • Model Boat Mayhem is Great!
  • Location: New York (the other one)
Re: A few steam questions
« Reply #31 on: May 28, 2020, 04:05:10 PM »

OK, today's haul:
Ten pints (about 5l) of battery acid, $9.
Plastic bucket (I'll be careful) with a lid, $2.50.
Silicon O-rings, 6x1mm (8mmOD) $1.72/100. 

Silicon O-rings, 9x1.5mm (12mmOD) $2.00/100. 

They couldn't find the 3x1mm...  All other sizes are available, minimum order is $15 per size (about 700 O-rings), six weeks delivery.
623, 624 and 625 Bearings $0.55 each.

Most of the designs I have seen for small steam engines recommend O-rings but offer no suggestion of sizes, Frazer?

Now, back to the salt mine   <:(

Logged

frazer heslop

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 245
  • Location: Durham
Re: A few steam questions
« Reply #32 on: May 28, 2020, 10:23:42 PM »

Most of my engines are Imperial the smaller have a 0.070 cross section the larger .103
Silicone O rings are for static applications from memory but they are what I use and just bung a new one in when needed
Groove sizes on this site not the cheapest but I dont want several hundred
With O rings fitted you will need a lubricator as they dont like to run just on wet steam
The 3mm are they for the piston rod seal if so just make a standard packing gland and use ptfe tape it will make little difference
https://www.glrkennions.co.uk/silicone-o-rings.html
Logged

belli

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 35
  • Model Boat Mayhem is Great!
  • Location: New York (the other one)
Re: A few steam questions
« Reply #33 on: May 28, 2020, 10:39:10 PM »

Those sections are much heavier than I thought, 1.7mm - > 2.6mm  My thinking was that on such small pistons, 8-10mm, 2mm section would be simply too large.  I'll call tomorrow and see what they have.

Correct, the 3mm was for the piston rod, never thought to try PTFE tape.   I do have some graphited/grease/yarn kinda packing, quite large, about 1/4" diameter, was going to try pull it to pieces and make a seal from that.  I did also buy some 1/8" square graphited yarn for the Stuart 10 pistons.

I try to machine the pistons to fit the bore but never quite seem to manage a good fit.  Tried lapping with polishing compound, making a new piston, trying again, etc.  They just never seem quite right.  Maybe the fits are good but I just don't know what a good fit is.   I'm hoping with the O-ring I can machine the piston slightly under size and the O-ring will provide the fit.   Most of my bores are honed with a Sunnen machine at a friends place but the smaller hones are missing their stones.  I guess I'll get some stones ordered soon.

Thanks,


Logged

frazer heslop

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 245
  • Location: Durham
Re: A few steam questions
« Reply #34 on: May 28, 2020, 10:49:35 PM »

I also unpick a strand from 1/4 packing either works OK for me
A thou clearance on the piston is my target for steam engines Hot air engines are a different matter on these I have made some external laps to size the pistons
Dont make the ring grooves undersize as it will become a problem as the engine goes over BDC or TDC it will bind a wee bit of wiggle room is better
The more important thing is the piston is concentric to the piston rod as is the bottom cover and packing gland .This is why I use the glue chuck as my kit is simply not accurate enough to just use a collet
Probably telling my Granny how to suck eggs
cheers
Logged

derekwarner

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 8,321
  • Location: Wollongong Australia
Re: A few steam questions
« Reply #35 on: May 29, 2020, 12:50:46 AM »

belli.....3 x 1 o-rings


3 x 1 o-rings ...[9-020 or 6-018] are non preferred sizes and may be available in 70 Shore NBR which is not suitable for our modest steam pressures


[/size]2.9 X 1.78 [1-006] is probably the closest generally available in FPM or Silicon to suit a 3 diameter shaft Silicone is listed as ~~ 70 Shore A and is recommended as for static applications FPM [Viton] is listed as ~~75 Shore A so is more suited to dynamic [piston or rod gland] applicationsAs frazer notes...picking smaller strands of graphited cotton yarn [J Walker Packings] is absolutely suitable :-))  for both piston and gland, although may need a little preload to attain the first steam pressurization


Derek
[/font]
[/size]Derek



Logged
Derek Warner

Honorary Secretary [Retired]
Illawarra Live Steamers Co-op
Australia
www.ils.org.au

belli

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 35
  • Model Boat Mayhem is Great!
  • Location: New York (the other one)
Re: A few steam questions
« Reply #36 on: June 11, 2020, 09:54:04 PM »

Progress but slowly....

