Jump to content
I Forge Iron

Linear forge burner plans


AxL

Recommended Posts

Put a 60 degree bevel in the tube, and the transition between the reducer and tube is near perfectly seamless. I'll weld it up next week, and then it's just a "simple matter" of making a saddle and gas tube... Have a great weekend everybody!

 

PS. Sorry for the lack of pictures, my phone got smashed last weekend and the loaner phone's camera isn't working.

Link to comment
Share on other sites

  • Replies 60
  • Created
  • Last Reply

Top Posters In This Topic

Update: I've welded the tube to the reducer, and it seems straight and true. As far as I can tell anyway. Here's hoping...

I also beveled the top of the reducer and made the saddle. I'll get to welding the saddle tomorrow hopefully. Getting close. Need to find a suitable pipe for the gas tube, or just turn something on the lathe...

Link to comment
Share on other sites

Their are two ways to guaranty that a gas runs axially true and central down the mixing tube. The older method is to use something like set screws to alter the jet's aim as needed; the other way is to very carefully set up the gas jet assembly to run dead center  to the mixing tube. This burner is designed to take easy advantage of the second method.

Method two can still be modified afterward to change the jet's aim, by the use of flat washers, which can be deliberately filed or sanded into wedge shapes, so that the gas assembly can be re-aimed by turning the washer, before clamping down on a locking nut.

That should read  "...to guaranty that a column of gas runs axially true..."

Link to comment
Share on other sites

On 8/11/2017 at 8:37 PM, Mikey98118 said:

The gas pipe is one-half of a 6" long schedule #80 1/8" pipe nipple

I'm gonna keep on asking stupid questions, as the sizes of the pipes and nipples aren't obvious to me.

I checked the McMaster catalog, and if I understand correctly, the tube needs to be 3" long and basically accomodate for inside thread for a 0.8 mm MIG tip and enough wall thickness to make threads to fit the saddle? I think I'll put a ball valve at the end and a 90 degree elbow off that to fit the gas supply to. Does this sound good?

Edit: Or an elbow before the valve maybe...

Link to comment
Share on other sites

yes;  schedule 80 1/8" pipe nipple, that is cut in half, is the most convenient form of gas pipe in the USA, because of the pipe thread left ready for use at one end for mounting such parts to. If you have British or European parts available, you would simply recalculate the inside and outside diameters needed on the gas pipe. Also, by stopping the outside thread short of the end with the MIG tip, you gain more leeway in gas pipe diameters. There are some European MIG tips available, with small threaded ends. Finally, by silver braze alloys common solders, and thread locker, can all be used to seal threaded parts together, so pipe parts need not me used at all. What parts you use is only a matter of convenience.

Link to comment
Share on other sites

  • 2 weeks later...

Almost finished (I hope). Couldn't find a suitable bolt of alumunium to make the choke plate, so I'll figure something out next week. I'm not sure if the gas tube is long enough though, at it's lowest point It gets the tip of the MIG to the narrowest point in the reducer, but not down into the actual mixing tube. As far as I understand that might be long enough, hope you can weigh in on that Mikey. Gotta find som parts for the gas too... I'm cautiously optimistic for lighting it next week!

Have a good weekend!

20170915_123203.jpg

20170915_123255.jpg

20170915_123301.jpg

Link to comment
Share on other sites

The burner is looking good, but you need to move the gas jet deeper into the burner; its tip should rest between 1/4" and 3/8" away from the opening of the mixing tube. You also want to bevel the end of the gas tube.

Nothing prevents you from running the burner while you are waiting to finish the choke.

Link to comment
Share on other sites

 

The burner is looking good, but you need to move the gas jet deeper into the burner; its tip should rest between 1/4" and 3/8" away from the opening of the mixing tube. You also want to bevel the end of the gas tube.

Nothing prevents you from running the burner while you are waiting to finish the choke.

It can be moved deeper, like I said in the previous post, it can be moved as deep as the opening of the mixing tube. When you say bevel the end of the gas tube, you mean the end where the nozzle sits, yes? The business end? The end that's attached to the reducer is already beveled. Is 60 degrees the correct bevel?

