Giving FreeCAD a Try

[Everett]

Hey everyone, after some suggestions I was curious about FreeCAD and if it was any easier to use than the last time I tried it a few years ago. So, I got the latest version and installed it. Still not quite getting the hang of parts of it but I think I'm just too used to Fusion and Alibre Atom and need to learn this one's idiosyncrasies too. I suppose one of my biggest concern is that at some point I might not have access to Fusion and need a Plan B or C.

As I have just gotten my first 3D printer, and wish to use it to fiddle with making gears in the not to distant future, I figured to try modeling a gear in FreeCAD but darned if I wasn't having trouble figuring out where that function is found. I know how to make various gears in Fusion as there are scripts readily available with dialog boxes to input parameters but all I've found so far on the FreeCAD forums is some Python code snippets. I have never learned how to program using Python, and while I'm always up for learning new stuff my hobby/shop time is limited due to wee ones lately so it would be handy if there was something simpler to use for gear model generation in this package.

Forgive me if this is a silly question but I figure if I can get nudged in the right direction I can continue on from there. Thanks!

 

[PeterT]

I'm not familiar with FreeCad or Fusion, but I think I can take an educated guess as to where the difficulty might be residing. The (involute/cycloidal) gear tooth form is basically a construction of recognizable geometry like circles & arcs, but also other elements that are described by equations relating to the gear size & type itself. Its like drawing a line in CAD, but what is occurring behind the scenes is y=mX+b which is it's generalized equation. Some CAD programs (I think Fusion is one of them) apparently bundle some useful modules or routines where you input defining gear parameters, maybe OD, pitch diameter, number of teeth etc. & it works out the magic in the background. Other programs don't offer these modules. But typically all parametric CAD modelers allow you to define dimensions, not just as absolute values like diameter = 1.234". You can relate one dimension to another to another so its kind of like building a little program but without an external language. The video link isn't the one I was trying to find but it demonstrates the SolidWorks flavor of doing this. Recognize that even simple spur gears can get quite sophisticated as various attributes vary as a function of size (clearance, root fillets, crown radii...). So that is an example where the form may not be solvable with just equations, it may have to refer to a lookup table. Solidworks interfaces with Excel.

A lot of the freebie download gear stuff I've seen is not always 'complete' so kind of depends on what your needs are. Will a download 3DP gear mesh & turn, probably. Could you machine it & install in your transmission, probably not. Also there are many different forms of gears & each has their own math behind it, sometimes simpler, sometimes much more complex. Anyways FreeCad is supposed to be 'a lot like' SW so it wouldn't surprise me if some of the developers made some extra apps to assist in this regard. Or you might be able to mimic the workflow in the video. But it might be one of those walk before you run type deals, get a handle on basic drawing & dimensioning.

Another analogy might be cam design (as in a cam shaft not Computer Assisted Machining). You can probably draw a very sophisticated cam just using the suite of standard CAD commands, but you would have to know the exact design recipe behind it beforehand. Similarly there are sophisticated standalone cam programs out there, or might be ($$) toolbox plug-in to the big apps, but generally those aren't found in most standalone CAD packages AFAIK.

Spur gear - Wikipedia

en.wikipedia.org

 

[Dan Dubeau]

I downloaded it last weekend and dove in. I've always been one to pick up new cad/cam software's pretty quick, as I liken them to driving cars. they all are pretty similar, some have more bells and whistles, but you don't learn specifically how to drive a honda accord, and not be able to figure out how to hop in a silverado and figure it out pretty quickly. You might not like it, but you'll still be able to get from a-b, you just have to find out where all the different button are, and get comfortable with it over time.

That being said, I didn't take to it right away, and after poking around for a bit, have come to the conclusion that it just works a bit different than what I'm used to. I will have to attend a few youtube university classes to figure out how IT want's to be operated, and figure out the preferred workflow and terminologies before I give it a proper go.

I use Rhino, Mechanical desktop, and Solidworks for cad at work/home. I've also dabbled in fusion for home stuff on and off over the years. I've been looking for something cheap and powerfull to migrate all my home shop mechanical designs to, and Alibre was also at the top of my list. Not a big fan of fusions cloud based system on my expensive rural internet. Cheap and powerful software though.

I'm more looking for something that can handle mechanical assemblies a bit better. Structural tubing designs, BOMs and that kind of stuff. I've been using Mechanical desktop for about 20 years, and it's like another hand, but the newer workflows and programs are simply faster and better IMO for a lot of what I do now. It's time for me to update my skills....As much as it pains me to say it.... We're still in the middle of a solidworks migration at work which TBH is dead in the water at this point.....but that's out of my hands.

 

[PeterT]

Sounds like you are well experienced. It will be great to have your perspective on the matter. When you say 'middle of SW migration' do you mean moving away from to another package or vise-versa?

I've also given Alibre an occasional look. I'm not into CAM at present but who knows in the future. One thing, you have to dig into the details of what is included for each package level.
Have you had any direct experience or personal reservations about the software?

Alibre Software Pricing & Purchasing

Alibre Atom3D, Workshop, Design Professional, and Design Expert CAD software available for purchase online or from your local reseller.

www.alibre.com

 

[Brian Ross]

Everett, if you want to model gears, you will have to add the Gears workbench. Under the tools menu there is an AddIn Manager. When you open that look for the fcgears add in. Once you have added that and restarted FreeCad you should have a Gears workbench in the Workbenches drop down. From there it is pretty self explanatory.

 

[Everett]

Awesome, thank you - I will look into that tonight after the kids are in bed. I was not aware of what kind of things needed adding in as I have very little experience with FreeCAD.

I never claimed to be smart, just almost pathologically curious. Often getting me in over my head, lol