Trouble with 4th axis

[ArtF]

lol, Im with Phil, a sprocket in 2.5D is easy and very accurate, hard to do in 4th axis.

When I speak of a tangential angle and PI, I'm really saying that for many types of profiles, there is a point at which you cannot tangentially shave below. Its because if you rotate that point to the correct spot for shaving, the tool will
shave off points above that point which are not supposed to be cut. Involutes can be cut from base circle upwards, sprockets from about 70% upwards to the top. Some pulleys can be shaved a bit, some not at all. The real rule would
be , "If a points normal goes below zero degrees or above PI, it cannot be shaved by tangential shaving."

  This is why GM never allowed anything other than spurs...involutes are the only shape that truly allows shaving.
GT tries though a bit of AI to do any shape, and will attempt to do the best it can based on the tool shape I store in memory. Its not based on formulas but on coordinates of a stores tool shape. As a result, "Results will vary"

  Its all a matter of what the math allows more than anything else. Ill willing to implement anything, if its
possible,many things just aren't, even though they sound like every reasonable wishes. :-)

Art

[Stephen Fornelius]

I'm a great believer in learning from those who develop ideas.  Mucho respect, and I'm going to try both the fly cutting and the 2.5D cutting. 

A couple of ideas I'm playing with if I want to keep the integral collar idea.  1)  hold the workpiece in a vice with a v-block, 2) mount it in my 4-jaw on my rotary table (paid for it - got to use it!). 

The prep work will be to lathe the collars leaving .11 for the sprocket, then use a long enough end mill (.75 maybe), so I can do a slow cut on the sprocket portion.  Once the sprocket it cut, then part off the piece on the lathe (or hacksaw) and face the ends.  Drill and tap for a set screw.

I'm going to try the 4th axis with something smaller so I can use a typical epicycloid fly cutter.  Thanks Art for making the profiles on the drawings.  Helps a lot and I also check them against an existing wheel with the proper tooth profile.  Just more things to learn to do!

Steve

[philbur]

Hi Steve. What mill are you using (size and rigidity) and what size sprocket are you planning.

Phil:)

[ArtF]

Steve:

  Your going about it right. Your also pioneering , I dont think anyone has yet cut a sprocket on 4th axis, keep up all informed. :)

Art