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If your careful with them O-rings work fine and dandy. As for gs rated tape, I stated out using it, but unlike O-rings, people get hard of hearing about using it carefully. The end result is tape threads shutting off flow in small gas orifices, so I've been suggesting sealant on MIG tip threads for several years. I use non-hardening Loctite for that :)

However, that use has little to do with this trick.

I also suggested that electrical tape would serve in some cases; I have employed it in test burners for about fourteen years, but thought about it good and hard before bringing the subject up. Furthermore, I would never allow a burner to leave my garage with electrical tape, or any other "temporary fix" on it. But with gasket sealant? Yup.

That should have read "gas rated tape."

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I feel you about that, people go to -100 IQ when you explain how they should use PTFE tape. I have been using the "new" Loctite 55 cord for water and gas for some time now, works way better then the old flat tape (or the hemp wire and the green putty).

 

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It is indeed a huge improvement, you still need to wind it on the right way of course. but after you fitted everything you can still adjust it, something that is impossible with normal sealing tape. You also need way less, and if says on the container how many windings each size of threat takes.

 

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You had me wondering there Mike. :)

Never use any sealant or thread lock, tape or paste, compound on an oxy system! Teflon tape in an oxygen atmosphere is extremely flammable, it burns very energetically. (explosively)

I've about used up all the thread tape I have. I only use thread paste, it's so much easier to get right and you don't need to use instructions more complicated than "a LITTLE bit."

I'll have to check out Loctite 55. Thanks for the tip.

Frosty The Lucky. 

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6 minutes ago, Frosty said:

Never use any sealant or thread lock, tape or paste, compound on an oxy system! Teflon tape in an oxygen atmosphere is extremely flammable, it burns very energetically. (explosively)

Pure oxygen mostly complicates materials in compressors and hoses; other than backfires in totally worn out equipment, which is terrible enough to make one-way valves mandatory on oxy-fuel torches these days (you just don't know the meaning of the phrase "dead man walking" until you've rest a backfire up  a torch hose, and shut the valves as it raced up the last three feet). What most material safety rules on oxy-fuel torches came out of was the even more terrifying chemical interactions between acetylene and some metals!

Considering that acetylene first became popularized as a safer fuel than hydrogen...! And, it is!!!

Twenty years ago, there was easily found information on this subject on the Net, but acetylene is fading out as a torch fuel, so that may not be a snap these days. As for hydrogen; it has become a political football, so safety information is know probably  "facts needing careful massaging" these days :P

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Shut the valve on a backfire? I once had a "how to safely work with gasses" course where they had Acetylene/oxygen burner with see trough hoses and he showed us how fast it would go trough a 5 meter hose, it reached the flame stopper before you could even react.

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That was a true story, and a very bad memory. Acetylene is a very fast burning fuel, but torch hose fires proceed at their own pace. I am aware of how fast both hydrogen and acetylene can burn; that's why they are explosive; not just flammable. Propane burns slow enough that it is classified that as flammable, but with the right conditions it it explodes. An expert on the subject,I ain't. But, what happened, happened. I stand by what I wrote.

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Lamp thread is too large for use in micro-burners. Fortunately, the same mounting scheme can be carried out by threading brass tubing; thus, allowing ever smaller gas assemblies to be installed in ever smaller burners. Brass tubing in millimeter sizes are available through Amazon.com in sizes from 2 millimeter (0.079”) up to 6 millimeters (0.236”), and in fractional sizes from 1/16” to 13/32" O. D. in .014" thick walls. Small brass tubes, which come in millimeter sizes, can be nestled inside of one another, to build up convenient shapes and silver brazed of soldered in place, with the outer tube threaded.

    MIG contact tips can be modified (or replaced) with refrigeration tubing and/or needles used as gas orifices.

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Three pieces of 4mm I.D. by 7mm O.D. by 300mm long seamless brass tube300mm Length 7mm OD 1.5mm Wall Thickness are available from Amazon.com for $16.89.

    4mm is 0.15748”. 1/4-27 thread for MIG contact tips have a minor diameter of 0.205” so this tube can be thread for MIG tips at one end.

    7mm is 0.275”; thus, accepting various 1/4” dies. By stopping the outer thread short of the last 3/4” of length, you can use this heady wall tubing for gas assemblies.

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Why build small burners at all?

Few of us want a micro forge or jeweler’s furnace. But there are many who want more concentrated heat from their air-fuel torch. More concentrated? Yes; A $5 blue flame pocket lighter has way better flame management than what is offered in commercial air-propane torches.

Other people are looking to maximize fuel efficiency in heating equipment. Naturally aspirated burners have large turn-down ranges. So, it seems a wide selection of burner sizes isn’t needed. But heat management is about more than how well fuel burns.

    The reason burners, whenever possible, are aimed on a tangent, is to cause their combustion gasses to swirl around equipment interiors; creating a longer distance from burner flame to exhaust opening. A longer exhaust path increases the amount of "hang time” for energy to be deposited on equipment interiors. That seems obvious doesn't it?

    What isn't so clear is that most of the heat gain isn't added by hot gases blowing a few inches farther at a given velocity; it’s due to the continuing drop in velocity over the added distance. Combustion gases begin to slow as soon as they leave a flame envelope, but gases from small flames decelerate faster than those from large flames.

