evfreek

Recently, I lost my pedestal grinder to a downsizing. A garage sale arbor grinder ("blacksmith grinder") replaced it. These things look dangerous. What is the most pressing part to guard? The wheels or the pulley? Someone told me the v-belt, since one can get a finger nipped. I think it is the wheel. Here is an example of one of these old grinders. I have a buddy who runs one of these, and he insists it's perfectly safe.

Thomas is absolutely correct. If you see sparks when the motor is running, it is a universal motor and can be slowed down by lowering the voltage or putting a resistance in series. The permanent magnet motors work really well with the lowered voltage approach. I just use a junk battery charger for my leaf blower powered forge. No modification required to the leaf blower! If you don't have a battery charger, you can use a cheap resistor (incandescent light bulb in series: you can often get these free when people are ditching them for CFL's).

How important is sheet metal to you? What do you plan to use it for? If you really want to buy that Harbor Freight mig welder, be aware that it is missing a lot of important parts that you will need to add to make it weld like a name brand welder. There is an ongoing thread at www.weldingweb.com on exactly what to do. Otherwise, it will barely work and most people either mod them up or throw them away. Just because it says "China" doesn't mean that it is bad. Of course, that may be a good indication. Once I made a bunch of tools and stamped them "China". I showed them to a Chinese (supremacist) and she sniffed up her nose and said, eeew, looks like they were made in America Here's what I used my stick welder for recently: weld up some guards for a wheel grinder (14 ga, so they weren't really sheet metal) weld an angle tool rest join a foot to my anvil (1 1/2" thick full pen weld) fix a junk pair of tongs If you can find an inexpensive welding class in a community college or adult education place, I would echo the others' recommendations to take it. You will learn a lot about what welders can do and what you want them for. Make sure that the classroom is well-equipped and that you get plenty of time behind the hood. You'll be telling the newbies what to do in no time.

Hi Matt. Here are some pictures. They should be self explanatory. Oddly enough, there is some inaccuracy at the end of the cuts. I don't know where it is coming from, but I think it is caused by tilting of the file or taking too big of a bite. By the way, the first cut should be done with a knife-edge needle file. A typical triangular thread file is much too coarse.

Hi Matt. I just did this, and it was quite a chore. Phil's answer looks correct, but it may not be all that practical. In those days, there were lathes, but screws were more like chased than threaded with a single point tool. Kind of like what used-iron was saying. Bob's suggestion about the paper spiral sounds really clever. I wonder how it would work on a fine divider thread. Here is how I made mine. I built a jig out of wood and angle iron. I clamped a spring steel file guide (mangled sawzall blade) at the thread angle. At the far end of the jig was a screw with the same pitch sunk in two nuts, one captured, and the other to control slop. I then turned the screw 1/4 turn to advance the blank, and cut against the file guide with a three cornered file on a squared cross-section to make a four cornered tap. Four or three cornered taps are easy to forge, but do not cut well because they do not have the right relief. It does work, however. I could thread the finished nut on by hand. But, I probably will not do this again very soon :blink:

Hi. Thanks for all the comments. I am sure all of these methods will work. The one with the salt and flour sounds particularly promising. Thomas' suggestion of making blister steel is a good one if I need to make steel out of wrought iron, but it will not work for my application, hardening a threading tap. The reason I know this is that I saw Phillip Baldwin demonstrate exactly this process at a blacksmith conference. He used bars of old wrought iron from a shipwreck, and pack carburized them with charcoal for about 12 hours. This made blister steel, which would have been disastrous for my tap. The blister steel was weak at the blisters, and needed to be "refined" by welding it together in order to homogenize the inclusions. Fortunately, the tap survived one use, which was all I needed it for, but it got goofed up pretty badly.

