History About Carlo Donà Tools Contact	History The early years In 1994 I purchased an affordable metal lathe, partly due to a long standing interest in robotics and partly with the thought in mind to make some custom punties for friends at Pratt Fine Arts center where I was working as a glass tech at the time. Lino Tagliapietra had just completed his first summer workshop and had a collection of Italian pipes and punties which clearly played an essential role in making the delicate work that he produced that summer. Most of the local goblet makers I knew purchased their pipes and punties either from Italy or other European tool makers. At the time it was possible to purchase small pipes in the US but the sizes were either limited or awkward and the material used was often stainless steel. Originally I set out to make a set of tools that came as close as possible to copying the italian tools that I saw Lino, Dante Marioni, or Josiah McElhaney working with. It seemed that with the proper tools I could solve a critical supply issue for local glass blowers who were interested in goblet making. Of course things are never that simple. The first big problem I encountered was finding materials. The very first glass blowing tool that was made at Spiral Arts was a 10mm punty. The steel was ordered from a company in Illinois who we managed to get to drop their minimum purchase and sell us a single piece of material cut to size. The bodies of the Italian pipes were metric and the type of steel they used wasn't obvious. While I was able to approximate the metric sizes, it was almost always impossible to find exact matches. In materials we were limited to either a mild steel seamless tubing or 4130(cromoly) aircraft tubing. Some of our first experiments were with the 4130 tubing and 6" long stainless heads. The 4130 warped badly at the weld and cracked when it was overheated and quenched. It would be nearly 8 years before I would return to 4130 and successfully build a great series of pipes with 11" of stainless in the heads. The wrong alloy Many of our early pipes had heads made from 316 stainless steel, which seemed to work great and was readily available at our local distributor. We made pipes with these heads for nearly 2 years before problems began to appear. It was when we learned that all the pipes we had sold only 6 months before to one of the biggest hot shops in Seattle were all sitting in the corner because the heads had begun to fall apart. We discovered that the 316 quickly developed lots of tiny cracks - carbon segregation - and would begin to throw scale if they were aggressively cooled. What we learned was that the 316 was absorbing carbon from the flames of the pipe warmer much faster than the higher temperature alloys. The carbon would then separate from the nickel and chrome in the metal and form a matrix of cracks and a coating of scale on the inside of the head. Now all of our pipe and punty heads are made from 310 or 309, high temperature alloys. Scale from within For the first 5 years of making pipes we had an unusual problem with scale, a black crusty material that comes from the inside of the pipe and appears on the inner surface of a blown bubble. We were hearing from a couple of customers that they had problems with brand new pipes spitting scale. We would get this complaint every year or so, and we thought it might be something that came out of the pipe after fabrication, a steel chip or dust. Finally someone brought over a sample of some cups they had made with pipes that we had sold them the week before. The glass was clearly specked with a magnetic carbon, indicating that the scale was coming from the steel body and not the head. Cutting the pipes open revealed nothing. We replaced the tools and shortly thereafter received a despairing call, the scale was still there. It was then that the rash decision was made to buy a very expensive "boroscope". A boroscope is a long narrow tube with optics and a light that allows you to look deep inside of things. The boroscope gave a magnified image of the sidewalls of the pipe and the head. What we discovered was that a tiny band of scale was forming just above the weld between the head and the pipe body. To pop free, the scale needed a little moisture and heat to turn it to steam. Much to my horror I discovered I had been selling pipes that came with scale. The problem fortunately turned out to be easily solved, we changed our weld settings and began purging the inside of the pipes with argon during welding which prevents the steel from oxidizing and forming scale. We now make it a regular practice to inspect the inside welds of our pipes with the boroscope before they get sent out. Heads falling off In 1999 a very smooth and seemingly expert salesman from a local welding store was in the shop looking at our setup and he mentioned that he had a new welder that we should check out, the latest generation of pulsed mig welders. He assured us it would be possible to cut our weld time by 1/2 and greatly increase the quality of our welds. Somehow I fell for the pitch a bought an ESAB pulsed Mig. Indeed the welding was extremely fast, and the welder made a cool mosquito like sound. We were able to weld a pile of pipes together in a fraction of the time it was taking with the old TIG welder. It was after about a week when we got a call from a "very important" glass blower who was in the middle of a demonstration for a group of collectors when the head of his new pipe fell off. Looking back, it would have been really funny to see it happen but at the time we were absolutely horrified. Within a couple of days we were getting calls from people on the other side of the country asking "What's up with the heads on your pipes falling off?", a testament to the efficiency of the glass community's gossip circuit. We discovered we could knock the head of a pipe welded with this fancy new welder by simply giving it a hard blow with a hammer. We had put together about 30 pipes nearly all of which we were