Latticino

I feel your pain, as I also attempt to make knives and struggle with grinding (particularly double edged pieces and recurves). In addition to use of new belts I do have the following, culled from recommendations given to me over the years: To avoid wasting steel and belts, you can practice many of the grinding motions on wooden blanks. Inexpensive wooden yardsticks (that used to be given away for free) are great stock for this. You still need to start with a new sharp belt, but the grit lasts a lot longer. Get as much light as you can on your grinder area, particularly at the point where the edge is. Filing jigs with carbide faces are great tools for getting your plunge and tang shoulders really well defined. Order of operations for grinding a typical blade as I see it: profile, flat ricasso, tapered tang, distal taper for blade, bevels, swage, edge Change grinding angles slightly if possible for different grits to be able to see when you clear scratches Can use Dykem or permanent marker and machinist's layout tools to layout bevels and find edge centerline. This can really help with symmetry. Each to their own, but I prefer the look of saber grinds with the primary bevel is parallel with the blade edge rather than the spine. When beveling, once a flat is established "find" that flat each time by lightly touching the platten before pressing hard to begin grinding. Trizac belts are awesome... So are ceramic belts, but they are optimized for high pressure grinding. If your grinder motor can't take it they are less effective and long lasting. Flat plattens wear over time. Check yours with a steel square.

If I were forging my own, I might be tempted to forge it like a tennon with a larger diameter top that protruded above the socket. That way you could slide a purpose made claw tool under it to lift the pin if it ever got jammed. Kind of hard to describe, but easy to sketch if you need.

As I'm not an acoustic or jet engine expert (though my father once designed turbine blades for Pratt & Whitney), I don't completely follow this article. However it does have something interesting to relate regarding combustion generated noise: https://www.sciencedirect.com/science/article/pii/S1540748914004003 .

My pin appears to be mild steel, but I haven't spark tested it. I can certainly see the logic for making out of at least 4140 or the like, but I don't know that I would harden it. Some day you might have to drill it out... If nothing else it is good to have the pin project up out of the locator slot at least an inch or so. This will allow use of a vice grip to help pull it out. Actually my pin is cylindrical, rather than "D" shaped, so it can be rotated to help free it if jammed.

As far as I am aware, while stainless steel is often used for health care tools and surfaces, it is NOT inherently anti-bacterial, before or after forging. It's surface is relatively inert due to the chromium oxide coatings that develop, limiting rusting, but while that surface can be easily cleaned it does not prevent organic growth like silver and copper are reported to do. What you may be referring to is the problem that some stainless steels exhibit once forged; where they lose their chromium oxide layer due to the excessive heat. If I were making surgical instruments I would bring the surface to a high polish with successively fine abrasives, then investigate "passivation" (an acid based electropolishing operation).

Even in poor condition a A&O power hammer can be repaired to something fairly desirable. In good, working condition it would likely fetch in excess of $6,000 around here (location does matter). You shouldn't have trouble getting better than scrap prices from a smith. I would look for a local association for assistance.

Frosty, Yes originally I thought it was a 20 x 20 space (like mine), then I reread the OP and saw 200 SF rather than 400 SF... Mia Culpa

A typical single burner propane forge may have a burner rated for between 80,000 BTUH and 110,000 BTUH. IF that heat isn't captured and exhausted fairly directly a 12,000 BTUH window shaker air conditioner isn't going to do much. If it is exhausted, as it should be for fume control at least, you need to deal with the conditions the required make up air brings in (along with any solar load and building envelope load from your walls). Assuming the building is a simple 20 x 10 cube, the surface area exposed will be around 1,000 SF. If the building is a generous R-11 (you are insulating your walls and roof, right?), and outdoor conditions are say 90 deg. F, the envelope load will be on the order of another 2,000 BTUH. The ventilation heat load would be (for say 10 air exchanges), will be around another 11,000 BTUH. Note that this doesn't include any solar load calculations, and is a rough approximation at best. I have seen air conditioned shops. However, these usually are separated between hot forge areas that are only ventilated, and cold grinding and assembly areas that may be air conditioned. The cost of heating a room with a forge and then trying to cool it mechanically is prohibitive for most folks.

