47.5 x 47.5 inch / 1206.5 x 1206.5 mm
All geometry for machining should be drafted in Model Spaceonly at full model scale. Do not enter Paper Space nor scale your model by other means. If you work piece is 24 x 24 inch, it should be drawn as 24 x 24 inch in AutoCAD.
Right-Click and choose "save link as" to download the AutoCAD 2007 laser cut template for file preparation.
Use POLYLINES for rectangular objects and lines.
If a continuous/closed shape is made out of more than one polyline, make sure that you join all lines.
To do this, key in "pedit" (enter polyline edit menu), then "M" (select multiple lines). Select the objects and hit Enter.
Hit Enter again to convert to polylines, then select Join from the cursor menu or key in "J." Hit Enter to skip fuzz distance and Enter once more to finish and exit.
Keep at least 1/8 inch space in between closed shapes, and also between closed shapes and the material outline. It is okay to place shapes closer to one another than 1/8 inch if required by the project, but remember that there is a substantial width to the cut produced by the laser.
Be absolutely sure that there is no duplicate geometry stacked directly below the finished shapes. If there is, the laser will cut these lines again and again, ruining your material and damaging the laser bed. (Oh please, Oh please - check this...)
AutoCAD has a built-in (partial) solution for this. Select all line work and key in "overkill." In the OVERKILL window check all settings. (Checking the PLINES option ensures that line segments overlapping polylines will be deleted and vice versa.)
Hit OK and AutoCAD will report any duplicate geometry deletions.
Imperfect overlaps can be deleted by adjusting Numeric fuzz.
Don't place too much faith in this tool... it's not perfect. Your vigilance is still required.
The laser cutter has a porous, honeycomb steel bed. This allows negative pressure from the bottom to help "pull" the laser through the material and remove soot and smoke from the cut line.
Small pieces can either fall through the honeycomb or become partially engulfed and turn upright, putting them in danger of touching the laser head. This will corrupt the job and could damage the machine.
To avoid this, tab any small "island" cuts by connecting them to outer material with solid geometry. Tabbing is also useful for maintaining larger pieces' positions relative to the material, as seen below.
For more on tabbing, including a table of optimum tab sizes for common materials, click here.
Assign your geometry to a specific layer: (CUT, ETCH, FILL, your material dim).
Only the AutoCAD Shape Entity (*.shx) fonts can be used. If special fonts are used, they will automatically be converted to AutoCAD Shape Entity (*.shx) format when saved as a AutoCAD Interchange File (*.dxf)
Assign text to the appropriate layer (CUT, ETCH, or FILL).
To specify fill, assign the outlines (all stroke, no fill) of the geometry you intend to be filled to the layer "FILL."
While you can specify the intensity and/or density of the fill in the Special Instructions/Concerns portion of the DAAPspace RPC submission page, it is up to the laser operator to create any fill geometry.
By default, the outline of the fill will not be etched unless otherwise specified.
Position the artwork so that the origin is in the lower left with at least 1/8 inch space in between the edges of the material and your geometry.
To place the origin at 0,0,0, draw a line by keying in "L" and enter the first point at "0,0,0." Then drag the lower left corner of your material to that point and delete the line.
Measure your material and create the outline on the layer "your material dim".
To set units to inches go to the Format menu and select Units.
In the Drawing Units window, set Type to Architectural and Insertion Scale to Inches.
Often objects such as windows and furniture are imported into AutoCAD as blocks. To break blocks down into usable geometry, key in "explode," then window pick any blocks and right click to finish.
This action may have to be repeated several times for nested blocks (blocks within blocks).
Hatching is most often used for etching material textures such as brick and tile into architectural models. Hatches are essentially blocks and should be treated as such for machine prep.
To break down hatches into usable geometry, key in "explode" and window pick any hatch objects. Right click to finish.
Remove extraneous information from your file by keying in "purge."
In the Purge window select Blocks and Layers and check Purge nested items. Then click Purge All and Yes to All.
You may find that there are layers without geometry that you are unable to delete. This is because they are referenced to another drawing.
To remedy this, key in "xref." In the EXTERNAL REFERENCES window, right click on any linked files that are not being used and select Detach to remove them.
To do one last check for extraneous geometry, key in "zoom" (enters zoom menu) then "E" for zoom extents.
If any geometry shows outside of your material boundary, delete it prior to submitting your file.
Save the file as AutoCAD R12/LT2 DXF (*.dxf).
Upload the AutoCAD Interchange File (*.dxf) to its corresponding job on DAAPspace.