By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Jan 24th

Using Smith Little Torch

All Topics | Latest Posts

Search for:  in Thread Title in  
Chris TickTock07/05/2020 09:05:02
383 forum posts
26 photos

Hi, just unpacked and connected my Smith Little Torch which I bought a few months ago but due to one thing and another haven't used yet. Been looking up all my notes and watching videos etc but am unsure of a couple of points if any one can offer an opinion I would be grateful.

Firstly on one video the guy says most people turn off the torch by turning off oxygen first (my system is oxygen and propane) before the propane as is safer but you get a pop so he turns off the propane first and no pop. I do have flashback arrestors connected up and wonder what is the proper way to turn off the torch.

The second point is the torch comes with 5 tips the smallest being no 3 through to the larger no 7. I have been unable to find advice on what tip is often used for what jobs. My uses will generally be silver soldering on a small area with brass usually with the occasional heating of steel to harden such as my 1/4 inch square wheel cutter which will be my first job. Like most tools I guess experience is king but it is always worth asking what others do.

Chris

SillyOldDuffer07/05/2020 10:17:01
5746 forum posts
1211 photos

Good example of why internet videos should be watched critically! Many are great, some dodgy, and a few downright daft. I'd put turning the fuel off first in the dodgy category.

We have a chap who knows the safety advice is to turn off oxygen first but decides not to because he doesn't like the pop. Unlikely he's spotted an improvement that a century of experience has missed. Maybe he's a genius, but the idea is suspicious.

In practice, turning the oxygen off first has a number of advantages:

  • It immediately removes heat from the flame
  • The operator can see the oxygen really is off (not the same as thinking it is) because it has a visible effect on the flame.
  • The operator can see when the propane really is off because the flame dies.

Other way round.

  • As propane is turned down the flame briefly gets hotter and passes through a mix ratio that might flash back. Not a major risk I feel, but...
  • The operator can't tell the propane is fully off because the flame dies early. May not be obvious that a flame can be extinguished by an excess of oxygen, but it is so. When the fuel mix is very weak, the flame at the nozzle can't produce enough heat to sustain combustion in the face of a flood of cooling oxygen.
  • The operator can't see the oxygen is really fully off because there's no flame to show it.

I think the main risk is quite subtle: if the torch is put away leaking propane and the propane can collect (poor ventilation), it might go bang later due to a spark or firing up for another session. Although gas explosions do happen in workshops, accidents due to leaks inside vans and tanks seem more common.

Wouldn't want to overstate the danger. As the amount of gas in a Little Torch is quite small, natural ventilation in most workshops will de-risk it considerably. But there's a lot of energy even in small bottles, not good if it releases all at once. I reckon I could seriously damage a house by MacGyvering an explosive mix from a Camping Stove Cartridge in one suitably sized sealed room. (Probably need several goes to get it right!)

Another major point, best not to develop a bad safety habit using a small torch and carry it forward later to a big one. Especially if you progress to welding inside submarines!

The video suggests an idea that seems OK, but I think pop reduction is low value and achieving it is potentially dangerous.

Dave

Oldiron07/05/2020 10:38:39
442 forum posts
22 photos

Which tip to use for what job really is a matter of experience, type of fuel, mass of job etc etc. I would suggest that you set up some practice pieces and have a go. A tiny concentrated flame can blow right through a thin piece of material whereas judicial use of a bigger flame might give better results. It really is a suck it and see thing.

Practice practice practice and not on the job you are in a hurry to get finished.

Good luck. regards

Bill Phinn07/05/2020 17:48:53
316 forum posts
63 photos

I'm a turn off oxygen first man myself as well. Turn off propane first with a big burner on a large torch [i.e. a much bigger torch than this Little Torch] and you risk a popping sound that will deter you from extinguishing propane first ever again.

Did you get the Smith manual, and specifically the pink leaflet giving the pressures recommended for each of the tips? It serves as a bit of a guide to what to use each tip for.

The video you saw wasn't this one, was it? The demonstrator says he uses the smaller torch tips almost exclusively. I don't know why this is, because nearly everyone I know who uses this torch mostly uses only the larger tips [5,6,7], as I do. Maybe it's something to do with the fact that the guy in the vid is using acetylene, whereas I and other users I know all use propane.

If this is the video you're referring to, did you see the horrendously unsafe condition [14 minutes in] of the "new" hoses he put on his old torch? He said the new torch was given to him by a friend. Some friend! I suspect the torch was a counterfeit.

