Copyright (C) 1986-2008 by Daniel H. Hudgins, All Rights Reserved.

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This Web site is dedicated to the thousands of "users" of my programs, those who have helped test my programs over the last 22 or so years, and especially those who shared their experiences with me.

You must read this notice: This is a licensed Web site (HTML document and associated files). You must read and agree to be legally bound in contract by the Terms of Use and conditions given in the End User License Agreement ("EULA"), Legal Notices, Instructions, Warnings, Disclaimers, and all other text in "SECTION: 0" of "This Web Site" (HTML document and associated files) before reading or using any of the information, software programs, and or files, contained in, linked to, and or associated with, "This Web Site" (HTML document and associated files). Any use or "Beta Testing" of "This Web Site" constitutes your acknowledgment of your full agreement with the current End User License Agreement ("EULA") and your decision to have this current license supersede all prior and contemporaneous agreements and understandings. Information and files in "This Web Site" (HTML document and associated files) have been placed here so that long time users of "The Author's" programs DANCAD3D.COM (tm) , DANCAM.EXE (tm) , or DANPLOT.EXE (tm) could help proofread the text of the documentation files or screens displayed, and also help test data files, example files, and or any software programs that might be made available from time to time, to aid "The Author" in finding mistakes, bugs, and other errors, omissions, defects, mistakes, and faults. Everything in "This Web Site" (HTML document and associated files) is "Beta Test", "Beta Code", Experimental, Preliminary, requires proofreading, or is being evaluated for possible revision, and is NOT warranted to be free of defect. To help "The Author" report any bugs, foul-ups, defects, or mistakes that you find, see "SECTION: 8" for instructions. "This Web Site" (HTML document and associated files) and all other files and programs by Daniel H. Hudgins are made available "AS IS" without warranty of any kind express, expressed, or implied. All offers and specifications are subject to change or discontinuation without notice of any kind. Please read "SECTION: 8" of "This Web Site" (HTML document and associated files) before trying to contact "The Author."

SECTION: 7.20 is for some "general" discussion about Metalworking, see also the program files in the current distribution of my programs, the other parts of this HTML documentation, and the current On-Line version of this Web site for information more specifically about my programs. Any comparisons of my programs or methods to some others is only given as a vague generality of my opinion and is not intended as a recommendation or reference to any particular products, or methods, always make your own evaluations and comparisons before taking any action.

The illustrations in the sections and sub-sections of SECTION: 7.20 are not intended to be examples of recommended or proper practice, and in some cases may illustrate methods that you yourself would not apply as shown. The variety of illustrations, showing both practical and discouraged practices, has been included to provide illumination of the general metalworking principles discussed in these sections, and other parts of the documentation, in order to help the reader understand some of the many issues relating to the practical matter of producing parts of usable quality by manual, semi-manual, semi-automated, or fully automated machine operation, and how CAD and CAM software, such as my programs that are described in this Web site, might be of assistance to that end.

A couple of the photos in subsections of SECTION: 7.20 where taken using a Sears (tm) Craftsman (tm) Atlas (tm) type lathe, the others were taken while using a ShopTask (tm) model 17-20 type 3-in-1 multi-purpose combination mill, drill, and lathe. When a manual machine tool is retrofit for computer control you need to consider how safety shields should be added, and where the emergency power cutoff switches should be placed.

Be sure to watch all of the video clips linked to in SECTION: 4, in order to see my CAM program DANCAM.EXE (tm) being used to automatically make a part under a form of Computer Numerical Control a.k.a. CNC, and to also see other narrated lessons on how to use my CAD program DANCAD3D.COM (tm) for related tasks.

When making parts, whether by manual or automated means it is frequently necessary to make holes of various sizes. Holes can be made by using a drill, a two flute center cutting end mill, or a boring head. Small deep holes can probably just be made by using a drill. When larger deep holes are required drilling starts with a small drill and then several successively larger drills are used until the desired larger size hole is obtained.

Before you can start drilling the surface of the work-piece needs to be pricked with a center punch, a center drill, or in some other way. Under computer control all of the drill points can be "started" with a small center drill before a second tool path is executed with the drill in the chuck. When drilling flat work-pieces with my CAM program DANPLOT.EXE (tm), the tool path to drill holes can be made by just drawing a dot where each hole is to be drilled. If you need more complex drilling cycles my CAM program DANCAM.EXE (tm) can read tool path files the make the drill move up and down to clear the chips, and drill holes of different depths and from points at different heights on the part.

After drilling holes the hole diameter can be slightly enlarged by using a reamer. Taper reamers are sometimes used to make holes have a taper, i.e. for those who want to use taper pins rather than set screws since taper pins might give a closer fit.

