jsurgeson

Hi Brian

Thank you for taking the time to answer my questions

What you say makes a lot of sense, especially with regards the flare, what do you suggest in terms of dimensions for a suitable flare, also does the flare reside inside the forge wall or protrude into forge?

The jet points for both burners are located as shown in image give or take some manipulation to aim them down the center, but they started off in approximately the same position.

How critical is the position? would say a 1/4" difference in position create this problem?

Do you think my position of the jets is correct in relation to the throat?

Burner tubes same length.
No restrictions or burs or obstructions that I can find.
The burners are about the same in terms of stability however the bad one requires the choke to be a lot more closed to run stable. The length of the blue flame is a lot shorter (1 1/2" or less) than the stable one. The good one I can adjust choke from almost closed, greenish flame (rich I assume) to soft orange flame with almost no blue flame (lean) and stable in between with a nice 2" - 3" blue flame extending from end of burner with softer orange filling space.

The bad burner only burns stable in one position (choke) anything else make flame unstable. This position changes very slightly as the forge heats up till it starts spluttering continuously.

I also have a 1/2" gap around the burner tubes and forge wall?

Hi /D

Thanks, first post has full forge spec, but quick version:

Overall Length:12" (Reducer + Tube)
Tube Only Length: 10"
Tube Dia: 1"
Reducer Length: 2" (2" - 1")
Jet:- 0.6mm mig tips

Both jets are positioned in throat pretty much the same position, within 2mm.
Tubes end at inside face of forge.

After reading many posts I came to the conclusion that flares did not seem to make much difference except when running outside of the forge. I have never run them outside, dont see the point as they are not going to work there. Also the fact that one burner works ok all the time seems to confirm no flare is needed.

Hi All

I am a knifemaker, stock removal only till now, I have just finished making my gas forge and acquired a very basic setup. This is my first attempt at any blacksmithing, yes I know I am supposed to learn how to do basic forge work before I try welding/pattern welding/damascus etc.

However as my only desire is creating blade steel and not to do blacksmithing in general I thought I would jump in at the deep end. I mostly want to create decorative bits like mokume and contrasting pattern stuff for bolsters etc.

I took a 8" piece of 1/4" inch cable and welded it into this rather small bit of usable steel. As you can see 1/2 of it did not get used. This took me about an hour and about 20 heats. Not very good or cost effective as the gas probably cost more than it is worth. :confused:

I have to still learn to consistently judge correct temp as I tend to not heat enough and end up breaking weld and having to redo.

I quickly ground it a bit with a #220 belt and etched in ferric chloride for 5 mins. Not much contrast is there? Am I likely to get any more.
I assume the correct way to finish a piece of cable up is to grind and polish to finished size, then etch in acid? What do you do after etching or is that it?

Hi jimbob

Thanks, I checked that and the tank was not getting cold at all.

I changed my 20lb tank for a 40lb tank and that has solved the loss of pressure problem but has not solved the stability on one burner problem.

I think that although the loss of pressure problem caused the one burner to run badly, even with bigger tank running at constant 12psi it still misbehaves, but not as bad. So I think that it still has something else that is causing it to run badly, but blowed if I can see what.

I thinks I have solved 50% of the problem :cool:

I am no expert with regards gas, but here goes, the pressure is dropping after 10 - 20 mins because:

At 10 - 15psi the consumption is higher than the bottle can supply (vaporise), so after a while most of the gas is liquid and cant supply the required pressure. I assume a larger capacity bottle, say 40lb (18kg) min should solve that problem.

It unfortunately does not explain why the one burner works down to 4psi while the other wont.

Any help with a list of things to check or possibly reasons based on other experience with this problem would help.

Ok this is what I have done so far to try and pin point the problem.

Problem:- Back burner starts to stutter after 10 - 20 mins
Action:- I reversed the burners so back is now front.
Result:- Problem moved to the now front burner.
Conclusion:- Problem is related to that particular burner, this then excludes position in forge, size of forge, back pressure, opening sizes back and front.

Further observations:-
Gas pressure, on starting 8-12 psi, on fault 4-5 psi.
One burner works fine at this pressure but the faulty one wont.
Burners are theoretically the same, but obviously not.
When left off overnight, next day pressure back up and all works ok again.

Questions:-
Why is pressure dropping?
Can a faulty reg cause this?
What causes one burner to not work at lower pressure while other will?

Hi Dodge

Sorry for delayed response, was very late when I posted.

It does get nice and hot, image makes it look nicer than it actually is, but it definitely gets hot enough.

The tank is a 20lb (9kg) bottle, (It is marked as 11.2kg thats bottle incl)
Ambient is 20 - 30 degC very humid
Tank does not frost up

If I turn the pressure all the way up when full it max's out at about 16psi.

Why I thought possibly regulator, when you first turn it on you get a loud thud a fews seconds after opening bottle before regulator opens and allows gas, also pressure adjustments seems to be erratic, but thought it was more the gauge than the regulator.