I am building at approximately the rate that I can source the bits I need.   The fire bricks arrived today, I can now build a mini hearth for welding the boilers together.

Here's a photo of the first two flanges, they came out better than the second two  :o .   The first form I made was too shallow and as the flanges were rolled over they extended past the end, I screwed a piece of scrap to the back of it to complete the flange so that I could check the size.  Once happy I turned a new form that was much longer and just .2mm smaller and this gave me a very good fit.  I have attached a photo of the fit, it presses in easily with my fingers but do you think the solder will still flow or does there need to be a bit of clearance?

The new form is held in the soft-jaws, allows me to remove it and replace without loosing dimension.  When parting off the flanges I could do all four and they were exactly the same.  Tool was CBN and it cut the copper very nicely.


I am also curious what the 'black' is on the commercial boilers (Cheddar, et al), is it paint or some chemical process?  Should I make little feet and solder them to the boiler or how are they mounted?

One boiler is about 4" long and the other is about 5" long, both are 3" diameter.   I will run a 7/8" fire tube through the lower half with about six 5/16" cross tubes.  Does this sound like a good idea?  I hope to make a gas burner for it.

There has been some progress on the engines, I will make new standards for the double acting cylinders and keep these two for some simple single acting ones.

Logged

frazer heslop

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 245
  • Location: Durham
Re: A few steam questions
« Reply #37 on: June 11, 2020, 10:15:05 PM »

The black is just VHT paint
The fit I tend to go for is about 2 thou clearance or a very easy slide fit. I like to use a couple of rivets or copper rod to keep the end caps located when soldering. It stops them from moving just as the solder melts and saves a shed load of swearing
Iv just flanged my plates as well and the gas tank plates . I dont have the luxury of soft jaws so tend to friction turn them
If you look on Cupalloys web site in the Model Engineering section is a very good write up about silver soldering and its wicking properties
You may struggle with that blow lamp for hard soldering read silver soldering in the UK
On my other boilers the feet are held by the banding for the lagging
Remember a copper tube under external pressure will take a lot less pressure to collapse it compared to the same pipe under internal pressure. There is a big difference
On a 3inch boiler I would use a larger flue around 1 1/4
I have been experimenting with flues using a home made calotherme simply a tin the flues fit into and measure the temp rise in a given time and gas used and Im finding the plain flue no tubes with a poker type burner uses less gas heats the water quicker and the exhaust temp is 100 degrees C lower than the water tubed one although this is just experimental at the moment .Im using wet back deign as in the flue turn 90 degrees within the boiler shell
Keep well cheers
frazer
Logged

belli

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 35
  • Model Boat Mayhem is Great!
  • Location: New York (the other one)
Re: A few steam questions
« Reply #38 on: June 11, 2020, 10:40:24 PM »

The gas torch in photo is used to light the larger one....   It has a click starter.

The bigger torch I have is still a bit small I think, the front 'nozzle' is about 1" in diameter, heats the flanges to red in about one minute.  Most of my tools are sourced at porn shops and I haven't seen a larger one yet, to buy new is quite pricey.  I'll figure something out.

Your comments on the boiler are interesting, I thought that the cross tubes would slow the flow of the heat and transfer more of it into the water.   Maybe I'll try the 4" boiler without the cross tubes, I can get some 1 1/8" tubing, maybe make the fire tube out of that then.  The next size up I have is 1 1/2" which I was going to use for the gas tank.
Logged

frazer heslop

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 245
  • Location: Durham
Re: A few steam questions
« Reply #39 on: June 11, 2020, 11:03:54 PM »

In the UK the gas tank would need to be tested to 400psi from memory so you would need to calc the right gauge of pipe. Although that may not be the case in the USA I would ask around before going ahead it may save a bit of time
Im not convinced myself over my finding and need to try and have a word with a couple of guys who know there onions better than me
My thinking is that the poker burner gives a greater heating surface for the flue and the air velocity through the flue is lower but this is getting far above my knowledge or capabilities .
I think Malcolm Beek did a center flue design a few years back that was in one of the model boat mags. I will have a look tomorrow during my playtime in the shop
The problem with flued boilers for simple steam plants is the lack of water capacity=run time  . That why Iv been playing with T style boilers. The top of the T gives or acts like a large steam dome and allows for more water space in the main tube
You can see the idea in this wee videos
https://youtu.be/zfPa4YFEPsw


https://www.youtube.com/watch?v=sW6PKkHYcaQ
Logged

frazer heslop

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 245
  • Location: Durham
Re: A few steam questions
« Reply #40 on: June 12, 2020, 01:53:58 PM »

