As before, I'm reading Joe Martin's book, Tabletop Machining. Now I'm interested in his remarks (pp.132ff) about how he designed the compound slide for the Sherline Lathe. I don't really understand what he is saying and I don't think I will unless I sit down and patiently write an essay articulating in detail the thought processes that go into a design like that. He does give the impression that it would be worth the effort to understand it.
I have no experience designing stuff like that and what I'm wondering is, what else can one read to acquire the background to appreciate his remarks in as much detail I seem to require?
Ignorantly, Allan Adler snipped-for-privacy@zurich.ai.mit.edu
Allan wrote: "...I'm reading Joe Martin's book, Tabletop Machining.
There is no such page reference in my copy of "Tabletop Machining". Joe describes his compound slide for the Sherline Lathe in several parts of the book. Bear in mind, the compound slide for the Sherline Lathe is adapted from the "compound" normally used on larger lathes. *It is an optional Sherline part*. The "factory" cross-slide of the Sherline lathe is not a compound slide as used on larger lathes. Sherline's cross slide moves only across the bed (90 degrees). There is no provision for locating the tool post at any other angle to the work piece, such as on regular compound slides, for the purpose of turning a taper on the workpiece. Tapered cuts on the Sherline are normally made by setting the headstock at an angle to the bed.
IMO, you should not be concerned about the design of Sherline's compound slide until you have studied the rest of "Tableshop Machining". If you have a good grasp of machining fundamentals as performed on the Sherline, understanding the *optional* compound rest will present no problems. I must admit, I have had Sherline's compound rest since they came out in 1998 and it is still in the box. On the rare occasions I have turned tapers on the Sherline, it has been done by setting the headstock to the requisite angle.
In reply to my question about the preparation needed to appreciate the comments in Tabletop Machining on how Joe Martin designed the compound slide for the Sherline lathe, Bob Swinney made some helpful and informative comments.
Regarding his advice:
I fully intend to finish reading the book. However, I often read several related books at the same time. I find that I get a lot more out of them that way and also learn to estimate their usefulness as references. I also try to have at least one question in mind that I can think about while I'm reading them. I think it helps keep me honest in my reading.
I don't know how soon, if ever, I will buy a lathe since I am financially challenged (that used to be called "broke") and since I haven't figured out where I might be able to set it up, my apartment probably being unsuitable for various reasons. Meanwhile, I'm giving priority to being about to think about how to plan projects in all necessary detail on paper.
It's good to know that the Sherline "compound slide" is actually a cross-slide and is not really a compound slide in the sense the term is used for larger lathes. Maybe it is not an extremely useful part. It doesn't matter. What I found interesting about Joe Martin's comments about it was the problem solving aspect of designing it, about which I wish he had said more and I'm glad to learn that in fact he does later on in the book (I'm up to p.149 now). I'm not sure, though, that the level of detail I require to think about it is provided, but I'll keep an open mind about it.
It occurred to me after reading Bob Swinney's reply that my original question in this thread might have been confusing in that the word "design" actually has several meanings and that I should probably have been a lot more careful in phrasing my question. Another point of confusion might have been that I wasn't really aware that the term "compound slide" already had a fixed, technical meaning in the general context of lathes and metal working and therefore that talking about designing one might imply less room for problem solving and innovation than I might have assumed.
I have a few books on drafting that I picked up over the years at library sales and I was looking them over the other night. One thing that struck me which I'd never really noticed before was how many of the drawings one is asked to copy come with names for the parts being copied, even though from the standpoint of the skill being taught it is not really necessary to know their names or anything about them. Anyone who has taken such a course and intended to use it in connection with machinery would probably have acquired a certain amount of passive knowledge thereby about different kinds of machine parts. I'm still trying to decide whether to spend a little time on the exercises in one of these books.
A friend of mine is sending me a used copy of Virgil M. Faires book, Design of Machine Elements, reprinted from an edition from the 1930's. No doubt it is way out of date but I think I'll be better off, from the standpoint of literacy about machinery, reading it than not. At the very least, maybe it will help me to ask better questions.
Ignorantly, Allan Adler snipped-for-privacy@zurich.ai.mit.edu
There are many texts far older than '30's that will give info that is still contemporary on lathe (machine) design/function. Robert Smith's "Advanced Machine Work" comes to mind. (Smith was an MIT prof.) Also Ocar Perrigo's "Lathe Design" from app. 1916. There are works that pre-date Perrigo by many years that can still teach much. Another MIT prof who wrote on lathes was Robert Woodbury, though his "History of the Lathe" only goes up to 1850. I hope you get to run some lathes, interspersed with your reading. Frank Morrison
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