There are different philosophies regarding hammer face hardness. Some folks want their hammer faces to be diamond hard (the hardest thing in the shop). Others, like myself, prefer their hammer faces to be pretty hard, just not necessarily harder than the anvil face. The logic there is that it is a whole lot easier to reface, or even replace, a hammer than it is an anvil. Unless you have only been using the hammer for a short time, I would be tempted to just reface the hammer to address the slight mushrooming you are seeing. Up to you of course...

Other considerations are the compressor itself. Das mentioned oil or "oil-free" types. There are also single stage or two stage compressors (look for number of cylinders). Typically the latter provide more compressed air at higher cfm. It is important to realize that compressors are rated for pressure at a specific airflow (i.e. 11 CFM at 90 psi). This becomes critical if you are running equipment with significant demand for compressed air (like a sandblaster or power hammer). Needless to say your motor selection should match your available power and environmental situation (TEFC for locations with a lot of metallic dust for example).

There are some engineered ceramics companies that produce custom high alumina crucibles and other specialty components. Might be able to go to them for a custom casting, but I suspect it would be prohibitively expensive. Here are some from Selee:

Another alternative would be too do something like what Tim Zowada does with his forge kits:

I've used Mizzou, but not casted anything with it for over 20 years, so going by dim memory here. I used it to cast burner blocks and did some light troweling into the bottom of my ceramic blanket glassblowing glory hole for molten glass resistance. I don't recall it troweling any better than Kastolite, and I've never tried to do successive sections of either to build an arch from a series of installations. I have troweled Greencast 97 over the top of a large clay form to make an arch for the top of my glass furnace. That worked very well, though the form had to be removed carefully while the refractory was setting. I did add SS needles to the dry mix for that, which made it not a whole lot of fun to mix up by hand. Personally I'm in favor of casting the inner skin of the forge in Kastolite with a removable inner form. This is certainly feasible in 3/4" thickness, which IMHO is a good compromise for an inner liner.

Another alternative would be to go over to natural gas. It is pretty convenient, though you will need either a dedicated blower for a fan powered burner, or gas compressor for a NA one..

I think you are underestimating the side forces the pressing of a piece of stock may have on your frame and guides. There is a good reason for those heavy weight guides on fly presses, hydraulic forging presses and power hammers. I would be careful of the potential for off center force, the guides binding, and the whole thing wracking. Just the offset of the chain from the center of the axle may cause you trouble. Still, best of luck with your build. I'd love to be proved wrong.

It has been so long since I signed on as a new member that I have forgotten. Perhaps if we don't already have it, instituting a gate keeping question or two about blacksmithing would help keep down the spam posters...

Such a cute little press. Don't have too much to add to the above, though I expect that two factors will come into play that haven't been considered: type of steel and how hot you will get it when you stamp your touchmark. There is going to be a large difference between stamping, say, H-13, 52100, and D2 vs. mild steel or wrought iron. There will be a similar difference between stamping steel at a red heat vs. at a high yellow. I suspect you will be able to get this to stamp a 1/2" square touchmark on hot steel with not much trouble. I have a 3/4" round touchmark and stamp it with a 4# hand hammer. Needless to say it will be important to lag your press down to something that is rigid and relatively immobile for best effect.

If you can't find an air/acetylene torch kit used on Craig's List, MAPP gas torches put out a lot more heat than the cheap plumbers propane ones. I got one of the larger ones at a big box store and have used it for tempering back tangs more than once. I would certainly follow Buzzkill's recommendation to have some sort of heat sink to avoid having the heat run back up the blade.

