Buzzkill

To me it seems like you're trying to force an analog control on a digital tool. I've built an electric furnace/heat treat oven with a PID controller. For most of these setups the relay is either fully on or off, and the time spent on or off determines the temperature rather than trying to use something that holds valves partially open or uses variable current. I'm not suggesting it's impossible, but it does seem like you're making it far more complicated than it needs to be in my opinion. If you have your Frosty T burner(s) properly tuned, then you never have to adjust the air. All you have to do is change the gas pressure and it will pull in the right amount of air. A bypass setup with the lowest functional pressure for the burner and then a solenoid controlled main line set for somewhere near the max pressure you plan to use is all you need. A PID controller with an autotune feature will figure out the rest of it. Of course if you change the configuration of your forge or use significantly larger or smaller openings at the front or rear you may have to recalibrate. If you want to ensure that you aren't dumping fuel into your forge when the flame isn't lit you can use flame sensors much like commercial furnaces do. I'm not sure, but a PID controller may even have a setting that can detect that no increase in temperature is occurring and shut off the fuel. I only learned the things I needed to make my oven function, so I'm not familiar with all the possibilities.

For the first iteration of my DIY power hammer I used tow straps instead of a linkage. I wanted to minimize the number of metal on metal wear surfaces. It worked ok, but with the design I used it required fairly frequent adjusting/tightening to keep everything lined up properly. This makes me wonder if I could use a tire instead of the entire linkage/spring assembly. Unfortunately the tension on the linkage arms does affect how well the hammer runs, and I'm not sure there's a reasonably good way to change the tension on a used tire.

Right. You got the surface area in square inches and then multiplied that times the thickness to give you cubic inches of volume. You can then use the density of Kastolite (lbs/cu in.) to calculate the minimum weight of kastolite needed for your build. It seems to me that you have it right (assuming you used the right number for the density of kastolite. I didn't check that). When you get it completed and ready to use, the whole thing should be on a frame or something to elevate it a little bit so that you can put a bed of dry sand or something else to contain any molten metal that would exit your drain hole if the crucible fails. You want nothing flammable or anything that could be holding moisture (like concrete) to come in contact with molten metal. Always assume that there could be problems and prepare for them so you won't be surprised and you will limit the potential for injury. Based on your postings on here I think you are moving in a generally good direction and speed on this. I know when I get excited about a project it's hard to slow down and do things the safe/right way. However, the success rate goes up and the injury rate goes down when I force myself to do that.

I probably wasn't as clear as I could have been. You can cut a couple inches off the bottom in much the same way you intend to do at the top for your lid. In fact they should both have a hole in the center, but a much smaller hole in the floor piece. What I'm suggesting is 3 separate pieces that comprise your melter. The bottom piece is the floor, which should have a drain hole in the center to allow molten metal to escape when there is a crucible failure. You can cast the floor with a small channel that runs to a hole that will be covered by the plinth that the crucible sits on. The middle piece is just the the cylinder with the burner, and of course the removable lid (ceiling) sits on top with a hole for exhaust gases to escape. It may be a good idea to use some combination of latches, clasps, or hinges to hold everything together in use, but once it's cooled down you can separate the pieces and service them or replace them individually as needed without having to rebuild the entire thing. I came up with the same number as you for the minimum amount of kastolite required for your build. Experience has taught me to always get more than I need because the chance of me doing everything perfectly the first time I try it is quite low.

Unless your floor and ceiling are going inside the cylinder, the length (height) won't change. If you have a flat surface that you will set the cylinder on it won't take any additional space inside the chamber. The same goes for the top. They will still need insulation and refractory, but they can be removed/replaced separate of the main body. I suggest making it this way since it will be much easier to deal with if (when) a crucible fails inside your melter and you have to clean things up. In the worst case you can just replace the flat floor that the cylinder sits on and not have to rebuild the entire thing. I do agree with your math if we assume a 10 inch wall height though.

I'm not sure I understand what you did with your math there. The cubic inches of the inside of the melter may be helpful for determining your burner size, but what you really want to calculate the amount of refractory you need is the surface area of the chamber multiplied by the thickness you intend to use to get the volume of the refractory. You said the diameter is 11 inches. After putting in 2 layers of wool your diameter is 7 inches. The height is 14 inches. you should be able to take it from there. After you apply .25" of refractory that will only leave you 6.5" of working space for your crucible and tongs. You may want to go shorter and fatter. I think starting with 14 inches in diameter and 11 inches tall would probably serve you better.

