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Forges 101


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16 minutes ago, Mikey98118 said:

portals toward the back

Thanks, I am trying to reproduce the swirl that my much smaller forge produces.

I will most likely not cater to the propylene fuel anytime soon as I am not efficient enough with the hammer to make good use of the time spent at the anvil. And those higher heats are not necessary for my amateur butchering.  My " I think I need" is the co-pilot for a lot of my projects. It helps me form a standard for what is acceptable in the things I do. But I do like to exceed expectations.

The stand was a bar stool I scrapped at the local recycle a few months back.

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  • 2 weeks later...

Rigidized the first layer of blanket with one 3/4" burner. This forge will accommodate two. The second port is stuffed with blanket.

The second layer of blanket plus the kasto should help soften the flame impact and create more swirl. I also saved the cut-out from the forge entrance to use as the baffle door. The burner is choked. Once it warms it can be opened up to full air.






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On 1/14/2020 at 12:24 PM, 671jungle said:

The burner is choked. Once it warms it can be opened up to full air.

Open it up more, the opaque yellow flame isn't doing any good, just burning fuel and altering YOUR breathing air.

I don't recall if you said so forgive me for asking if you have, please. Why are your burners so close together?

Frosty The Lucky.

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On 1/14/2020 at 4:58 PM, Frosty said:

Open it up more

It is just barely choked. It blows off the nozzle until it heats up a bit then it can handle full open. The nozzle still has the thread from the stainless reducer. I will try opening it up to try to get the flame to stick.

On 1/14/2020 at 4:58 PM, Frosty said:

forgive me for asking

I consider you one of the great teachers on this forum. It is an honor to catch a question or response from the Elder Curmugeons. How many times have you answered the same questions and repeated instructions to newbies like me. The least we can do is explain a method to our ignorance.

My reasoning for the burners so  close together is to place them toward the back of the forge and increase swirl hangtime before the flame exhaust out the front. Trying to mimic the swirl in my small two 1/4" burner d-forge.

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Going back a ways 671.  I am playing with blanket and kastolite so often that I had to go back to that post to know what I was talking about.  

The originals are still around.  I can't say that about the firebricks.  They all turned to rubble.  

They are great.  I have had them yellow on one side and I am able to briefly touch the backsides to move them.  One ham handed day I knocked one off the front porch and it impacted the floor while orange.  He is still around and shows no evidence of the abuse.  

The matrikote peeled off of them but it was applied before I knew to butter them up.  I haven't reapplied it yet.

I will be making baffle walls for the mini forges with the same method.  We like the size 4.5" x 4.5" x 2".  Kind of a half brick.  We will eventually have a bunch of them to pile up and point burners at for the odd jobs.

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On 1/14/2020 at 5:32 PM, 671jungle said:

It is just barely choked. It blows off the nozzle until it heats up a bit then it can handle full open. The nozzle still has the thread from the stainless reducer. I will try opening it up to try to get the flame to stick.

I almost pulled a good one! I finished the post, sent and read Mikes reply and it didn't jibe with my recollection so I went back and looked at your last one and xxxx xxxx I was responding to someone else! :o Your forge is looking hot enough to do most anything you want. It may be a LITTLE bit rich but we're talking a few strokes with a nail file at a time fine tuning. Watch your ventilation.

Ah you flatter me sir, I'm just a guy who likes to tinker and talk. I got a jump on making NA burners when an old coffee shop friend dumped a box of induction device: fliers, papers and such on me. He was hoping to find an application patent and make a buck but I couldn't figure out a way to make one of these things inflate tires so he lost interest.

Anyway, when I started messing around I had the advantage of a bunch of paperwork showing the basic ratios and how they worked together to induce motion in fluids. 

Mostly though, helping folks makes me feel good, I'm selfish like that. :ph34r:

Frosty The Lucky.

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7 hours ago, Frosty said:

I almost pulled a good one!

I was confused at first. Then realized what was happening. I am working on the second burner and will try opening it up. The original black iron reducer I used as a nozzle produced a neutral flame and had no issues after a minute of warming up. I could wave it around like a wand and the flame would stick. The stainless reducer has a shorter body so I'm thinking grinding the threads out will hold the flame?

10 hours ago, Another FrankenBurner said:

This is after the forge had been going for a few hours.

That is great! I may follow your lead for my baffle doors. Might also be a great way to make a forge body.

How did you get the aggregate into the fibers? Or were they sifted out?

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I did not sift out the aggregate.  We made a form out of blue Styrofoam covered in packing tape.  Then mixed up kastolite to ram into this form along the bottom and up the walls.  This created a hollow inner which we put a piece of rigidized ceramic blanket.  That was then top coated with more kastolite.  This makes a hollow block with blanket inside.  

