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

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To view or use the current version of this Web page you may need to reload or refresh the display of this page by your browser. Just clicking on the browser's [Reload] or [Refresh] icon may not be enough to insure that all of the page's most current contents have been cached and displayed. Some browsers may have additional commands to help display the page's most current contents such as: holding down the [Shift] key and clicking on the [Reload] icon, holding down the [Control] key and clicking on the [Refresh] icon, holding down the [Control] and [Shift] keys and clicking on the [Refresh] icon, pressing the [Control] and [F5] keys, pressing [Control] and the [R] key, or some other combination of keys or clicks. Check to see which commands your HTML browser uses to load the most current page contents into its cache and then to display them onto the screen.

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 in round parts. In the lathe you can make a round hole down the center of a round part by putting a drill in a drill chuck inserted into the taper of the tail stock.

When drilling in the lathe the work-piece rotates and the drill remains fixed. Rather than using a center punch to prick the part to keep the drill from walking off of the starting point, in a lathe a center drill is used to make an indentation that the drill will later follow into the work-piece. A center drill is a short drill used for making the dimple that can be used by the live center or dead center to support long work-pieces in the lathe. The crank, or hand wheel, on the end of the tail stock is used to push the drill into the work-piece.

Here you see a center drill be used to start a hole in a disk. When a ring shaped part is being made, a hole needs to be drilled into the part so that the boring bar can be inserted to enlarge the hole to the final dimensions.

You should probably have several sizes of center drills so that you can make dimples sized appropriately for the drill that will be used to start the hole. When drilling the hole it is good to back the drill out every so often in order to clear the chips from the channels in the drill so that the drill does not seize in the hole and snap off.

In this close-up you can see that the tip of the center drill is stepped, and makes a small straight sided hole surrounded by a larger cone shaped hole. Do not crank the center drill into the work-piece past about two thirds of the larger taper, since the center drill is not designed to drill holes, only make a dimple.

Once the part has been dimpled a drill can be used to drill into the part. Be sure to back the drill out of the work-piece frequently so that the drill does not seize and break off. When you are going to drill all the way through the part be careful when going through the back side since the drill can catch when breaking through and snap off. Also be careful when drilling all the way through so that the drill does not hit the chuck or the chuck's jaws.

When drilling very deep holes it is not a good idea to push the drill in past the channeled portion since the chips will not have any way to escape. If you need to push the drill in with only the solid shank exposed back the drill out after only each small cut so that all the chips can be cleared from the drill's channels. Also you should not bring the jaws of the drill chuck too close to the work-piece since any misalignment of the tail stock will not be able to be taken up by the drill flexing and the drill is liable to break off.

The three jaw chuck does not have sufficient grip on the part to be able to hold it still when using large drills to start with. If you start with small drills, and slowly increase the diameter of the drill used, the load on the lathe spindle motor, and the grip of the chuck on the work-piece required, may be tolerable.

When using large drills there is the very real chance to hitting the chuck or the chuck's jaws, so advance the drill slowly checking to see if it is going to hit any of the moving parts as the drill comes out of the back of the work-piece.