Friday, July 26, 2013

Gloves in the machine shop

Well somehow I have managed to post a little over one hundred articles on this blog. I just want to take a second to thank all the readers that follow the blog, and especially those who participate in it with their comments. The feedback and interaction is what stimulates me to carry on with the blog project. Thanks again for your support.

The subject of this post has the potential to be somewhat controversial. What I want to talk about is wearing gloves in the machine shop. Many of you out there may have noticed that in some of the blog pictures or on my YouTube videos I am wearing gloves while operating machinery. I have received several comments asking about this practice so I thought I would explain it in more detail.

When I was an apprentice I got yelled at a few times for wearing gloves in a situation where it probably wasn't a great idea. Those old loud codgers were just trying to protect me which I thank them for. The typical metalworking shop is loaded with machinery just waiting to bite the unwary. They were doing their job and protecting me like one of their kids.

Not that long ago I did a shop study. The subject of the study was injuries to my hands while working in the shop. I actually called them insults but that's beside the point. As many of you well know in the course of working in a machine or metal working shop you expect a certain number of minor hand insults and dings as part of the job. As part of my study I recorded anything that happened to my hands during the course of working in the shop.

After some time had elapsed logging entries I reviewed the specifics of each insult. The object was to filter them into several groups. The first group was injuries or insults that would have been prevented by wearing some kind of a hand protection. The second group was insults that would have been greatly minimized by wearing gloves. And the final group were injuries that gloves would have not made any difference.

I admit this was a limited study conducted by a minor klutz. I will tell you there were no insults that gloves would not have made a difference. In other words everything that happened to me during the study period would have been totally prevented or greatly minimized. Also during this period there were zero close calls because of wearing the gloves.

Now before you jump down my throat and say how dumb this sounds lets talk about it. I've been working in metalworking shops for forty years now. I can say that I've done some pretty good dings to my hands over the years but they still have all the fingers and everything works fine. Also things have changed in that forty years.

When I first started in metalworking there were not a huge variety of glove options readily available. Thanks to manufacturing technology we now have a huge number of choices for personal hand protection for a large cross section of specialized  hazards. Hand injuries are quite common and some smart business people realized the huge potential market there was for hand PPE. In the old days you just used your leather gloves for everything unless it was cleaning the shop toilet. For that you shared a pair of somebodies hand me down dish washing gloves. There was a fifty fifty chance of a hole or leak in them to add to the fun.

So where I'm heading with all this is my opinion is the risks of wearing gloves around many types of machinery are very manageable.  Just having the right gloves on in the shop has a huge potential in reducing hand injuries and insults in the metalworking industry.

I have been experimenting with some gloves in the machine shop for more than a year now. I don't always wear them but I try to do it regularly and note the situations where my spidey sense tells me its a bad idea (like the belt sander) as well as when I note a positive effect like my hands don't cramp as easily from pinching small parts while de-burring. The gloves I have zeroed in on have some gripping abilities that enhance  your hand grip and allow you to use less pressure or apply more pressure when needed.

The gloves I like and have settled on for most work are the Maxiflex Ultimate. These are a close fitting precision dry handling glove coated with nitrile foam. The dexterity is so good you can pick your scale off the bench or floor with them on. Some Airgas welding supply shops carry them and S&S safety solutions in Martinez CA stocks them.

The small injuries that occur most frequently are things like getting cut on a burr or chip, bumping a sharp tool  bit or insert while handling a part in the machine, dumping scrap in the bin, unfolding a band saw blade etc. All preventable with gloves. As machinists and metalworkers we very rarely get cut from any rotating member on the machine. Those old guys yelling at us did their job well on that count. We get dinged by bumping into things, reaching for things, in other words all the other things besides the rotating machinery.
Nobody blinks an eye when a chainsaw operator puts on a pair of gloves. Why do we get so nervous when a machinist operates a milling machine with a gloves on? Neither person is touching the moving cutting edge right? There are dozens of industry examples of people wearing hand protection while in close proximity to rotating machine parts. The general shop rule is to never directly touch a moving surface, blade or machine member with your hand. Well if you adhere to this guideline when wearing gloves you will stay relatively safe.
Now there are lots and lots of things I would never do with gloves on in a million years. But after forty years experience I can spot these situations with an excellent success rate. Most of that comes from having made many of the mistakes that hurt and learning from them.  So if you are a beginner then I suggest you proceed with caution. If something bit you before then pay attention.