    The law of diminishing returns reduces fuel savings in miniature equipment, but faster heating time, and increased portability remain major advantages. Portability? Yes; miniature equipment isn’t all that portable, if it must be fed from a five-gallon fuel cylinder!

    Do multiple flame burners (ex. Ribbon burners) take deceleration further? Yes, they sure do; unfortunately, ribbon burners themselves tend to be large. Over time, compact ribbon burners will be perfected, but first there has to be a lot more interest in doing so; there isn’t much, because ribbon burners provide the most advantage when heating large equipment.

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     The more you slow an electric motor the hotter it gets

Flex-drives complicate speed control problems, because the faster you run them, the hotter they get. Industrial grade flex-drives found on Foredom tools are set up to run at 18,000 RPM or less; these are, by definition, the best of the best. How can we expect a Chinese import “freebie” to run at 35,000 RPM? So, you have dueling needs with a flex-drive mounted on a rotary tool. What to do? Run the tool at half speed, in short bursts to let both drive and motor cool off; use it no more than you must. Does this sound inconvenient? What part of flex-drives don’t belong of rotary tools didn’t your get?

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    If the pipe nipple you choose is too short to end up with a 3-1/2” long gas tube, with one of its threaded ends cut off, remember that schedule #80 pipe is thick; you can thread its inside even in areas that have outside pipe thread, and afterward the outside thread will be lost when you taper the gas tube’s forward end.

    Whether its threaded or not, taper the gas pipe back about 3/4” so that its taper blends smoothly into the MIG tip’s body, with little or no lip.

    Clean out all burrs in the gas pipe, and then screw your MIG contact tip (gas orifice) into position on the end of the pipe. Don’t forget to use thread sealant, gasket seal, or pipe dope on the MIG tip’s threaded end. Do not allow the sealant to touch the last two threads on the MIG tip. The slightest gas leak between tip and pipe can cause backfires in the burner. But any sealant, thread, or tape that enters the tip will end up clogging the gas orifice. If you choose gas rated tape or thread, remember to wind it counter clockwise.

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If you blow a control circuit, do you have to throw away your tool and buy another? That depends. If you’re into electronics, it is simple to de-solder the circuit and replace it with a short length of wire. If not, it’s still simple, but you will have to buy a soldering tool, some rosin core solder, and some electric wire of the same gauge (size) or larger than what was used in the circuit; the cost will be about the same as replacing the tool, but you end up with something extra out of the deal. Your repaired tool will only run on full speed, unless you use a separate speed controller, but that is what you should have been doing in the first place. There is little or no noise or smoke generated when this circuit blows; you may not notice anything more than your tool suddenly quitting.

 

When the armature fries: If you see smoke and electrical sparks coming from a tool’s air vents, you just overheated its motor for the last time. If spare parts are available for your tool, you will easily find them online. Just input the product name and add “parts list.” You will need another armature assembly, and a new set of brushes (unless it’s a brushless motor).

Can this happen, when you did nothing wrong? YUP, you bet it can. Every time an electric motor is heated up, even a little bit, there is some damage to the varnish on its windings; the damage is cumulative. That varnish is the insulation keeping those windings from shorting out.

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Mr. Porter,

 

 I have read only a small portion of this thread and I am grateful that it is still active. I think I may have acquired your book while inheriting a box of blacksmith books from a friend. If not, I am going to purchase it, the information is worth far more than the cost.

 I currently have four new Rex Price of Hybridburners 1” forge and foundry burners and one T-Rex burner. I am designing a new forge that does not need to be capable of forge welding, just needs to get hot enough to easily  do traditional forge work like scrolls, twists and sculptures etc. 

 in addition to the burners I have two boxes of soft fire bricks rated at 2600 degrees and plenty of hard fire bricks. I have six full rolls of 2” thick x 24” 2600 degree blanket. Believe it or not, I found all six boxes plus some odd pieces on the side of the road which had fallen off of a trailer or truck. What are the odds?

 I am planning to build something similar to a forge I saw on YouTube called a Super C. It has a C shape with a 2” opening running along the side of the forge body at floor level. The opening is normally closed with the soft brick until you need the extra room, such as when you are forging larger scrolls. The overall length will be approximately 24” with a cast floor and 4” of wool all around. The ends will have sliding doors made from the soft bricks.

 I am currently calculating the number of burners required and already have plans for an idle circuit.

 If I haven’t completely confused you with my description, and you are aware of others whom have built similar forges, please send me in their direction. That goes for anyone who reads this post.

 Again Mr Porter, thank you for taking the time to write the book and to engage in this thread. Thanks to everyone else as well who have contributed to this thread. 
 

Gary

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You may have used up several years worth of good lot, with that haul :)

I think the "C" forge is one of the cleverest designs I have read about. The rest of your stuff sounds pretty first rate. The only direction I could recommend, that you haven't already covered would be heat refective coatings. You'll have plenty of time to look into those, while building that forge; they while go especially  well with his construction choices.

Hope you post more on on your forge build, here with us at IFI.

That should read "heat reflective coatings."

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