Generally speaking it is a good idea to check with manufacturers regarding the uses of their products. I don't want to discourage that. However, as someone who personally tried to use one of the many refractory mortars/cements out there for my first propane forge, I can confirm that at least the brand I used did not hold up. Kastolite 30 is a good choice for a water setting high alumina insulating refractory material. It's rated up to 3000 degrees F and can be used as a flame face in addition to sealing in the ceramic wool fibers. It benefits from nearly 100% humidity during the curing phase. I usually enclose the casting in a plastic bag with a wet towel draped over the Kastolite material for a day or so to ensure that it stays as damp as needed for curing. Ambient humidity should not be considered good enough. Since you said you know close to diddly, it should be stressed that handling molten metal can be extremely dangerous - far more so than forging. It requires a fair amount of PPE to minimize the chance of serious injury if when something goes wrong. I have a limited amount of casting experience myself, but I would highly recommend trying to find a local college with a class or a local casting club/group that can assist you with all the particulars while you are getting started. All this metal working stuff can be really cool and rewarding, but it's not worth being maimed or worse due to lack of knowledge or protective equipment.

A few things: Are you truly making a smelting furnace? In other words are you taking raw ore and ending up with a consolidated metal ingot? Or are you melting pieces of metal that are already mostly purified? This is an important distinction. First, it helps us understand what you are trying to do, and secondly different temperatures are usually required for smelting than melting. Next we need to know the metal that you are either melting or smelting. 2500 degrees F sounds really hot - and it is - but if you were smelting iron ore (or even melting iron for a pour) you would most likely exceed that temperature. For copper or aluminum it might be a different story. Next, regardless of what the manufacturer tells you, most of the refractory cements simply do not hold up for long under direct flame impingement circumstances. They are designed to stick pieces together rather than to take the brunt of hot, chemically active flames. I wouldn't be comfortable using something rated for 2500 degrees in my forge, let alone something that would require higher temperatures. The refractory I use is rated for 3000 degrees, and it's not uncommon to see people using something rated for 3200 degrees. Again, that's for forging/forge welding, which can be accomplished at several hundred degrees cooler than melting or smelting iron or steel. Depending on the type of refractory it is, removing the water more quickly doesn't necessarily give you the results you want. A lot of us use a water setting refractory that cures best (most strength and minimal cracking) in a high humidity environment. After a day or so of curing we do have to remove the excess water slowly by gradually raising the temperature. If done too quickly it can create steam pockets which can reduce the effectiveness of the refractory and/or actually explode in extreme cases. O/A flames tend to be very hot and somewhat focused even if you are holding the torch back 6 to 8 inches. It's really not the right tool for the job. I don't know if you are seeing the results of rapid surface heating creating steam pockets or something else, but in my opinion you do not have the appropriate material for the job either.

Same thing in my area. There are 5 hospitals total in 3 cities within 30 miles of me, but all of them belong to one of two major health care provider conglomerates. Nearly all the urgent care, specialized care, clinics, etc. are also associated with one or the other. My PCP was in an independent practice with a couple other physicians when I started with him, but now he's also under the umbrella of one of the 2 major providers in my area. I think it's the health care industry version of the national chains squeezing out the "mom and pop" grocery stores and gas stations.

The center part of brake chambers are also a good source of casting aluminum, but you may have to find a way to safely deal with the 1/2" diameter spring coiled up on one end. There's not nearly as much aluminum in one of those as a rim, but it's a much more manageable size. I'll be watching this with interest. At one point I was considering this route, but recently I was able to pick up a Montgomery Wards metal lathe (which was made by Logan and is essentially their model 200) for a hundred bucks. I'm just waiting for warmer weather so I can reassemble it and assess the condition. It won't surprise me if I find the need to cast or machine some new parts for it.

Sorry guys, I'm with acein on this one. He's been asking about hardening of 4340 and how to maximize the hardness of it. He then asked if a specific sequence of techniques/processes would result in the maximum hardness, and instead of anyone actually answering the question he was asked how that would work. That is not helpful at all. He never stated it was a FACT that a process would result in a certain hardness. He ASKED if the hardness was achievable with that technique. Glenn specifically asked us to be respectful of newcomers. I can't fault them for becoming defensive and sarcastic when their questions are met with responses that could certainly be interpreted as obnoxious even if they weren't intended that way. There seems to be a return to excessive curmudgeonly responses lately. For the record, the pinned heat treatment thread does NOT cover flame hardening (at least I didn't see it), so implying that his answer is contained in that location is disingenuous at best. Why is it so hard to just answer the question if you know it, or link to a previous post that has the answer? If you don't know the answer then why bother responding in an antagonistic manner?