A funny side story about fingers. I had a welding student many years ago that came to class with one of his fingers swathed as only the medical industry can swathe something. When we asked him what happened his story sent shivers down my spine.

This particular student worked in a structural steel shop as a helper of some sort. He was helping rig a large I beam for rolling over with the crane. I guess the sling was offset from the center of gravity so the beam would  roll when they lifted it. Well he somehow managed to get his finger between the table and the beam. The thing that gives me the willies was how he described the damage to his finger.

When he related the story to us I asked the question, Ouch, that sounds bad. What happened to your finger? He paused for a second thinking about it and said, "Well have you ever stepped on a hot dog?" Apparently the end of his finger burst out much like a stepped on hot dog. Youch! I can't eat a hot dog now without thinking of that story.

Now that is an example of an event that gloves would not have made any difference except getting less blood  on the workbench.

The gloves I prefer for machine work I discovered by accident. We were in the process of moving and between my wife and myself must have 200 cubic feet of books that had to be moved. Now if you have moved you know not to load book boxes very heavy or else you kill yourself. What happened was my hands naturally dried out handling dozens of boxes. Take a look at the UPS drivers hands for a clue as to what happens when you handle cardboard boxes all day long.

After work one day we were loading a truckload of boxes to take over to the new place. I had a used pair of these gloves that I forgot to take out of my coat pocket. On a whim I put them on just to keep my hands from going UPS. I noticed the advantage immediately. The gripping force to hold the box securely dropped to roughly half. It was like spider man gloves for boxes. After having this dramatic example I started experimenting with the gloves for all kinds of things, like working in the metal working shop.

So here we are fast forward. My experience with wearing gloves in the shop has been manageable, positive and hand healthy. Here are some of the positive benefits I have seen from wearing gloves in the shop.

  • Lower gripping force required to hold items.
  • I can tighten the drill chuck significantly tighter by hand wearing these particular gloves.
  • I can carry more weight in each hand than I could before.
  • Hands stay warmer and cramp less without the sweating.
  • Hands stay cleaner in general. Nice when you have to run to the office and do something.
  • Cuts and nicks are reduced to near zero
  • Vibration isolation

The vibration isolation properties are well worth it. If I have any amount of jitterbugging to do my fingers end up feeling like their electrified for the rest of the day. Wearing gloves reduces this to nothing.

This article is just my opinion and observations from actual shop testing. Its okay if you disagree. I'm not forcing anybody to drink my flavor of Kool-aid. Gloves in the shop is not right for everybody. So in closing I suggest you conduct your own test and see if you find any similarities with my observations. Report back your own findings and opinions and please be careful when testing and don't do any of the following things,

Belt sand. Any converging gaps that the tip of the glove could get sucked into are bad. Plate rolls and moving chains and sprockets fall into this category.

Grind tiny tool bits on the bench grinder.

Don't polish on the lathe by gripping the paper directly to the work wearing gloves.

Don't stick your finger in a rotating bore to check the finish. In general don't touch anything rotating. But that's already a standing rule.

These gloves are completely useless for hot stuff.

Thanks for looking.

Tom Lipton

Tuesday, July 9, 2013

Double Curved Handwheels

There is something lacking in many modern mechanical components. The plain utilitarian aspect is partly driven by cost considerations and manufacturing optimization practices. Why do we fall in love with old machinery and equipment? Many old machines are visually pleasing as if the designers really cared that the visual impact of the machine was an attribute worth investing in. Sadly most of the demise of art in machinery is cost and profit driven. We can all appreciate nice looking machines but are voting is generally dictated by our checkbooks.

