Managed to model a finger joint box with relieved fingers --- now how to actually cut it? Allow OpenSCAD to write out files?

translate([x,y,z]) {
    /* Nothing here has any way to access the the new origin in global coordinates. */
}

Hi William, I've not followed this whole thread, but if you want to cnc finger joints, I would not start with scad. What cutting tool will you be using, and what is the material? What tolerances are you looking for? Unless you intend standing the pieces on edge, you will not get square corners profiling them with a router bit, although if in wood, with a small diameter bit, woodfiller can solve that. If you are using edm, plasma, laser or waterjet, then that will require a different solution, depending on how thick the material is too. The tricky area is the interface between theory and practicality. It would be relatively trivial to 3d print it, if it was just a proof of the model you were looking for - But you'd most likely have to take into account tolerances again.

Best wishes,

Ray

I don't need a tracing of the outlines, I need a series of offset lines for specific fingers --- the radiuscut module movements.

As I've noted in pseudo code I have the numbers there (I appreciate JordanBrown's note about the numbers being in the local coordinate space --- I'll have to see if it's necessary to re-work things so that any transforms are taken into consideration --- actually, this is pretty easily done in G-Code).

Yes, I know now that I can write things into the Console and extract/filter them --- but that's a lot of extra post-processing which isn't convenient, and isn't suited for a naïve end-user and I'd like for this to be a supported and turnkey usage of OpenSCAD.

Is there an OpenSCAD developer who is interested in CNC and doesn't have a machine and who thinks implementing this would be feasible? If so, please contact me directly and we'll see what can be worked out.

William

-----Original Message-----
From: cbernhardt [hidden email]
To: [hidden email]
Sent: Thu, Aug 13, 2020 12:36 pm
Subject: Re: [OpenSCAD] Managed to model a finger joint box with relieved fingers --- now how to actually cut it? Allow OpenSCAD to write out files?

To answer your original question “how do I get those numbers out of RapCAD or

OpenSCAD and into a DXF or SVG?”

I took your 3d_Fingerjoint.scad file and exported it to an STL.  I imported
the STL file into AutoCAD and traced a POLYLINE around the boundary of the 4
pieces and then exported a DXF file of just the POLYLINES.  And imported
that into OpenSCAD.  I can understand why you choose not to use AutoCAD but
FreeCAD (according to their manual) can do the same thing.
<http://forum.openscad.org/file/t1309/outline.jpg>



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Hi,

Use scad for showing the picture, but imnsho, you would be better off generating the gcode separately. I've attached a screen shot of a simple box generator - no cad used whatsoever. The joints are not finger joints, but are a sort of stepped butt joint, modern glues are stronger than the wood.

I'm not sure if you need the ballnosed bit, or the tapered bit. Tool changing is a pain, unless you have some high end machine, or possibly designing a machine specifically for making finger joints. I've used  cutters similar to this, quite successfully for wood carving, which sort of combines a taper and a ballend.  https://www.amazon.co.uk/SpeTool-Tapered-2-Flute-0-25mm-Coated/dp/B077883PDW/ref=sr_1_13?dchild=1&keywords=tapered+milling+cutter&qid=1597401368&sr=8-13

I'm guessing you have a sort of flatbed cnc routing table, and you do not really want to have to change tool bits, or manipulate the sheet which you are machining, and all pieces will be the same thickness for an individual box. I hope the juice will be worth the squeeze. It will be fun getting the fingers correct at the corners. Maybe start by restricting the dimensions to a multiple of the finger size  plus.

Best wishes,

Ray

Ray West wrote:

>I've not followed this whole thread,

Apparently.

>but if you want to cnc finger joints, I would not start with scad.

It's the CAD tool which I prefer to use --- and I've modeled fingerjoints in it before:

https://community.carbide3d.com/t/cnc-finger-joint-box/8880

>What cutting tool will you be using, and what is the material?

I am planning on using a 1/4" square endmill, a 1/16" ball-nosed tapered endmill, and a 1/4" radiusing endmill.

>What tolerances are you looking for?

Tight enough for a void free joint.

>Unless you intend standing the pieces on edge, you will not get square corners profiling them with a router bit,

I created a fixture for doing that:

https://cutrocket.com/p/5cb25f3380844/

and I've cut boxes thus:

https://cutrocket.com/p/5cb536396c281/

It's a tedious pain.

>although if in wood, with a small diameter bit, woodfiller can solve that.

The refuge of the incompetent woodworker --- I'm trying to design a joinery system where joints have no visible voids --- hence the radius endmill which I intend to use to relieve the fingers to match the radius left by the 1/4" endmill. See the images at:

https://community.carbide3d.com/t/design-into-3d-boxes-magazine-storage/16238/54

and

https://community.carbide3d.com/t/cnc-finger-joint-box/8880/113

and

https://imgur.com/g9pQxS6

William

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boxer gui.tif (1M) Download Attachment

... | sed -n 's/^ECHO: "\(.*\)"$/\1/p'

If you're willing to work form the command line, it seems like the only feature you need is "emit only echo output, and don't decorate the echo output", perhaps as a -o variant.  (But -o requires fixed file extensions, since it determines the file format from the extension.)

