Need help drawing plate

[LTAZ]

Hi, I'm just getting started in Autocad and I've taken a class, now I'm in between semesters waiting on the next class to start, so I've found a couple of assignments on the net that I'm drawing. I'm stuck on a few of the circles of this plate. The 4 R3 circles on the left part, I can't figure out how to get the exact placement of them. I have the center line that they go on, but can't figure it out. Also, the 2 farthest right circles that go on the r48 circle... stumped on that as well. Thanks for any help guys!

 

[LTAZ]

What I have so far......

 

[ReMark]

You could use Polar Tracking or change the angle of your crosshairs to match that of your centerline using the SNAPANG command.

[LTAZ]

Not quite understanding.

[ReMark]

Not quite understanding.

 

Have you even looked at your AutoCAD Help files?

 

A third option would be to find the midpoint of your centerline and draw a circle there with a radius of 20 units. Where the circle crosses the line (in two places) draw a circle with the indicated radius of 3 units. Then construct the two remaining circles in any matter you choose. When you are finished drawing all four small circles erase the first (large) circle.

 

There are probably an additional three ways to draw the circles I haven't even thought of but I have not had my first cup of coffee yet so I'll let someone else volunteer that information.

[JD Mather]

Quick look at this I would say whoever did it didn't know what they were doing.

Am I missing something or is there a missing dimension on that row of holes?

I'm guessing that the second hole in the row is at 25 on the X.

Making that assumption I would create a vertical construction to find the intersection and then using geometry to solve the other locations

- draw a line perpendicular to the centerline you have for the row at the center of this circle.

Then offset 20mm as needed for the other centers.

 

Second question is pretty easy (see attached image).

 

Practice, practice, practice.

 

Also, if your field is Mechanical - you might want to spend your valuable time learning one of the next generation CAD tools like Autodesk Inventor.

Students can get Inventor for free from http://www.autodesk.com/edcommunity

Edited December 27, 2010 by JD Mather

[rkent]

They didn't provide enough dimensions for the left holes so simply space them evenly between the top and bottom horizontal lines, and each circle is space 20 apart.

 

The circles on the right have angles called out and you have the center line dim.

[Jack_O'neill]

I agree with the others, you'll just have to guess at the placement of those holes. They told you the center to center distance, but there is no indication as to the actual location. You also don't have enough information to place the R3 holes that are layed out radially there in the middle of the drawing. If you look closely, that 60° dimension has nothing to do with those holes, and other than the diameter dimension they gave you, you really have no idea as to where they are.

 

I hope that this drawing is really an exercise where you are supposed to find and fix all the things that are wrong with it. You send this to a machine shop, you are going to get it back with numerous requests for clarification.

[bbankston]

The dimensioning is foreign to me, LTAZ. I'm trying to recreate it as well. What's up with X,Y coordinates?

[bbankston]

LTAZ,

 

Unless I'm missing something - everything works except for the area I have circled. See attached. That's a real bad tagent with the arch R6 and the 30 deg. downward line and the arch R24 doesn't even touch arch R6. Methinks the drawing is dimensioned wrong?

[JD Mather]

Here is the solution - 1 missing dimension (assumed circle tangent to 13 line)

2 incorrect dimensions 50.3 and 56.3 wrong and not needed.

Plate.zip

[Jack_O'neill]

Hi, I'm just getting started in Autocad and I've taken a class, now I'm in between semesters waiting on the next class to start, so I've found a couple of assignments on the net that I'm drawing. I'm stuck on a few of the circles of this plate. The 4 R3 circles on the left part, I can't figure out how to get the exact placement of them. I have the center line that they go on, but can't figure it out. Also, the 2 farthest right circles that go on the r48 circle... stumped on that as well. Thanks for any help guys!

 

[ATTACH]25412[/ATTACH]

 

I've had time to redraw this now and can offer a couple of suggestions. The 4 r3.0 circles on the left can not be accurately placed with the information given. You can kinda sorta visually line them up, but there is no way to know where they are accurately. You can't even say for certain that they are centered in that web between the cut-out and the edge of the piece, though it appears to be so.

 

The other 2 circles you asked about on the r48 radius...you know where the center of that radius is. To locate the two circles, draw a line from the center of the 48.0 radius off to the right (parallel to the x axis) some distance more than 48 (actual doesn't matter). Then draw a circle at that center with a radius of 48. You'll delete this later. Rotate the line you just drew up 36° and draw your r5.0 circle at the intersection of the line and the r48 circle. Then rotate the line 26° more degrees and draw another circle at that intersection. Now erase the circle and the line and your r5.0 circles are placed where they should be. You can use the same method to place the other 2 r5.0 circles by using the center of the 39.0 radius shown in your example.

 

As for the 6 r3.0 circles in the middle of the drawing, you can accurately place 2 of them, those being the ones at the top and bottom of the radial layout. The other 4 appear to be at 60° intervals, but unless I'm just not seeing it, there is nothing on the drawing to indicate that. The 60° dimension given refers to the two r5.0 circles on the 39.0 radius.

 

There is an area of the drawing that comes out a little strange. BBankston mentioned it, that being the r6.0 fillet in the lower right (center at 181.7). The first thing you need to be sure you do is check to make sure that the 30° line that forms that edge starts at a -2mm, and not a +2mm. Whoever drew this originally using ordinate dimensions running both directions from "zero" was trying to get the guys in the machine shop to come to his office and flog him. The first 15 years of my adult life were spent in a tool and die shop, and dimensions like this are extremely annoying to work from. There are occasionally reasons to do it, but its usually done in both axes from a location hole or pin. To do it in one axis and not the other is confusing and invites a wrathful response from people who will visit the drafter with large hammers in thier hands. The reason I say this is that the 2.0 dimension if above zero will not let the 30° line come in tangent to the 6mm fillet at the bottom. That's why bbankston's drawing didn't come out right. Drop it down to 2mm below the zero point and it works (well close enough, it's not quite tangent to the circle). Even at that, the other side of this fillet won't come out right with these dimensions. The vertical line from the big arc above won't be tangent to the fillet. It is machinable like this, but it won't be a smooth transition.

 

I'm sure all this is as clear as mud, especially to someone new. If you or anyone reading this has any questions or need clarification (or need to point out a mistake on my part) don't hesitate to either post it here or email me.

[LTAZ]

Wow, thank you for the help guys.