If you go the contact tip route (a good idea) you can save yourself a lot of misery by drilling most of the way through from the back side (the threaded end) with a larger drill bit, then drilling out the front end with the small one.
The changeable tips allows you to try different sizes in progression, then put in a new tip and drill it to the size that worked best. Mounting the tip so you can adjust it fore and aft to vary the air draw is handy too.
Cheers Trevor Jones
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by the drill [check for minimum quantity typically 6 or 12]
Unka' George ================ When we are planning for posterity, we ought to remember that virtue is not hereditary. Thomas Paine (1737-1809), Anglo-American political theorist, writer. Common Sense, ch. 4 (1776).
another tip if you have problems drilling small diameter holes -- use what is called a jiggle pin.
basicallly a much larger hole, with a wire inserted and bent over to retain it in the hole to reduce the area.
much easier to drill and less likely to clog.
Unka' George ================ When we are planning for posterity, we ought to remember that virtue is not hereditary. Thomas Paine (1737-1809), Anglo-American political theorist, writer. Common Sense, ch. 4 (1776).
Do a Google on "Forge Burner" ( I'm sure you have but I don't remember which site I saw it on) somewhere I saw a chart listing the hole diameter of MIG nozzles and the recommendation to use them for the metering jet. Also there is considerable discussion of jet sizes and recommended pressure regulators on several sites.
The burner I built is a copy of the Rex design as it seemed to be the most efficient type, although in actual practice it may not matter. I don't remember the actual sizes but to select the metering jet size I arbitrarily decided on 10 PSI fuel pressure and then drilled the jet so that was as close to a neutral flame as possible.
Re drills,:any mechinery supply shop should be able to supply either individual drill bits to #80, or a set thereof.
Bruce in Bangkok (brucepaigeatgmaildotcom)
Geez, George. You really gotta work at your attributions when you reply to posts.
You replied twice to answer a question that I did not ask. :-)
Cheers Trevor Jones
Home Depot (at least here) doesn't carry smaller than 1/16" but I stopped by Ace today and found #56 thu #60. Alas, still not enough heat.
Here's the rig at full throttle. Notice I have to step down from 1.25" to
3/4" using two reducers. I can't find anything that will go to 3/4" except 1" (eventually required for my furnace intake).What if anything could I do without welding or spending more money to get this sucker hotter?
= Ben
Got any soft firebricks? Ceramic wool insulation? Use them to insulate and close up the space you have inside your furnace.
What is the refractory you used? If it was a heavyweight solid refractory, it's gonna take a while to get up to temp. You won't melt anything in it until the furnace is up to temperature. Lightweight castable has better characteristics than the heavy, and is not overly expensive at $35 or so a bag. Refractory in the phone book yellow pages.
When a jeweller melt precious metals he does a couple things. One is to limit the amount of other materials he has to get to heat. Another is to pound the heat into the metal and crucible at a rate that allows for rapid heating and melting. Usually this is with a rosebud tip on a Oxy-Acet torch. If you want to melt your silver with that flame (which looks plenty hot enough, as I have used a Bernzomatic propane torch to melt silver in the past) you will have to close up the amount of material you are to heat. Firebricks (lightweight ones, like pumice) are good, ceramic better, but pricey. A small slice of light firebrick under the crucible (keeps the heat from being drawn down to the cold floor) and a surrounding pile of stacked bricks with the burner stuck into the side of the pile, should do.
If nothing else, put a plinth of refractory under the crucible to allow the heat to flow around it, rather than aiming the burner at your crucible.
The flame looks OK to me. Flares on the burner end are a pretty OK thing for use on a forge, but should not be required on a furnace. In the furnace, with the lid on, is where the way it burns counts. Tune the flame in there.
Did you read up on the mini-mongo on the Riell forge page?
Cheers Trevor Jones
Oh yeah. If you want to melt a small amount of silver, put it on a slab of charcoal, or just on a slab of wood, and pound the heat to it. You will get a mess of flame and smoke untill the charcoal forms, but the heat will go into the metal rather than into the crucible or refractory. Try it with a Bernzomatic. I used to melt silver coins this way.
Cheers Trevor Jones
I have some inswool, will line with that and giver a shot.
Yes, I read much of the site. The designs for Reil, EZ , T-Rex and Mongo are all about what I have (latest mod tonight). The flame is clean but as soon as I hook it to the furnace, no good. So I'm wondering if it's the 90 degree turn throwing things off. The only diff is the 90 degree and lack of flare.
Why drill them at all? Just but one of each available size and swap them until you get what you want.
I don't think this would be too good in this application. The high pressure propane uses it's velocity to mix with the air. The jiggle pin would disrupt the flow. These burners work best when the gas is introduced directly down the middle of the burner tube. One good idea I saw (I think from Rupert Wenig) was to use water to check the alignment. Put the water through the mig tip and see if it is centered.
Because of a couple reasons. Firstly is that the tips, come in sizes for wire, not always the optimum size for the jet you want. The main one is that you only have to buy one pack of tips.
The drills will be useful at a later date. :-)
Tips, only if you have a mig welder.
Cheers Trevor Jones (who pounds brass rod into the end of a pipe nipple, shapes the outside, and drills as required)
Thanks Roy that must be it. I will remove the 90 and shoot it straight in.
As a side note I GOT IT with the burner over the kiln!! Finally!!
Ron's suggestion to get the crucible off the refractory did the trick. Didn't realize it was sucking the heat out like that. Basically lined the kiln with inswool, pointed the burner right up the middle and boo-ya we got all sorts of melted silver. Was able to easily reduce a full pound of sterling to casting grain in no time at all.
Although not exactly like the others I've seen, my burner now works wonderfully with a #60 dead drilled dead center through a cap fitted to 1/8" pipe I rigged to run the middle and end at the sweet spot 1.25 reducer. So stoked!!!
Thanks to the many replies here and the web (Reil, EZ and T-Rex sites). You guys are awesome thanks again.
=B
I don't know much about gas burners but I do know that changing the orfice size does not give exactly the same effect as changing the gas pressure. In addition to the amount of gas flow, the velocity of the flow is important. High pressure and a small orfice will give higher velocity than low pressure and a large orfice. The velocity needs to be appropriate for the flame propagation velocity or the flame will pop back (velocity too low) or blow off the burner (velocity to high). It seems to me that best tuning would require adjustment of both ehe orfice and gas pressure as well as the air flow.
Don Young
Use MIG welding tips for a jet. Available in a variety of sizes, and cheap. The thread on the end is usually either M6 or 1/4", depending on the brand
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