Playing around with freeCAD, 3d printers an gears.

Ok.. I want to use my 3d printer to make a small rotary table for Halloween pumpkin.  I’m thinking of printing out something with bearings races similar to an angular contact bearing with an integrated ring gear.   I have a couple pinions I could find a use for those raptor gears that I replaced.   I rolled them against some 48 pitch gears in my surplus gear box and they it seemed to roll pretty size..   At least I thought they where 48 pitch… I guess I should do a lil calculating…
There’s a nice little sight with a bunch of formula for spur gears.   So to calculate DP Pd = (N+2) / OD =   (20+2)/ .455 = 48.3 ~ 48

Let me try that the other way… OD = (N+2)/22  22/48 = .458  Ok… Seems like that’s right… So.  Ok.. So since freeCAD only does metric (big sigh) we need to bounce around systems.   So I’m thinking I want a 48 pitch ring gear some where around 100mm 3.937″   So that means I need about 3.937 X 48 ~ 188.97.    Just for fun lets go with 200 teeth.

So.. I need to fill in the freecad input screen.  According

48 Dp => goes to a circular pitch of 1.661 MM.
Other Particulars Addenum .0208″
Dedendum .0270″
WD .0478
Circular Pitch .0654

So.. I want to figure how to get that into the input form which from the repository looks like this(with its fault values:)


I need to look at  y, c,&j  at bit The problem that I’m having at the moment.  Is that if I use the code that’s in the repository and try some subtraction everything goes blank.  Not sure whats going on here with that..
(Everything comes to a screeching halt)… I had gotten an alternate script but that seems to take a lot of time.
Well this isn’t going to get solved tonight.

[Edit , wanted to fire up the printer and just print out a 200 tooth 48 dp gear…]
When I tried adjusting the first 2 parameters an this is what I got..  (Looks pretty but not exactly what I was looking for…
Let me drop the number of teeth to 59 and see what happens.

Ok.. This is rather amusing… with 59 teeth generates a gear with a few missing teeth.  Ok… Lets try 40 and see if we get something.



Freecad Export to Stl... Something looking a bit weird
Freecad Export to Stl… Something looking a bit weird
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