Machinist Tools
Background

I started to recognize and really pay attention to the world of machinist work and tools near the end of my time as a student at the University of Iowa. The majority of this newfound attention and borderline obsession with precision and precise tooling came from YouTube, with educational and entertaining home shop and machine shop owners alike sharing their work and manufacturing methods in video format.

The event that I remember most influencing my curiosity is a series dedicated to rebuilding and calibrating an old Colchester lathe found in a junk yard. The creators of the series discovered both a twist and six-thou (thousandth of an inch)-deep rut in the ways of the lathe. They used a combination of dial indicators, clever problem-solving methods and granite parallels to generate a map of the flatness error in the lathe ways so that they could either decide to re-grind it or re-scrape it back to flatness.

Prior to this video series, I had never heard of hand scraping, surface plates, parallels, set-up blocks, feeler gauges, spirit levels or test and dial indicators. It opened the door to dozens of other popular machinist YouTube channels. Each dedicates countless hours to sharing their techniques, teaching about the tools that they use and the relevant math, and giving firsthand experience through video in the obstacles that they face daily. Finding and watching the content produced by these channels has allowed me to cram a massive amount of education into a relatively small section of time.

Some of the most educational channels include Oxtoolco who taught me about surface lapping, This Old Tony who operates his home shop and shares useful welding, milling and lathe-turning tips among other things, Abom79 with his industrial lathe and linear shaper, and Clickspring who often works with small clock-related mechanisms. There are plenty more such as AvE, Physics Anonymous who performed the aforementioned lathe rebuild, Matthias Wandel, Alec Steele and Welding Tips and Tricks to name a few, each with their own unique content and delivery methods.

These channels and their projects fueled my interest in precision tooling and manufacturing, which I began pursuing in 2017 when I purchased a tenths-graduation dial indicator. It was the first of many machinist tools that I plan to make use of in the future, but I found great deals online for them, some broken, and took advantage of them. I have had to repair some of the vintage tools I’ve collected, but I don’t mind, because it feels like reviving a small piece of history when I successfully repair a tool. I don’t plan to stop adding to my arsenal of machinist tools any time soon and await the day when I can set up my own home shop in which to use them.

Detailed Description

My first introduction to large precision machinery occurred in 2016 when my Design for Manufacturing class allowed us to use both a manual lathe and mill to make a brass hammer head and cylindrical aluminum handle to match. We were given access to a Hardinge lathe, which I am now slightly familiar with due to YouTube machinist videos, and a Jet mill with a digital readout and stepper-motor-controlled axes. I still own neither a lathe nor a mill of my own and wouldn’t have anywhere to put either if I did, but I am in the process of building a lathe that I designed in Creo Parametric.

The first precision tool that I purchased to begin my collection is a Federal Full jeweled C21, which has a resolution of 0.0001 inches, or a tenth of a thousandth. It got knocked off of a counter during the first week that I owned it though, and it landed vertically on its shaft which formed a small dent in its rack and caused it to bind during use thus rendering it unusable. Though I eventually did form my own spacers to offset the rack to a different operating section while also increasing the total range of the indicator, a replacement C21 was purchased in place of the one that was broken.

Almost immediately after buying the dial indicator, I drove to the SHARS warehouse and picked up an A-grade black granite surface plate and a 12-inch-long 0.0005-inch-graduation spirit level. I was intrigued by the many uses of 1-2-3 blocks, so I ordered myself a precision pair, said to be within a tenth of a thousandth of an inch of the given dimensions in every dimension, within a tenth in parallelism across the surfaces, and within a tenth in perpendicularity measured at the top edge of the surfaces.

The next thing that I added to my growing list of tools is a 0.0001-inch-resolution test indicator also made by federal. At the time, the only model I could find available online had a “small” dial face, where I preferred a larger face to better allow for estimation of the next digit of accuracy when reading the dial. Less than a week after I purchased the first indicator, I found a listing for a broken version of the exact same model, but with a “large” face.

Recently, I pulled both apart and cleaned the grease and grit out of them which was interfering with the springs’ ability to wind and unwind. I had to epoxy the lens onto the rim of the large test indicator since the seller’s images were misleading. They gave the illusion that the lens was properly attached to the rim when in fact the lens that came with the indicator didn’t even seem to match the indicator body that I received, since it didn’t fully fit and was completely detached. Both indicators operate properly now, as usually a broken indicator just needs some careful internal cleaning to revive it.