It shouldn't be a problem. You will most likely not be reaching temperatures greater than 500 F in the cooking chamber. I don't think that will cause problems with either premature ignition or excessive degradation of the burner surface. In a forge we are sometimes reaching temperatures in excess of 2300 F, so the burners have to be able to withstand that heat for hours at a time without failing.

Frosty's burner was designed to be used in a forge. Those burners in the first pic do not appear to me to be built exactly as Frosty specified. Using a reducer fitting for flame retention is usually better than nothing, but it is not ideal. A lot of naturally aspirated burners will blow the flame off the end of the mixing tube at moderate to high pressure even inside a forge or furnace until the chamber is heated to the point where it glows. Usually you can turn them up as high as you care to at that point.

Glad it helped. Any time you use vinegar on metal you should make sure you neutralize it afterwards with something like baking soda. If you don't then metals prone to corrosion will experience it in short order most of the time.

I come from the school of thought that says, "Check the easy things first." To me the easy thing is to use it again until your problem starts to recur. At that point look at the pressure showing on the gauge. If it's lower than you set it and/or dropping, then you are nearly out of fuel or you're using gas fast enough to chill the tank. You can always take the burner and supply lines apart later and clean them if you need to, but if it's a simple matter of making a water bath for your propane tank .... well, you decide which is easier.

Since the burner is top mounted, once you shut the burner down the mixing tube will heat up if the forge is hot. A hot mixing tube will promote early ignition and flames burning inside the mixing tube. However, you were showing 30 psi at your regulator. Even with a hot mixing tube I would expect it to behave differently than what I saw and heard in the video. In general burners don't just "go bad" where the performance deteriorates slowly and then they don't function. Things can get plugged up and nozzles oxidize to the point where they have to be replaced, but there are no moving parts to wear out. Even if they did, the orifice would become larger from wear and allow too much gas through. That is not your problem here. If your other burner is also experiencing a decrease in performance that suggests to me that your regulator is failing (that could happen in a more gradual way) or you got a propane canister with some material in it that is plugging up your burners. There is one other option that is possible, or even likely. Since you are using a small (BBQ size) propane tank, it may cool off fast enough to be a problem. If you use the gas quickly enough, the temperature in the tank will drop to the point where it affects the pressure. You can even freeze up the regulator in some cases. However, you were still showing 30 psi on your gauge, which is on the output side of the regulator. That makes it unlikely for the regulator or tank freezing to be the issue *unless* the pressure drops rapidly when you turn the gas on at that point. If it does, then that is most likely the source of your problems. Try placing the propane tank in a shallow pan of water and see if that changes things. Alternatively you can link 2 or more propane tanks together to slow the cooling process.

From what I saw it doesn't appear that the pressure on the gauge is going through your burner. The whistling/chirping sound is consistent with flames burning inside the burner tube. That happens when there isn't enough pressure in the fuel stream to keep the flames at the end of the burner. Usually at 30 psi you'd have a very hard time keeping the flame from blowing off the end of the burner unless you choked off most of the air. So, if I'm right you have one of a few possible issues: 1) You have a faulty regulator that isn't allowing the pressure shown on the gauge to go into the fuel supply line, 2) Your fuel line is partially plugged, 3) The orifice on your burner is way too small or is partially obstructed, or 4) the jet is aimed so far off center in your burner that it can't function correctly. The last one is the least likely to me since 30 psi of fuel with the right orifice size should still produce a lot of flame even if it wasn't suitable for forging.

As I understand it, the only reason you can etch forge welded cable to get a pattern is due to the decarb layer that forms on each strand as you consolidate the material into a billet. Generally speaking, multiple (successfully) forge welded layers of the same alloy steel will only show up as a single layer when etched. So, with cable we end up with a thin layer of something approaching mild steel around a core of high carbon steel for each individual strand. The contrast between mild (or mid-carbon) steel and high carbon steel is not nearly as stark as the contrast between a nickel bearing steel and a high carbon steel without nickel. It's shades of gray for the cable or maybe gray to black. Regardless, it's more subtle than high contrast combinations like 15N20 and 1095. Unfortunately I have next to no experience producing a good etch on cable steel, so I can't give you a "best" way to bring out the pattern.