Hi. I love fiddling around and trying to make do with less. So, when I surfed around the Internet, I noticed lots of references to using sugar for case hardening mild steel. Apparently, the legend is that POW's used this method to harden homemade wire cutter jaws. The sugar would melt and coat the steel, allowing the carbon to diffuse in at a bright heat. So, the other night I tried this out on a piece that was a little too precious for an untested process. Not such a good idea . Also, having watched sugar burn, I should have realized that this was not going to work. After heating the piece to a good red heat (starting to scale), it was dipped into a mixture of charcoal powder, sugar and baking soda. The stuff ignited, fluffed up really badly, and did not really stick. Talk about candy-coating the subject! Anyway, sugar shell coating works at candy-making temperatures, not steel hardening temperatures. I should know better, since I scratch-make candy. Internet searches do turn up failures, including those of commercially made compounds containing sugar. These have become displaced by things like Cherry Heat and Kasenit. But, I couldn't find any of those at the local store. Anyway, the tool failed. By the way, Cherry Heat and Kasenit both work. I have seen successful application of both at demo's. I just don't want to buy a whole can, and anyway, it is much more fun to experiment. These homemade mixtures seem much more suitable for pack case hardening. I would recommend dispensing with the sugar, because it fluffs up too much.

Hi Toreus. That's correct. Unfortunately, it doesn't work so well, because of the weak (thin) spot at the twist and the tendency to pick up a cold shut. I was thinking that I could improve on Mark Aspery's method . If I were to try it again, I would upset more and push the upset back before notching and doing the twist. At the same time, I would not control the side spread of the bar, since one needs extra thickness at the twist point. As it stands, my wolf-jaw tongs are fine, and I just used them for a successful project recently. My process could use a lot of improvement. If in doubt, just use Mark's process. It is almost guaranteed (unless you try to monkey with it a little bit ).

Hi Toreus. I made some comments on this subject in the original post in: The "hybrid method" that I was referring to was employed for making a pair of wolf's jaw tongs. Phil is absolutely correct. Getting the mass at the bit is the tricky part. After that, it's just some routine shaping with a narrow fuller.

Your intermediate product does not look much like your initial sketch, so it is hard to tell where the welds are. Remember that the weakest part of the "cone" is the attachment point to the block, so make sure that you have full pen there, not just a weak blob. It looks like the rods are kind of backed up on a step, so that may be workable.

I have heard that you can put lump charcoal ash in the compost heap, but not ash from charcoal briquettes. Supposedly, there is too much coal in the latter. I don't know about this. It seems that the coal in charcoal briquettes is more like coke, and has most of the sulfur cooked out of it. This is not true with cheap Chinese cooking bricks. They have so much sulfur in them, it really makes the food taste foul. Wood ashes are alkali, and will keep down the odors in the compost heap. I once did a study on this, and any quick lime generated from roasting the calcium carbonate naturally present in the wood can transform the potash into lye, which is a little harsh for the garden. Oddly enough, I have found wood ash water from forge ashes has much lower potency than regular ash water. It may be due to the lower residence time.

Hi monstermetal. That is a great thermometer. It goes higher than the typical thermocouple K probes that I am familiar with. Is it an optical pyrometer?

I have had bad luck with coffee can forges. I think that the problem with them is too little torch for the volume. If you look at successful hand held torch forges, they look more like one or two soft firebricks which are hollowed out. Recently, I was experimenting with forge welding with oxy-propane. I failed. I asked a fellow demonstrating with a torch at a blacksmith meeting for advice, and he told me that he failed with oxy-acetylene Of course, his torch welding was excellent, but this was *forge* welding. I made a little hollowed firebrick forge with a propane torch, and had no trouble forge welding small pieces. Of course, every time I twitched and touched the hot firebrick with the fluxed piece, it would blacken and recede something awful :angry:

Yes, I agree. My favorite political blacksmithing topic is when the San Francisco Chronicle ran an article about that gasoline tanker fire that softened the overpass girders causing them to collapse. The article was subtitled "Blacksmiths Exonerated", since after the collapse of the WTC towers in NY, we were considered kooky when we said that fires fueled by ordinary hydrocarbons could soften steel. It is easy to offend visitors at a demo by talking about this . I guess anything can be politicized these days.

Nice leaf! Keep up the good work. The head of a RR spike makes a decent veining tool. Make sure to dig the vein for the stem very deep and key it in there real good.

