FILLET UP PLEASE MODULE 11 OBJECTIVES On completion of this Module you will be able to: Construct a Fillet radius between two intersecting lines. Construct a Fillet radius between two parallel lines. Construct a Chamfer between two intersecting lines. **************************************************************************************************************** In all of our drawing sessions to date we've had to fit an arc to a line in order to fillet or 'round-off' a corner. This has been a matter of searching through the arc options and utilising the option best suited to the task in hand. For example, the drawing above uses three arcs. If we look more closely at arc No. 1 we can see that we need to know the values of three of the below variables to construct this arc. Start point of the arc S End point of the arc E Radius of the arc R Angle subtended by the arc Centre point of the arc C We will require only a few of these variables depending on the arc option selected. But, as you can see, it may get quite involved. AutoCAD will allow you to simply select the lines you wish to fillet and the radius of the arc to be used in the fillet operation. The AutoCAD 2D Tutor (R2013) Page 11:1
Start from Scratch a New drawing and Zoom, Extents. FILLET Using Snap, Grid and Ortho as you like, draw the two squares shown below and we will look at AutoCAD's Fillet command in more detail. Install the Fillet command: Home Modify OR Modify TB Typed command: FILLET _fillet Current settings: Mode = TRIM, Radius = 0.0000 Initially the Radius, (for the fillet), is set at 0. To change it,- R (Radius) Specify fillet radius <0.0000>: The prompt returns to: 20 Pick the first line at P1, (the line highlights). Select second object or shift-select to apply corner: Page 11:2 The AutoCAD 2D Tutor (R2013)
Note: The shift-select to apply corner option will over ride the radius set (20 units in our case) and result in a radius of 0 being applied to the corner of the two lines selected. Thus, previously filleted corners will have the fillet removed and be squared off. Position the cursor over P2 (don t pick just yet) the preview fillet will be shown. If you are happy with the preview fillet, pick on P2 and the fillet will be completed. Re-select the Fillet command and notice the Current fillet radius is defaulted to 20. R (Radius) Specify fillet radius <20.0000>: 25 We have now set the new default value for fillet radius to 25. We can, however, alter that value at any time during our drawing/design process. Now, continue the command. So, select your corner again, (select two lines). This time the corner has a fillet of radius 25 units. Fillet the remaining corners on the outer square as follows, (remembering to reset the fillet radius value as required). Radius 0 This option is very valuable in the trimming and cleaning up of lines that have been drawn freehand, (lines drawn not using Snap, "continuous", etc.) Reinstate the Fillet command and pick one of the lines making up the corner with a radius of 25. At the second prompt: Select second object or shift-select to apply corner: Hold the Shift key down and pick the opposite line that makes up the corner. The initial arc remains, but the corner will also be squared off as the current radius setting is overridden and becomes a value of 0. The AutoCAD 2D Tutor (R2013) Page 11:3
Another option is to set the radius to 0 and then Fillet. Draw two lines like those below somewhere away from your two squares: Install the Fillet command: _fillet Current settings: Mode = TRIM, Radius = 22.5000 R (Radius) Specify fillet radius <default value>: 0 Pick the two lines you have just drawn one after the other, picking the vertical line below the horizontal line. The lines are now filleted with a fillet radius of 0 units, hence cleaning up the corners and deleting the unwanted portions of the lines. Picking the vertical line above the horizontal, would have filleted the opposite direction. Filleting Non-perpendicular lines In this exercise we have only filleted corners at 90 or right angles. However, AutoCAD will fillet any two lines at any angle. To prove this, draw two lines at some angle and set a radius of 25. AutoCAD will fillet them when asked, (providing the default radius is not so large as to destroy one of the lines when trimming it back to the arc). Page 11:4 The AutoCAD 2D Tutor (R2013)
Filleting Parallel lines Not all the lines to be filleted need to have an intersection point or to intersect if they were extended. Fillet can also apply an arc to lines that are parallel. Use Snap and Ortho to draw two parallel lines with different lengths as shown below. Apply the Fillet command to the lines at both right hand ends, picking the shorter one first. The fillet is positioned so that it is trimmed back to the end of the line you picked first regardless of length. The size of the radius is adjusted to join the lines with a semicircle regardless of the fillet setting. Undo the fillet and then re-install the Fillet command and apply it again picking the longer line first. This time the radius is positioned at the end of the longer line and the shorter one is extended. Install the Fillet command again to see that the radius used to fillet the parallel lines is only a temporary value and the Current value remains unaltered. Now, Fillet has one more very useful function. Trim mode The 'Trim' option allows you to select whether AutoCAD trims the lines back to the fillet radius or leaves them untouched. This option is used in other commands, e.g. Chamfer, as well. Draw two intersecting lines. Re-install the Fillet command. _fillet Current settings: Mode = TRIM, Radius = 25.0000 T (Trim) Enter Trim mode option [Trim/No trim] < Trim>: The default value for Fillet is to trim the lines. N (to select No Trim) The AutoCAD 2D Tutor (R2013) Page 11:5
