Wooden Gears?

[spalm]

Well, I got my first CNC going. Now to figure out something to route with it. First thing that came to mind was my second router, but the wifey thinks I should slow down and do something else with it first. So a wooden clock was discussed. It will also hone my Autocad skills which are non-existant[IMG]. Found some plans on the web, extracted a few dxf files and routed them. I had to manually set the Z axis in the gcode files as VisualMill saw it as only a 2D object. They were a real crowd pleaser. Also gives the XY table a good work out.

Now I want to design my own and am a complete newbie with Autocad. How do you draw a gear? I found a little application called 3DGEARS.lsp that I loaded into Autocad and it lets me draw them but then I don’t know how to save them so VM will see them. I think I have a major mental problem with 2D or 3D. How do I draw a hole down the center? Should I save it in DXF or DWG and what is the difference? Do I do this with layers, or is it something else. Should I export it to IGS?

Thanks in advance,
Steve

[ger21]

Originally Posted by spalm I had to manually set the Z axis in the gcode files as VisualMill saw it as only a 2D object.

You set the depth in Visual Mill.

Originally Posted by spalm How do you draw a gear? I found a little application called 3DGEARS.lsp that I loaded into Autocad and it lets me draw them but then I don’t know how to save them so VM will see them. I think I have a major mental problem with 2D or 3D. How do I draw a hole down the center? Should I save it in DXF or DWG and what is the difference? Do I do this with layers, or is it something else. Should I export it to IGS? Thanks in advance, Steve

Sounds like you need to take a drafting class. Just go to File>Save as, and save it as a .dwg file. For cutting a gear, you just want a 2D profile. The main difference you'll notice between .dwg and .dxf, is that a .dxf will be a bigger file. If the application your using can read .dwg, use that. If not, use .dxf

[ynneb]

What is this "3DGEARS.lsp" application. Is it like a plugin?
Is it a freebie? Where can we get it?
I tried to google for it but found nothing.

[spalm]

I'm tring to post a sample but I'm lost in Autocad right now. Sorry, the name is 3DGEAR.Zip (not plural) which contains the lisp program. It can be found at http://www.cadtoolsonline.com/free.htm

The drawing contains a gear with a center circle that I drew. It is 2D while the gear is 3D. Is there a extrude-cut command like I got used to in the Alibre demo?

Thanks,
Steve

[DareBee]

For working with AutoCad and a router (that machines in 2.5D only) it is easiest (probably best as well) to do all your CAD in 2D and import the DWG into VisualMill, that way all your regions will be ready to go with no additional work. As Ger said about VisualMill you just set your depths in the Cut Levels tab when you are programming your 2.5D profile cutting. I suppose you could try to program in 3D but it is a waste of time for your application.

[spalm]

Thanks guys.

The finish level in VM was set to 0. Once I changed that my output is much better.

I will stick with 2D.

I just discovered polar arrays. I believe I'm on the road. (need to read more!!)

And to think that I could not even spell CNC until 4 months ago.

Steve

[ger21]

Originally Posted by ynneb What is this "3DGEARS.lsp" application. Is it like a plugin? Is it a freebie? Where can we get it? I tried to google for it but found nothing.

Benny, AutoCAD usesa programming language for automating tasks called LISP. AutoCAD's version is AutoLISP. It's kinda like creating macros, only in AutoCAD, macros are what they call VBA programs. Am I confusing you yet? IYou could say that they are a type of plug-in. There are thousands of free lisp programs on the internet that do all sorts of things. AutoLISP is a big reason AutoCAD is so powerful.

[CNCRob]

Hey Spalm,
The gears you cut look great. What kind of bit did you use and how did you hold them in place? Thanks-Robbie

[spalm]

The gears were cut with a 1/8" flat bit. They are 4 and 6 inches. The 1/4" wood was held in place with double sticky tape. I did two passes of 1/8" each to get the depth. Make sure to use a sacrificial board underneath to complete the cut.

Steve

[nine6]

does anyone know of a freeware or shareware program to generate
2D gear profiles that does not require autocad? its a bit out of my
price range and i just want to mill gears.

thanks

[Ken_Shea]

nine6,
Alibre Design Express is a free program, quite powerful for being free and you will not outgrow even the free version anytime soon. .
Unfortunately it will not directly draw gears. Now I am not saying that gears cannot get complicated but with a little research on your part in gear design and a small learning curve I would not think drawing simple gears would give you a gre at deal of trouble. I did it in High school (back when gears were just invented) and as I recall it was enjoyable.

Alibre design:
http://www.download.com/Alibre-Desig...-10619206.html

Here is one link for starters on gear design:
http://www.csparks.com/watchmaking/C...rs/index.jhtml

Ken

[nine6]

for anybody that is interested, i think i just answered my own question.

http://www.ohyeahcad.com/download/