I was talking to an engineer friend of mine on this very subject and he had a pretty good line of reasoning worth sharing. Before the invention of automatic machine tools many machine parts were cast in steel or iron. All of these parts had to have foundry patterns made for them at some point. There is a  big fundamental difference in the manufacture of something like a machine hand wheel that is cast and one that is machined. The hand wheel is just a simple example of the potential for adding some pleasing aesthetics to an otherwise mundane part.

When a part is cast the pattenmaker makes the pattern one time. This one time effort yields thousands of parts with all the features and embellishments the patternmaker puts in. The fundamental effort to produce the part is the same for all the parts cast from that pattern. Whatever the extra cost for the time the patternmaker spent to make the part beautiful is spread over the cost of the thousands of parts that follow.

The modernization of some of these manufacturing processes has eliminated most of this decorative aesthetic in machine parts. Modern generally means spartan, or clean crisp simplified lines. Is it better? I like the modern style when its well executed with thought behind it throughout the article or machine.

But what I wanted to talk about in this article is something that old time machinery buffs all over can agree on. Who doesn't like a nice old time cast iron hand wheel or pulley? In particular one with double curved spokes. There is something cool about the curved arms and legs of a simple article like a wheel that give it life at a basic level.
A simple valve handle with double curved spokes. It looks poised to turn all by itself. All the operator has to do is give it a little nudge.
 These pulleys were at a recent flea market for $400 each when I passed them in the morning. When I walked by a couple of hours later they were both gone. Somebody made something cool out of them.
And we finally come to the actual subject of the article. This is a handwheel for a fine arts etching press. The hand wheel is the signature part of a high end etching press. The large wheel diameter gives the operator fine control of the printing process with low human power input. Most presses have some kind of gear reduction to further reduce the force on the operator. A few presses have hand wheels in the five foot diameter range.
About six years ago I built a small etching press for my wife to print small etching plates with. It was really a stop gap for building her a larger press. Well the time has come to get moving on the big project for real. I have laid the groundwork for building the press in my home shop. A few items like the lathe were selected on their ability to produce the needed parts for the machine. A crane and forklift were added for good measure and spine health. I figured I might as well start with some of the more complicated bits of the machine. The hand wheel and drive system are first on the list.

I wrote a blog article and posted a YouTube video of the heart of the system. The press I'm currently working on will be larger than the French American Tool press in the picture above with a much more interesting handwheel. The current design projections put the final weight around 3500 lbs to put the project in perspective.
Here is the layout of the handwheel in Solidworks. My goal was to try to duplicate the graceful tapering curves like we see in old cast iron handwheels. I set the Solidworks sketch up and drove some of the proportions with equations to allow me to create handwheels of almost any diameter by changing one number. The layout is interesting in how the arc tangencies are created. If folks are interested I will do a separate article describing how to do it. Post a comment if this is something you would like to see.
Here is the Solidworks model of the handwheel sub assembly and Wabble drive for the press. You can see the motif of the press is the curved spokes. The arms of the Wabble output follow the same layout.
Here is the beginnings of the handwheel for the Ox tool etching press from the layout above. Looks kinda dinky right?
For those of you that have been following the steady rest built on YouTube you can get a sense of scale now. The handwheel is four feet in diameter and and inch and a half thick. The spokes are five eighths thick. When I had the handwheel sections burned out by Nowell Steel in Antioch. I threw in the steady rest profile while they were cutting inch and a half plate. I need the steady rest to machine the large solid rolls for the press. The steady rest that came with the lathe can only handle seven point eight inches in diameter so I had to build a larger one.
I was worried about the open C shape moving around when they oxy fuel burned the profile so I had it cut larger to allow me to machine the profile accurately. I don't want the rim to run out much so it will have to be carefully put together. Here I am preparing the blank for machining. I weld it to a backing bar that is then clamped in the vise allowing me full access around the profile with a tool.
Even in steel not much weld is required. You just have to get it in the right place and not cut it away!
Here is one segment after profiling. I used a one inch diameter high speed cobalt fine pitch roughing end mill made by YG tools that I cant say enough good things about. Two passes three quarters deep and approximately a quarter inch on the periphery. Three hundred fifty rpm at six inches per minute feedrate. One tool removed maybe forty pounds of material and is still fresh as a daisy.
Here is the finish left by the end mill. I have cut off the backing bar and smoothed the welds. Eventually the rim will be rounded off so it feels better in the hand. These joints will be weld prepped and then blended for an invisible seam.
In this shot you see the wood sample I gave the "customer" for approval of grip size and rounding. I have some serious grinding in my not too distant future.
All five segments sitting together on the weld table. It measures right on the forty eight inches. There will be notches cut at the rim joints to insert the spokes to make a rabbet joint. Next will be an assembly fixture to make sure the segments are aligned in as good a circle as they can be for welding.

