[max_imum2000]

i am currently building a new cnc with ballscrew, thk slides , servos , and everything to achive best accuracy i can get.
i was wondering will i be able to cut gears and pullies with my 3 axis machine ?
i mean to put a 5ml aluminum sheet (or plasitc) and gut the gear pattern on it so that the thickness of the gear will be the same as of the sheet
will that be possible with very small carbide bit for example ?

has anyone did it ?, please post pic if u did

thank u

[miljnor]

I have done sprockets (just another type of gear) so I don't see why you couldn't do it.

Definitaly not the fastes or best way to make gears but it will work.

Don't have any pictures but look at a motorcycle gear and that will give you an idea of what we made.

[keithorr]

I've downloaded dxf files from Boston Gear or somebody and cut delrin with a 3 axis and a 1/16" endmill. The problem is getting a long enough flute to make a thick enough gear. The smallest tooth gear I could make with a 1/16 mill was 16 pitch.

[miljnor]

if you had a 4th axis you could do it like a gear hobber does it. Although programing it would be a PITA.

[stuart]

go to gary's clock site for gears --just one example.

http://www.pathcom.com/~u1068740/pictures.html

[Servo Wizard]

MAX_IMUM,

Here's an example of cogg cutting. I made those on a 3 axis Bridgeport mill with a homemade indexer.

Servo

[ViperTX]

You should be able to make simple gears with your gantry style router....I would still opt at a minimum for hobbing the gears on a Bridgeport with the horizontal spindle or axis....however the Bridgeport people refer to that....(horizontal mill)....

[miljnor]

Here's an example of cogg cutting. I made those on a 3 axis Bridgeport mill with a homemade indexer.

hey servo wizard, could you explane that cut path a little and tell us what tooling you used?

Those are some VERY nicely done gears.

[chineguy]

Servo Wizard.
Very nice work. Looks like you know your stuff.

[Fireflowers]

I've seen chainrings being made for bicycles out of a 1 meter lenth of aluminium round bar. The whole bar was hobbed then the rings were sliced off with a horizontal band saw and finished machined on a cnc machine centre!!

[max_imum2000]

servo wizard
was that a 3 axis machine !!!!
job well done .
please share it with us
how did u do it
and if you can publish a plans for your indexer
and how the tool path work and so we will all kiss ur hands

[Servo Wizard]

miljnor,

The tool path cuts multiple coggs with a woodruff type cutter with a convex radius. You can see that the indexer wheel has fewer posititions than the number of teeth on any given sprocket along with an index that is uncommon to the others. The limiting factor for the number of coggs cut per index position was the cutter shank contacting the sprocket. Bear in mind when you view the tool path that the cutter was .875" in diameter so the tool path had to be offset.

The indexer is actually more interesting then the sprockets. It is interfaced with pneumatics and one electric solenoid valve. Let's see if any one can figure out how one solenoid valve causes the detent pin to retract and then actuate the pneumatic cylinder that rotates the index wheel.

Servo

[Servo Wizard]

max_imum,

I did not keep files for the indexer because it was a One Off production. It's a relatively simple design but it would be difficult to convey the details in words. The indexing lever rotates on a sprague bearing which facilitates free wheeling when it returns to the initial position. The indexing detent pin is also a spool valve which supplies the pneumatics for the indexing cylinder. Don't feel bad if you don't comprehend those details, I have 40+ years of experience and day dreaming behind my projects.

The tool path is what I refer to as a simple Zig Zag Stick Tool path, however the geometry is not simple as it involves 32 pairs of involute arcs per cogg. If you study the previous pictures you can see how the tool path functions

Servo

[miljnor]

so basical a "kellering move" over the gears tool path with a set stepover and this is with NO indexer movement while cutting???

I was mainly interested in "does the indexer move while cutting" or is it stationary and just rotates after every segment. The later i would pressume

[Servo Wizard]

miljnor,

Yes you have it right, the indexer remains stationary while the cutting tool cuts the group of coggs.

Those sprockets were manufactured for use on High-Tech road racing Gokarts that are powered with motorcycle engines that have a 6 speed gearbox. Several of the Left coast Gurus had attemped to manufacture the sprockets but the splined gearbox output shaft presented a problem for them. Every engine came equipt with a 13 tooth chain sprocket which did not fit into the gearing scheme so I found use for all those tool box sprockets. I no longer have pictures of the back side of the flanged sprockets but the attached tool path picture tells the rest of the story.

BTW, You're revealing your age when you use words like "kellering".

Servo

[miljnor]

what!

darn I will have to stop using antiquated sayings!

besides I am very young! NO realy!

well maybe not, but damn I still look good!

[JBV]

Made a gear with my 2 axis (so far :P) converted mill and a 5 mm endmill

[max_imum2000]

i assume this is a foum cutter ?
whats the dimenstion of the smallest gear u think u can make ?

[JBV]

Thats a 10 module, stub involute 20 deg gear with 10 teeth (100 mm pitch diameter) made in 19 mm thick MDF I don't know how small module i can cut for a given endmill ! I just loaded the gear into cad and measured

Just made it because i only have 2 axes converted on my benchtop mill so far.. And a gear seemed like the most interesting 2d part to make If i had a rotary table i would use cnc to grind a cutter with the exact tooth form for the intended gear (generated from a program) and then index and cut each tooth one by one.

[smoregrava]

Do I understand you rigth Servo wizard? You milled a pocket at the backside of your Belt sprocket that fitt outside the 13 tooth chain sprocket. And you used screws to hold the chain sprocket to the belt sprocket.? Then you did not need to make that inside spline.

Anyway a beautiful work