Bevel Gear positioning

[BillM]

Hi Art

The attached  zipped .gth file poses a question regarding using bevel gears.

I created two 60tooth straight bevel gears 90deg axles, and forced the size to be 174mm.  I placed the 60T wheel on the project and then placed a 60T pinion connected to the wheel.  I changed the pinion number of teeth to 50, regen'd, The module of the 60T and 50T bevel gears remained unchanged as did the size of the 60T wheel.  When I added the 50T pinion to the 60T wheel in the project,  the 60T wheel and the 50T pinion no longer aligned properly.  The angle between the 60T wheel and the 50T wheel was no longer 90degrees.

This behavior is probably not a bug simply my misunderstanding of bevel gears.

Bill

[ArtF]

Hi Bill:

    Bevels are designed in pairs, the teeth on one actually change the size of the other. So if you regen, the bevel will lose its mesh.
If you intend to place bevels, you need to make them as a pair, and not regen between bevels. In essense the cone pitch changes
when you change the number of teeth, so the two cones no longer roll on ech other ( if you picture two bevels as cones..)..

  Unfortunatley, GM has brain trouble when it tries to mesh them, it cannot tel that the pair are not original sisters of eachother..

Thx
Art

[BillM]

Hi Art

The more I played with the bevel gears I realized that they had to be in matched pairs.

I am curious though,  why can't the "pinion" have more teeth than the "wheel"?  The E Howard Tower clock I'm trying to simulate actually does have on the #2 arbor a 50tooth bevel driving a 60tooth bevel gear.  After that there are 4 more 60-60 bevel pairs and the final set is a 60T driving 4 50Tooth bevels to go to each of the motion works for the 4 dials. 

I think you would find the simulation as interesting as my last Chronometer one.

Bill

[ArtF]

Bill:

  Should be able to have any number on either bevel, ( really by definition the pinion is the one with fewer teeth,
but GM simply calles them wheel / pinion by left or right gear on the design screen ). But you should be able to
have either one be the larger number... or just place the pinion first...

Art

[BillM]

Hi Art

The reason I asked the question about the Wheel/Pinion tooth settings in the tool is that the interface enforces the rule that the pinion needs to have fewer teeth than the wheel.

Any attempt to set the pinion to a greater tooth count than the wheel results in a message regarding tooth counts and a regen resets the pinion tooth count to the wheel tooth count.

Bill

[ArtF]

Hi Bill:

  Yes, thats a recent thing , when I switched to Gearotic 2, I switched to specifications
that were strict on some parameters, and the formula's for a wheel depend on the pinion
and vise versa, so I think bevels are the only one that enforces that rule where the pinion
must have fewer teeth. However, you should be able to place a pinion, then place a wheel on it..
so the end  effect is the same..

Art

[BillM]

Hi Art

Rather than start a new topic, this is somewhat related to the positioning  bevel gears.  I am using matched sets of bevels.

Attached is a jpg of a 4-way bevel test.  I first ran into this when putting together the E Howard clock simulation.

The driver is the spur gear.  I added a 60T bevel gear above the gear and then added a series of 50T bevel gears to the 60T bevel.  My goal is to position the 50T bevel gears exactly front, back, right, left as defined by headly.

When I add the second bevel 180degrees from the first, Gearotic2 placed the 50T bevel on the same shaft as the first bevel.  When I then added two more 50T bevel gears to the 60T at right angles to the first two, again they were placed on the same shaft.  The attached jpg shows the weird shaft assignments.

This was not the behavior that I expected.

My work around to force proper assignment of shafts was to place the 2nd, 3rd, and 4th 50T bevel gears at an angle less than quadrant angles from the first.  Once Gearotic2 created each 50T bevel gear on its own shaft, I moved them to proper position using the "move on wheel" command.

The gth file even when zipped is too large to post.

I don't know if anyone else creates weird arrangements of bevel gears. 

Bill

[ArtF]

Hi Bill:

Thx, I can prety much guarantee your the expert there, bevels are there for 3d, and few have ventured as far as you.
Sounds like something has broken from the days I made the balls of bevels. Ill run some check though. :)(

Thx
Art