[LDCad] Some Gear Rotations are "disconnected"

[NikosSprocket]

Hello

I am new with LDCad (but not with CADD) and I am baffled with the following issue.

For some gears, when I try to rotate them so the teeth mess correctly, the hub and the teeth are "disconnected"!

For example for 32269 if I rotate it clockwise the hub will follow my rotation but the teeth will rotate counter-clockwise!
Another example for 3648b I can only rotate the hub but not the teeth.

I have tried both using the GUI rotation {R} and the entry {Ctr-r} with the same result.

Am I missing something?

Nikos

[Philippe Hurbain]

Isn't it an illusion caused by rotation grid stepping, similar to car wheels that seem to rotate backwards when sampled at 25 frames per second?

[Owen Dive]

Hello

I am new with LDCad (but not with CADD) and I am baffled with the following issue.

For some gears, when I try to rotate them so the teeth mess correctly, the hub and the teeth are "disconnected"!

For example for 32269 if I rotate it clockwise the hub will follow my rotation but the teeth will rotate counter-clockwise!
Another example for 3648b I can only rotate the hub but not the teeth.

I have tried both using the GUI rotation {R} and the entry {Ctr-r} with the same result.

Am I missing something?

Nikos

I have long since given up making sure my gears meshed properly when building digitally.
But if you want to be precise, my suggestion would be to compute exactly how much rotation you need for any given gear (half of one tooth), and then apply that directly. For example, if you have two 20-tooth gears on grid-aligned axles, you need to rotate one of them (and the axle, and everything attached to that axle, which is why I gave up!) by 360/20/2 = 9 degrees, and you *should* get something much prettier.

Owen.

[N. W. Perry]

Isn't it an illusion caused by rotation grid stepping, similar to car wheels that seem to rotate backwards when sampled at 25 frames per second?

Yes, I can reproduce the behavior by using a 15 deg rotation step (which I believe is the default). Changing it to something else makes the rotation appear normal. Either way, it's just an illusion (but a fun one).

[Max Martin Richter]

Another example for 3648b I can only rotate the hub but not the teeth.

If you go with the default option of 15 degrees the teeth will visually not rotate, cause there is one tooth each 15 degrees. ;-)


If you want to adjust the gears correctly, you need to calculate them separately as written in another post.
As I do this always you can just search for a technic model done by me in the OMR. ;-)

[NikosSprocket]

If you go with the default option of 15 degrees the teeth will visually not rotate, cause there is one tooth each 15 degrees. ;-)


If you want to adjust the gears correctly, you need to calculate them separately as written in another post.
As I do this always you can just search for a technic model done by me in the OMR. ;-)

I used 1 degree increments and can see the hub rotating but the teeth do not. This only happens with the gears i have mentioned.

[N. W. Perry]

I used 1 degree increments and can see the hub rotating but the teeth do not. This only happens with the gears i have mentioned.

With 1-degree increments you should see everything moving. Any chance to show us a screencap?

[NikosSprocket]

With 1-degree increments you should see everything moving. Any chance to show us a screencap?

Sorry for the delayed response but finally I got back to the "puzzle" and this time the gear moved correctly at the one degree increments. Also, I noticed the "illusion" at 15 degrees using a pin and a tooth through the gear so I can see the move. Pretty cool and funny how are brain interpolate things wrong sometimes!!!

Thank you all for all the great input.