draw gear to a set diament

[dlaery]

I use the gear geanerator but I don't know how to draw to a gear to a certain diameter.

this will be 3 gears in a row

I need them to be 1.85 inches..

is scaling an acceptable way to get the size I want?

ok, now I realize that Pitch diameter is what I want to use to get the right diameter.
What does the DP and Module represent?

NumberofTeeth = 20
Module = 1.5
PressureAngle = 20
Thickness = 3

NumberofTeeth = 20
DP = 24
PressureAngle = 20
Thickness = 3

 

[Ken226]

I use the gear geanerator but I don't know how to draw to a gear to a certain diameter.

this will be 3 gears in a row

I need them to be 1.85 inches..

is scaling an acceptable way to get the size I want?

ok, now I realize that Pitch diameter is what I want to use to get the right diameter.
What does the DP and Module represent?

NumberofTeeth = 20
Module = 1.5
PressureAngle = 20
Thickness = 3

NumberofTeeth = 20
DP = 24
PressureAngle = 20
Thickness = 3

They basically measure the same thing, but imperial vs metric. Diametral Pitch is used in imperial gears, module is used in metric.

Diametral Pitch is the ratio of tooth count to pitch diameter (inch)
Module is pitch diameter distance per tooth (mm)

With metric gears, use the module to set the distance between gear axles. The following formula:
(Module of Gear 1 + Module of Gear 2)/2 x (Number of Teeth on Gear 1 + Number of Teeth on Gear 2)/2

 

[dlaery]

Thanks!

 

[Ken226]

That is one of the things I love about David's gear utility add-on,

It calculates this info for you, in the UI.

 

[bolsover]

I use the gear geanerator but I don't know how to draw to a gear to a certain diameter.

this will be 3 gears in a row

I need them to be 1.85 inches..

is scaling an acceptable way to get the size I want?

ok, now I realize that Pitch diameter is what I want to use to get the right diameter.
What does the DP and Module represent?

NumberofTeeth = 20
Module = 1.5
PressureAngle = 20
Thickness = 3

NumberofTeeth = 20
DP = 24
PressureAngle = 20
Thickness = 3

OK - so at present, you are using Alibre Script to generate gears. That is just fine - but it does not generate helical gears.

If it is helical gears you need, I suggest you try my add-on it is available via resources UtilitiesFor Alibre or direct from the Git hub repository: GitHub.

There are a few different downloads including a .exe, .zip and .rar. the .zip and .rar just contain compressed versions of the .exe and need to be extracted to your local machine before running the .exe. The only reason for the different types is that some users have reported problems downloading because either their browser or anti virus product reports a false positive. There is no virus.

The UtilitiesforAlibre.exe will install the Add-on to your local machine and this will then be available in Alibre.

There is some documentation for the project here: UtilitiesForAlibre

I'm reasonably sure you will be able to generate the gears you require including helical forms that are easily mirrored to produce the herringbone gears you want.

David

 

[dlaery]

thanks i have installed it and still trying to figure out how to use this.

 

[bolsover]

thanks i have installed it and still trying to figure out how to use this.

Please let me know if you need any assistance.
I think best place to start is with the involute spur and helical gears. Just try building a few gears to get a feel for the tool. try changing the module size and number of teeth while looking at the table - it all recalculates automatically as you change the values.
Once you understand how the spur gears work, try entering a value in the helix angle box and generate a gear - you'll soon get a feel for how it works.

There is some error checking to ensure values are 'reasonable' but it is still possible to ask for something that can't be calculated!

The link I provided to the documentation is worth checking out - there is some detail of the maths involved.

David

 

[dlaery]

how do I constrain these gears? or where do i start?
should I have saved a print screen when I did the Utilities?
I have to draw a housing with bearing in the housing to run these gears.

 

[HaroldL]

Joseph's video may help

You'll need to add some holes to the gears, model some shafts and bushing/bearings, and put arrange them in an assembly. Use the Gear constraint to link and mesh them together.

 

[bolsover]

how do I constrain these gears? or where do i start?
should I have saved a print screen when I did the Utilities?
I have to draw a housing with bearing in the housing to run these gears.

+1 For Joseph's video. The really important measure is centre distance. Quite often, a gear design will start with that as a constraint. It is for this reason I wrote the utilities calculator to work with gear pairs and not just a single gear. I also allow you to switch between automatic (centre distance calculated from the pitch diameter) and manual where the user has the adjust the module and tooth count appropriately.
Once you have the gears with the correct separation in the assembly, you have to eyeball the meshing before applying the gear constraint. I know that this is less than optimal but I've not had time to come up with a better method.

 

[DavidJ]

Well gears have to have an integer number of teeth. If using gears from a standard series you'll be limited as to centre distances that are possible.

If 3D printing gears then you could use a non-standard DP or Module value, to give more freedom on centre distances.

If there are 3 gears in a row, do they have to be all in a straight line, or could you offset the middle gear to adjust distance across the 2 outer gears?

 

[dlaery]

I used David Bolsover's utilities and now a day later I don't remember what number I used. if you don't know what the pitch is but know the diameter and number of teeth, is there a way to figure out the pitch?

 

[bolsover]

I used David Bolsover's utilities and now a day later I don't remember what number I used. if you don't know what the pitch is but know the diameter and number of teeth, is there a way to figure out the pitch?

You could just use the utilities to recalculate your gears - all the dimensions are shown in the table including outside diameter, pitch diameter and root diameter.

 

[DavidJ]

Yes - there are simple equations which link number of teeth, pitch diameter, outside diameter and DP or Module.

One web page showing the basic equations is https://www.engineersedge.com/gear_formula.htm

 

[bolsover]

As @DavidJ says, the formulae are well known and for the most part not too complex. I have put tables with examples of (most ) formulae used in the documentation. http://bolsover.com/utilitiesforalibre/formulae.html
I intend to include links to downloadable Excel spreadsheets with worked examples... Sometime..
David

 

[dlaery]

well i finally got ot this far.

Thanks for the help!

 

[dlaery]

ok, now the design calls for larger diamenter gears. it looks like I just start over. or can I scale the gears and will that work ok?

 

[albie0803]

Start again. If you scale the gears you will most likely end up with non standard tooth sizes.

Gear selection normally runs:
Tooth size required for power to be transmitted - what module or DP to use
Ratio desired
Limitations that set the number of teeth in the smaller gear
OD modification to adjust centre distance if desired.

As it looks like your 3 gears are the same number of teeth, just calculate the OD with Mod x (Teeth + 2) to get the OD close to what you want