Eyeballing the center hub material for the handwheel at one of my favorite scrap yards Bataeff Salvage in Santa Rosa.

Thanks for looking.

Tuesday, July 2, 2013

Tour of the Dial Indicator

After thirty years I think I have my dial indicators finally dialed in so to speak. Its not that it took that long but rather a slow series of optimizations and additions that make it feel right, at least until something better comes along. I have quite a collection of dial and test indicators in my tool collection. The very first indicator I bought was a Starrett one inch travel dial indicator. I remember well that it was expensive. To add insult to that you can currently buy a pretty good "Tecklock" or "Aerospace" for less than twenty dollars and it will probably come with its own magnetic base to boot. How these can be made for this price and shipped here is beyond me. A life lesson is don't compete making commodity items. Stick to unique and innovative devices and technologies. There is always somebody out there willing to work cheaper than you.

Well I still have that Starrett indicator, and because I paid in a painful to my pocket way it gets treated with the respect commensurate with its price. As a counterpoint I have probably broken or damaged more than one of the offshore brands during the same time period partly because I didn't need to be careful because of the price.
The use of this indicator has morphed over the years I've owned it. In the olden days I used to use this one and a twin brother with two inches of travel a fair amount on the lathe to keep track of Z positions. Now it gets used mostly to monitor weldment movement or perhaps the true X component of the compound rest when threading with the rest set at thirty degrees. The other place it sees some use is when I need to use the tailstock with fine depth control for some reason. With the mighty magnet I can snap it on the side of the tailstock and add a kantwist clamp to the tailstock quill as a rest for the tip. Presto instant tailstock ARO. (Analog Read out)
The next indicator I bought way back when was the classic test indicator. For many years I used this Starrett last word as my primary test indicator everywhere in the shop.
If this is the only test indicator you know then fine. Its a decent well priced test indicator with a large and long     following. I didn't realize how much better a test indicator could be for a long time. My first inkling was when I had occasion to borrow a workmates test indicator for some long forgotten reason. Sorry to say that my last word is now relegated to certain lathe jobs where small is right. I keep it on a small pot magnet so I can snap it on to the Aloris tool post quickly. Other than that It doesn't see much use.
The small pot magnet makes it really quick to get in the machine. Also the last word is one of the more rugged test indicators. It will take the vibration from tapping a part into alignment with a hammer without complaining.
 The difference in the action of test indicators is marked. Visually the Alina and the last word are virtual copies of one another. I don't know which came first, the chicken or the egg but the Swiss interpretation is superior. I quickly added an Alina to my growing stable of test clocks. The one in the picture above stays setup for quick insertion into the height gage. One advantage to having more than a handful of indicators around is the savings in time locating and connecting all the diabolical jointed accessories needed to adapt the indicators to each specialized use.
I sometimes get the feeling that all the indicator manufacturers didn't talk to each other very much. At least the AGD stepped up and (American Gage Division) set some useful standards for dial indicators. I leave a few indicators setup for each of the most common applications in the shop. Over the course of a year that might be a significant amount of changeover time saved. At least that's my excuse when I see another one I want.
Another indicator I have been using more lately since the four jaw chuck was mounted for a long period of time is the old standard issue back plunger type. The upper indicator is a Starrett button back, but Lufkin, and Mitutoyo also make a nice one. I like it because it has a no messing around contact spring in it and .200 (5mm) travel. The large diameter button contact point doesn't see every little imperfection in rough stock like a fine tipped test indicator. It rules the roost for tramming the milling machine head as the button glides over the tee slots like they aren't even there.
