25-05-2015 21:39

cad321

Re: pic: Help with solid works gears

This table is what I use for all of my gear work. I find that it has everything I need when working with gears. Keep in mind that you should leave a small gap between the distance calculated. Ive seen several opinions on this forum about what the "proper" distance is to add however I tend to add about 0.005" to it.

25-05-2015 21:43

R.C.

Re: pic: Help with solid works gears

http://www.wcproducts.net/how-to-gears/

Use the Calc at the bottom of the page

25-05-2015 21:59

asid61

Re: pic: Help with solid works gears

(T1 + T2)/(DP*2) + C should be the distance between two gears.
T1 is the teeth on gear 1. T2 is the teeth on gear 2. DP is the diametrical pitch (usually 20 for FRC gears). C is the clearance, an added distance between gears to ensure that manufacturing tolerances don't force the gears to close to each other. Two gears must have the same DP to mesh properly.
Basically, you want the "pitch diameter" of two gears to be tangent, with a spacing of C between the two diameters. The pitch diameter is equal to T/DP, where T is the teeth on the gear and DP is the pitch. Just draw a circle, plus that in for diameter, and add C to the resulting number. Do the same for t your second gear and make the two circles tangent.
On a part to be milled or CNC'd, I use a C of 0.000". For waterjetted stuff I am starting to use 0.003" in case the holes are too close and I don't want to mill it as well.

25-05-2015 22:36

orangemoore

Re: pic: Help with solid works gears

I suggest you design the plates using circles as place holders for gears instead of creating an assembly. This will make your life a lot easier.

This video should show how this works.

https://youtu.be/GCjBx3TXB6Y?t=19m32s

25-05-2015 22:52

Dunngeon

Re: pic: Help with solid works gears

The 610 design files are very useful for this as well, among other things.

610 Design Files by Ryan Tam

26-05-2015 00:20

rcmolloy

Re: pic: Help with solid works gears

On top of the plate design using circles, I would advise using sketches to making your entire 2-D conceptual design before moving forward. It can keep things organized really well if you dimension and use relations properly.

26-05-2015 08:14

Chris Endres

Re: pic: Help with solid works gears

A really useful page I use quite a bit: http://computers.martinchick.com/spur_gear.html

You'd want to calculate the (Pitch Diameter)/2 for both gears, add them, and that'll be your distance between centers. I usually add about 2-5 thou (0.002"-0.005") to the sum, just for tolerances in manufacturing.

26-05-2015 10:21

Bennett548

Re: pic: Help with solid works gears

Here is a solidworks file used to design a 3 CIM gearbox:

https://drive.google.com/file/d/0ByD...ew?usp=sharing

It has a 50 tooth gear in the center, with three cims with pinions driving it. On each cim we have included 3 different sized pitch diameters (12, 14, 17) so that the pinions can be swapped to get different ratios. Each pitch diameter circle is driven by an equation: pitch diameter = number of teeth/ 20 +0.002 because these are 20 dp gears. I have also added 0.002" to all pitch diameters to get the 0.002" extra on all center to center distances. Also included in the first sketch are mounting hole locations for the cims with each of the different pinions. Around each pitch diameter I have a circle 0.1" larger in diameter to show where the tips of the gear teeth are to make sure nothing will collide with them. Also shown are the bolt heads of cim mounting screws to make sure everything will clear.

The 0.002" extra value is not a strict rule. We have found that it works well for enclosed gearboxes that are waterjet.

I wish solidworks had sketch annotations so I could label every circle. It can get ridiculous trying to remember what each of the dozens and dozens of circles represent when doing a more complex gearbox.

Here is a screenshot of the assembled gearbox:
https://drive.google.com/file/d/0ByD...ew?usp=sharing

The cim mounting hole locations in the plate that the cims mount to is driven by the sketch in the front plate, so that any change made to the front plate will propagate through the whole assembly.

These gearboxes are a good example of how you can use solidworks bottom-up (start with sketches) or top-down (start with assemblies and use the parts to drive sketches for other parts). For example the gearboxes start with sketches, but the robot bellypan uses components placed in the assembly to drive the position of mounting holes.

26-05-2015 19:05

nathannfm

Re: pic: Help with solid works gears

While I know the calculation is simple this is still a handy tool, especially being web based, think you could add 32DP to the drop down? You are the guys who sell those gears after all.

26-05-2015 19:07

zinthorne

Re: pic: Help with solid works gears

Thank you so much for the help!