How hot your forge skin will get will be determined by the insulation value of your inner layer (type and thickness of the "refractory bricks"), the way the combustion exhaust exits from your door openings, and how hot you run the interior of your forge. This is very difficult to predict (and can vary quite a bit depending on the insulating value of the bricks used). I would use it, as is, for initial firings and measure the peak surface temperature. Then select a coating to suit that temperature. Are those "hard" kiln bricks, or "soft"? If the former, they will have substantial thermal mass to heat up and potentially more thermal transfer losses. If the latter, please keep us posted on how long the forge "roof" holds up. Soft bricks are very prone to thermal shock and/or brittle failure. Hopefully your design includes provisions for relining your forge. Even under the best of circumstances you may have to replace it periodically. On my first brick forge, I used some leftover 2300 deg. F rated bricks that I had from another project and the bricks opposite the burner melted away...

I'm not sure I follow your logic. If you work 6/12s on a regular basis and never have time to take off for vacation, when are you going to build all this equipment much less use it? Hydraulic presses and power hammers definitely make work easier, but if you don't have basic blacksmith skills under your belt (at best) they can just screw things up more quickly. At worst you can get badly hurt. Sounds like time is your most valuable commodity. You will learn so much more quickly from direct instruction, starting with safe blacksmith practices. There appear to be several shops/schools in your area, a New Mexico Artist Blacksmith Association in Corrales and even the Turley school in Santa Fe. If you don't have the time to attend, perhaps you should send your father and he can teach you once he learns.

For the air filter shell: 16" - 4" (for the two layers of 1" blanket) gets you an ID of 12". You will want to limit your shell thickness as much as possible (say 3/4" max) since it is currently a "hard" refractory (like Mizzou) rather than an insulating one (like Kastolite 30). The high alumina content of Mizzou is certainly preferable, even better would be Greencast 97. If you have never cast refractory before, it isn't all that easy to ram into a 3/4" thick shell, but it is possible. To be able to remove the inner form you will need both a release and method of reducing it's diameter. I also used a sonotube when I cast my Kastolite shell at around 3/4" thickness, but cut a slice out of it and put in a flat section for the floor with tape, so I could remove it after the refractory set. Fortunately these refractories don't shrink a lot while drying, but if you don't preplan to remove the inner form you will regret it. Mizzou doors will be effective, but heat sinks as well. Heat sinks are a balancing act. Good on one hand as they act like "heat batteries" when you open a forge door or put in a mass of cold steel, bad as they take longer to heat up to forging temperatures (thermal mass) and reduce the overall insulation skin value of an equivalent forge liner that used a castable insulating refractory. You have made the typical forge designer mistake of making your first forge a bit oversized. We all typically go that route. Two issues with this: use of excess fuel and lack of ability to heat effective sections of the stock without overheating others. This latter becomes a particular problem if you are primarily working in high carbon steel (say for blades). If you do end up building tire hammers and hydraulic presses you will be able to work larger stock, but as a beginner I wouldn't necessarily go that route. I would strongly recommend that you and your father take a week long smithing class at one of the better schools to see if and what type of blacksmith work you enjoy before you jump completely into the deep end. Some folks find out it really isn't for them, or they prefer a different type of smithing that doesn't involve as much post forging work (bladesmithing, for example, is typically around 10-20% forging with the rest being stock removal, heat treatment, handle/guard/sheath finishing...). Don't be fooled by Forged in Fire. Blacksmith tools and equipment are currently selling at relatively high prices, but the bubble appears to be getting ready to burst. Don't be sure you will recoup your investment if you decide this isn't your thing after getting fully setup. You can make some incredible metalwork with a small fraction of the tools and equipment you are contemplating getting. That is a beautiful (French?) double horn anvil. Certainly won't hold you back at all.