Chris TickTock07/05/2020 18:02:32
383 forum posts
26 photos
Posted by Bill Phinn on 07/05/2020 17:48:53:

I'm a turn off oxygen first man myself as well. Turn off propane first with a big burner on a large torch [i.e. a much bigger torch than this Little Torch] and you risk a popping sound that will deter you from extinguishing propane first ever again.

Did you get the Smith manual, and specifically the pink leaflet giving the pressures recommended for each of the tips? It serves as a bit of a guide to what to use each tip for.

The video you saw wasn't this one, was it? The demonstrator says he uses the smaller torch tips almost exclusively. I don't know why this is, because nearly everyone I know who uses this torch mostly uses only the larger tips [5,6,7], as I do. Maybe it's something to do with the fact that the guy in the vid is using acetylene, whereas I and other users I know all use propane.

If this is the video you're referring to, did you see the horrendously unsafe condition [14 minutes in] of the "new" hoses he put on his old torch? He said the new torch was given to him by a friend. Some friend! I suspect the torch was a counterfeit.

I found adjusting the flame tricky the first time following a video but quickly got the hang of it. i used the no 5 tip and went very well for hearing to cherry red. It certainly was instructive on checking the torches hoses. On thw whole love the torch thus far.

Chris

Steviegtr07/05/2020 23:49:47
avatar
1228 forum posts
115 photos

When I 1st started work it was as a sheet metal worker. One of the 1st things we learned at college was the safety of oxy/ acetylene working. Turning the torch off was to 1st turn the flame down, then sw off the Acetylene. Followed by the Oxygen. It does not pop loud once the flame is turned low. I have always done this with oxy/propane too. I guessed the same strategy. When welding it was always No2 or 3 nozzle, but with a full size torch so don't know the sizes on yours. The large nozzles were good for pre heating cast before a repair.

Steve.

not done it yet08/05/2020 08:32:52
4630 forum posts
16 photos

Turning off is usually (not always) the reverse of turning on?

Chris TickTock08/05/2020 09:25:04
383 forum posts
26 photos
Posted by Steviegtr on 07/05/2020 23:49:47:

When I 1st started work it was as a sheet metal worker. One of the 1st things we learned at college was the safety of oxy/ acetylene working. Turning the torch off was to 1st turn the flame down, then sw off the Acetylene. Followed by the Oxygen. It does not pop loud once the flame is turned low. I have always done this with oxy/propane too. I guessed the same strategy. When welding it was always No2 or 3 nozzle, but with a full size torch so don't know the sizes on yours. The large nozzles were good for pre heating cast before a repair.

Steve.

Appreciate the post Steve, there certainly seem to be 2 schools of thought on which one is switched off first, I am in your camp and it is worth stating to turn the flame down first.

Chris

Keith Long08/05/2020 11:31:08
831 forum posts
11 photos

Chris

Section 8-9 onwards of the torch user's manual (Using the torch with alternate fuel gasses) is quite clear. Para 8-10 (Extinguishing the flame) 1 turn off the oxygen, 2 turn of the fuel gas.

Why would you not follow the makers recommendations, they probably know far more about the safety aspects of the torch than anyone putting up a YouTube video.

Gary Wooding08/05/2020 13:07:41
691 forum posts
181 photos

I use a Smith's Little Torch with oxy/propane for jewellery. I Tun down the oxy and, if the flame looks too big, reduce the propane to balance the oxy, then continue until I can turn the oxy off completely. Then I turn off the propane. Lighting is the opposite - first the propane then the oxygen.

I use the larger tips for melting platinum, and reserve the small tips for soldering small, jewellery sized, pieces.

The flame is very hot and it's very easy to melt whatever you want to solder, so, as has already been said, practise, practise, practise. With experience it's even possible to anneal silver wire.

Barnabas Taylor08/05/2020 15:18:58
29 forum posts
2 photos

Hi Chris,

I tend to use the larger size heads for my jewellery work, swapping to the smaller ones for really fine detail. You will find it impossible to use the smallest couple of heads with propane, they need Acetylene to burn properly. I also made a larger head with just a plain length of copper pipe, I forget what diameter it is off the top of my head but that certainly helps for larger items. I probably will make a more sophisticated version in the future to get a more stable flame, some sort of circular 'ribbon' burner. I always turn off the oxygen first, no popping noises ever experienced. I get popping when I wack the oxygen on too fast and blow the flame out!

Chris TickTock08/05/2020 15:22:10
383 forum posts
26 photos
Posted by Keith Long on 08/05/2020 11:31:08:

Chris

Section 8-9 onwards of the torch user's manual (Using the torch with alternate fuel gasses) is quite clear. Para 8-10 (Extinguishing the flame) 1 turn off the oxygen, 2 turn of the fuel gas.

