As I mentioned back in Desktop Fab, Basic Machining and CNC last fall I took the Basic Machinist course at Simi Valley Adult School. I am taking this opportunity to document the class a bit more. The main effort was on 8 projects, with basic math and print reading supplementing and supporting the projects. The projects provide opportunity to use most of the machines in the machine shop.
There are a number of safety and basic use videos students must watch. These are all on DVDs and small 12″ CRT tvs are provided with headphones. The videos vary in age but generally are fairly old…. Some appear to be from the early 1970s and transferred from filmstrip originals to videos and then DVD. They are series of stills and you can hear a ‘ding’ just before each frame change, which was the old cue to film strip operator to change the frame. Generally quality of both video and audio is pretty low, but the information is good. Some of the old hair and cloth styles give away their age.
The first project is a simple T-Slot cleaner (sorry no pics). It is used to clean out the t-slots in Mills and other machine tools. The tool is made from a piece of flat sheet steel. Students first draw out the shape to scale, then inscribe it on the metal – paint part blue, then scrape lines with scribe tool. The basic shape is then cut using a hack saw, and filed to shape with a metal file. Test fitting is done with two different Milling Machines in the shop, as t-slot sizes do vary.
The second project is a V-Vlamp. This project requires using most of the tools in the shop. Students first draw the block and clamp ring to scale. The block and clamp blanks are then cut from steel stock – a horizontal band saw chops them to rough size. The block is placed in a lathe and facing cuts are made to bring the two ends to size. The block is squared to 1.900″ in the vertical mill, then layout ink is applied and scored according to drawings. A horizontal mill is used to mill out the slots in sides and bottom of V. A band saw is used to cut the basic shape of V, and burrs removed. A vertical mill and existing V block are used to mill the V. Lastly a surface grinder is used to bring all sides (including V) to size within tolerance. The grinding process is very time consuming and a bit messy. This completes the block. The clamp follows similar process: cutting stock, squaring in lathe, layout ink. Center is drilled out using the lathe, the outer shape is cut using a band saw. The top hole is drilled and tapped with the aid of a tap holder in the vertical mill. The screw is fashioned from a piece of 3/4″ stock and turned on the lathe. Threads are then cut and the end cap made by cutting off a piece using the lathe’s cut off tool. The turn handle and end cap are press fitted into screw after it is assembled into the clamp.
The third project is a vise stop. This is a very useful tool later on. Actually we used one when making the V-Block Clamp. It is attached to the vise block of a mill (CNC or manual), allowing a measured/centered part to be removed and replaced without having to re-measure. It was a fairly simple piece to build, requiring milling, drill/tap and surface grinding. One trick is to drill the three holes with the pieces clamped together. This insures the holes will line up.
The fourth project is a screw driver handle. It is made from basic steel stock and so is not really strong enough to be a real screwdriver, but it lets us learn several techniques. We actually used the original stock back in Project 2 as practice for cutting threads. First we cut The stock piece is held in the 3 draw lathe chuck using a ‘Lathe Dog’, a clamp that transfers the rotary motion to the piece when held between centers. After practicing cutting threads, we turned the part down to size… sizes actually. The handle portion is knurled, drilled, and bored. The cap is turned from another piece – rounding well applies careful planning of depths on a manual mill. The cap is press fit into the handle.
Project 5 is an indicator holder – device used to which an indicator can be attached. Mostly it is an exercise in turning aluminum on a lathe. The different diameters are intended to be grasped in different sized chucks.
Project 6 is is a Tapping Center. Two parts are turned from HR Steel. The upper piece is turned to two diameters and then both ends are drilled out. The lower piece is drilled and pointed to 30Deg. A rod is used to join them, with a spring between. The upper piece goes into a mill chuck. The bottom point goes into the back end of a tap handle over a hole to be threaded. The Tapping Center holds the tap handle vertical while it is turned by hand.
Project 7 is an Angle Plate. It is used to clamp a part at an angle. It is made by cutting two chunks of 1/2″steel and milling them flat, and drilling an array of holes in the upper. A third chunk of 1/2″ steel makes a hinge between them. Once milled to size, the pieces are assembled and ground flat. The end and side plates fabricated from 1/8″ steel plate. Note: the class curriculum was changed shortly after I finished, with a hole gauge replacing this part.
The last Project, #8, is a hammer. This uses all the lathe turning and knurling tools we learned before, along with the Taper Cut. The handle is drilled out to give the hammer a proper balance. The hole is threaded and an end cap is fabricated to fit. The head requires some tricky turning to get all the curves, including the very fine dome on the face of the hammer head.