R (Radius) Specify fillet radius <25.0000>: 20 Pick the two lines you have just drawn, one after the other. This time the fillet is drawn but the lines are not trimmed back and remain unaltered. Reset to the Trim condition when you have finished. Multiple Fillet The Multiple option of the Fillet command allows you to do continuous fillets with the current radius setting rather than allow just a single fillet operation. Using this option will save exiting and restarting the Fillet command each time you wish to fillet a set of objects. You must use the Return, Enter or Esc key to end the fillet command with a Multiple option in force. Try it on the inner box. Undo your work when done. Polyline option We shall consider the 'Polyline' option in a later Module. A polyline is just a special group of objects (made up of lines and arcs if so required), which, once drawn, are considered one object. Fillets can also be applied between circles, arcs and lines as required. Try to fillet the example below, but experiment by selecting different points on the objects and observe the results. The system will form the fillet to best suit the points picked. In the case of lines and arcs, these will be trimmed when the fillet is formed. In the case of lines and circles, only the line will be trimmed and not the circle. CHAMFER In addition to the Fillet command, there is its close relative, Chamfer. We will now experiment with this option. Install the Chamfer command. Home Modify OR Modify TB Chamfer Page 11:6 The AutoCAD 2D Tutor (R2013)
Typed command: CHAMFER _chamfer (TRIM mode) Current chamfer Dist1 = 0.0000, Dist2 = 0.0000 Select first line or [Undo/Polyline/Distance/Angle/Trim/mEthod/ Multiple]: As you will see, the format for the use of the Chamfer command is very similar to that of the Fillet command we've just looked at. So in answer to the system prompts: D (Distance) Specify first chamfer distance <0.0000>: 30 Specify second chamfer distance < 30.0000>: 60 Now we have set the chamfer distance of the first line selected to 30 units and the second to 60. We have set the system "default" values. Select first line or [Undo/Polyline/Distance/Angle/Trim/mEthod/ Multiple]: Now to chamfer one of the corners of your inner square. Simply select the two appropriate lines (check whether, like the fillet command, a preview is offered). Remember, the first line will have a chamfer distance of 30, the second at 60. Having set the chamfer default values, it is possible to move around the drawing chamfering any other corner or set of lines that require chamfering with these values. As with Fillet it is possible to alter these default values to any sizes you require. Chamfer the rest of the corners of the inner square using the Multiple option. Chamfer can also be used to close two lines as Fillet 0 and the shift-select to apply corner did and works in the same way. Change the Dist1 and Dist2 values to 0 with Trim ON and try it. The 'Trim' option also works just like those in Fillet. Try it too. Reset the Trim option when finished. The AutoCAD 2D Tutor (R2013) Page 11:7
40 Angle chamfering Besides defining the chamfer from two distances, the Chamfer command can use an angle definition. To demonstrate this, draw two lines of lengths 100mm, at right angles, with the end points touching and then re-install the Chamfer command. _chamfer (TRIM mode) Current chamfer Dist1 = 30.0000, Dist2 = 60.0000 Select first line or [Undo/Polyline/Distance/Angle/Trim/mEthod/ Multiple]: A (Angle) Specify chamfer length on the first line <Default value>: 40 Specify chamfer angle from the first line<0>: 30 Chamfer the two lines to the distance and angle you have selected. 30 Method Chamfering The remaining option in the Chamfer command is Method. This controls whether distances are to be used or distance and angle to define the chamfer. Give it a try. When you have finished return Chamfer command to the Distance method, which is the default. The Polyline option will be covered in a later Module. SUMMARY To Fillet in two-dimensions: 1. Pick Fillet, 2. Pick Radius or type R, 3. Type in radius value, 4. Select required lines to be filleted at the set radius. Page 11:8 The AutoCAD 2D Tutor (R2013)
To Chamfer in two-dimensions: 1. Pick Chamfer, 2. Pick Distance or type D, 3. Type in chamfer distances required, 4. Select required lines to be chamfered at the set values. The first line picked will have Distance 1 applied and the second line will have Distance 2 applied. TASKS Erase all the experimental drawings on the screen and draw the following. Set Layers for the title block, outer profile and holes. Use different colours to enhance your drawing. The dimensions are for drawing purposes only and are not required on the display. Save as the drawing named XX11A. The AutoCAD 2D Tutor (R2013) Page 11:9
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