|Home | Online Order | DXF Made Easy | WMW Repro FAQ | Hobby | Calendar | Conversions|
Back To DXF Made Easy
DOS reserves special characters for use in its operating system. These characters should be avoided in your drawing name, layer names, symbol names, or anything else to do with your drawing if at all possible. These characters include pretty well all punctuation marks, with the exception of the dollar sign ($) and the dash(-). Using the "$" is not recommended as it is used in layering conventions by AutoCAD for special uses, i.e. to show an XREFed layer. To keep safe, use only alphanumeric characters and dashes.
WHAT YOU ARE EXPORTING
MiniCAD writes out only those layers which are visible or greyed to the DXF file. Invisible layers are not exported. All symbols in the library, whether used or unused in the drawing, are exported. Things which are unique to the Macintosh environment do not get exported, e.g. PICT images. All classes and the information contained in them are exported, whether visible or not. Please take note of this, as you can really get embarrassed by things which show up on the other guy's screen that you weren't expecting. Worksheets are not exported.
NOTES ON VARIOUS ITEMS WITHIN MINICAD
Fill patterns, including "white" or "opaque" are not exported. As a rule, AutoCad does not use fills, although it can use solids in some cases. There is no equivalent to null opaque fills, i.e. white fills. Therefore you cannot "hide" something with white fills. DXF does not understand MiniCAD fills, therefore they are all truncated. The outline of filled objects remains, even if the line type was none or line weight was zero. Objects hidden by the fills become visible. Since opacity does not exist in AutoCad, the concept of hierarchy (objects in front or back) is not applicable.
Hatches are understood by DXF as a series of individual lines. Although they can give you the visual effect you want, they will make your file sizes increase. Unless you really need them, keep it simple.
All fonts are brought in as the default "Standard" style. All fonts will look alike, and look like stick fonts as a default. The font insertion point is remembered, and the font is justified on it. Left, Right, and Center alignment hold true. Although the text starting point is remembered, AutoCad text is usually fixed width (i.e. it has no kerning between letters), and you should expect differences in the length of your text strings.
If you have a text string which is longer than 256 characters, you will not be able to import it into Autocad - remember this in your copyright notice, often this is longer than the 256 character limit. The result will be an error on import of the "premature end of file on line xxx" .
MiniCad drawings can get text entities which are a size of 0 in them. Commonly this is caused by pasting text from a large scaled layer to a small scaled layer. This generates an unimportable DXF file.
MiniCAD symbols are exported as blocks. Note for users of MiniCad v4.: If any symbols have both a 2D and 3D component, you must either export 3D DXF, or get rid of the 3D component. For example, if you use the wall tool in a symbol (even if you do not assign a Z value for height) you have a 2D/3D hybrid symbol. This will cause an undefined block error when 2D DXFing into AutoCAD. This has been corrected since MiniCAD 5.
Symbol names are converted to DOS style names, i.e. spaces and special characters are turned into underscores. If you have symbols in which the only difference in name is special characters, you will get a duplicate definition of block error in AutoCAD.
If you are in the habit of deleting all the symbols in your symbol library to make smaller DXF files, be sure that you understand that classes are still exported even though they are invisible. If you have an instance of a symbol placed in an invisible class which is not in your symbol library, the resulting DXF file will not import into AutoCad.
AutoCAD has two types of line entities - lines and polylines. Lines in AutoCAD have no thickness assigned to them when drawing, instead the thickness is given at the time they plot by matching the line color to a pen weight. Polylines have a thickness or line weight assigned to them, but are more difficult to work with than are lines. In my experience, people prefer lines to polylines.
When you export a MiniCAD drawing, all lines with a thickness greater than 1 mil are converted to polylines. Lines of 1 mil are treated as lines in AutoCAD. If you expect that someone will need to modify your drawing, you can make their life easier by changing the line weight to 1 mil. This should also reduce the size of your DXF file. Remember - symbols need to be edited from within the symbol itself, a global change will not affect your symbols. Additionally, global modifications will not modify a layer which is at a different scale than the active layer, even when Show/Snap/Modify Others is selected from Layer Options.
Lines of 0 mil (invisible lines) are also exported as lines in AutoCad, just as though they were 1 mil lines.
Because walls are a unique entity to MiniCad, they are not supported as walls in DXF. Fills do not transfer. Symbols such as windows which have cut the wall are kept, and the wall breaks where the symbols were inserted remain clipped in the resulting DXF file. If you have filled walls (even white fill), be aware that the walls are filled by creating a separate polygon in MiniCad. As a result, you will have the 0 mil lines exported with your file. This will show itself in a) duplicate lines along all your walls, and b) miter lines at all your wall ends. To get around this, remove all fills before exporting.
