How to set dimension when using gear maker?

[Anonymous]

I'm trying to make a gear from my r/c helicopter. when using the gear maker it will not let me change the dimension of the gear. When I put all the info into the gear maker the gear comes out way to big.

[etfrench]

You'll need to be a lot more specific about the information.  What is the module # or diametrical pitch of the gear? What is the pressure angle? How many teeth? Is it a spur gear?  What size do you expect it to be?

[Anonymous]

Ok sorry I'm just starting out trying to learn. How would I determine the module number and pressure angle number to enter? I have the old gear in my hands that I'm trying to make. thanks for the replay.

[etfrench]

Start by measuring the diameter and counting the teeth.  Metric (Module #) and Imperial (Diametrical pitch) gears are close to the same size, but you can usually tell which by the diameter and tooth count. 

Pressure angle is usually 20 degrees or 14.5 degrees.  I think 20 degrees is more common now.

Try entering the number of teeth in the gear dialog, then modify the Module # (or Diametrical pitch) until the diameter of the gear matches your gear.  Try to use common module or diametrical pitch settings. 

Note: Scaling gears to make them fit doesn't work well.

[Anonymous]

Ok thank you so much been struggling with this. Can you tell me what root filet radius is?

[Anonymous]

I can't go low enough on module number to make the gear small enough. I get this error "some input argument is invalid".  

This is the numbers I entered

Metric

20 deg

module 2.00

teeth 124

backlash 3.45

root fillet radius 0.588

gear thickness 12.00

hole diameter 29.85

[HughesTooling]

The backlash looks too big, you can set it to zero and see if that helps, you'll only want a small amount like 0.02 or 0.05. Also the root rad looks big, try setting it to 0.1.

To get an idea of module from the gear you have divide it's OD by the number of teeth plus 2. So a 2 module gear with 124 teeth will be 126 x 2 so OD of 252mm.

Mark

[TheCADWhisperer]

As best you can measure (do you have some calipers?):

What is the distance between the center of the drive shaft and the driven shaft?

How many teeth are on the smaller drive gear?

How many teeth are on the larger driven gear?

What is the outside diameter of the drive gear?

What is the outside diameter of the driven gear?

(Does the RC Helicopter manufacture site have this information?)

[Anonymous]

There are 124 teeth on the gear I'm trying to make and 17 on the other one. I have a caliper but there is a hub that bolts to the gear I'm trying to make so to  find the center is going to be hard.

[TheCADWhisperer]

There are several ways to take the measurements even if you can't remove from shaft.

If both gears are assembled in position 

measure across gears, then subtract G1/2...G2/2.... clear as mud?... let me make a diagram.  back in a minute.

Why didn't you answer my question about the gear diameters?  Are they both broken to bits?

When you are measuring - be sure to get across the major Outside Diameter and not between a couple of teeth.

[TheCADWhisperer]

I should have mentioned that this will just be a starting point as what is really needed is the pitch diameter considering the teeth overlap a bit.

The addendum (distance from pitch diameter to OD can be calculated).

A process of back-and-forth comparison can hone in on the dimensions that will be needed.

Assuming you will be 3D printing these and knowing that 3D printing is not a particularly precise manufacturing process will necessitate a bit of adjustment as well.

[Anonymous]

Thank you so much for your help the OD of the drive gear I'm going to get for you later I have to take some of the heli apart for that the main gear that I'm making has a OD of 125.94mm

[etfrench]

Sounds like a module 1 gear:

Teeth: 124

OD: 126mm

Pitch diameter: 124mm

Pressure Angle: 20 degrees

Teeth: 17

OD: 19mm

Pitch diameter: 17mm

Pressure Angle: 20 degrees

[Anonymous]

Module 1 is really close if not right on. I need to now make the gear teeth sharper and deeper. How do I do that?

[etfrench]

Can you provide some pictures of the gears?  It would be very unusual for a spur gear to have non-standard teeth.

[Anonymous]

Ok here is a picture of the gear I’m trying to make.

[Anonymous]

 Since the pinion gear is in the helicopter I gave you a picture of it from the  manual.

[etfrench]

They look normal to me.  I'm pretty sure you don't want to change the tooth profile.  Since you're making both gears, they should mate well.  If you're 3d printing them, you may need to spend extra time calibrating the printer.

[Anonymous]

I’m only making the big White gear. I’m not making the pinion gear so the tooth profile has to match the smaller pinion gear

[Anonymous]

So can I change the gear tooth profile using the spur gear maker?