Pocketing letters

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PUIQ
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Joined: Fri Aug 31, 2018 1:18 am

Pocketing letters

Post by PUIQ » Sun Sep 16, 2018 5:24 am

Hello,

I wrote an email to Andrew @ QCAD asking if I could use QCAD to automate the creation of metal nametags (aluminum and brass) with a CNC machine and a small database. I should make the request public so Ribbonsoft and the community can benefit from any answers.

"The tags I have now were made with some pocketing on the letters (I think Times New Roman font) and a couple symbols. I want the font size to shrink when needed to fit in the predetermined text area. The idea I have overall is to have an Access database create a BMP with 16 nametags and then send the file over to some GCode generation software and have it cut the tags seamlessly without any further interaction. Maybe there is a better way to do it, but I'm looking for software to help me get from data to the actual carved tags. "

He responded:
QCAD comes with a powerful scripting interface (JavaScript), that allows you to
add virtually any kind of functionality to it as either GUI tool or command line
tool. Basic JavaScript programming is required.

Your problem would break down into:
1. - Creating a document with the desired text (addText)
2. - 'Exploding' the text into polylines (Explode.explodeEntity)
3. - Offsetting these polylines to create the "pockets" (RPolygonOffset)
4. - Exporting the resulting polylines as G-Code, i.e. iterating through polylines
and writing G1/G2/G3 for each segment, G0 between segments, etc.
I'm trying to do this manually first so I know QCAD can do it before I buy it.

I'm at step #3, but having a hard time doing it manually in QCAD. If I select the outer polyline and create the pockets toward the inside, it completely fills in letters like "b" and "e." I would like it to stop at the boundary of the inner polyline so it's actually a letter. I've attached a picture showing what is going on. Can anyone help get the automatic pocketing to stop at the inner polyline?

I haven't yet solved the shrinking of the text as needed to fit the text on the tag. If anyone has ideas on that, it would be much appreciated.

Two other attachments help show what I'm looking for. Desire 1 & 2 show the letters tapering a little bit inward at certain points. I'd like the pockets to stay inside the the outer polyline so they can be very thin in certain spots.

The nametags are 1x3" in size, so the letters are about 4 mm tall. There probably wouldn't need to be much pocketing done on these, actually. I just want to make sure I can make the same tags.

Thanks for any help!

Best
C
Attachments
Desire1.JPG
Desire1.JPG (13.58 KiB) Viewed 2520 times
Desire2.JPG
Desire2.JPG (11.91 KiB) Viewed 2521 times
Pocketing.JPG
Pocketing.JPG (66.86 KiB) Viewed 2522 times

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Husky
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Re: Pocketing letters

Post by Husky » Sun Sep 16, 2018 8:24 am

Hello PUIQ - welcome to the QCAD Forum,

that looks challenging. 8) Maybe there is a reason why they mostly use single line fonts for 4 mm (?) text. :wink:

Here are my thoughts.
I you are talking about a milling process then I doubt that you will find a milling cutter which is able to create a clean pocket for a 4 mm letter. All what you can do is to mill the contour with an engraving cutter.

If we are talking about a laser cnc then I would assume your tool path is much easier to create/program when you use ONE offset contour PLUS a hatch. The created gcode should first laser the hatch and then the offset to get a clean pocket.

Husky-2018.09.16-02.png
Husky-2018.09.16-02.png (55.41 KiB) Viewed 2509 times

Just my two cents. :wink:
Work smart, not hard: QCad Pro

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Clive
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Re: Pocketing letters

Post by Clive » Sun Sep 16, 2018 2:18 pm

Hello PUIQ,

This is a simple task, there is no need to mill the letters by pocketing, too small! Simply keep outlines and any inner contours like with an 'e' and use a hatch fill instead. I have done this type of things lots of times with text, a laser cutter would be used to engrave the fills accurately and precisely and the engrave depth can be changed, but does depend upon what material is used - only laserable metals of course could be used!
For the best support please state your operating system, QCAD version and add any supporting DXF/DWG files, screenshots etc...

PUIQ
Newbie Member
Posts: 3
Joined: Fri Aug 31, 2018 1:18 am

Re: Pocketing letters

Post by PUIQ » Mon Sep 17, 2018 12:01 am

Hello Husky and Clive,

Thanks very much for your quick replies!