Layer names will be truncated or modified to meet AutoCAD capabilities. If you have two layers which are identical except for the special characters (which are converted to underscores), those layers, and all objects on them, will be combined into one layer. For example, the layers "1/4 room" and "1 4 room" will be on a layer "1_4_room". All layers are on and visible when brought into AutoCAD.
Note for version 5 users: If you use Layer Colors (in your MiniCad preferences) you should be aware that the color matching in MiniCad v5 has a bad habit of exporting the lighter colors as white. In AutoCad, this results in layers which have no color, and the information does not appear. The AutoCad user must then enter the Layers dialog and assign a color to those layers in order to make them visible. In other programs, it is not as simple to clean up. Best bet is to avoid the use of Layer Colors when exporting.
Be aware of your layer scales. MiniCad exports all layers to a single scale, the smallest in the drawing. If your consultant is dropping his blocks (symbols) into your drawing, he will not appreciate it if your drawing has an unexpected scale.
As an alternative to exporting your layers to DXF, Classes can optionally be substituted for layers upon export. Keep in mind that, when doing so, you are not exporting any of your original layer info. Also bear in mind that the top-bottom ordering will be reversed, i.e. the class which is on the top of the menu will be the layer on the bottom of the menu.
Classes are NOT layers. They are a MiniCad method of using visibility to control your drawing. All classes and objects on them are exported.
I have experienced a number of instances when exporting by classes that an invalid layer name is generated, and this creates a DXF file which cannot be imported into AutoCad. For this reason, I avoid exporting by classes whenever possible.
All layers are exported at the scale of the layer with the smallest scale (as in 1/8" scale is smaller than 1/4" scale). Therefore, layers at different scales are brought into AutoCAD at the wrong size, e.g. an object on a layer which is at half scale compared to the full scale layer will come into AutoCAD at twice the size. A drawing done at 1/4" scale with a 1:1 title block layer will turn into a normal sized drawing, with a postage stamp sized title block in the center.
To convert a layer to a different scale: place locus in the top and bottom corner of the sheet for positioning guides. Go to the Scale... menu command, or the Scale option under Layers... and change this layer to the scale you wish. Select all objects on that layer and use the Scale Object... command. Use a scale factor which is the ratio of the scale that your drawing is at. For example, to convert a 1:1 title block to 1/4" Scale, multiply by 48 (1/4" = 1:48).
CORRUPT DRAWINGS OR OBJECTS
Corrupt objects are translated through DXF following the same conventions as normal objects. Most common are objects which are off the normal page area., and leftovers from previous DXF imports.
Remember, the less you export, the less chances of something going wrong. Clean your drawing up before you export, and get rid of all the unnecessary items.
DXF files created by MiniCAD version 5 and below only allow for 7 basic AutoCAD colors to be exported. All other colors will be "rounded" to similar colors. MiniCad 6 and up exports all colors (Thanks Sean).
If you are working on a white background, the items with a pen colour of black are changed to white when they are imported into AutoCad. Bear in mind that AutoCad users consider color to indicate line weight.
Dimensions are brought in as individual entities, i.e. several lines and some text, rather than as dimension entities. The effect is much the same as if you had ungrouped the dimension in MiniCad.
Worksheets and their data are not transferred through DXF into AutoCAD. This holds true whether or not the worksheet has been placed on the drawing.
If you need the information from your worksheet to be exported, a workaround is available. First, isolate your worksheet so it is the only thing visible. Select your worksheet and zoom to normal scale. This will cause the worksheet to be centered on the screen. Then export as PICT. Now re-import the PICT (as PICT, not as PICTURE) and it will come back in as objects instead of a worksheet entity. Ensure than it is aligned with your original worksheet and everything will work.
Text which has been linked to symbols is not transferred into AutoCAD via DXF. You can get around this for exporting by Symbol to Group. This may be changed in MiniCad v6, I have not had time to test yet.
Bitmap images which have been placed, pasted, or otherwise imported onto your drawing are not transferred through DXF. If you REALLY need that bitmap image on the transferred AutoCad drawing, you can save it as an IBM formatted TIFF file, and in AutoCad release 12, it can be imported with the TIFFIN command. This is not recommended.
Preparing a DXF file from MiniCAD
Following the steps listed below will result in a fairly clean DXF translation. Given the constraints of the DXF format, and the wide variety of methods used to create a drawing, it is by no means all encompassing. The priority in this example is usability by the receiver without the risk of failed import.
