How do I create a DXF file for engraving

[David George 1Participant @davidgeorge1]

I am in the process of making a press tool to make some dial indicator disks. The body of the tool is 2 inch diameter with a 180 degree scale for pressing into a thin brass disk. I have drawn the main piece of the tool and as the engraving is quite small was going to ask a local company to laser engrave it for me but I have sent the model of the piece to them but they want me to provide a DXF file of the engraving as that is how they work. When at work I had engraving for mould tools engraved by them but the drawing office would make the DXF file for the engraving. Has anyone any clue how I can make one.  The lines are 0.020″ wide and the characters are 0.055″ tall.

 

The engraving is mirrored to get the correct writing on the part. I only need a DXF for the engraving does that cause a problem when creating it from my model.

David

 

[JasonBModerator @jasonb]

When the Small first screen of Alibre comes up click the furthest right icon of a drawing rather than the usual new part or new assembly.

From there you create a drawing selecting paper (landscape A4 blank will do) The next screen that opens allows you to select the part you want a drawing of, it’s orientation and what views.

That then puts the part on the drawing sheet where you can move it about, scale (1:1 for this job) and add any dimensions. I would put at least one then they have a check of overall size.

Finally when happy save and then go to File and then export as a DXF

Re laser engraving make sure it is going to be deep enough to use a sa press tool

[David JuppParticipant @davidjupp51506]

Like Jason says.

If you only want the details of the engraving to display in the DXF, you’ll need to hide some projected edges of the part (perhaps).  To do that add a new layer in the 2D drawing, call it something meaningful (e.g. ‘invisible’) and turn off visibility for that new layer.  You can assign any lines that should not show to that new layer.

[David JuppParticipant @davidjupp51506]

I’d also check with the engraving company about exactly what they need in the DXF to give your desired result on the finished part – e.g. do the ‘lines’ need to be filled in?  Can they work with outline fonts, or do the characters need to be filled in, or do they expect single stroke fonts? (which Alibre can’t handle).

[John HaineParticipant @johnhaine32865]

Will laser engraving give enough depth for a press tool?

[David Jupp]

On David Jupp Said:

…do they expect single stroke fonts? (which Alibre can’t handle).

Please could you say in general how Alibre handles fonts. I have never used it, but suspect the above statement may have only a very narrow scope of truth.

A single line engraving font would be (is as a matter of fact, e.g. on the CamBam website) available as a True Type font file in the same way that Times New Roman is available as a .ttf file. From what I read, Alibre uses TrueType as standard. A Hershey font is another very closely-related item. See also:

http://www.imajeenyus.com/computer/20150110_single_line_fonts/index.shtml

https://k40lasercutter.com/product-category/single-line-fonts/

[JasonBModerator @jasonb]

I’m sure David can explain it better being Alibre Staff but the problem that I see is that Alibre treats each letter as a sketch which must be closed and then it can be extruded. It does not class a line as a closed sketch so woun’t be able to extrude it as a feature.

So your typical Times New Roman has a line all round and an area between. A single line font is just that a single line with no area to extrude. See below where it flags up an error for a line but not the text

[David JuppParticipant @davidjupp51506]

Single stroke fonts have no width so can’t be used to produce standard features.

The ‘thin wall’ features available in higher levels of Alibre don’t support text at all.

[John HaineParticipant @johnhaine32865]

CamBam can generate “filled in” letters and engrave them as intaglio.  It probably also has the ability to engrave them in “negative”, i.e. the letter shapes stand up. (Extaglio?)

[blowlampParticipant @blowlamp]

If you don’t already have it, then I think CamBam might be what you need to use for this job as it’s a little more involved than it first seems. CamBam is free, if you don’t use it to make g-code once the trial period is over.

Take a DXF out of Alibre and into CamBam, from there I think you will be able to use CamBam’s ‘Fill Region’ options to fill the text you already have to create infill curves for a laser to follow. You can then Export the whole lot out as another DXF for laser engraving.

‘Fill Region’ is under the Draw menu and is easy to use.

The picture shows the five options for filling a Region. I know the first three look the same, but the results they produce are subtly different, depending on the geometry they are applied to. You can make these curves as dense or as sparse as you need.

 

Martin.

 

[JasonBModerator @jasonb]

I notice there is some variation in spacing of the lines in the above image, with a laser is there a risk of going too deep if the beam passes over the same area more than once?

[John HaineParticipant @johnhaine32865]

<p style=”text-align: left;”>You don’t need a dxf file, text for engraving can be entered directly into Cambam</p>

[blowlampParticipant @blowlamp]

Jason.

The offset curves generated from the characters are correct, but where they merge in the centre of the character it inevitably becomes less even.

The original poster may have to experiment with the various options for each character to get the desired results. 😉

 

Martin.

[blowlampParticipant @blowlamp]

John.

 

The original poster could start afresh, but it would be pointless if he already has a good drawing from Alibre.

 

Martin.

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