Why would you not follow the makers recommendations, they probably know far more about the safety aspects of the torch than anyone putting up a YouTube video.

Keith, the advice is as you say but remember the Smiths little Torch works with many gases including acetylene. With acetylene it is important to turn the oxygen off first. Maybe Smiths are careful not to give confusing advice?? There are reasons with alternative fuels that turning off the fuel gas first is the way to go. Like many things in engineering there are opinions. From my research (albeit not extensive) we will have to agree to differ on this one as I said there are different opinions here.

Chris

Edited By Chris TickTock on 08/05/2020 15:24:26

Chris TickTock08/05/2020 16:17:20
383 forum posts
26 photos
Posted by Barnabas Taylor on 08/05/2020 15:18:58:

Hi Chris,

I tend to use the larger size heads for my jewellery work, swapping to the smaller ones for really fine detail. You will find it impossible to use the smallest couple of heads with propane, they need Acetylene to burn properly. I also made a larger head with just a plain length of copper pipe, I forget what diameter it is off the top of my head but that certainly helps for larger items. I probably will make a more sophisticated version in the future to get a more stable flame, some sort of circular 'ribbon' burner. I always turn off the oxygen first, no popping noises ever experienced. I get popping when I wack the oxygen on too fast and blow the flame out!

Hi Barnabas,

Done more research on shutting down and on a small torch such as the Smiths Little Torch I have changed my mind as any sensible person should do and think shutting off the oxygen first is the way to go.

Why: Well apparently if you have a leaky fuel torch valve and turn off the fuel first it will put the flame out so you could miss the leaky valve. Also risk of flashback.

However welders often advise turning fuel off first as turning oxygen off first can create a large flame which could cause issues.

My ignorance now looks at having set up the regulators for a given pressure you should leave them as is and just turn off the tanks. i am minded to release the regulators to a loose position to minimise diaphram damage. but what do you guys do, do you bleed the torch and loosen the regulators or not? (I have a oxy / propane system)

Chris

SillyOldDuffer08/05/2020 16:21:41
5746 forum posts
1211 photos
Posted by Chris TickTock on 08/05/2020 15:22:10:
Posted by Keith Long on 08/05/2020 11:31:08:

Chris

Section 8-9 onwards of the torch user's manual (Using the torch with alternate fuel gasses) is quite clear. Para 8-10 (Extinguishing the flame) 1 turn off the oxygen, 2 turn of the fuel gas.

Why would you not follow the makers recommendations, they probably know far more about the safety aspects of the torch than anyone putting up a YouTube video.

Keith, the advice is as you say but remember the Smiths little Torch works with many gases including acetylene. With acetylene it is important to turn the oxygen off first. Maybe Smiths are careful not to give confusing advice?? There are reasons with alternative fuels that turning off the fuel gas first is the way to go. Like many things in engineering there are opinions. From my research (albeit not extensive) we will have to agree to differ on this one as I said there are different opinions here.

Chris

...

Sorry Chris I must demur!

Being a technical subject Engineering isn't about 'opinions'. Politicians work with opinions, engineers work with facts. Engineering demands reasons, evidence and evaluation to the best of our abilities. In technical matters we have to be prepared to abandon: A belief or conclusion held with confidence but not substantiated by positive knowledge or proof.

Opinion is OK when I say the best colour for a Little Torch is pink and everyone else agrees it's red. No problem because our views are matter of personal choice and nothing to do with engineering. Conversely, an engineer who believes pi is 22/7 is wrong. We cannot agree to differ about his error and there is no value in going along with him.

Likewise, there's reason behind why "Oxygen Off First" is the preferred answer, so why disagree? I see no advantage in doing it the other way round. My failure to find an advantage isn't opinion: it's a conclusion due to absence of evidence so far. As I'm often wrong, can Chris provide a reason for working a torch contrary to instructions? What supports 'There are reasons with alternative fuels that turning off the fuel gas first is the way to go.'?

Very educational this forum. I'm happy to be told I've got it wrong again. It's how I learn!

After posting I see Chris got in first and has blown me out of the water completely.   I retreat in confusion to find sack-cloth and ashes!

Dave

 

Edited By SillyOldDuffer on 08/05/2020 16:25:20

Baz08/05/2020 16:37:07
373 forum posts

I was always taught that acetylene is turned on first and off first.

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
Allendale Electronics
Warco
emcomachinetools
Eccentric July 5 2018
cowells
ChesterUK
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest