I have one for Nelson

[Tony Wells]

I have some of those "very-near" measuring devices and still use them. Of course, lots of micrometers have the 0.0001 scale vernier style, but I have some 18" (I think) and some 40" calipers on hand when I need them. The 40's are a little awkward, but seem accurate. No rejected parts from missed dimensions anyway.

 

[Rbeckett]

Ok guys,
I hope I am not jacking the thread, but what is the difference between and engine and a motor? Same rules apply if you google the answer. Plain english every man answer is the best. So whats the difference?

 

[Nelson]

fix·ture/ˈfiksCHər/

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1. A piece of equipment or furniture that is fixed in position in a building or vehicle.
2. Articles attached to a house or land and considered legally part of it so that they normally remain in place when an owner moves.

jigs and fixtures

Components of machine-tool installations, specially designed in each case to position the workpiece, hold it firmly in place, and guide the motion of the power tool (e.g., a punch press). Jigs can also be guides for tools or templates, as in the furniture industry. Special cramping jigs that ensure squareness are set up so that, for example, a wardrobe can be glued up in one operation by power-driven rams. See also assembly line, interchangeable parts, mass production.



A Jig is a tool that one uses to establish the placement of a fixture, for instance a set of pre-made steel bars that when locked together would give you the location of the boltholes that will mount a fixture to its' support base, column, wall, etc. As in a pattern used to mount a bathroom sink to the wall. A "Jig" is used to lay out where an overhead rail scale will mount into an existing rail system, and locate where the transverse lever will hang, where the dial or indicator will mount, then another jig is used to show where to drill holes and set the indicating device. The "Jig" saves time and money because you don't have to lift up and take down the actual parts and makes the installation go faster.[/TD]
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For those working in a production or machining setting, then the terms jig and fixture are not new to you. You are probably also aware that these two aforementioned devices are involved with fastening work pieces during machining operations. A jig is used for guiding the tool to operate the correct location, while a fixture is used to hold the work piece for machining. Discover other differences between jig and fixture below.
1. Size
Jigs are normally very light in size and they are not fixed onto the machine table. This is because it has to move around guiding the cutting tool unlike the fixture that is clamped onto the table. Furthermore, the fixture is quite bulky in construction and it helps hold the work in position. The other reason why the fixture is fasted onto the table is to ensure that the work piece does not move when the machine starts operating.
2. Application
Fixtures boast of a wider application range as compared to jigs. In fact, fixtures are made for applications wherein the cutting machines cannot be easily guide like a drill. When using these work holders, a center finder, gage blocks or edge finder positions the cutter. Some of the examples of common fixtures include lathe fixtures, milling fixtures, grinding fixtures and sawing fixtures. Furthermore, fixtures can be utilized in any machine operation that demands an exact relationship between a tools’ position to a work piece.
3. Accuracy
Another key distinction between a jig and a fixture lies in accuracy. Here, a jig is more accurate than a fixture. In fact, jigs are typically used so as to ascertain the high precision of parts during production. This action helps control the quality control costs.

To sum up, jigs and fixtures help to save labor and even less skilled workforce can effectively work complex machines through their assistance.


From http://www.carrlane.com/catalog/ind...B2853514359482013180B041D1E173C3B2853524B5A5B


DEFINITIONS
Often the terms "jig" and "fixture" are confused or used interchangeably; however, there are clear distinctions between these two tools. Although many people have their own definitions for a jig or fixture, there is one universal distinction between the two. Both jigs and fixtures hold, support, and locate the workpiece. A jig, however, guides the cutting tool. A fixture references the cutting tool. The differentiation between these types of workholders is in their relation to the cutting tool. As shown in Figure 1-1, jigs use drill bushings to support and guide the tool. Fixtures, Figure 1-2, use set blocks and thickness, or feeler, gages to locate the tool relative to the workpiece.

Figure 1-1. A jig guides the cutting tool, in this case with a bushing.


Figure 1-2. A fixture references the cutting tool, in this case with a set block.
​

Jigs
The most-common jigs are drill and boring jigs. These tools are fundamentally the same. The difference lies in the size, type, and placement of the drill bushings. Boring jigs usually have larger bushings. These bushings may also have internal oil grooves to keep the boring bar lubricated. Often, boring jigs use more than one bushing to support the boring bar throughout the machining cycle.
In the shop, drill jigs are the most-widely used form of jig. Drill jigs are used for drilling, tapping, reaming, chamfering, counterboring, countersinking, and similar operations. Occasionally, drill jigs are used to perform assembly work also. In these situations, the bushings guide pins, dowels, or other assembly elements.
Jigs are further identified by their basic construction. The two common forms of jigs are open and closed. Open jigs carry out operations on only one, or sometimes two, sides of a workpiece. Closed jigs, on the other hand, operate on two or more sides. The most-common open jigs are template jigs, plate jigs, table jigs, sandwich jigs, and angle plate jigs. Typical examples of closed jigs include box jigs, channel jigs, and leaf jigs. Other forms of jigs rely more on the application of the tool than on their construction for their identity. These include indexing jigs, trunnion jigs, and multi-station jigs.
Specialized industry applications have led to the development of specialized drill jigs. For example, the need to drill precisely located rivet holes in aircraft fuselages and wings led to the design of large jigs, with bushings and liners installed, contoured to the surface of the aircraft. A portable air-feed drill with a bushing attached to its nose is inserted through the liner in the jig and drilling is accomplished in each location.
Fixtures
Fixtures have a much-wider scope of application than jigs. These workholders are designed for applications where the cutting tools cannot be guided as easily as a drill. With fixtures, an edge finder, center finder, or gage blocks position the cutter. Examples of the more-common fixtures include milling fixtures, lathe fixtures, sawing fixtures, and grinding fixtures. Moreover, a fixture can be used in almost any operation that requires a precise relationship in the position of a tool to a workpiece.
Fixtures are most often identified by the machine tool where they are used. Examples include mill fixtures or lathe fixtures. But the function of the fixture can also identify a fixture type. So can the basic construction of the tool. Thus, although a tool can be called simply a mill fixture, it could also be further defined as a straddle-milling, plate-type mill fixture. Moreover, a lathe fixture could also be defined as a radius-turning, angle-plate lathe fixture. The tool designer usually decides the specific identification of these tools.
Tool or Tooling
The term "tool" encompasses both jigs and fixtures. Essentially, it is a generic term describing a workholder which is identified with a part or machine. Sometimes "tool" is used to refer to a cutting tool or a machine tool, so it is important to make clear distinctions.
Workholders
Another term which describes both jigs and fixtures is "workholder." A broad term, it frequently identifies any device which holds, supports, and locates a workpiece. In addition to jigs and fixtures, vises, collets, clamps, and other similar devices are also workholders.
PERMANENT AND TEMPORARY WORKHOLDERS
Jigs and fixtures are most often found where parts are produced in large quantities, or produced to complex specifications for a moderate quantity. With the same design principles and logic, workholding devices can be adapted for limited-production applications. The major difference between permanent and temporary workholders is the cost/benefit relationship between the workholder and the process. Some applications require jigs and fixtures solely for speed; others require less speed and higher precision. The requirements of the application have a direct impact on the type of jig or fixture built and, consequently, the cost.
Permanent Jigs and Fixtures
Workholders for high-volume production are usually permanent tools. These permanent jigs and fixtures are most often intended for a single operation on one particular part. The increased complexity of permanent workholders yields benefits in improved productivity and reduced operator decision-making, which result in the tool having a lower average cost per unit or per run. Therefore, more time and money can be justified for these workholders.
In the case of hydraulic or pneumatic fixtures, inherent design advantages can dramatically improve productivity and, hence, reduce per-unit costs even further, even though the initial cost to construct these fixtures is the most expensive of all fixture alternatives. In some cases, where machine-loading considerations are paramount, such as a pallet-changing machining center, even duplicate permanent fixtures may be justified.
Permanent jigs and fixtures are typically constructed from standard tooling components and custom-made parts. Figure 1-3 shows a typical permanent workholder for a drilling operation.

Figure 1-3. A permanent workholder used for a drilling operation.​

Low-volume runs and ones with fewer critical dimensions are often produced with throwaway jigs and fixtures. These tools would typically be one-time-use items constructed from basic materials at hand and discarded after production is complete. Although throwaway jigs and fixtures are technically permanent workholders, in effect they are actually temporary.
General-Purpose Workholders
In many instances, the shape of the part and the machining to be performed allow for the use of a general-purpose workholder such as a vise, collet, or chuck. These workholders are adaptable to different machines and many different parts.
Since they are not part-specific, their versatility allows for repeated use on a variety of different or limited-production runs. The cost of these workholders would usually be averaged over years and might not even be a factor in job-cost calculations. The general-purpose nature of these workholders necessitates a higher level of operator care and attention to maintain consistency and accuracy. For these reasons, general-purpose workholders are not preferred for lengthy production runs.
Modular Fixtures
Modular fixtures achieve many of the advantages of a permanent tool using only a temporary setup. Depicted in Figure 1-4, these workholders combine ideas and elements of permanent and general-purpose workholding.

Figure 1-4. Modular workholders combine ideas and elements of both permanent and temporary workholding to make inexpensive-yet-durable workholders.​

The primary advantage of modular fixtures is that a tool with the benefits of permanent tooling (setup reduction, durability, productivity improvements, and reduced operator decision-making) can be built from a set of standard components. The fixture can be disassembled when the run is complete, to allow the reuse of the components in a different fixture. At a later time the original can be readily reconstructed from drawings, instructions, and photographic records. This reuse enables the construction of a complex, high-precision tool without requiring the corresponding dedication of the fixture components.
Figure 1-5 shows how modular fixturing fits into the hierarchy of workholding options, ranking below permanent fixturing yet above general-purpose workholders. Virtually every manufacturer has good applications for each of these three options at one time or another.

Figure 1-5. The hierarchy of workholding options.​

 

[Tony Wells]

In general, I think of electric motors and fuel/air or steam engines. Never a steam motor....just doesn't sound right, or an electric engine. That's just me though. I've never looked it up.

 

[Rbeckett]

Well darn!
I had hoped it would be a little tougher when I asked the Motor versus Engine question, but apparently we have some very clever and smart folks who answered the question right quickly. Nobody got it wrong, so I don't see where I could add anything to the already great answers. I wil keep looking for some more stumpers and start a new thread when I find em!!!!

Great answers guys!

Bob