I'm not sure exactly what question you are asking. Is it that you, for some reason or other, you want openscad to be able to produce a text file, possibly a list of coordinates, that you will manipulate somehow to produce tool paths, or is it that you are trying to design a joinery system? If you are trying to design a joinery system, then openscad is not much use, other than perhaps as a check to see if the object looks OK. For the sort of tooling/machinery you are most likely wanting to use, even if openscad could write a text file, it would probably be more awkward adjusting that file, than starting from scratch, and writing raw gcode. As you say you have done similar before, you know how straightforward that is, then there is little point in trying to push openscad in a direction that apparently few are interested in.

Although openscad can produce the model, then you are stuck in getting another view of it. If you create the model by some other method, most likely you can more easily get more views of it (MVC paradigm). In other words, generate a list of coordinates, then you can display them on a screen (openscad/whatever) and generate offsets for Gcodes for machining in whatever way you wish.

Have you actually made a sketch of how a couple of the fingers, say, actually mesh together, when prepared by what ever router bits you can use?

Best wishes,

Ray

If this stuff was easy, everybody would be doing it...

I've done boxes like that already:

https://willadams.gitbook.io/design-into-3d/3d-project and https://cutrocket.com/p/5e8fd99cc1578/

and as noted, I've already managed to get the corners right for a fingerjoint box, which was the beginning of this conversation which apparently no one deemed worthy of actually looking at.

https://imgur.com/g9pQxS6

I want to do my CAD and CAM in OpenSCAD --- all I need to make it available to in an elegant (in terms of scientifically correct) and robust fashion which naïve users can make use of it is a way to get some numbers which I am using to call modules in OpenSCAD already into a text file without any extraneous stuff which has to be filtered out.

Yes, I could use some 3rd party tool --- then I get to tell folks:

 - install OpenSCAD and use it to set up your design

 - install a second tool, and run this other file as well, and tell it where you put your OpenSCAD file and what name you saved your Customizer preset under

It's an unnecessary complication --- if only OpenSCAD would be allowed to have a bit more control over writing out text files --- which would be useful for other purposes as well such as B.O.M.s

Yes, I've done something along those lines as documented in my article in:

http://www.tug.org/TUGboat/Contents/contents40-2.html

but it's a lot of extra baggage when a simple couple of preferences and one basic capability could sidestep it:

 - write out console with each run of openscad

 - when writing out console filter to only lines output by echo

 - use custom file extension ____ instead of .nc 

(though it would be nice if that last could be specified in the language/file as a command)

William

-----Original Message-----
From: Ray West [hidden email]
To: William F. Adams via Discuss [hidden email]
Sent: Fri, Aug 14, 2020 6:47 am
Subject: Re: [OpenSCAD] !![SPAM]!! Re: Is there an OpenSCAD dev who wants a CNC machine? (was Re: Managed to model a finger joint box with relieved fingers --- now how to actually cut it? Allow OpenSCAD to write out files?)

Hi,

Use scad for showing the picture, but imnsho, you would be better off generating the gcode separately. I've attached a screen shot of a simple box generator - no cad used whatsoever. The joints are not finger joints, but are a sort of stepped butt joint, modern glues are stronger than the wood.

I'm not sure if you need the ballnosed bit, or the tapered bit. Tool changing is a pain, unless you have some high end machine, or possibly designing a machine specifically for making finger joints. I've used  cutters similar to this, quite successfully for wood carving, which sort of combines a taper and a ballend.  https://www.amazon.co.uk/SpeTool-Tapered-2-Flute-0-25mm-Coated/dp/B077883PDW/ref=sr_1_13?dchild=1&keywords=tapered+milling+cutter&qid=1597401368&sr=8-13

I'm guessing you have a sort of flatbed cnc routing table, and you do not really want to have to change tool bits, or manipulate the sheet which you are machining, and all pieces will be the same thickness for an individual box. I hope the juice will be worth the squeeze. It will be fun getting the fingers correct at the corners. Maybe start by restricting the dimensions to a multiple of the finger size  plus.

Best wishes,

Ray

On 14/08/2020 02:56, William F. Adams via Discuss wrote:

Ray West wrote:

>I've not followed this whole thread,

Apparently.

>but if you want to cnc finger joints, I would not start with scad.

It's the CAD tool which I prefer to use --- and I've modeled fingerjoints in it before:

https://community.carbide3d.com/t/cnc-finger-joint-box/8880

>What cutting tool will you be using, and what is the material?

I am planning on using a 1/4" square endmill, a 1/16" ball-nosed tapered endmill, and a 1/4" radiusing endmill.

>What tolerances are you looking for?

Tight enough for a void free joint.

>Unless you intend standing the pieces on edge, you will not get square corners profiling them with a router bit,

I created a fixture for doing that:

https://cutrocket.com/p/5cb25f3380844/

and I've cut boxes thus:

https://cutrocket.com/p/5cb536396c281/

It's a tedious pain.

>although if in wood, with a small diameter bit, woodfiller can solve that.

The refuge of the incompetent woodworker --- I'm trying to design a joinery system where joints have no visible voids --- hence the radius endmill which I intend to use to relieve the fingers to match the radius left by the 1/4" endmill. See the images at:

https://community.carbide3d.com/t/design-into-3d-boxes-magazine-storage/16238/54

and

https://community.carbide3d.com/t/cnc-finger-joint-box/8880/113

and

https://imgur.com/g9pQxS6

William

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