First - Save As under a different name. For ease of finding the file, save it on your Desktop. Give it a name such that you can tell it is a temporary file. Better still - have a folder called temp items on your hard drive to keep yourself organized.
Make your drawing as clean as possible. Remove unwanted layers and information. Purge the symbol library of unused symbols. Remember - when you delete a class, all the items which were in that class are put into the class "none", so you cannot simply remove a class and expect that the items are gone too. In order to remove items which are in a class, you can do the following. a) reverse the visibility of all your classes, i.e. make visible classes invisible, and vis versa. b) make sure the active class is one which you want to remove c) select all, and delete d) make all those invisible classes visible again and finally e) purge unused classes.
Further to cleaning up your drawing, you should get rid of any objects outside the bounds of the page.
You want to change all your layers into the same scale. This will allow you to make global modifications necessary to creating a good DXF file and ensure that the resulting file is at the correct scale. Go to the odd-scaled layer(s) and place a locus at the top right and bottom left corner of the drawing sheet. This will force the position of the objects to remain the same as you manipulate them. Unlock any locked objects. Do a symbol to group to allow symbols to scale. If you have nested symbols, you may need to do a shallow symbol to group first. Now go into the Scale... dialogue and change only this layer to the same scale as the rest of the document. The size of the objects will change proportionally. Now select all, and use the Scale Object command with the proper ratio to restore the objects size relative to the page size. If the locus you placed in the corners does not line up, move them to the correct position. Be aware that if they do not line up, it is a good indication that you have off page objects which need to be deleted. In version 5 of MiniCad and above, there is a handy external command "Fit to Objects" which will help you detect them. If you reverse the order and do the Scale Objects before the Scale... command, you will get unexpected results.
Next, change your Layer Option to Show/Snap/Modify others. Select All, and (if you still have anything locked) Unlock. Then Ungroup several times, pressing Okay when prompted about ungrouping walls, dimensions, et all. Use the ungroup command enough so that you are confident that all your nested groups are ungrouped. Do a Symbol to Group command and a few more Ungroups. Repeat this until you are confident that you have decomposed everything on your drawing.
We reduce symbols to groups for several reasons;
1) so that the line weights change to 1 mil during global modifications, and
2) so that text linked to records appears in the translated files.
3) to reduce the risk of an undefined symbol error when re-importing into the other CAD program.
If you are using MiniCad v5 or above, do a Purge Unused Objects and get rid of unused everything. If you did the above steps right, you should have no symbols in your library, but you will have any empty folders they were organized in. They do not matter.
At this point, you may want to remove all lines of 0 mils. To do this, go to the Custom Selection... dialog, and create a command to select only 0 mil lines. The command should read something like...
This should result in all 0 mil lines being selected so you can delete them.
Now change all the remaining line weights to 1 mil. If you want to add more layers and/or rearrange the layering of your drawing to make it more editable on the DOS side, do that now. Since AutoCad users assign line thickness by colour, the ideal situation is if your lines are coded by colour as you create them. If you don't use colors to differentiate your lines, at least try to assign unique layer colors and check the "Use Layer Color" option under your preferences prior to exporting. This makes editing your drawing easier for the AutoCad user. Remember that not all colors are supported, so turn your monitor depth down to 16 color and select the basics. If there are no dimensioned lines on your drawing, or if your drawing is not to scale, it would be nice if you drew a dimensioned scale bar in the bottom corner so that the scale could be verified after importing.
Given how much most consultants like your dimension on their drawing s, you might be wise to hide all your classes except the dimension class, cut all the dimensions from all the layers, and option-paste them onto a new layer called dimensions.
Remember - only visible layers are exported and all classes regardless of visibility are exported.
From under the "File" menu, go to "Export", then to "Export DXF". A standard Macintosh file save dialog box will appear. Enter a name for the DXF file and press the Save button. You are given options as to exporting classes, layers, pen fore, and pen back as layers. Use "Layers" unless you have set up your system specifically for exporting by one of the other options. You are then given the option of "Export 2D and 3D Objects". I would highly suggest you choose this option, as I have experienced difficulties whenever I have tried only exporting 2D. The checkbox for decomposing 3D symbols can be ignored, as you should have already removed your symbols.
The name you use should follow DOS file naming conventions. It should be 8 characters or less with no DOS special characters in the name (* & ? . : etc). At the end of the file name it should have a ".DXF" extension.
For example valid DXF names
bad DXF names
first floor plan.dxf
Congratulations - you have made a fairly good DXF file. Put it onto a DOS formated disk and away it goes.
If you are running a modern version of system software, you have the ability to format, read, and write DOS disks. If you are running an older version of system software, you may need to use a third party utility to write to a DOS disk. If you modem the file, do not use MacBinary transfer.
Importing a DXF file into MiniCad
In the simplest case, importing a DXF file is nothing more than going to the Import DXF... menu and bringing the file in. However, life is rarely simple. While I can't cover every possible contingency here, we will go over a few of the most common problems.
Remember - you can't revert back to an unsaved drawing! Save your drawing as soon as you have imported it, and then make your adjustments.
While the manual says that you should start with a clean drawing, I've had better success with metric drawings when I preset the scale and units. First, set the page size to about the right size. Then go to Units... and select the units you want, usually millimeters. Go back into Units... and choose Custom, and reduce the drawing stored accuracy to a reasonable number. Then go to Scale... and choose the scale you want. Now you should be able to import the DXF file. If you still have problems with the imported file being at the wrong scale, it could be that it is done in meters instead of millimeters, for example a drawing in meters at a scale of 1:.5 is equivalent of a 1:500 drawing in millimeters.
IMPORTING A PAPER SPACE DRAWING
When you import a DXF file which originated with a paper space drawing, you have everything at the same scale, regardless of how it appeared in AutoCad. Clean up the model space portion of the drawing first, usually this is everything but the title block. Set the scale to the correct drawing scale, place it in the correct position on the sheet and so forth. Then turn on the paper space layer(s) and scale them up by an appropriate amount. This may put them off position (most likely in fact). Group the objects, and position them via the Reshape dialog box. If you are lucky, the paper space entities may be inside a symbol which makes scaling easier.
WRONG SCALE AFTER IMPORT
This is possibly the most frustrating problem to have with an imported file. Sometimes an easy fix is to check under the Custom Units option of the Units... menu and see what the units per inch is set to. If it is simply confused by a factor of 10, or by 2.54 (metric eh?) you can adjust it here. More often, you need to use the Scale Objects... command and resize everything to fit. Sorry, I don't have any quick fixes here.
Communication is still the best answer. If you know the page size that the AutoCad drawings was set to, and know the scale that it was meant to be at on that page size, then pre-set those into a blank MiniCad drawing, they will not be changed when you import the DXF file.
There a a few ways which you can guess at the scale of a drawing from the DXF file itself. Most DXF files will have a Header section which has information about the file in human readable form. Open the DXF file in a text editor and look near the top for the LTSCALE and DIMSCALE variables. These are the linetype (dash) scale and dimension scale variables which the AutoCad user was working under.
EVERYTHING IS WAY OFF PAGE
Doing a Select All and pressing Command-3 will put you at 100% zoom in the center of what you have selected. Press Command-9 to set the origin (your cursor should look like a rifle scope). Then deselect all by clicking in a vacant area, and press Command-4 to fit your view to the drawing page. Press Option-Command-9 (snowflake cursor), and click in the center of the page.
THE DRAWING HAS A GREY AREA CLOSE TO THE PAGE
Your accuracy is set to high for the combination of units and scale chosen. Go into the Units... command, select Custom Units, and reduce your stored accuracy by a decimal place. This is also caused by having imported the DXF file at the wrong Units settings.
THE DRAWING IS TOO SLOW TO WORK WITH
You can clean up a DXF import fairly quickly by doing a few things.
Remember - you cannot Revert to Saved... unless you Save your document first, so the first step after importing a DXF file should be to save your work!
First, select Active Only from the Layer Options. Zoom out to see just a bit more than the whole page. Go to the top layer. Do a Select All and Group - you should see either nothing (indicating that nothing is on the layer), or all the selection handles of the group. If you only see a few of the group selection handles, you have objects off page you are not seeing. Ungroup and nuke the off page objects. Command-Down Arrow will bring you to the next layer. Version 5 and up users can do this easier with a Fit to Objects command.
After you have made sure you have no off page objects, you might find that reducing symbols to groups and deleting the unused symbols can speed things up. This is heavily dependent on how the drawing was created, so be sure to do a Save before you experiment.
We've seen a number of drawings that have "extras" in them which add to the overhead. Watch for empty text blocks, stray arcs, etc. which may be off page. Remember that you can go About MiniCad... from under the Apple menu and see how many objects are in the drawing.
Improperly scaled linetypes (dash styles) can reduce drawing speed to a snail's pace. The sign of this is when a line draws at a very slow speed across the page. This indicates that the drawing was imported at the wrong scale, and the dashes are too close together. Delete the dash style with one that draws normal, or edit the dash style to a more normal spacing.
©1996-2001 Dave Weber firstname.lastname@example.org
last modified December, 2001