Cambam + CNCwrapper + 4th axis

[Bubba]

Hi David, yes, it is lot faster and smoother. My 4th axis worm gear ratio is 10:1.

 

[Bubba]

Hi David
Could you post the relief (3Dmodel) in .stl format. I want to try the MecSoft Freemill program to see if I get lucky producing toolpath that cuts along the spirals. Thanks.

[dh42]

Hello,

  good luck

++
David

[Bubba]

Thank you David. Now I can play...

[EddyCurrent]

In light of several years experience since this thread was started, is there a better way ?
I'm thinking about making a worm, as in gears, out of wood and obviously the tooth or thread shape has to be somewhat correct.
Currently I don't have a 4th axis but I've been looking for an excuse to add one.

[dh42]

Hello Eddy,

a spur gear or inclined toothing ?

If it's spur gear, you can create the 3D profile for only one tooth, then use 3D machining to cut the tooth and repeat with the method used here with the spline shaft (section: Use of the nesting with a 4th rotary axis)

http://www.atelier-des-fougeres.fr/Cambam/Aide/English_addendum/Nesting.html

An example to cut a spur gear and it's shaft that use both Wrapper for the shaft and the method shown above for the gear. (pignon_arbre)

The second example show a way to cut inclined tooth with a toolpath transformation on a 3D profile the do the angle + a nesting to repeat the tooth + wrapper. (pignon_arbre_héli)

++
David

[Dragonfly]

Eddy,
I have the feeling that these days very similar thoughts circulate in our heads

[EddyCurrent]

David, just to be clear, this type of thing.

[dh42]

Re

Ok, I think it's possible with the methods above.

++
David

[lloydsp]

The 'classic' method to make that sort of worm gear arrangement "anti-backlash" is to cut the gear from two thin sheets of metal (as if one piece). Then mount one of them rigidly on the shaft, and mount the other snugly against the first with a clamping collar, but 'freely rotating'.

Then the free half-slice is strongly spring-loaded radially against the fixed one, such that the teeth pinch the worm between the two half-gears' (now slightly mis-aligned) teeth.  The maximum torque allowed before backlash returns is determined by the strength of the spring.

Lloyd

[kvom]

I think is is asking about the worm, not the gear.

[Garyhlucas]

A company that makes worm gear reducers with extremely low backlash uses an enveloping worm that wraps part way around the gear. Then it is cut in half and one side is keyed and slides on the shaft. An adjusting nut drives the two halves together.

[dave benson]

Hi Eddy
There is a process called Hobbing where you generate the worm wheel with a tap held in the spindle of a lathe
and the blank wheel is free to rotate on the cross slide. There are some detailed blogs on HSM and other machinists sights on how to do this as well as a few videos on you tube. If you are making the wheel out of wood (and you don't have a lathe)then perhaps you could  hold the tap in your spindle and make a jig for the blank to sit on bolted to your table. Just a thought.
Dave

[EddyCurrent]

Thanks for your suggestions.

I watched some videos about Hobbing before posting but that was mostly about making the circular gear that fits to the worm.
The worm I'm thinking about would not be to any standard thread, I'm not certain yet but it could be 3" diameter with a pitch of about 1/2" or more.
Using a wood lathe for example would be no good due to the low speed required.
The best method I can think of at the moment is to make it using hand tools but I'm going to experiment with some drawings today to see what CamBam and wrapper can do.