Tangential Saw shaving 4th axis

[JustinO]

I can't seem to get the guy who wrote SolidWorks to pay any attention to me. Just as well; their spur gear tooth faces are made from one circular arc.

You're doing well, Art.

Thanks,

--Justin

[David]

Hi Art

Had a couple of hours, so started by finding a newish 0.016" saw, a better mandrel and some supporting discs (leaving about 0.2" teeth exposed)
I am still using the over long and unsupported mandrel for the blank, the blanks are the cheap hardware washers.
The teeth (72) are 0.6 module, at the base circle tooth width is 0.0325" and the tooth space is 0.037" which given the difficulty measuring is very close to the theoretical 0.0708".
Is the tooth space a little wide? The quality is just superb (IMHO)  ;)
Many thanks for your great software and support
David

[ArtF]

David:

  Nice work!..

Probably fine for clock wheels, but the space is a bit large, Im thinking it would require a bit thinner saw to make it thin
enough. The program is very good at accuracy, but a bit forgiving as to the diam being too large, it will cut anyway and
make the space too wide. Im thinking this is why the spaces look a bit wide.. but I'll have to check the math.. It may just be
the rooting is too wide.. seems I meant to check somethign there..

Art


Art

[David]

Hi Art

Moved on to trial pinions for clock, 8 tooth 0.6 mod. I noticed what may be an error in that for a 72 tooth wheel the OD given on the tools and project screen is the same at 1.762" the material size is calculated to be 1.777" an increase of 0.85%. For an 8 tooth 0.6 mod pinion the tools screen gives OD 0.238" the project screen 0.25" and the material size 0.2649" an increase of 11.25%. Not sure if this is supposed to happen or is an error. In both cases the OD on the tools screen is correct according to tables.
I have encountered a practical difficulty in that a 0.238" blank needs to be turned and then a length turned to say 0.165" for about 1" to provide clearance for the saw especially during A axis rotation . This is a bit flimsy and although I have done a couple of teeth in brass, I doubt the finish would be good in the preferred silver steel. Is it possible to have the cut applying Y axis retract before A axis rotation for small tooth numbers? This would permit cutting on a blank of the correct size without the length turned down  for clearance, but perhaps more productively also cutting of a length of material that can then be parted into a number of pinions saving material and ultimately the planet :D
Best wishes
David

[ArtF]

Hi David:

  That sounds reasonable. I will look into adding this for saw selections. Ill let you know how I make out, might take a few days...

Art

[David]

Hi Art

Had a few days break from gears, drew up some clock plates and machined them on the CNC mill, at least I can see them without an eye glass or microscope.
Back to gears, and tried a 0.55mod 12 tooth 0.125" bore gear in brass still, until you are able to look at the saw retract issue.
Very pleased how it turned out (pics attached) pitch circle at 1.171mm ( 0.066"0 very close to the standard 0.070") given the linear measurement rather than on the arc.
The space is 0.65mm (0.0256") and the tooth 1.041mm (0.041")
Question do you think this is now about right, both in visual appearance and measurement?
Best wishes
David

[ArtF]

David:
 
  The rooting looks pretty good, though the involutes look somewhat pointy.. but when you get
real small things get so critical that those really dont look too bad. I guess the test is if they run..

Art