CAD – FireBears https://firebears.org FIRST Robotics Team 2846 Roseville, MN Tue, 30 Aug 2022 21:30:08 +0000 en-US hourly 1 https://wordpress.org/?v=6.4.3 https://firebears.org/wp-content/uploads/2016/02/cropped-photo-1-32x32.png CAD – FireBears https://firebears.org 32 32 Calculating Drivetrain Speed https://firebears.org/calculating-drivetrain-speed/ https://firebears.org/calculating-drivetrain-speed/#comments Tue, 23 Apr 2013 02:30:28 +0000 https://54.188.23.233/?p=442 Calculating Drivetrain Speed Read More »

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An important fact about your robot is the speed of the drivetrain.  Having said that, how do I calculate the speed of the drivetrain?  Fortunately there is an easy to use calculator called the JVN Calculator. You can find this at JVN Mechanical Design Calculator

You need either Excel or an open source spreadsheet program such as OpenOffice.

To use:  Open the calculator and select the worksheet for the type of mechanism you want to calculate.  Copy the appropriate motor data from the motor worksheet.  Modify the purplish colored cells with the appropriate data for your robot or what you think you would want on your robot.  Try 1 motor, or a larger wheel circumference, or a lower wheel coefficient to see the effects on the robot speed and current draw.

Older versions of the calculator are located at:
http://www.chiefdelphi.com/media/papers/2059
http://www.chiefdelphi.com/media/papers/1469
The older versions have slightly different information, and in some cases, have more information.

Can you calculate the speed of the 2013 KOP Drivetrain? Information on that is found here: 2013 KOP Drivetrain

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Calculating Roller Chain Links https://firebears.org/calculating-roller-chain-links/ https://firebears.org/calculating-roller-chain-links/#comments Thu, 18 Apr 2013 02:17:55 +0000 https://54.188.23.233/?p=425 Calculating Roller Chain Links Read More »

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Roller chain is usually used in robots that we build for the FIRST Robotics Competition.  #35 roller chain is the standard chain pitch that we use on the FireBears.  It is strong.  It is also tolerant of minor misalignment issues.

When designing with roller chain it helps to design for the specific center distance to eliminate the need for chain tensioners.  How do you calculate this?  Thankfully there are chain calculators on the internet that you can use.  One such calculator is located here:
Roller Chain Calculator

#35 roller chain has a chain pitch of .375 inches.  Put in the sprocket sizes you need to achieve the reduction ratio you want and that are also available.  Then put in the distance that you have available (most likely you will get this from your CAD model).  This will give you the count of links needed.  From there you can use the top calculator to round down (or possibly up) to the nearest even number of links.  That is your center distance.  Use this calculated distance in your CAD model to correctly space your shafts so you don’t need to use chain tensioners.

Sprockets can be found at:

 

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14 CAD tips from SolidWorks https://firebears.org/408/ Sat, 06 Apr 2013 20:02:27 +0000 https://54.188.23.233/?p=408 Here is a scan of a SolidWorks document that has 14 tips for designing robots using CAD.

CAD – 14 Tips to Design Robots

The same tips are available here as video files:
http://www.solidworks.com/sw/education/vex-robot-design-kit.htm

Enjoy!

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