While the small indicator was the only one that I had in working condition, I combined it with a Brown & Sharpe indicator stand and a precision one-inch diameter G5 ball bearing and used the combination to check the 1-2-3 blocks’ perpendicularity and parallelism. I found that the manufacturer’s claim about their perpendicularity seemed to be accurate, as was the given parallelism value, but the surfaces of the blocks had valleys in them in line with the holes that decreased the block width in each dimension by between four and six tenths, making their flatness values pretty horrible and not within specification.

I acquired a few lapped Arkansas honing stones which I tried using with honing oil to bring down the high spots on the 1-2-3 blocks, but the process was so tedious that a few hours of work only brought one side of one block within specification. I may just live with and be mindful of the flatness errors that they carry when using them for measurements as it seems that bringing them to the specified flatness values using a lapped stone would take far too much time.

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For a few dollars I found a feeler gauge set which, while not very accurate in its blade thicknesses, is still precise in terms of its blades’ parallelism. I could always check the true thickness of its blades using a micrometer and potentially re-scribe the blades with those accurate values. For my coarser and harder honing needs I decided to pick up a 400:1000-grit two-sided diamond honing plate. However, I quickly noticed that it had large error in its flatness which I checked for good measure on my surface plate, finding a diagonal bend which creates a four thou gap between the surface plate and one corner when the other three corners are in contact with the plate. Realistically, it can still be used for most projects that I would need it for, but the lack of precision in the manufacturing of honing tools frustrates me.

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I was given a third dial indicator as a gift in 2017 with a one-inch range and 0.0005-inch resolution. Similarly, in 2018, I was given a very old Lufkin V32X test indicator which I had wanted for nearly a year. It was manufactured such that the front dial face had only a four-thou range packed into one revolution of the dial rather than eight though which most other indicators have. This means that values are easier to read by a factor of two on the Lufkin model making it proportionally easier to predict the next digit of accuracy in a measurement if necessary. The high standard of craftsmanship in Lufkin indicators was also a very attractive factor.

Though the model that I was given has no mounting dovetail, it does have a stem which should work fine for mounting it to indicator stands, and it features a secondary dial to count the number of revolutions made by the primary dial. It is so named the V32X, as I discovered, because its total range is 32 thou which takes place in eight revolutions of the primary dial, and it has a large face, designating it an “X” model. I also prefer the longer lever that it utilizes to the short levers found on my Federal brand indicators and their small-ball tips.

Sadly, the seller of the Lufkin indicator was also misleading, and the person who purchased it to give to me had no idea that it was broken. I spent nearly a full day worth of accumulated time working to replacing the internal cantilever spring with a section from a coil spring that I ground down to the correct diameter. The original spring had broken off and been removed by the previous owner, leaving behind a tiny protruding stem of what was originally there.

I first attempted to use paper clip sections to form a replacement spring, but they were too ductile, then I tried to use sewing-needle sections which were too brittle to allow me to bend the necessary hook into their ends, and finally I settled on real spring steel from a large coil spring. Though it seemed like I would not be able to get my cantilever spring replacement to stay in place, I was eventually able to use a fine piercing blade on a jewelry saw, which I purchased specifically for the purpose of repairing the indicator, to cut the receiving slot to be slightly deeper. Once the spring was in place, I lightly hammered a sharp piece of high-speed steel acting as a center-punch to roll the surrounding steel edges over the spring and hold it in place, as was the mounting method used to mount the original spring. I eventually fine-tuned the angle of the spring and got the indicator to function properly in both directions as it was intended to be used.

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Rather than the traditional design of ruby bearings constraining all of its axes, the Lufkin indicator used four ball bearings to support the main internal lever and spur gear. One of them released its five balls while I was working on repairing the indicator due to the wall of one of the bearings having been damaged by the previous owner. It took a large number of magnets and quite a lot of time to recover the balls from my carpet as they are each 0.7 millimeters in diameter. Once I got them all back into the bearing housing, it functioned properly as a bearing again, and as long as the indicator is closed up, the balls are not capable of escaping.

For a few years, I was able to get away with taking fairly accurate measurements with a basic set of vernier calipers that I had purchased on eBay. I knew, though, that if I wanted to take measurements with precision in the ten-thousandth of an inch range, I would need to obtain a micrometer set. I first acquired a mechanically-digital one-inch micrometer with a Vernier scale indicating tenths, carbide tips and a ratchet knob, then moved on to purchase a cheap, very similar model with no digital readout.

