Another annealing question

This topic has 21 replies, 11 voices, and was last updated 22 January 2012 at 19:58 by Sub Mandrel.

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20 January 2012 at 15:29 #5881
Chris machin
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@chrismachin
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20 January 2012 at 15:29 #82546
Chris machin
Participant
@chrismachin
Hi , Tried this afternoon to anneal the 0.7mm sheet for my Polly engine with a blowlamp with butane / propane mix cannister but it appears to not get hot enough to do the job !

What should i be using ? Can i get a propane only cannister for such a small blowlamp ?

Thanks

Chris.
20 January 2012 at 16:06 #82549
Les Jones 1
Participant
@lesjones1
Hi Chris,

I do not think the problem would be solved by using propane. I think you need a larger burner or use a lot of insulation around the work to conserve heat. I do not think propane is available in the small canisters as to keep it liquid a room temperature requires a higher pressure than butane so the container would have to be stronger. MAPP gas which is hotter than propane is available for some models of burner but is more expensive. It is £10.78 for a 400 gm cylinder from “Toolstation” (Item code 71066)

Les.
20 January 2012 at 16:43 #82552
JasonB
Moderator
@jasonb
As les says its not the gas its the BTU of your burner. You really want a small 4.5kg propane bottle and a 1″ burner, you will need something this size to solder the boiler as you will need to get the whole thing to cherry red.

You local builders merchant or traditional hardware store will have the Calor cylinders and machine mart to reasonably priced burners, torches & regulators

J
20 January 2012 at 17:22 #82555
Chris machin
Participant
@chrismachin
Thanks all for the help.

There’s a gas torch with regulator and hose with 3/8″ connections in machine mart catologue (item pc108) which has adjustable flame intensity and three nozzles – 25mm,40mm and 50mm- its about £ 30. Is this the type i need ?

Ta
20 January 2012 at 17:29 #82556
JasonB
Moderator
@jasonb
The bigger two nozzels may be a bit OTT on all but the largest boilers but its the best buy. I use a similar Bullfinch torch and the 1″ nozzel for 99% of what I do.

J
20 January 2012 at 17:31 #82557
Brian Dickinson 2
Participant
@briandickinson2
I have used a small GAZ stove before now. It has a wider spread of flame.
20 January 2012 at 17:31 #82558
Chris machin
Participant
@chrismachin
Another question ….

Does it need to be propane if i used a large gas torch or would the 25mm nozzle work ok with calor gas (butane) – reason i ask is i have a large bottle of butane,would save the extra expense of buying propane if so.

Thanks again.
20 January 2012 at 17:46 #82559
JasonB
Moderator
@jasonb
Most of the Butane regulators don’t flow enough gas and I think the bottles cool a lot quicker if they did which gives a drop in pressure.

You can’t use a propane regulator on butane as propane has a left handed thread.

J
20 January 2012 at 17:52 #82560
Chris machin
Participant
@chrismachin
Ok , Looks like a propane bottle investment then !

Thanks again for your help.

Chris.
20 January 2012 at 17:57 #82561
Bill Starling
Participant
@billstarling10428
Dear Chris,

I have made two Polly
engines on the SMEE training course. (Highly recommended, great fun
as well very useful.) We used solid copper 1 ¾ ins dia x 20 swg tube
for the boiler. This was supplied by SMEE but, if you have any
difficulty finding some, I gather 42 mm copper pipe from plumbers’
merchants is also fine. It is certainly much easier than bending
brass plate. You can still get practice at bending tube from plate
with the burner – smaller and easier!

I use butane for
heating (simply because I’ve got some). My biggest burner is a
Sievert 2941, which has a 25mm nozzle. No problems in silver
soldering the ends onto the tube to make the boiler. Smaller, size
3939, burner used for small stuff.

Good luck with your
engine. It’s very satisfying to see it come together.

Bill.
20 January 2012 at 18:00 #82562
David Littlewood
Participant
@davidlittlewood51847
Chris,

Is that an etched brass kit you are making? I have found that etched brass boilers in 0.7mm sheet are best rolled without annealing, it can get very sensitive to dents and dings if it is too soft. Best thing to use is a small set of bending rolls, but you can get away with rolling round a suitable bar, smaller than the desired diameter to allow for springback.

If you do need to anneal, getting to very dull red usually suffices, don’t get it too hot. Butane actually has a higher calorific value per m^3 than propane, but as someone said above its boiling point is much higher so it tends to stop evaporating when it gets cold (as all liquids do when they boil).