As I understand it the area being tested is proportional to the distance the test is at, and the temperature is averaged within that area. Apparently the mechanism used for determining the temperature has some relation to the emissivity of the material in question and can be confused by metering multiple materials simultaneously (and Jarrod indicated that was worse at elevated temperatures, which doesn't make sense to me - but I'm not a physicist). Bottom line is that closer sensing is probably fine up to a point (probably related to the size of the optical sensor being used). He may be concerned with accuracy within +/-0.5% , while I don't need quite that level of accuracy at 1,500 degrees (+/- 1 or 2% is probably acceptable for the heat treatment I do).

I purchased one of those from Amazon as well. Around $60, if I recall correctly. Seems fairly accurate based on comparisons with thermocouples in a heat treat oven, but have read other postings from "authorities" that indicated there can be fairly large discrepancies based on the size of the cone and emissivity (note that the one he is commenting on is only rated to 1,500 deg. F, not the same as the one John and I have): This from Jerrod Miller (a metallurgist): I have yet to find one I trust for what I would call a reasonable amount of money. Two big things that a lot of people do not realize with IR thermometers is the size of the cone for the reader (close to the gun reads a small area, farther away a bigger area) and emissivity constants (a material dependent value). When we get to the temperatures we care about in smithing, emissivity constants become important and you will need to calibrate and adjust it for the material. The cone for the one you linked has a 12:1 ratio, so at 12 inches your diameter being measured is 1 inch. So unless you can be sure to be measuring just your steel, you will get contaminated readings (measuring the forge wall with the wrong emissivity constant for it).

The limitations on your burner operation are also related to a number of factors, so it isn't a simple answer. The forge interior temperature directly influences the flame front speed (the velocity of the flame burning back towards the fuel/air source at the outlet of the burner). You want this flame to be stable, and located right at the outlet of the burner. As I've noted on numerous occasions, it is a balance between the velocity of the air/gas mix at the outlet (set by the volumetric flowrate) and the flame front speed. If it is too far off, it can easily "flame out" and, hopefully reignite (forge will appear to be "huffing". If too far into the burner outlet you can get preiginition in the mixing chamber (anything from "popping" to small explosions). Burner outlet area may need to be adjusted to achieve a "sweet spot" (though there are also burner outlet designs that work at a wider range - flame retention outlets and multiport outlets). As is pretty logical, a larger outlet will support more fuel/gas mixture at a lower flow speed, typically leading to a more "powerful" burner, but one that may not be able to be turned down as far without burning back into the mixer. You also have to be careful, again for flame front speed reasons, when turning down your forge from high to low fire. My recommendation is always to turn off the gas and just run on the blower until the forge drops to the desired temperature to avoid having the flame burning back faster than the lower air/fuel mixture can support. Overall length of flame can also be a factor (as Thomas stated), with how long the dwell time is inside the forge. Longer dwell leads to more energy transfer. Choice between oxidizing and reducing flames have been well described by Buzzkill. There are also characteristic forge interior sizes that work better with different flame configurations (both forge interior volume - for proper combustion, and forge width opposite the burner outlet - for properly developed flame length). I expect the 1" burner may be too large for your 250 cubic inch forge, but that is hard to tell without experimentation. You can always choke it down to a 3/4" outlet with a reducer to see. Best and most efficient path to increasing forge temperature IMHO is to ensure you have good operable doors. This is easier with a blown burner, so you are already on the road to success. Good luck.

There are a couple of different ways to reduce the airflow from a blower. If the motor is capable of speed control you can reduce the RPM. On most blowers, but not all, you can "ride the fan curve" by increasing the resistance on the blower outlet with a valve or slide gate of some sort (some can go unstable at elevated external pressure). On some blowers you can reduce the airflow by restricting the inlet (but this can be a problem for others, overheating the motor). You can also add a waste gate that directs some of the air elsewhere (possibly to a slot diffuser at the opening of you forge to direct the dragons breath upwards). Lots of options, but first you have to ask yourself: How do I know I have too much air? How much fuel/air mixture is needed to burn to maintain a stable flame at the forge temperature I need for the forge I built (changes at different interior temperatures)? Should I reconfigure the burner outlet before reducing airflow?