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Some Notes on Power Tools for Burner and Forge Building

The first power tool I was ever allowed to touch in my father’s steel shop was a nine inch angle grinder, that mounted an 11” grinding disc; it was built in the early nineteen-fifties, seemed to weigh a ton, and made my arms vibrate for minutes after every use; how does a skinny eleven year old boy learn to cope, hour upon hour with such a monster? It had no safety guard. The choice was cope or get chopped up. Over the last sixty odd years I have used every new generation of chop saws and angle grinders that came along, making a living with them and keeping all my limbs. Over this time the biggest factor I’ve seen in the success of new tools is advertisement—not quality, nor handiness. I’ve also watched lots of fools get chopped up. Where is this all leading? Just make sure that the advice you listen to doesn’t come from a source who brays; they seldom have to share your disappointment--or pain.

Combination three-inch angle grinder/angle head rotary tools make the best special power tool choice for people building heating equipment, because they can do all the cutting, grinding, sanding, and power filing operations needed to construct a burner, and equipment it heats, and remain a first class tool for construction of the equipment your burner will run afterward.

    I haven’t run across a 3” pneumatic angle grinder that is convenient to handle, unlike the 2” pneumatic angle grinders (which are under powered); there are two-handed long neck models available, like the  3” High Speed Extended Reach Air Cutoff Tool from Harbor Freight  Tools. 

     Angle grinders are constantly being reduced in motor and gear-head size, to attract new customers. I personally prefer 280 watt motor driven 3” grinders, because they are meant to be operated one-handed, and provide all the power you can safely use in a grinder this small. Too much power in a hand operated tool can be worse than too little! You want just enough power to handle the tasks at hand. By the way, I never operate them one-handed; using both hands, properly braced.

Caution: There is no such thing as a “safe and sane” power tool; sane, yes; but never completely safe!!! Modern wheel guards are especially necessary on miniature grinders because your fingers are placed closer to cutoff discs and grinder wheels than with larger models. Wheel guards that can be easily positioned through 360 degrees provide no advantage at all by their removal; only the tendency to form a very bad habit.

Warning: Never mount a chainsaw carver blade, or toothed cutting blade on one a grinder; such blades are problematic even when cutting wood, because of severe “kick-back tendencies, when mounted on a two handled power tool; they will cause severe injury when run on small angle grinders, because there is no second handle, and therefore no ability of properly bracing the tool against severe kickback. On two handled grinders, the increased torque makes them even more dangerous.

   The 280 watt 3” angle grinders being discussed here, are over three times stronger than a 220 watt rotary tool. This is because a motor’s output power is calculated by multiplying torque times speed. A typical rotary tool tops out at 35,000 RPM but these angle grinder/rotary tool combinations only run at 12,000 RPM; thus a whole lot more torque is included in their overall power ratings, while a lot less frictional drag is built up in their bearings and gears. High torque motors are far less likely to be burned out, when misused by novices, than low torque high speed motors.

    The rotary tool function allows thin 1-1/2” cutoff wheels to be employed in 1/8” mandrels, giving you a generous range of cutting possibilities; a Dremel’s 1-1/2" cutoff wheel kit is recommended for this purpose when cutting with very rotary tools; they can be purchased online from many sources such as eBay and Amazon.com; they are also available in-store at Lowes, Home Depot, and most other large hardware stores, and online. Thus far, the top choices in spindle and disc kits use Dremel’s EZ lock mandrels; these employ a spring loaded locking head, which is very forgiving about adjusting to newbie mistakes .

    A top speed of 12,000 RPM allows small hole drilling with these tools, without the serious loss of power experienced when trying to drill with a regular turned down variable speed rotary tool.

The 280W Mini Angle Grinder Polish Machine (from DHGate.com and other import sources) is a true 3" (75MM) angle grinder. Their literature states that this tool is set up to mount up to 4” grinding wheels and cut-off discs; the photos on various sites show a steel guard big enough to accommodate one; both description and photos are outdated. This tool now has a guard meant for 3” wheels. Size, motor speed, and torque are designed for one-handed use; the gear head is only 1-1/2” wide; it also mounts 1/8” rotary tool accessories in its hollow spindle, allowing 1-1/2” cutoff wheels to be employed in 1/8” mandrels. The price of $68.49 is on the high end, but shipping is usually free. length is just over 7-3/4” (18.5cm) and body width is a little less than 2” (5cm). It uses English and Asian power sources (220V and 50Hz), but can be conveniently used on 110V circuits with a step up voltage transformer: You can usually find one or more sources for them on eBay.