able to track down and fix. It's been the only time we've had problems with heads falling off since. Filthy plastic mouthpieces When I started making pipes, I looked at the tools people like Lino and Dante were using. Every glass blower who's skills I admired seemed to be using all metal pipes, usually from Italy. The mouthpieces on those pipes were either steel or brass, and occasionally stainless. The first pipe I built was going to have a steel mouthpiece. Lino had described to me how to forge the mouthpiece and it turned out to be rather simple. For a brief time we experimented with brass, but soon switched to forged steel. The first 2000 pipes we manufactured, almost all the mouthpieces were forged steel. What we discovered was that this put us at a competitive disadvantage, because most glassblowers had pipes with plastic mouthpieces and were not about to switch. There is a perception that plastic is a preferable material, reducing the threat of chipped teeth, easy to clean, easier to replace. While this reasoning is debatable, it turns out to be much more productive to just make pipes with plastic mouthpieces. So, we decided to make them. Our first plastic mouthpieces were made by turning the mouthpiece, fitting it onto the pipe, and then sanding the pipe and the mouthpiece to get a nice finish. We were using the finest sandpaper available on the plastic, a 1200 grit emery cloth, and it looked great. Once again we discovered the errors of our method the hard way. We were visiting a shop that had recently bought a pipe to sample, but had never put in an order for the quantity they said they were shopping for. We discovered that they had just purchased a complete set of our competitor's pipes, and there in the pipe rack was our pipe, with a dark gray plastic mouthpiece. It turned out that the process of sanding was leaving microscopic scratches that were statically charged and were literally pulling the dust out of the room. The mouthpiece could be cleaned, but the scratches held the dirt in, and the results were mouthpieces that looked horrible. We now polish all our plastic mouthpieces with a plastic polish that leaves the surface bright, clean and not statically charged! Grips that slip There are basically two kinds of material that work well for grips, a spongy black vinyl rubber, and radiator hose. The spongy grip is by far the most popular, although it only works well for body sizes 3/4" and under. The problem is slippage. Since the vinyl rubber has no internal structure, when it is torqued, it wants to slip on the pipe, the larger the pipe the more likely you are to actually be torquing the pipe and the spongy grips simply don't work well. The radiator hose has a fiber casing inside the rubber and is very durable and resistant to torquing. Quality radiator hose isn't made in sizes less than 3/4", leaving one with only the spongy grip option. There are two methods for installing grips; with air or with double stick tape. The spongy grips are installed using compressed air. The grip is forced over the mouthpiece and then air is blown in around it while it's pressed onto the pipe body. It goes on very quickly, and the friction between the grip and the pipe body is good enough to keep it from twisting. The radiator hose grip is installed by first putting a layer of 3M double stick tape on the pipe, spraying a lube on it and then pushing a heated grip on with a press. Stainless sections and scale in big pipes In the early days, we would occasionally get complaints about scaling in our larger pipes (bodies 3/4" +), perhaps one in 40. It seemed that the source of the scale was overheating. When we would get the pipes back it looked like they had been overheated by reaching too deeply into the glory hole. We simply fixed them and didn't give it much thought. At some point we started to cut heads in half, primarily to figure out the effectiveness of various pipe-cleaning techniques, (little brushes really don't do anything). What we discovered was that the larger steel pipes all were scaling near the weld when they got overheated, but the stainless wasn't. The next time we got a pipe back with scale, instead of just pulling off the head, reaming and rewelding, we put a 4" section of heavy walled stainless before the head. Realizing this was probably a good idea, we built some big lightweight pipes - which normally would have scaled - and had some people who were doing murrini work brutalize them with overheating. The scaling problem was nearly eliminated. We now put a stainless section in all the steel bodied pipes with diameters larger than ¾". It's been 4 years since we've had any problems with "young" pipes and scalling. Improved head shapes - The tulip head The tapered shape of pipe heads has been around for ever. It's just a simple straight taper from the body diameter to the head diameter. The primary reason for this is that it's always been simple to manufacture. The difference in complexity between turning a shape with curves and a shape with straight lines in a manual lathe is huge. It's safe to say that unless there would be an extremely compelling case for making a curved head shape, there is no way it would get done the old way. Now that we have CNC lathes, the difference between cutting curves and straight lines is essentially 0. There is no difference in machining time and only a few minutes of difference in the initial programming. Given this, we thought it would be interesting to see if there is a noticeable difference between shaped heads and straight heads. At this point the difference is mainly esthetic. Some people who notice it say that indeed, it works better, perhaps because there is not an abrupt angle at the edge of the head. Even though it's a subtle detail, it is something I think improves not only the function of the tool, but also gives it a unique style. The next time you pick up a Spiral Arts standard workhorse pipe, make note of the shape of the head.
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