GearHeads Corner

Simulating a V-bit use, it cuts into the teeth in tangential mode.

Also, rooting doesn't work well with a V-bit - the tool just moves in the X and Z. It doesn't move in Y axis to remove the material properly. And the depth steps aren't divided equally - the final step is very large.

Also, no matter what tool - defining a Final Pass makes no difference at all.

Thanks,
Dan

Dan:

Very true, the code is designed for endmills, ball or standard, but wont take any V tip or other shape into account.
I had never heard of any reason to use a Vtip.. is there a logical reason a shape like that woudl be desirable?

Art

Hi Art,

Had to cut a couple of gears 48 DP. The max. tool diameter for these is 0.68mm. Not something practical. Thought I could use a V-bit to make them. Have a box of engraving V-bits, 20? with 0.4mm tip.

Dan

So is it feasible? Are you planning to fix/make it work?

Dan

Dan:

  I had a request for tapered bits for that reason. I will try to add this in the fall, I think I can do it just by correcting for the
angle of the taper. In actual fact a 20% taper will produce a PA of 20 by natural math.. so I know it will fit in there somehow.
Wont be till Oct. time frame though.

Thx
Art

ArtF wrote:   I had a request for tapered bits for that reason. I will try to add this in the fall, I think I can do it just by correcting for the
angle of the taper. In actual fact a 20% taper will produce a PA of 20 by natural math.. so I know it will fit in there somehow.
Wont be till Oct. time frame though.

Beside the issue of speeds and feeds, it seems like it's a reasonably straightforward coordinate transform away from the slotting saw method.  Though, if you're cutting with an engraving bit, I've got to hope it's a small gear.

>>like it's a reasonabl y straightf orward coordinat e transform away from the slotting saw method.

It is indeed. Fair point though, a taper is stronger than a flute.. VTool would prbably never work thoguh, its likely
a 45 degree would hit the next tooth before it shaes the proper one.

Art

VTool would prbably never work thoguh, its likely a 45 degree would hit the next tooth before it shaes the proper one.

Yeah, the easy case is when the pitch cone half angle of the taper on the cutter is less than or equal to the pressure angle of the gear, and the end diameter of the cutter is less than the bottom land of the gear.

It is possible to do a little better, which could be significant if someone wants to cut a 14.5 degree pressure angle gear with a 15 degree taper cutter, but it seems like engraving cutters are available in a wide variety of taper angles.

https://www.youtube.com/watch?v=vDf0lEN3ekg
https://www.youtube.com/watch?v=_LYaMqaUpqw

Anything you do for us flycutters is appreciated....

Thanks, Art.

--Justin

An interesting approach to cut miniature gears using a slitting saw:

https://www.youtube.com/watch?v=rgv0q23Bx0Q

Don't know how it works as the slitting saw seams to be cutting sideways as well, while it is only designed to cut forward...

Dan

I suspect its a very fast in and out motion, its too small to see the resultant alias marks. Its a grea technique, but only for microminiature gears I suspect..

Art

Dan wrote: Don't know how it works as the slitting saw seams to be cutting sideways as well, while it is only designed to cut forward...

As long as the chip load is small enough, it shouldn't be that different from cutting into a tilted surface.

ArtF wrote: Dan:

  I had a request for tapered bits for that reason. I will try to add this in the fall, I think I can do it just by correcting for the
angle of the taper. In actual fact a 20% taper will produce a PA of 20 by natural math.. so I know it will fit in there somehow.
Wont be till Oct. time frame though.

Thx
Art

Hi Art,

Are you going to work on adding this?

Thanks,
Dan

Dan:

  This one Im looking into as well.

Art

Hi Dan:

  Ive finished investigating issues with allowing VBits and such, the problem is twofold, first, the program is no longer using
involution theory for toolpaths, it now uses graphics so that its compatable ( as much as can be) with other tooth forms,
from pulleys to Epi's. ).
  This means I cant simply zero out the pressure angle or convert it because the shape is already identified as the
target tool touch locations. This means at best a non flute shape would touch on the tangent point of the shape,
but wouldnt actually shave anything else. Not much of a solution Im afraid. Gearotic 1.0 used involution to calculate
a tooth, it could actually have done the job, trouble is it was good only for involutes, no other shape.

  I have though modified the program for next release, if you use a tapered bit, it will compute the tangent points
from the bottomflat location of contact. This means in theory you can use a tapered bit with less than pressure angle
taper to get a proper profile. It could help with small tools, it isnt really tangental shaving though
unless its a straight flute...

Art