Link to comment
Share on other sites

 

The business end, which end with a MIG tip coming out of it. You do this for streamlining. Otherwise the incoming air will be slowed and weakened, as it passes by the threaded end of the gas tube.

I read it all wrong, i was thinking of the mixing tube! Gonna get it done today and test fire it this evening.

Link to comment
Share on other sites

As is so very common at this stage, you have a disappointing flame :(

But, what every photo show me is how to put it right :)

Pay close attention to how the flame is actually touching the nozzle; that shows that the nozzle's diameter is insufficient. Cut off a section of of this nozzle, and use it as a ring inside a tube or pipe with an inside diameter that matches the ring's outside diameter. The new flame will suddenly double in power.

The second clue is the off center flame tip in every photo; that is made by either a nozzle out of axial alignment with the mixing tube (unlikely with such a gentle flame angle); or it can made by a misaligned gas jet (the much more likely culprit). Even if you perfectly centered the gas assembly in the the burner, its gas jet is made of soft copper. It is a common problem for the MIG tip to be bent out of alignment. Fortunately, soft copper parts can be bent back into alignment quite easily :D

Link to comment
Share on other sites

I would by no means call it disappointing, I expected nothing like this. I expected to have made som critical error at some point and the burner not working!

I'll get started on a new nozzle and try to tweak the misaligned parts back into alignement. I'll try to move the gas tube back a little too, play around and see what happens.

Thanks guys, updates to come!

Link to comment
Share on other sites

I made a new nozzle and did my best to align the parts. As far as I can tell (measured with a laser) it's straight and true. I honestly can't see much of a difference in the flames, so either my eyes aren't tuned for this or I have made no difference.

Thoughts?

20170921_164027.thumb.jpg.0fc6a74bf3ff64a2b674d21b07f1c877.jpg20170921_162940.thumb.jpg.90f8668b197b84a000660d4241eb32a9.jpg20170921_162930.thumb.jpg.f6f2e0ef7c4f1cb449c572136dfa49fa.jpg

Link to comment
Share on other sites

But I see plenty of difference. The flame is now running straight. So what? No big deal? that's right; it's no big deal, at present. But, once we get your flame properly tuned, it would have reduced the flame's stability, and that is a real big deal; one you don't want to deal with while trying to finish tuning your burner.

I think the new nozzle is right, and will assume you varied the amount of overhang, to tune it for a hard flame. If that is the case, I would also assume you are using a MIG contact tip with an over large orifice; what wire size is it rated for?

Link to comment
Share on other sites

The smallest MIG contact tip available is for .023" welding wire; it has a .031" orifice; this is actually a little bit large for a 1/2" pipe burner. 1/2" schedule #40 pipe has a nominal inside diameter of .622"; if your mixing tube has a larger inside diameter, we well have to insert a short length of capillary tube (probably about 5/8" long) in a MIG tip, to compensate. What is your mixing tube's inside diameter?

Link to comment
Share on other sites

I have some good news and some better news. First, your mixing tube inside diameter is a few thousandths  smaller than a pipe would be, so that isn't your problem. The better news is that your MIG tip is one size too large; trade it out for a .6 mm tip, and your problem will vanish. Then, you can finally fine tune your burner for the flame you deserve  :D

Link to comment
Share on other sites

You're closer, but not quite there. I can't prove the red secondary flame is from oxidation of the flame nozzle, but the fact that it started after your burner's flame got hotter is a strong indication of it. Is your flame nozzle made of mild steel, rather than #316 stainless?

Stop reducing the amount of overhang on your flame nozzle (past the end of the mixing tube), only after the flame snuffs out, and then add only 1/16" to 3/32" back to the overhang length, to stabilize the flame. You are very close now; your burner only needs a little further nudge.

Link to comment
Share on other sites

It is stainless, but maybe not 316. It might some residue from grease/WD40 or whatever was in the tube when it was used. I pulled it from the scrap bin at work. 

I'll give the adjusting another go later today or tomorrow. I tested it today on a small piece of steele and it had no trouble heating it to hardening temperature. This is fun!

Link to comment
Share on other sites

  • 2 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...