To cover more of the remaining measurement range, I purchased an old set of Tubular micrometers in an eBay listing after reading an extremely long article covering hundreds of vintage micrometers and their features, their manufacturers and the general quality of their products. The set contained three micrometers, a 1-2-inch, 2-3-inch and 3-4-inch, which had not been officially calibrated since 1982. I calibrated them myself using a precision G5 ball bearing and by carefully repeating measurements in the same locations on my 1-2-3 blocks, stepping up the indicators, and adjusting them slightly each time.

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The final true precision instrument that I obtained is a set of Starrett adjustable parallels, numbers 154-A through 154-F. I acquired these in late 2018 as a gift and cleaned the rust off of them, as they had been used before coming into my ownership. I measured them all on my surface plate for parallelism and found that the largest parallel, the 154-F, has the worst error of the six parallels in the set when it’s fully extended, reaching a six-thou deviation from parallel. Every other parallel in the set seemed to exhibit one thou or less error. With their age and the nature of adjustable instruments like these, less than one-thou error is very nice to see, so I can live with the other parallels remaining the way they are. I may test the large parallel again to ensure that its error really is as bad as it looks, then try to regrind it if the error is in the parallelism of its surfaces rather than curvature in its tracks.

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I also have other small, less significant tools, some of which can be considered precision, some that are just useful to have around. I was given a large Swiss Army multitool as a gift many years ago by my uncle which I use almost daily. I found that working with small electronics often requires tweezers, so I purchased an anti-static set of differently shaped tweezers to make life easier when removing small screws and maneuvering circuit components for soldering.

Although it doesn’t perfectly fit within the category of machinist tools, a digital multimeter is often a useful tool to have available in any machinery setting. They can be used to troubleshoot issues in machine circuitry or test to ensure that objects are properly grounded to prevent injury. I personally use mine quite often for circuit design and testing when working with Arduino and other electrical systems to check that my connections are solid, to ensure that circuit paths are properly isolated and to verify resistance and voltage values. I recently received both a high-amperage inductance-based current meter and a Mooshimeter ohmmeter to mess around with. The current meter uses a loop and hall effect sensor to determine current flow due to the magnetic field strength induced by its flow and can be very useful in testing high-current systems like my arc welder and metal melter. The Mooshimeter is incapable of reading currents higher than 10 amps without damaging its electronics, but it is instead designed to send its readings remotely to a Bluetooth device to be read and potentially exported for later analysis.

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Many of the YouTube channels focused around machining tend to reference Machinery’s Handbooks, of which there are 30 editions, which Wikipedia rightly calls the “bible of the metalworking industries”. I obtained a copy of the 11th edition of the book which was published in 1943 and contains a plethora of machine-related terms, definitions, techniques and standards. Thus far I have read the majority of its section covering gears and industrial gear-production standards and methods. The YouTube channels that I frequent reference the book for everything from material properties to gear-tooth-forming depth-of-cut and have made it a habit to check the book before the internet, mostly, I believe, to preserve some of machining’s elegant antiquity. I love how much useful information is packed into this book and, despite the simplicity of finding answers online, I plan to try and use this book when I operate in my own home machine shop whenever possible to make the experience more genuine and stick to tradition.

I often found that I didn’t have the drill bit size that I needed available, so I purchased a set of 29 molybdenum-coated high-speed steel drill bits ranging from 1/16 to 1/2 inches incremented by 64ths of an inch. I have found that they are very precisely ground, and the Huot drill index case that they came with makes protecting, organizing and accessing them very easy. I purchased the set from Drill Hog for 50 dollars on eBay mostly because it came with a lifetime replacement warranty allowing the owner to ship back any broken bits to be replaced through mail at no charge.

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To compliment my molybdenum bits, I purchased a cheap set of cobalt-coated step-drill bits which I used to drill 3/4-inch holes into the top section of wood on my nixie tube clock. Without the step bits I wouldn’t have had any precise method of shaping those holes to the desired diameter, so they’ve really come in handy. I also have a small, circular plane level originally used in a spectrometer, a set of uncommon screwdriver bits, some metalworking files, a fine-cone butane pencil torch and some cheap synthetic-diamond Dremel bits. It will be great to finally own a lathe and mill as part of my tool arsenal, so I can begin to work on real precision projects without wasting unrealistic amounts of time doing precise work by hand.

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