Average Reviews:
(More customer reviews)The author's stated purpose in writing this book was to provide a back to basics introduction to machining using small manual machines in a one-of-kind parts and prototyping environment. The author succeeds admirably in meeting his stated purpose. It should be noted that this is a practical treatment giving specific step-by-step procedures needed to create a particular feature using a particular machine tool. Furthermore, it must be kept in mind that what is cost-effective in an industrial setting when production runs are in the thousands or tens of thousands may not be so in a prototyping environment. Mr. Marlow does a great job of concentrating on procedures that can be cost-effective in a one-off environment.
Two notable features of the book in general merit special comment. First, the book is presented in a question and answer format. While this may seem unusual at first, it actually serves the very useful purpose of easily enabling the reader to locate and find information pertinent to a specific machining question. Second, the book uses plentiful line drawings that are absolutely superb. In comparison to the usual photographs, the line drawings used here have one gigantic advantage. Namely, photographs inevitably wind up blurring and obscuring details, some of which may be highly significant. In contrast, the line drawings in this book are models of clarity, usefully illustrating all relevant details. I frankly consider the line drawings in this book to be the best I have ever seen, and they are a major reason for the usefulness of the book.
The first four chapters of the book contain basic introductory material on measurement tools, basic hand tools, filing, sawing, grinding reaming, broaching, and lapping. This is all good, solid, useful stuff. The discussion on broaching, for example, is the best introductory treatment of this I have ever seen. Next, there is a chapter on drilling operations followed by a chapter on threads and threading using taps and dies. Although not encyclopedic in its coverage of various thread standards, the basics are covered thoroughly and again, it must be mentioned that the author uses superb line drawings to convey meaning.
Following the discussion of threading, there are chapters on turning and milling operations in which the author discusses a range of machines representative of those that might be found in a home workshop or a small prototyping operation. In the milling section, for example, Mr. Marlow discusses both the Sherline tabletop mini mill and the Bridgeport. A feature of interest is that the author does not discuss the ubiquitous (and to some, infamous!) mill/drill. I was particularly impressed with the thoroughness of his instructions for operating the Bridgeport mill, and I couldn't help but think that this chapter of the book would be invaluable to a home shop machinist purchasing a used Bridgeport. More than just an instruction manual for the Bridgeport, the book also provides general procedures for producing specific features that translate to any machine of a similar type. Mr. Marlow's discussion of how to mill dovetail slides, for example, is a model of thoroughness and clarity. Although Mr. Marlow does provide some introductory material, he wisely refers the reader to "Machinery's Handbook" and its voluminous tables for many specifics on "feeds and speeds".
The later chapters of the book cover such topics as fastening methods, basic metallurgy, and safety/shop practices. The section on metallurgy, while quite basic, I found particularly useful in helping me remember some of my college courses from long ago. Again, this is all good, solid, useful stuff, and presented at a level (neither too elementary nor too theoretical) that makes it extremely useful at the home machine shop level. I found the final chapter of the book in which Mr. Marlow presents a wide variety of "tricks of the trade" extremely interesting. It contains the sort of practical how-to information that almost never seems to be covered in print.
Finally, there are two appendices, one on sharpening lathe tools and the other providing a list of sources for tools, materials, and supplies. Although I do have two minor misgivings about the lathe tool sharpening appendix discussed in the paragraph immediately below this one, I must admit that Mr. Marlow's two page description of sharpening steel lathe tool bits is by far and away (again, because of the superb line drawings) the most easily understood of any I have ever encountered.
I do find a few minor flaws with the text. Table 8.5 on page 353, for example, has gotten the last two column-headings inverted. That is, the RPM figures listed under 5/8-inch cutters should actually be those listed under 3/8-inch cutters and vice versa. Mr. Marlow achieved near-perfection in his appendix on sharpening steel lathe tool bits, but there are two minor flaws.
The first flaw is as follows: In the line drawings at the top of page 483, he shows "side clearance angle" and "end clearance angle". In the subsequent table of sharpening angles, however, we find neither "side clearance" nor "end clearance". Instead, we find "side relief" and "front relief". Now it is true that the sentence immediately preceding the table: "What are typical rake and clearance (relief) angles for HSS tool bits?" does imply that clearance and relief are synonyms. But, aside from being (perhaps?) hard to catch, that still does not answer the problem. For if we understand that in referring from the table back to the preceding illustrations we are to substitute "clearance" wherever we see "relief" in the table, then we would wind up searching in vain through the illustrations for a depiction of what is meant by the "front clearance". Whilst the meaning may be clear to the experienced or well-read amongst us, this discrepancy is irritating and could be quite confusing to the novice.
The second flaw, and here I realize I am opening up a can of worms, is Mr. Marlow's advice to "dip the tool in coolant frequently to keep it from overheating and annealing".
Now I freely admit that I am not a metallurgical scientist, but I have had opportunity to talk to a number of folks who are. And here is what I have been told. Dipping the tool in coolant is a holdover from the days of sharpening carbon steel tools which do have an annealing temperature low enough to be easily reached in tool grinding. And of course, once the tool is annealed, its hardness is gone, and it is useless for cutting. I am told, however, that the annealing temperature of virtually all HSS alloys is sufficiently high that it will not be approached during a tool grinding operation. So annealing of HSS is not the problem. Apparently what IS the problem is that the HSS tool may develop a series of micro-fractures or cracks when shocked by the sudden dip in coolant from a heated state. Now I have also been told that HSS may develop the micro-fractures from overly aggressive grinding as well, but that this is less likely to occur. So if what I have been told by some folks I know to be quite reputable metallurgical scientists is true, it seems to me that it would make sense to grind less aggressively (this is not an industrial production job, after all) to help avoid unnecessary heat build up and to eschew the use of a coolant dip. Note that if facilities are available to have constant coolant flow over the tip of the tool, the sudden shocking issue would not arise---but such facilities are probably not available to the average reader of this book.
I wish Mr. Marlow had covered two additional topics. First, drilling flat-bottomed holes is a subject that continues to vex. Some sage advice here would have been much appreciated. Second, a chapter on shapers, analogous to that on milling machines, would have been of interest to me. Admittedly, I have not seen a shaper in industrial use for years, but there are many of them still in use in home machining operations, and for those folks who have them, a good modern text would be useful.
I cannot help but comment on the one reviewer who was disappointed that Mr. Marlow did not recommend specific machines. First, I suppose Mr. Marlow's inclusion of Clausing drill presses and lathes as well as Bridgeport milling machines may constitute a recommendation of sorts. Secondly, given the wide variety of new (not to say used!) machine tools available, I don't see how it would be feasible for anyone to review them all and make specific recommendations. Finally, which machine tool is best depends upon a number of factors: budget, space available, intended use, etc. So Mr. Marlow was, in my opinion, wise to adopt the approach he did.
While this book would probably not be of much use to an experienced machinist, it certainly is the best single introduction to manual machine operations for the home shop machinist I have ever seen. It would be nice to see Mr. Marlow turn his attention to two additional topics: motors/variable frequency drives and CNC machining. With regards to the former, I understand that one can do wonders nowadays with VFD's and that the price has come down to make them truly affordable. Yet specific information useable by the non-specialist is hard to come by. Second CNC systems and conversion kits seem to be coming down in price and bringing CNC machining into reach of the small prototype shop/home workshop. If Mr. Marlow could address these two topics with the same precision and clarity he did for manual machine tools with this volume, he would provide a valuable service.
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Machine Shop Essentials: Questions and Answers
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