Under CAM control of the machine, medium to large holes that are not too deep can be made with an end mill. One advantage of using an end mill to make holes is that several holes of different diameters can be made without having to change the tool, you just draw the tool path to have the small diameter end mill move in quasi- circles to produce larger holes. In DANCAD3D.COM (tm)'s drawing editor the [P]olygon command can be used to draw the quasi-circles required in your tool path to make holes larger than the end mill's diameter.

When you clamp a part that requires several holes you sometimes will need to un-clamp the part an rotate it in order to drill all of the required holes. Here you see the stepped blocks stacked under the clamps since the part was thin, and the clamps need to be almost level to work properly, i.e. the tip of the clamp just a little lower than the back end.

When you think about using computer control of your machine tool you should look into the issues of how the work-piece can be held so that as many operations can be completed without having to re-setup the work-piece or change the tool.

When using small drills it is a good idea to clamp the part for drilling since any movement of the work-piece may cause the drill to brake off in the part. For parts like this the three jaw chuck could be mounted jaws up on the machine's table to hold the part so that all of the upper surface would be exposed for drilling.

When you need to raise the part off of the machine table so that the drill does not go through the part into the machine's table, or to make up for the movement of the drill being short of going all the way through the work-piece, you can put "1-2-3" blocks under the work- piece. The "1-2-3" blocks are ground to close tolerances so they probably do not put the work-piece out of square, by much.

Here I only needed to use one bolt since the clamp's ends were resting on two points above the two points made by the "1-2-3" blocks. Normally you would always use two (or more) clamps so pressure is on two (or more) points in order to keep the work-piece from twisting around the single clamping point.

Although transfer punches are effective in accurately transferring the center punch marks from holes on one part to its mate, drilling straight through both parts at the same time probably produces better results.

Here some holes that do not go through both parts where tapped for set screws that where used to hold the tube still so that the hole could be drilled through the frame and tube at the same time. This hole was later tapped continuously through both parts, so it was important that the passage of the hole through the two parts was to be well aligned and on axis.

Parts that would be difficult to clamp to the machine's table can sometimes be held in a vice that is bolted to the "T" nuts in the machine's table's "T" slots. If the work-piece is very thin it can be helpful to put blocks of metal on each side of the work-piece between the vice's jaws and the work-piece to stiffen the work-piece under the side to side forces of the tool. Side forces can be greater when milling the edge of a plate than when drilling, and with the small drill used here stiffening did not seem necessary.

Clamping cylinders on their side can be problematic since they tend to roll away when the clamps are tightened. In this case a vice may be helpful since the cylinder is "trapped", i.e. captive, and cannot roll when the vice's jaws are tightened.

It is a good idea to use the dial gauge to align the vice's jaws to the machine's axis, particularly when holes will be drilled on the side of the cylinder along a line parallel to the height of the cylinder.

A center drill can be useful for starting holes on the side of a cylinder since it has less tendency to "walk around" and get out of the center punch prick.

Here a vice is helpful for holding a ring shaped part for drilling. To reduce setup time in rotating the part for drilling under CAM control a motorized rotary table on its "side" holding the part in a three jaw chuck, using the internal jaws, might be helpful in a situation like this.

Putting a tall cylinder in a vice would not work very well since it could slip across the direction of the vice's jaws faces. Another problem with this part is that the lower end is a slightly larger diameter than the top part that needs to be drilled.

Since the tilting table did not have mounting flanges on its side I had to use tall clamps to clamp the tilting table to the machine's table. To keep the work-piece from rolling away it was placed in one of the tilting tables slots and clamped there.

There were actually two parts being drilled at the same time, the cylinder and its cap. These where taped together to keep the cap from rotating while being drilled.

Here you can see the stepped blocks stacked up in order to get the clamps high enough in the small space available on the machine's table behind the tilting table.

Collets can be used to hold drills as a substitute to using the drill chuck to hold the drill. Collets are made in different sizes, but if you use reduced shank drills you can use the same Collet for the set of reduced shank drills since the reduced shank drills from the same set probably all have the same diameter shank.

When you need to make a large hole using a large drill, you need to start with a small drill, and then slowly increase the diameter of the drill used until you get to the diameter that is needed.

Here you see a closer view of the exposed part of the Collet in the vertical milling machine's spindle. When the length of the drill chuck plus the drill length is too long to get the tip of the drill above the work-piece you can use the collet to "shorten" the drill to work-piece distance.

When you are using a particular diameter drill you need to select a collet that corresponds to that diameter since collets only accept diameters a little larger or smaller than their rated dimension. A set of collets might be expensive to purchase, but you may be able to get away with just purchasing a few collets for the sizes of tool shank that you most frequently use.