I have looked at Peter Arnots and Malcolms boilers they both used a 28mm dia flue with  cross tubes
cheers
Logged

Geoff

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 738
Re: A few steam questions
« Reply #41 on: June 12, 2020, 05:11:44 PM »

Just to chip in and I'm a novice with boiler building but I do build my own oscillating engines. I know model practice differs from full size practice but the water cross tubes (and any fire tubes) are there to increase the surface area of the heating surface for the flame to reach and should allow for faster heat up time and increased steam production.


I've also looked at Peter Arnot's boiler designs and like the fact the fire tube bends upwards at 90 degrees internally so is surrounded on all sides by water. Having said this the Cheddar Puffin boiler version 1 uses return fire tubes in the upper half whereas the version 2 is like the Arnot boiler design. The Cheddar version 2 also uses a ceramic burner and holds 40% more water due to the internal design but is no bigger than the version 1 and it produces steam very well.


Very interested to see how your tests work out.


Cheers


Geoff



Logged

frazer heslop

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 245
  • Location: Durham
Re: A few steam questions
« Reply #42 on: June 12, 2020, 07:19:24 PM »

Hi Geoff, the Arnot boiler works very well I built it for my River Queen
 The flue burner Im using is an inverted radiant style . I agree with what you say about cross tubes but for some reason when Im testing these flues I seem to get better results with an inverted radiant burner in a plain flue .No idea why or if Im working this out correctly
cheers
Logged

belli

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 35
  • Model Boat Mayhem is Great!
  • Location: New York (the other one)
Re: A few steam questions
« Reply #43 on: June 12, 2020, 07:28:47 PM »

Frazer, when you say inverted 'radiant style' and 'poker', do you mean that the burner is a long, rectangular 'pan' with a ceramic element or mesh along its length?  Inverted, do you place this upside down?  Forgive my dumness...


I did buy some orifices (orifi ?) (jets?) yesterday, they were a buck a pair.   I lied when I said that I had 28mm tubing but I did get some today, was a full length (18'), bent a bit in the middle, paid $20 which seemed fair.


Here's a picture of the Arnot boiler for those not familiar.
Logged

frazer heslop

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 245
  • Location: Durham
Re: A few steam questions
« Reply #44 on: June 12, 2020, 09:49:45 PM »

The burner is a poker type. just a length of KS tube with several cuts half way through across it. Then it is wrapped in a fine mesh
The cross cuts need to be finer than the gauge of the tube or they dont burn well or at least the ones Iv made dont

The burner sits at the top of the flue with the slots facing down
I make my own gas jets and tune them to the burner when its in the flue. Starting with a 0.4mm hole that is closed down to .15mm (number 3 jet)using Colin Binnies idea except I have made a punch that is guided.These holes are then opened up using a tapered broach
The broaches are easily made from sewing needles or the likes of Cousins clock and watch part suppliers sell them
The flue is very close to the bottom of the main barrel about 2mm clearance
The Arnot boiler is a good steamer and powers my River Queen 7/16 x 1/2 inch V twin easily
The design Im looking at is 2/1/2 dia with a plain 22mm flue using a 1/2 inch poker burner with a wrapper of fine mesh eccentric to the main tube a bit like a cowboy wagon cover
Im looking at using a large steam dome to allow more water in the main barrel
Just not sure at the moment if to go with this idea or not. For simple boats I prefer simple pot boilers meths fired very toy like but when  I do a mock up it looks ungainly in the hull too tall
 
Logged

belli

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 35
  • Model Boat Mayhem is Great!
  • Location: New York (the other one)
Re: A few steam questions
« Reply #45 on: June 13, 2020, 02:44:30 PM »

Quick calc (3" boiler, 1/16" wall):   a 28mm flue takes up 6% of the water space (less volume) but adds 27% more heating area. 


I like the idea of the poker heater, simple to build and I think I can see why the cross tubes would be of no real benefit especially if the poker were the length of the flue.  The hot air velocity would also be less (I think).   The steam dome idea would also allow a little more water in the boiler but the benefit might no be that great unless the water sloshes around a lot, rough seas....