    At present (2020) no manufacturer makes this kind of 3” angle grinder meant for USA/Canada/Mexico power sources; they are all 220V 50Hz versions, meant for use in Europe and Asia. The difference between 60 hertz (Hz) used here, and 50 Hz used there, will not affect motor performance, and these tools have no delicate speed controls that might be effected by the frequency change; in fact they are rated for both 50 and 60 Hz right on the box. Therefore, they can be plugged into a 220V dryer outlet in your garage (you may have to run a circuit and outlet from the garage panel in very old buildings. Or, use the same 220V appliance outlet that laundry dryers run off of in homes); you’ll have to change the plug out for a 220V plug, or build an electrical adapter from a short piece of electrical cord with a 220V plug on one end and a 110V receptacle on the other. 

    Voltage transformers can be used to convert electrical voltage from a power source that is available, up or down to the proper voltage for a device you wish to power from a wall outlet. You must pay attention to the highest wattage the transformer can draw without overheating; exceeding that rating with the tool (280 watts) will destroy your transformer. You are much better off to use a transformer rated to handle more watts than the tool draws. By employing a step-up transformer, you can plug 3” angle grinders into ordinary 110V outlets on job sites. Converters are transformers with additional circuitry for converting back and forth between 50Hz and 60Hz frequencies, in case you want to buy a variable speed rotary tool from a European or Asian source; this tool is rated to run on bother 50 and 60 Hr.: http://www.voltagesuperstore.com/voltage-converters.html

    5/8” spindles are standard on small angle grinders so the new 3” angle grinder/rotary tools are set up to use cutoff discs and grinding wheels with 5/8” center holes; for that reason, these grinders are fitted out with disc flanges that have built in adapters (spacer rings)  meant to accommodate cut-off discs and grinding wheels with 5/8” arbor holes (good luck finding any 3” discs with 5/8”arbor holes here). It is more convenient to grind the spacer ring off the bottom flange, so that they can mount standard 3” cutoff wheels, with 3/8” arbor holes; these have been used on pneumatic grinders and cutoff tools for decades. Afterward, you can buy or make flange adapters to fit the very few 3” depressed center hole grinding disks with 5/8” arbor holes that may become available eventually. In the meantime, a great variety of 3” accessories are available, but they all have 3/8” arbor holes. Pay a few dollars more to purchase a model that comes with at least five cutoff wheels, to put off the hassle of adjusting to using the standard cutoff wheels with 3/8” arbor holes immediately.

Also, not all of these grinders include the rotary tool spindle; make sure yours does, before purchase.

Note: Because the arbor hole and spindle are close to the same diameter, it is necessary to mount  lower quality friction discs and grinding wheels tightly; any slippage between the two surfaces will lead to abrasion on the spindle’s thread.

High quality 3” (75mm) discs come with  built in aluminum bushings to protect spindles from being damaged by exposure to a cut-off disc’s  abrasive surface; the bushing also has a wide face on one side of the disc to provide a firm but compressible surface against one of a grinder’s two flanges, resulting in a better grip against slippage.

So why put up with all these hassles, just to employ a 3” angle grinder, instead of a 4-1/2” model? The “easy way’ is where the “thundering herd” Goes; it doesn’t lead anywhere you want to end up.    

Practical Mini Angle Grinder Polishing Machine/ Mini Cutting Machine; 280W and 220V 50/60 Hz. Basically the same tool as above for less money 31.98 pounds ($50.87) with shipping; Don’t hesitate to look through four or five eBay pages of “mini angle grinders” to find the best deals on this tool.

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Why use small angle grinders over rotary tools for sheet-metal work at all? When used for cutting, angle grinder discs can be placed parallel to the cut line, then moved down, and toward you; this is the safest possible power cutting position, as it is the least prone to kickback. Cutting discs in rotary tools have to be moved sideways along a cut line; providing several times the amount of kick back!
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Ever have such a great idea (hopefully), that you can't sleep? For writers, the curse in that comes when that leight bulb goes off at two AM, sunsets a "great write up "  :D

It may be possible to rig up a way to cut in parallel to the line, instead of transverse to it, with a standard rotary tool :P

Anyway, my hunch is strong enough that I sent away for a Black and Decker rotary tool through Amazon.com; once it arrives I will have the right size and shape rotary tool to mount a new accessory on, and try out the idea...

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Yeah, I've lain in bed with an idea going round and round till I got up and wrote it down. Unfortunately some of those seem pretty bad next morning, not enough to prevent me from writing them down though. 

A couple summers ago I missed a chance to buy a Rotozip set for $10. at a yard sale by making a counter offer. I always counter, paying asking isn't part of the game unfortunately sometimes the knee jerk habit backfires. The gentleman ran me off. I've used a friend's Rotozip and it cuts dang near anything with the right bit. Ceramic tile, glass, concrete, wood, plastic and steel like butter. This one even had the reciprocating setting to run one of those corner saws. Then there were the different guides, holders, etc. attachments in the box. 

I'm still kicking myself for that one, just the basic tool was around $100 and I bet there were more than that much in bits not to mention the other attachments. 

I'd dearly like to write up a comparison but. . . I've also had ideas bad enough to keep me up. <sigh>

Frosty The Lucky.

