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Gear cutter design information?

jeffbiss

Plastic
Joined
Oct 15, 2015
I'm a technical writer who uses Solidworks to work with client models, ultimately to produce graphics from Composer. So that I can support my clients when the need arises, I am working on creating blocks that will act as "gear cutters" when I need to model gears using the following youtube video as a guide:

https://www.youtube.com/watch?v=uj7BnldaOSc

Note that there is a problem with this method when creating gears with over 105 teeth as the angle determined by 360/(4*"N")-"alpha" goes negative at 106 teeth. I have a work around that produces gears with greater number of teeth, but am not sure of its accuracy.

My question is, does anyone have a suggestion for information in creating gear cutters, such as their cutting profiles?

I searched the Internet and get a lot of results for gears, but not the cutters. I understand that the gear cutters come in sets and each individual gear cutter can cut teeth for a specific tooth number range. I would like to know whether my output reflects actual cutter profile. When I produce gears, using the method shown it the video linked to above, the teeth don't appear to mesh as neatly as I expected. Ivan Law explains this in his book "Gears and Gear Cutting" as the portion of the involute used changes as the tooth number changes. I want to be as accurate as possible.

Thanks, Jeff
 
I'm a technical writer who uses Solidworks to work with client models, ultimately to produce graphics from Composer. So that I can support my clients when the need arises, I am working on creating blocks that will act as "gear cutters" when I need to model gears using the following youtube video as a guide:

https://www.youtube.com/watch?v=uj7BnldaOSc

Note that there is a problem with this method when creating gears with over 105 teeth as the angle determined by 360/(4*"N")-"alpha" goes negative at 106 teeth. I have a work around that produces gears with greater number of teeth, but am not sure of its accuracy.

My question is, does anyone have a suggestion for information in creating gear cutters, such as their cutting profiles?

I searched the Internet and get a lot of results for gears, but not the cutters. I understand that the gear cutters come in sets and each individual gear cutter can cut teeth for a specific tooth number range. I would like to know whether my output reflects actual cutter profile. When I produce gears, using the method shown it the video linked to above, the teeth don't appear to mesh as neatly as I expected. Ivan Law explains this in his book "Gears and Gear Cutting" as the portion of the involute used changes as the tooth number changes. I want to be as accurate as possible.

Thanks, Jeff

If you desire accuracy, then abandon the approximations of the Involute Mills and model the actual, resultant generated Involute. It's a simple enough matter to calculate the XY coordinates of the Involute of a given Gear when Pitch and tooth Count is given. From that, you can either model the gear as an entity and extrude from there, or model the tooth space and sweep or cut that from a solid.

Clear as mud?
 
If you desire accuracy, then abandon the approximations of the Involute Mills and model the actual, resultant generated Involute. It's a simple enough matter to calculate the XY coordinates of the Involute of a given Gear when Pitch and tooth Count is given. From that, you can either model the gear as an entity and extrude from there, or model the tooth space and sweep or cut that from a solid.

Clear as mud?
This is exactly how I do it when I need to model a gear that's not easily done with my normal methods. Extrude the profile and that becomes the cutter, array it around and subtract it.
 
This is exactly how I do it when I need to model a gear that's not easily done with my normal methods. Extrude the profile and that becomes the cutter, array it around and subtract it.

Wait thst wasn't clear, from the profile you get the 'space between' which becomes effectively the cutter.
 
I honistly and very much a lightweight as far as gearing goes, but occasionally we have breakdowns where we need to get gearing going using what we have, i use Grant's Odontograph to approximate the gear teeth. It is in Machinery's handbooks, 19 edition and earlier I believe. It uses two circles to aproximate tooth profiles, and I was amazed that when I layed a large papermill bull gear on a full scale print, it was a perfect match. Not sure if this helps and I am sure it is much cruder than what Zahnrad Koph said, but it has gotten me where I needed to go for the couple I have done.
Joe
 
... ..., i use Grant's Odontograph to approximate the gear teeth. It is in Machinery's handbooks, 19 edition and earlier I believe. It uses two circles to aproximate tooth profiles,

Commonly referred to as "the button method" these days. It's nice to see it properly named. Came from Grant's Treatise.

Not sure if this helps and I am sure it is much cruder than what Zahnrad Koph said, but it has gotten me where I needed to go for the couple I have done.
Joe

While I am admittedly a gear snob :) I am not snobbish about it. If it fills the need, that's all that matters. :)
 








 
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