But then if it was anything to do with bottle/reg etc it should effect both burners, not so?

Hi all

I recently completed my first gas forge, although it works quite well most of the time I am having problems getting it to work well all the time.

It starts ok and runs fine on both burners for 20 - 30 mins.

Back burner then starts to stutter, flame goes soft and burns inside burner tube, no adjustment of choke from full closed to full open makes any difference.

If I turn off gas to that burner and back on, it runs ok for a few seconds then goes wrong again. Front burner seems to run ok all the time by itself, although it appears to battle to run at pressures below 10psi once hot.

Can a faulty regulator cause this?

Please explain what are the conditions for stuttering, a soft flame that burns in the tube. Is it too much, lack of, gas/air etc.

If it starts and runs ok for a while what is changing to make it run badly?

I have used the water trick to make sure both jets are aligned correctly.

Both burners are identical in theory, specs of forge/burners below.

Dimensions are:
Internal:- 4.5" x 4.5" x 16" (115mm x 115mm x 406mm)
Burner:- overall 12" (300mm) 10" tube 2" reducer (2" - 1") burner has no flare
Jet:- 0.6mm mig tips

Cheers Frosty

Thanks for the image, in the near future I am going to rebuild a larger forge with less complicated burner design, preferably all black steel, less fittings, less bends = less problems.

For now, seen it works ok'ish, will live with it.

Thanks for all the help and advice.

Hi all

Joined the forum recently and thought I would see if there were any local (for me) blacksmiths.

You guys that live up "there" have all the fun, I am a knifemaker and when looking for groups for that, same thing happened, you are all up "there" :mad:

I suppose us Durban ou's don't like lifting heavy things

Anyway nice to hear from any Durban/Natal based smithy's

Dodge,

Yes I intended to do a restricted front door, as I have with the rear, just need to fashion some sort of simple hinge. On the other hand the internal dimensions are so small was thinking it was possibly a waste of time as it heats up pretty fast. I can take a knife blade from 0 - non magnetic temp which is only a few degrees under hardening temp of n690 blade steel in under 20 mins. On the other hand, seen gas is very expensive here every bit of saving counts.

Frosty,

Dimensions are:
Internal:- 4.5" x 4.5" x 16" (115mm x 115mm x 406mm)
Burner:- overall 12" (300mm) 10" tube 2" reducer (2" - 1")
Jet:- 0.6mm mig tips

Do you think the extra 2" on the burner will effect the way it burns?

You are right, now that it works almost right I need to clean them up and get rid of the unneeded holes and make pretty.

What is a "thread protector" never heard of or seen one, also I have no threads on my burner pipe, you cant get long nipples here. I dont have large threading tools so weld all joins.

Does the fit between the burner and box need to be perfect? does a loose fit like mine effect the way it burns?

Thanks for taking time to look at and answer my basic mistakes and questions. :)

Hi Frosty

Yeah they are aren't they? almost did not post them.

They work but as you can see the burner tubes have been butchered so much due to the, make remake of the piping I ended up with lots of unwanted holes.

The back burner splutters a bit even with the choke fully closed, I think that going down to a 0.6mm jet (was 1mm) with 1" tubes is starving the burners a bit. This improves when I put my hand over and block some of the air intake.

Besides them being completely ugly and badly made do you see any other obvious mistakes?

Thought I would show a few images of my new forge and show how the compression fittings worked out. :cool:

Yes I think considering the possible negative results of leaking gas from the wrong orifices and possible consequences, even if it might work its just not worth the risk, so I went out and bought some high quality brass fittings.

Ouch! :mad: they are expensive.

But I suppose if it is worth doing it's worth doing right. ;)

Thanks Guys,

You are right, makes sense to do it right first time.

Thanks for that, its kind of what I thought but was hoping that I would not have to redo it from scratch. :mad:

Just a thought (long shot actually) you say the burner that is "off and open" will act as a chimney and get very hot,
can I assume then that if the choke is fully closed it wont? or am I clutching at straws here?

Hi All

I am new to this forum and new to forging in general, so sorry if this has been answered before, searched but could not find specific answer.

Have just rebuild my home built gas forge after reading various posts on this forum. I am going from 1 to 2 burners, they are 1" Reil type burners with 0.6mm mig tips.

My first single burner I used 1/4" copper tube with brass compression tee's and elbow fittings, with my new double burners I used simple solder type fittings.

I did this without thinking if solder type fittings are suitable for this. :confused:

In my very short experience the bell reducer which houses the jets does not get all that hot, at least not hot enough to "unsolder" the fittings, does it?

Anyone offer any reason why solder fittings wont work?

Jeff

Hi to all

I am new to this forum and very new to blacksmithing.

I am a part time knife maker and have always wanted to forge my own blades as apposed to profiling from blanks. And that is how I ended up on this forum, trolling the web for useful info.

Hope to be able to make some useful contributions in the near future.

Jeff
No great thing is created suddenly. - Epictetus (A.D.200)