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  #1  
Old 06-22-2020, 12:34 AM
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juniorbrasil juniorbrasil is offline
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Make tracks

Hello.

I am with a project of tank E25, and the wheels and others parts are made and are on the post The armory. But until now I don't hade make progress with the tracks

So, someone could tell me how to calculate the space on tracks between the holes where the wheel teeth fit, because I tried to do it and it didn't work.

The holes are not matching the teeth, the first and second go well, they fit, but then the rest are out of alignment and I can't make the perfect fit.
I'm sending you a drawing with the measurements of the wheels and the track for you to see.
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Make tracks-tracks.jpg  
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  #2  
Old 06-22-2020, 12:58 PM
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Doubting Thomas Doubting Thomas is offline
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Hi, had the same problem when I started drawing tanks, and truck tires in Auto CAD. Is this your own design for the tracks?

To make them work you need a vertical Line from the center of the axle to the top most tooth of the drive sprocket.
Like the hands at 12 o'clock. (your black dimension 2.85)

The next is to draw a diagonal line in the center of the next sprocket tooth.
(the middle of your blue dimension lines 3.85).

The distance between these two sprockets is what you need to space your tracks on your left drawing,
or plan-view of the tracks. This distance is the center measurement between your two RED areas
in your plan drawing, center to center.

Once you have set the left plan drawing make your center drawing one match your left drawing.

Give it a try and it should work.

Jeff

Last edited by Doubting Thomas; 06-22-2020 at 01:12 PM.
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  #3  
Old 06-23-2020, 08:21 AM
cfuruti cfuruti is offline
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Assuming that track links have a flat inner face, the geometry for the easy case of articulations at the inner face is simplified as
Make tracks-sprocket.png
Here, the tooth count is low in order to exaggerate the angles involved. You want to correlate the link length L, hole length H, angle between teeth b, tooth angle a and sprocket radius R. I'll post the algebra later.
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Old 06-23-2020, 01:04 PM
cfuruti cfuruti is offline
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Let n be the tooth count, and the tooth-to-tooth angle b = 360º / n
Let a be the angle spanned by a tooth, and a < b
Let L be the length of a track link, and H the length of the hole. Suppose links articulate at the inside face.
Let R be the sprocket radius at each tooth's base
sin (a / 2) = (H / 2) / R, therefore H = 2 R sin (a / 2)
cos (a / 2) = r / R, therefore r = R cos (a / 2)
tan (b / 2) = (L / 2) / r, therefore L = 2 r tan (b / 2)

Actual links articulate between the inner and outer faces; the algebra above can be extended with an intermediate radius.
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Old 07-07-2020, 10:56 PM
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juniorbrasil juniorbrasil is offline
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Hello

Thank you for the tips.

I'm busy with work, but I assume that when I have a break, I'm going to do the test for the tracks and see how it works.

Thank you again.
Regards.
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