My 5" piece of tube I cut has a dent in the end, I tried to tap it out over a former, used a small ball pein from the inside without too much success.  I could see the light when the end cap was pressed in how it would open the gap next to the dent.  Drawing the tube I am sure has work hardened it  and I didn't really want to knock 1" off the tube.  I decided to try annealing it, my torch is definitely too small!  No amount of waiting would bring the end of the tube to red hot, granted I didn't pack bricks around it but simply kept the flame in one place.  Really need a bigger torch, horror of horrors, I might have to buy new  >>:-(

Logged

frazer heslop

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 245
  • Location: Durham
Re: A few steam questions
« Reply #46 on: June 13, 2020, 09:57:11 PM »

I have had a bit of a rethink on the boiler and as an experimental one it will be 54mmOD with a 22mm flue about 125mm long. This with the radiant burner giving about 0,2KW will allow the engine to run at a constant 500rpm assuming the boiler will deliver 2456ml of steam per min
Well thats the theory just need to order the materials and see what develops the 2.5 inch drum and plates can be kept for another adventure.
The velocity through the flue is a lot lower with the radiant burner than the normal torch style also as the velocity is lower the heat has longer to be absorbed by the flue. The plain flue does not generate turbulence like a tubed flue this also increase the velocity of the gases. This is for small flued boilers . A radiant burner is more efficient and uses less gas and due to the better time lag for heat absorption the exhaust temp is lower in my test about 100c to 170c also when i test temp along a flue it is constant give or take a wee bit
Another benefit using the radiant because it is using less gas I have not had a problem with the flame lowering due to the gas tank chilling or freezing
Thats about as well as I can explain what is going on in the plain flue as far as I know . I have done some testing on flue diameter to burner dia just need to check my maths for a rough ratio
I have taken a couple of pics of one of these burners operating in the flue if its of any interest
Many thanks to Sandy SCS steam for clearing up a few points my muddled brain was struggling with
cheers
frazer
Logged

belli

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 35
  • Model Boat Mayhem is Great!
  • Location: New York (the other one)
Re: A few steam questions
« Reply #47 on: July 06, 2020, 02:57:53 PM »

Ok, finally things are kinda back to normal (the new normal??).

I have wanted a simple to build hull for an SEL type steam plant and stumbled onto the Bowman Snipe type boats.  There is a thread on the other forum describing the construction but no dimensions.   I did ponder this...   

I made some forms from laminated pine and cut them in a curvy shape.  I laminated three layers of 1/8" birch with some glue that said 'waterproof' on the front and 'water resistant' in the little writing.  I didn't worry too much as I thought that if this boat ever did make it to the water and got so water logged that the glue joints separated...
There was a lot of 'spring back' of the laminated sides, probably around 3/8".  I glued the mold back together and cut a more curvier curve and for the second attempt used just two layers of ply, this result was much better but I think the front section where it is more curvy should have been curvier still but it is very close.
I also did get me some Gorilla's for the second glue up, coulda gotten Gators but the Gorillas were cheaper.  I used a mist spray bottle to slightly wet the wood before clamping and I think the joints will be sound.  Now to get the bottom glued in and I'll be off to a good start. 

This will be a rudder only build and with a simple spirits fired boiler using one of my SEL type reproductions.  I'll glue a deck on, strip plank it with the mahogany, white hull and I think it will look OK.

Logged

frazer heslop

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 245
  • Location: Durham
Re: A few steam questions
« Reply #48 on: July 06, 2020, 06:48:42 PM »

I have the dimensions for the Jenkins Bowman boats including Snipe .Eagle, Peggy , Peter Pan, and a few others just shout up if you need any sizes
Also for Stuart Turners Henley although that may take a bit of finding
The later Jenkins boats were cut from the solid like Russian dolls
keep well
Logged

belli

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 35
  • Model Boat Mayhem is Great!
  • Location: New York (the other one)
Re: A few steam questions
« Reply #49 on: July 06, 2020, 09:37:12 PM »

Cheers Frazer but this one is 'Bowmanesque' (spell checker says this word doesn't exist...).  I made it 26" as that seemed a good size, about 4.5" beam.  I made the 3/8" sides thinking that there would be lots of meat for sanding, rounding the corners and such but in hindsight I guess it's only ever going to be a fairly elementary boat.

Oh, haven't seen your build in a while.  :-)
Logged
Pages: 1 [2] 3   Go Up