David
20 January 2012 at 19:38 #82571
Chris machin
Participant
@chrismachin
Bill,

You’ve got me thinking now ! Might look at the copper tube idea as was concerened about the look of it after bending and silver soldering the joint , especially as i’m new(ish) to silver soldering – have done some air con brazing though.

David , no its not a etch kit , just making it from scratch from Tubal Cains book on simple steam engines.

If butanes been used succesfully for brazing the end caps on then i’ll stick with that for now and just buy a good 1″ torch.

Chris.
20 January 2012 at 21:03 #82586
,
Participant
@nousername29627
Chris,

I think you will find that genuine Calor dealers will exchange your butane bottle for a propane one at no cost apart from the refill charge for the gas. You can also swap for a larger or smaller bottle again at no cost apart from the refill charge.

This only applies to genuine Calor bottles as far as I know

Phil
20 January 2012 at 21:29 #82593
Sub Mandrel
Participant
@submandrel
I managed to silver solder (easyflo 1) a 4″ diameter by 7″ long centre flue boiler using the smaller Machine Mart set on propane and a gas blowtorch on the other end, and plenty of skamolex packing at the back. It was a slow task, done three times by the time I got all the leaks, and I will definitely get the bigger set before trying something like that again – but the MM torch works very well and is much better than a standard blowtorch, despite the burner being about the same size.

Neil
21 January 2012 at 09:52 #82613
Gordon W
Participant
@gordonw
If your calor butane bottle gets cold and pressure drops, more likely in this weather, just pour some hot water over the bottle. Had to do this all the time for houshold gas, until we swopped to propane.
21 January 2012 at 15:46 #82642
Speedy Builder5
Participant
@speedybuilder5
Chris, a word to the wise. I see you have done some air con work – DO NOT USE the silver solder that you used with the air con. I believe it would have been copper eutectic. Although this makes a nice joint, it could fail at the water / steam junction within the boiler. Only use the approved silver solders – preferably the cadmium free stuff.

Also do not use the Cu Eutectic on steel, as the joint will fail at very low loads. Have a look at the Johnson Matthey web site.

Silver soldering with the correct heat, flux and cleanliness is very rewarding – just use the right stuff.
21 January 2012 at 16:20 #82644
Chris machin
Participant
@chrismachin
Once again , thanks to all for help and advice.

I have today bought from machine mart a gas torch with various size nozzles up to 1″. It came with a hose and regulator for a propane bottle but i thought i’d try it on the butane which i already have. However when running on the butane the pressure appears very low althought the bottle is almost full. I then noticed that the max output of the propane regulator (which was supplied with the torch) was 4 bar. but the output of the butane regulator was 28mBar !

So can i get a higher output regulator for the butane bottle ? if not how are other people using butane ?

The regulator was used a few months ago on the same bottle to power the gas barbeque

Many thanks
21 January 2012 at 17:15 #82651
Les Jones 1
Participant
@lesjones1
Hi Chris,

When I first bought a blowtorch I ran it on butane but with an adjustable regulator than went up to 30 PSI (about 2 bar) This worked fine so IF you can get a suitable regulator yours should work OK. I had a look yesterday to see if I could find any suitable regulators but could not find any. Some on ebay claimed to be for butane and propane but were shown with the connection to fit a propane cylinder. Propane cylinders come with two types of connectors. One is a snap on type (There is no manually operated valve on this type.) the other is a screw connection. The regulators for the snap on type only seem to be available in the fixed low pressure type. I think butane cylinders also come two types. (So there are four different cylinder connections.) As you have found the low pressure regulator is not suitable for blowtorches as it is only 28/4000 = 1/143 of the output of the 4 bar regulator.

Les.
21 January 2012 at 18:51 #82657
JasonB
Moderator
@jasonb
As I said earlier most butane regs are low pressure you will need a High pressure one

High pressure regulators

The household BBQ ones won’t flow enough gas

J

Edited By JasonB on 21/01/2012 18:55:10
22 January 2012 at 00:03 #82675
Springbok
Participant
@springbok
Have a word with Cup Alloys he is one of the most knowledgable people

I know on this subject but sounds like a Seviert system for you. Have had one for years the canisters I get from my local builders merchant.

Bob
22 January 2012 at 19:58 #82722
Sub Mandrel
Participant
@submandrel
Sorry to mislead – that boiler was 3″ dia not 4″ – quite a big difference in the amount of copper!

Neil
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