I second that emotion, Frosty. When we were traipsing around the Yukon on snowshoes in temps between minus 20 and minus 50 it was definitely cold, but in some ways not as bad as when it's right around freezing. Snow just falls off your clothes like dust or sand when it's really cold. When it's around freezing water seeps into your clothing and freezes in the fabric. We always slept in underwear and T shirts even at 40 below (in our sleeping bags of course) due to the risk of sweat freezing inside heavier clothing. Watching people (or oneself) attempt to get dressed at -40 first thing after waking up can be amusing though. If we had to thread a needle to save our lives I think we would have all died. Parkinson's patients would have berated us for shaking so much. Gore-Tex gear does help a little with the wicking issue, but there are limits for everything.

You have it right. There didn't seem to be much difference between a T burner "top end" and an AFB inspired vortex inducer on the NARB burner block I used. There is a noticeable difference as a single port burner though. For several sessions I got absolutely no burn back into the plenum and no "poof" when shutting off the fuel when using the block that has over 180 ports which are about 3 inches long - even after being at 1280 C. However, since then I have had a little "poof" when I turn off the gas. I still can turn the pressure down to the point where it doesn't register on the gauge after being at forge welding temp without it backfiring or burning back into the plenum though. The down side is it is a large, heavy burner head, and all those small diameter holes make it a challenge to cast and clean. I made a disposable 3d printed mold form for the burner head. Once I vibrated in the refractory and placed the plenum I put the whole thing in a plastic bag for a day or so. My next step was to put the whole thing on the 3d printer bed and heat it to 100 C for about a day before removing the plastic bag and letting it set another day or so (with heat). After that I cut off all the exterior plastic, built a small fire, and moved the burner block and plenum gradually closer to the fire and then eventually in it. It was a several hour process, but ultimately the burner was in the middle of the fire with coals under it, and the plastic all burned out fairly well. It was still worthwhile to run a rod through all the holes I think. That's not exactly the prescribed method given by the manufacturer, but it seems to have resulted in a solid burner head with no cracks (yet).

I think I could make out that it's rated at 115v, Type S, and the manufacturer was Packard Electric Division then I could make out the word "Motors" and of course Ohio. Applying a little Google-fu, I came to the conclusion that the motor was made by General Motors in the Packard Electric Division, which is based in Warren, OH. I can't tell if it's S 7033, S 7035, or S 7036 stamped in at the top. I did find a 7035 OEM replacement motor on Grainger's site that is 1/2 hp, 1725 RPM, 115v and used in HVAC applications. I don't know if it's a match or not though.

I'm not sure how that would help, Steve. He mentioned that the motors he has have no markings of any kind on them any more. My understanding of electric motors is limited though. How could that be used to identify the hp of the motor? What are the pertinent features to look at or measure? I've got a few old motors myself that I'd like to check out.

I don't know how to DIY test an old motor for hp, but if you had the RPM rating, the voltage, and the amperage draw, I *think* you could calculate it reasonably accurately. One other thing to keep in mind on the motor: You really want a Totally Enclosed Fan Cooled (TEFC) motor for this application. If you use a motor with internal components open to the air, the abrasive and metal dust will most likely ruin your motor in short order.

If you go down to 1hp or lower with a 2 x 72 belt grinder you are going to have to sacrifice speed or you'll bog it down easily. My original configuration was with a 1hp single phase motor and step pulleys opposite each other like you might see on a drill press for changing speeds. On the fastest belt speed configuration I could easily stall the motor with only moderate pressure on the belt. I don't want to discourage you. My belt grinder went through several upgrades to what it is now. I used skateboard (longboard actually) wheels for the top and bottom of my flat platen and I made a drive wheel from 2x4's and Gorilla Glue on the first iteration. That drive wheel is now used on my DIY power hammer along with the same 1 hp motor originally used on my belt grinder. It was definitely better than not having a belt grinder, but it didn't take long for me to want more.

Just so you know where I was coming from there -- When I bought my 2hp motor, the 3 phase versions were less than half the cost of single phase. A VFD/3 phase motor setup also will "soft start" (at least mine does) rather than try to instantly be at max RPM. I don't know enough about the different motors and VFD's to know if you can effectively do variable speed with single phase without sacrificing horsepower. I do know that I like my grinder much better now with 3 phase 2hp and variable speed than I did at single phase 1 hp and step pulleys.