Decorating internal gears and scripting

[Alanb6448]

Hi everyone,

Having used Gearotic for the first time I am quite new to this so bear with me please, although I am not a newcomer to cnc and have written my own gcode programs in the past.

I have started to use gearotic 2 because I have in mind several projects (I too am getting more interested in kinematic sculptures ) including one that requires several gears specifically, an internal gear to be hidden within a bowl and used to drive other visible gears. I created version 1 of this a couple of years ago (see http://ab48.uk/otblog/gear-bowl-version-1-finished-with-mixed-results/ ) made out of hardwood. This seized solid after a couple of months when the wood moved. Now that I have built myself a OX based cnc machine I thought that I would start by revisiting this project and make the internal parts out of plywood as this would be more stable option. However I want to attach a hardwood rim to the internal gear as the visible part you moved. Hence the need to decorate the rim of the internal gear with 6 or possibly 12,  5mm diameter holes for glued pins that would attach the gear to the rim.

I  generated the dxf using gearotic and then imported this into cut2d to add the holes.  However it occurred to me that it should be possible to apply decorations such as this from within gearotic 2 (maybe you can ? ) especially if I wanted to use the gcode generated within the program itself.  I know that this opens a whole can of worms as the number of possible decorations is infinite. So really my question is about the possibility of plugging in a script to perform the operations required for the decoration and not just in this specific case but others as well. Is gearotic 2 so structured that it could be opened in this way?  The script could be a gcode sub or python code or whatever. A gcode sub with a standard name would be simplest I think and then called at the point the decoration needed to be applied.

As a general point I notice that the program is evolving to cover different areas using plug in modules. I think that if these modules were themselves scripts referencing a core internal model. Then this would open up the program and allow anyone to add functionality in an area they are interested in (with all the difficulties inherent in this approach).

Has this use of scripting been considered is it unworkable or just impractical?  Just a couple of opinions based on my ignorance and total lack of knowledge about gearotic  and is really an enquiry into what the future may hold.

Anyway thanks for a great program for generating gears I am sure I will be using it a lot.

Alan

[Mooselake]

Hi Alan, and welcome to the forum!  I've been watching your OT blog for some time.

The moosecave is developing a pile of v-slot and Misumi extrusions and other parts, along with a stack of sketches for an cnc ot pen turning gadget (not sure if it's a lathe or 4th axis router), kinda sorta like a Pen Wizard.  Since I'm also working on my procrastination skills it hasn't really progressed past that.  Yet.

Gearotic already has post processors, perhaps they can be used to do what you're looking for.  Art will know.

Kirk

[ArtF]

Hi Alan:

  Nice candle holder. :)

  I am only now adding scripting, as this summers project ( I take the summers off for personal projects...which usually
end up in Gearotic.. ) is scripting. It is very possible scripting will appear in Gearotic but as yet it is not. It is possible
to add some types of decorations as the spokes are all just DXF's really, where if you follw the rules can be replaced or added
to with your own DXF's.
  I havent decided as yet how scripting can be intergrated to Gearotics engine, but I am thinking on it. The scripting is being developed to
add motion control to Gearotic eventually. But its a road that will likely have a few twists as Im not particularly interested in
standard cnc operations and will be focusing on operations not usually possible in traditional programs.

  A separate wizard scripting module "Auggie" will be included in Gearotic this fall , but as yet Im not sure how much, or
exactly in what form it will attach to Gearotics main engines. Gearotic's direction is steered by users comments and questions,
and my own interests, I kinda follow a path based on what I think would be interesting, and what I feel would be hard for
me to do, but not impossible.

Art

[Alanb6448]

Thanks  Mooselake and ArtF for the replies. I have been watching with great interest the videos about auggie and I guess that I had that in mind when asking the question. I am looking forward to its release I did not realise it was so imminent.

Regarding the candle holder  :) it was a disappointment that the bowl was so small. I had in mind that the final finished item would have a much larger bowl. I have a chunk of sycamore that would give me bowl 460mm in outer diameter which was the size I envisioned for the final project. I also want to make the gears much smaller than the wooden ones I cut (with a small fly cutter) to fit many more in. That chunk of wood has been sitting around now for a couple of years so time I progressed it into a finished project.

Regarding that if I could ask a couple more questions. Any feelings as to the smallest gear size I could cut say using a 1 or 2 mm end mill ?  I have some 0.5 mm milling cutters but haven't yet managed to cut something without breaking one (cannot get the speed high enough and feed rate low enough I guess).

I am assuming that i would need to cut these smaller gears from thin brass sheet or plastic rather than plywood. I am also mightily tempted to use non-circular gears so again same question what is the smallest that could be machined ? Would smallest gear diameters of say 10 mm be achievable? 

Alan

[ArtF]

Hi:

>>Regarding that if I could ask a couple more questions .

  As many as you like. :)

>>Any feelings as to the smallest gear size I could cut say using a 1 or 2 mm end mill ?  I have some 0.5 mm milling cutters but haven't yet managed to cut something without breaking one (cannot get the speed high enough and feed rate low enough I guess).

  In 4th axis, your module is limited to the mill diam, so a mod2 for a 2mm gears, mod1 for a 1mm. ( generally). Varies by person too.. :)

>>I am assuming that i would need to cut these smaller gears from thin brass sheet or plastic rather than plywood. I am also mightily tempted to use non-circular gears so again same question what is the smallest that could be machined ? Would smallest gear diameters of say 10 mm be achievable? 

  In theory yes, the smallest Ive done is a 16 tooth bevel about 20mm in diam, but thats 3d printed, in wood my smallest has been around 2" diam. Ive cut many in 2.5D, and a few in 4th axis, basically it boils down to "whatever works".

Art

[Alanb6448]

Thanks again,

I do not yet have a 4th axis for my OX cnc still have to make one so 4th axis there is not possible yet. However I can cut 4th axis using my cnc based rose engine as I have 6 axis movements on that. I was thinking of using the OX for all the gears but will give the rose engine a go also.

Cutting in either mode is there a way to find the root width between teeth so that I could choose a mill diameter to fit or grind a flycutter to fit ?

By the way I came across a small problem generating two noncircular gears see attached images. Are you aware of this ?

Alan

[ArtF]

Hi Alan:

Click on the gear in the project screen, in the text will be "min diamter of tool", thats basically the rooth width..

If you output the DXF  the actual shape of the cutter to scale is spit out with the gear.

  Yes, the noncirculars can, though rarley , fail. The algorithm is still being tightened, its one of the only general toothing algorithms
out there for any shape, and as such, can still fail. Changing any setting slightly usually allows it to work. Experiment a bit and you shou;d
get a toolpath thats functional.

Thx
ARt