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Usually ideas work out for me; they just don't come very often :D


    I haven’t run across a compact 3” pneumatic angle grinder, unlike the 2” pneumatic angle grinders (which are under powered); there are two-handed long neck models available, like the  3” High Speed Extended Reach Air Cutoff Tool from Harbor Freight  Tools.

The GWS 10.8-76 V-EC Professional (from Bosch) is a moderately high priced cordless right angle grinder (around $100 to $140 depending on source and accessories), with sufficient power to do its work quickly; it spins 76mm (3”) cutoff disks and grinding wheels. Rather than use gearing to achieve a right angle position, a short squat brushless motor is mounted at right angles to its battery filled handle; it has a built-in breaking mechanism, which kicks in when the power switch is turned off. This  tool does fine for cutting and grinding flat surfaces, and well enough for cutting off pipe and tubing, but for fine detail work, it will prove awkward.

The Milwaukee 2485-22 M12 FUEL Lithium-Ion Right Angle Die Grinder is about 8- 4-1/2” long, with a .3 horse power brushless motor mounted at right angles to its battery filled body, in a head that is about 4-1/2” long (from spindle tip to rear edge); its spindle holds heavy 1/4” mandrels, and it is engineered to spin up to 2” diameter cutting discs and grinding wheels. Sufficient power for this work, with excellent handling and view for complex cutting. Prices run around $60 and up, depending on source and accessories offered.

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Safe use of rotary accessories

It is only forethought that prevents incidents from becoming accidents, or accidents from turning into disasters.

While using cutoff wheels, the direction of tool travel should be opposite to the rotation of a cut0ff disc, whenever possible (this is counter to the direction that friction is trying to push it along the material surface); doing so greatly reduces the chance that your wheel will bind in the work piece, creating dangerous kickback and/or shattering the disc. During those rare occasions that you must ignore this advice, switch to a smaller diameter disc and reduce speed, to diminish the force of kickback.

Warning: Never position your eyes directly in line with a cutoff blade, grinding wheel, or rotary brush. Keep your eyes, face, and neck out of the path of shattered blades and flung parts, regardless of safety glasses, goggles, face shields, or other protection that you may employ to stop normal debris; otherwise, acquiring such a bad habit will eventually bring you grief.

    Line-of-site with your work should always to be above “the plane of spin.” Any cut-off blade, grinding accessory, or rotary brush should be aimed in line with your chest; never in line with your face or neck. Several people have been killed by grinders kicking back into the neck; don’t think a shattered blade section from a cutoff disc won’t cut into an artery just as easily; is this likely? Fortunately the answer is no, but it does happen.

    With the part clamped so that your cut line is near to horizontal, position the blade just below the line; this gives an excellent view, while keeping debris trajectories well below your neck. Rotate and re-clamp the part whenever needed to keep the cut line in plain sight above the wheel.

Form a plan of what you’re going to be doing, before running a power tool. Spend a moment picturing what reaction you’ll need to make in case of kickback, for instance. You won’t have time to decide during an incident.

Always assume a safe work posture. There are three ways to grip a rotary tool:

(1)   As you would a pen, for fine detail work like engraving (only employed with pendant hand-pieces or with very weak rotary tools (ex. engravers).

(2)   As you would a knife (only used on out of position work (where you have no other choice).

(3)   Two handed, as you would a golf club or baseball bat; this is the safest position. Always use the two handed grip during bench work.

    Keep your fingers well away from accessories; especially cutoff wheels.

    Set your footing for best balance before operating the tool; sitting down with feet spread well apart is safest.

    Whenever you have the chance, brace your body, one of your arms, or one of your wrists against some solid surface, which is out of harm’s way. Try to keep one or both elbows close to your side when possible.

    If following these instructions seems too demanding, practice each recommendation, while you have someone push sideways a few times against your hands (with an unplugged tool in them). Kickback can push you out of position with equal force, and far too quickly to react in time—unless you’re already braced for it; if you are braced, a possible accident is reduced to just another incident.

    Never overextend your reach; especially during out of position work (ex. on ladders); doing so is an invitation to disaster.

    Tie back long hair, and don’t wear jewelry, a wristwatch, or loose fitting clothing.

    Be sure to secure the part being worked in a vice, or other properly constructed holding device.

    Wear eye and protection. Respiratory protection should consist of a two string dust mask at the very least. Earplugs are also highly recommended.

    Use common sense; don’t employ a large wheel on a small job, or use a more powerful tool than the work needs (ex. rotary tool versus 2” die grinder; 3/4” wheel versus 1-1/2” wheel; full speed versus reduced speed).

    All power tools should be “blown out” after each use (just lung pressure applied through a rubber tube can be effective for this purpose), and then stored in a dry place (or in a sealed plastic bag), for long life.


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