How deep is 1 atm

how deep is 1 atm

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This article describes the older model of the Smithy CB1220XL. The current model, called the Midas 1220XL, now features English dials and leadscrew and a half-nut for easier threading operations. I have been told that an upgrade to these features may be offered in the future for the older model that I have.

I have long been interested in metalworking; more so than woodworking, though I am learning to enjoy that activity also. Over the years, I have had the pleasure to occasionally have access to machine shop equipment for working on some of my projects. I had long wanted a small metalworking shop of my own where I could machine small parts for my telescope projects. Finally in 1996, I decided that the time had come to look seriously at getting a small lathe and possibly a milling machine to use in my garage whenever I wanted.

As I began to look at my own shop space and machining requirements, I realized that anything I ended up purchasing would be much less than I would like. It is a reality most of us face -- too little money, too little space, and too large dreams. I knew that my own choices would be governed more by space than anything else. The options I had were:

  • Buy only a medium sized lathe and use my drill press for light duty milling.
  • Buy only a medium sized lathe and add on a small tool post milling attachment.
  • Buy a separate small bench-top lathe and milling machine.
  • Buy a medium sized three-in-one combination lathe / mill / drill.
  • Buy a new home with large workshop and equip it with full sized used machines.

I immediately (and regretfully) eliminated the last option. Reading the USENET newsgroup rec.crafts.metalworking for a few months helped me eliminate the first option also. Many folks with much more metalworking experience than I presented evidence and opinions that milling on a drill press is not a viable long term option. The side loads on the spindle bearings can become too high and cause premature wear and ultimately failure. In addition, it was pointed out that drill chucks are also not made for the heavy side loads encountered while milling. The chucks have been known to disintegrate, sometimes violently, when used in this way. This knowledge eliminated option one on my list.

The second option on my list has been used by many for years and is generally recommended as a good way to get started with light milling. The main limitation is that the maximum length of cut is governed by either the milling attachment or the lathe's cross-slide, depending on the type of setup. Not knowing exactly how large some of my milling cuts might be, I was reluctant to commit myself to milling only on the lathe.

After thinking about the kinds and sizes of parts I would be making on the machine(s), I eliminated the third option rather quickly. Small bench-top machines of the type produced by Sherline enjoy an admirable reputation. I just felt they would be a bit too small for many of my purposes.

After more or less eliminating the other choices,

I was left with looking at the compromises of a three-in-one machine. In general, the rec.crafts.metalworking newsgroup membership has a low opinion of these machines. The reasons most often cited are: all the machines are imported; many have metric dials; many are incapable of performing threading operations or make it very difficult; many have a fixed, restrictive milling head spindle height; most have very small lathe spindle hole sizes; most have a limited distance between centers; all can require "dramatic" setups for even simple machining operations; all require you to do a lot of work to change over from a turning operation to a milling operation; and none are as rigid as a large lathe or milling machine. Thus the usual advice is to find the extra space somehow and buy large used American machine tools.

These are all very valid arguments against a three-in-one machine. I too, would love to have a 6000 pound super-rigid combination 14"x40" quick change lathe and 12"x48" knee mill that fits into an area four feet wide by five feet high by two feet deep -- and costs less than $2000. It just isn't going to happen. Since I was not attempting to set up a production shop, many of the concerns were not completely valid for my situation. If it takes a half hour to change over from lathe to mill operation, it only detracts from my hobby time. I enjoy working in the shop, even if the time isn't 100% productive. In terms of tool rigidity and horsepower, I can overcome those obstacles by taking smaller cuts. The final accuracy is the same, it just takes me longer than a machinist doing work for hire on larger, more powerful machines.

The three-in-one machine limitations that remain as compromises for the hobbyist are centered around size and the machine's feature list. This is where you must choose between cost and function. Try to envision as many of the possible uses for your machine as possible and use the information to rate the prospective machines you find.

In the lower cost hobbyist portion of the machine tool market, there are four main competitors with three-in-one machines. These are Grizzly Industrial. Harbor Freight Tools. Shoptask. and Smithy. There may be others, but these are the companies most often mentioned in this market.

Soon after gathering all the specifications, I had narrowed my choice to Shoptask and Smithy. An important aspect of my purchase choice was going to be service after the sale, if needed. I was not able to get any more details on the Harbor Freight and Grizzly machines than appears in their respective catalogs. (I like dealing with Grizzly. Their customer service is usually quite helpful, but the lack of detailed specification on their 3-in-1 machine forced me to drop them from consideration.)

I studied the specifications for the Shoptask and Smithy machines carefully, comparing all the features and ranking the features I thought most important. From reading the specifications, I began to form a view of how the machines would perform in various aspects of my use. My final decision came down to the following key factors. I considered each feature important to me and gave the edge to one or the other machines.

Dual Motors - lathe and mill powered by separate motors for additional flexibility.


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