I can see it does get challenging. ..and I can see how pocketing a 4mm letter isn't workable now.

As a note, for this project, I'll be using a milling CNC machine with metal nametag plates.

As I look closer at the current nametags, it appears that there's a B carve going on and the bit goes deeper for the areas where thicker parts of letters are wanted. The bit doesn't appear to be going very deep and looks like a bit with about a round end on it.

As far as getting the letters to show up against the metal surface, the tags come with a plastic protective coating on them. After the engraving is done, an acid bath is used to oxidize the surface where a protective plastic film has been milled away. That's all I really need to do is strip that coating away.

If I switch to single line as the approach for the letters and only do pocketing on the symbols, can QCAD CAM generate G-Code to manage deeper engraving to widen and narrow the letters at certain spots so it looks like a specific font?

...and specifically, explode polyline was suggested originally because I mentioned pocketing. Is there a different method to use when supplying text and carving it with a single line approach?

Oh.. and shrinking the text. Is it possible with QCAM to manage that so the text stays within a designated two-inch area?

I'm intent on making this work and I'll post the entire solution once I've worked it out. :-)

Thanks a lot guys!
C

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andrew
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Re: Pocketing letters

Post by andrew » Mon Sep 17, 2018 9:57 am

PUIQ wrote:
Mon Sep 17, 2018 12:01 am
If I switch to single line as the approach for the letters and only do pocketing on the symbols, can QCAD CAM generate G-Code to manage deeper engraving to widen and narrow the letters at certain spots so it looks like a specific font?
No. Single line glyphs are by definition rendered with a single line at a constant width. These fonts don't contain the information that would be necessary to widen / deepen while engraving.

Having said that, there are fonts in QCAD/CAM that are "single line" buy actually use multiple lines to create wider sections. For example the Roman series:
Screen Shot 2018-09-17 at 09.53.10.png
Screen Shot 2018-09-17 at 09.53.10.png (142 KiB) Viewed 2469 times
PUIQ wrote:
Mon Sep 17, 2018 12:01 am
Is there a different method to use when supplying text and carving it with a single line approach?
With a single line font, you would typically just use an engraving tool at a constant engraving depth.
PUIQ wrote:
Mon Sep 17, 2018 12:01 am
Is it possible with QCAM to manage that so the text stays within a designated two-inch area?
You could use the bounding box to find out the width of the text and then apply an X Scale factor accordingly.

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Clive
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Re: Pocketing letters

Post by Clive » Mon Sep 17, 2018 10:10 am

May I ask what engraving machine you would be using please?
For the best support please state your operating system, QCAD version and add any supporting DXF/DWG files, screenshots etc...

PUIQ
Newbie Member
Posts: 3
Joined: Fri Aug 31, 2018 1:18 am

Re: Pocketing letters

Post by PUIQ » Thu Sep 20, 2018 4:48 am

Hello gentlemen,

Thanks for your replies.

The unit I'm planning on getting is the Baileigh DWR-0906 desktop router. It's small, but I aim to kick out 16 nametags at a time with it.

The fonts in CAM, I'm not yet sure how to use, but I'm going to read some manuals and see where I end up. CAD and CAM is something one wants to fully understand before using expensive machinery that can damage things. I'm going to read the tutorials as a start. If there are other things to read, I would love the input.

One thing I tried though was:
1. Add text
2. Select text
3. Add tool in CAM
4. Generate toolpath

I loaded the G-Code from that process into Camotics and it looks like a valid way to go about this. The G-Code output had the tool tracing the outline of the characters. The only concern is getting a font with characters thin enough and the right sized bit to create that filled-in appearance. Would you say I'm on a decent path for this project? However, It does look like I have a tool too big and it's carving out the inner area of the letter A.

Thanks a lot.
C
Attachments
Camotics.JPG
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andrew
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Re: Pocketing letters

Post by andrew » Thu Sep 20, 2018 8:40 am

You'd typically use an engraving tool, not a mill to engrave small letters. Some engraving tools have a flat tip (indicated as "cutting edge diameter") to create a flat bottom surface:
Screen Shot 2018-09-20 at 08.38.43.png
Screen Shot 2018-09-20 at 08.38.43.png (14.36 KiB) Viewed 2357 times

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