Once I discovered Alina test indicators I was keen to try some other models from the same maker. This K-24 became my defacto go to test indicator for many years. It has a crisp action and never seems to get sluggish or gummy. It has the added advantage of the small dovetail along two surfaces on the body so you can use a variety of clamping options. I still use the heck out of this one. In particular when I have the chuck in the mill and a small feature to probe. The ball joint is snug and it stays put when I twist the bezel to zero the dial.
Now we come to the nirvana of test indicators. If you haven't test driven one of these then you shouldn't unless you feel like spending $200+. The Interapid has some distinct advantages over some of the other indicators that I have shown. Two of the best features are the long range of movement, .060 (1.5mm) and no  shift lever to go from one direction to the other. The action is like polished glass and as smooth as silk. About the only thing I can find fault with is the placement of the alternate mounting dovetails. For most of the time I leave this indicator set up in an Indicol holder. The holder allows me to sweep something in the mill without removing the tool. It also happens to fit on top of the Aloris toolpost as an alert You Tuber noticed the other day.
A simple trick I learned from a workmate not that many years ago was a simple way to position the indicator using the Indicol holder in the milling machine that saves time and headaches.
For maybe a thousand years I would just throw the Indicol holder and indicator on the spindle and indicate away. The only problem is when you sweep around the back you are bobbing and weaving to see the dial face that's hidden from view.
I've seen some guys use a mirror for this situation. I was too lazy to grab a mirror so I just did the bob and weave. Well one day I walk up to talk to this particular guy (Manny) and causally look at his setup. I mutter under my breath, crap. Manny asked me what was wrong? Oh nothing I replied, I just realized how lame I am. Crap I had even bought a vertical model of the Interapid indicator to "help" solve my problem. Now don't laugh too hard at me at least I can still learn a new trick once in a while. This is why I always say, keep your mouth shut and your eyes open.
Okay its pretty obvious when you see it right. The dial is facing up for the entire sweep,. I felt like a dunce for not figuring it out on my own.

The only other thing I think is worth mentioning is about magnetic bases. For many years I have used a Starrett double jointed rod type mag base. It has two knobs that have to be secured to lock the indicator in the desired position. Once again if this is all you know then everything is fine. The solid rod type is better than the ball jointed snake like holder that uses an internal cable to stiffen the ball segments. Great idea, but not quite superb execution.

When you have gotten used to riding a Honda for many years everything is hunky dory. Well when you hear a  Ducati in the parking lot you always look. And one day you finally walk over for a closer look. Well now you have to have one.
Somebody let me try their Noga indicator stand. Immediately you feel the advantage. Its silky smooth and locks in any contorted position with a single knob which is just what you want with an indicator. I bought one  straight away. In fact I like it so much I recently splurged and bought the little brother to my original. These holders can handle 3/8 (9.5mm) shanks and the test indicator dovetails without any loose adapters!

Here is the last indicator I want to show you. I saw this at a flea market and had to have it just for the USSR on the dial. I don't use it much since its metric. This thing is built like a Russian T-34 tank.  I often think about  machine tools and instruments from the former Soviet Union. They had a high level of technical prowess and manufacturing ability. Where are all the machines and equipment? I guess Russian machine tools and hardware is more readily available in Europe. We rarely see anything here in the United states. That was part of the appeal of this indicator. I tell people it came from a T-34 tank factory in the Ural mountains. I don't think its true but it sure makes a better story.

Thanks for looking.