Don't worry, I'm not planing to do the test with any (usable) gas left in the cylinder. Gas is too precious to vent . I have two of the old MAPP cylinders left, both from that conference a few years back. The students didn't drain them dry, and there is enough gas in them to do a bit of damage. I don't use them myself because I have a set of really nice hose torches that connect to the refillable cylinder (cheaper ), and an oxy-fuel torch if more heat is necessary. I am curious, however, and there is nothing like an experiment. Just chuck a piece of pipe over the end and give a tug with a scale. If it requires more that 20-30 lbs, call it OK. I hate to say it, but I might trust a blacksmith's experience over a professor's explanation.

Hi. I just saw a post on another forum about a potential hazard associated with trigger start MAPP gas torches. http://www.bernzomaticinjuries.com It is kind of scary. Apparently, the neck of the bottle can break off before the safety notch does, with horrible consequences. If you read the expert witness testimony, there is an MIT professor working for the defense with a huge CV of qualifications. His arguments, however, are kind of meandering and do not inspire confidence. Included in the post are comments from a blacksmith. Short story: he tested it, verified the danger, eliminated it in his torch. End of story. No waffling. I will be very careful about these torches in the future. I lent two of them to a rose workshop for the CBA and thought they were awfully convenient. After one is empty, I think that I will test it, blacksmith style.

I am looking for a way to find the instantaneous maximum pressure on the anvil as a function of hammer impact and material thickness. This is easy to compute for infinite and zero thicknesses, but I was wondering about the middle range.

Someone told me that you can put lump charcoal ashes in a compost heap, but not ashes from a charcoal briquette fire. According to that source, they are as bad as coal ashes. How much bad stuff is in them? The lump charcoal (real wood) works great. Can't comment on the 100% hardwood briquettes, but if they are 100%, they should be better than regular briquettes.

I tried one of these broken bits that a local smith gave to me. He told me that it was similar to an S series steel and had work properties. In my experience, it was not the same at all. I made identical tools out of this and an S-7 bar and let a couple of other smiths have at them. They ruined the tool made out of the bit. So I fixed it and it responded well to a water quench. It also sparked as a 50 point simple carbon steel. Some smiths in a demo shop complained about the people rotating through the shop goofing their hardy. I made one for them out of known S-7 (bought from a reputable supply and spark tested). Years later, it is still fine. I found that it was hard to work by hand, but still faster than grinding. There are spark photos in my gallery. They should be enough for you to figure out what your piece is.

Hi Frank. It does look like the scarf was made on the second shoulder, in the traditional way that you pointed out above. I agree, the other way is much weaker. The tongs still broke at the weld.

That too . I think that is yet another reason to spend time getting the scarf right.

Yes, that is what I was thinking when I saw the break.

Hi. A lot of people complain about forge welded tong reins being a weak point. There is a web site which says that you should not use borax to weld them (unless you are a "hobby" smith), else they will eventually come apart. I always thought that as long as the weld is in the right place and orientation, there is not all that much stress on it, and it is not being peeled, so it should be OK. I have even seen tongs with the reins protruding over an inch past the weld point because the maker just laid two bars together and whacked. These tongs looked like they had served well for decades, even though misaligned. Well, I finally saw some tongs with broken forge welds at a garage sale. I always assumed that the lips would crack and the weld would peel right open. Bad welds seem to have little peel strength. But no, these welds broke in a different way. The metal had a coarse grained fracture right below the lip. So, the weld did not break, it was the base metal. Maybe they were heated for too long, and there was excessive grain growth. Attached is a picture. Note that these tongs were selling for $5 per pair. This is the first time in a long time that I have seen tongs at a sale selling at this low of a price. So I guess that all those allegations are true. You can get tongs for $5 at a garage sale if you look long enough :rolleyes:

Hi. I really like the Harbor Freight sander/polisher. It has a variable speed control and tops out at 3000 rpm. It has the 5/8-11 screw on the end. And best of all, it has that familiar Harbor Freight smell to warn you if you are working it too hard. This helps prevent accidents. (If you have one with a power wire brush, you will not forget it soon )