Drawing a gear and a rack 3

[mkmech]

I have a gear and rack (these are physical units that I have in my hand) that I need to create a model and drawing for in SolidWorks. For this, I first need to make the relevant measurements on the gear and rack and then figure out how to reproduce in SW. My question is: what measurements do I need to take, how do I take them (i.e. what instruments do I use) and how do I draw them in SW. I have an older version of SW, so I might have to make these from scratch. I think there is a feature "Gear" in newer SW. Your comments will be greatly appreciated.

 

[ShaggyPE]

Newer versions of Solidworks have a mate option called gear mates. This allows you to mate two discs and assign a ratio. When you rotate one, the other rotates per the defined ratio.

As far as doing a drawing of a gear, it is not critical to actually draw the teeth (unless you want a pretty picture). The critical areas are typically tabulated on the face of the drawing. These areas are:
1. Diametral Pitch
2. Number of Teeth
3. Pressure Angle

As far as measuring the gears you have, you can count the teeth, and there are formulas that relate the diameter of the gear and the number of teeth to find the dimetral pitch. As far as the pressure angle goes, that deals with the shape of the tooth. I am not sure how you will be able to find that. Somewhat standard for pressure angle is 14.5 degrees

You may be able to check out

http://www.engineersedge.com

for more info.

 

[SBaugh]

thread559-121730

Regards,

Scott Baugh, CSWP
3DVision Technologies

http://www.3dvisiontech.com

http://www.scottjbaugh.com

faq731-376
faq559-716 - SW Fora Users

 

[MadMango]

Mkmech, my question to you is what purpose will the gear and rack models serve? Their end-purpose will determine how accurate your models need to be, what you will use to measure them and how they are constructed in SW.

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[drawoh]

mkmech,

The standard way to do accurate measurements of gears is to use three pins. The pins engage opposite teeth, and you measure across the pins. A textbook on gears should explain this all. This will help you confirm the pitch.

Dudley's Gear Handbook (McGraw Hill) has instructions on how to draw a gear involute. It works.

JHG