How to cut a time belt pulley?

[avayan]

OK Gurus,

Here is possibly a tough one for you. I watched the Tormach videos on the 4th axis and I have to say it seems easy enough for a total novice like me to figure this out. So I know that to cut my T10 19 teeth pulley, I will need to use the transformation feature and set the angle to 360/19 = 18.947.

Needless to say, I'll be using the 4th axis attachment.

What I wonder is: what is the best way to cut the actual pulleys V grooves or valleys? Seems to me these are not planar pockets. In the past, when I have tried to cut teeth as in rack and pinions, the output of the waterline roughing and finishing was just not enough. It would go down to the bottom plane, but would not cut the angled portion of the teeth.

Any good video or presentation out there showing the best operations and parameters to use when cutting stuff like belt pulleys or gears? Any plan on generating such a presentation if still not available?

Thanks for your input!

Best regards,

JIQ

[rowbare]

You might want to look at Gearotic Gearotic Motion. It does several series of timing pulleys as well as gears. It can output a DXF for use in Sprut or g-code for Mach3.

bob

[avayan]

Hi Bob,

Thanks for the input. I did forget to mention that I already have the model and it is ready to get cutting operations assigned on Sprutcam. What I did was go to 3D Content Central and download the model of a T10 Belt Pulley. It had the shields, but I pretty much just got the pulley information by segmenting the pulley in two, grabbing the vector information and then doing my own extrusion solid. This was done in Autodesk Inventor.

I then exported the model as IGES.

I have the model in Sprutcam and I know that I will use the fourth axis so the transformation tab will need to be programmed with an angle of 360/19 so the program is repeated 19 times at the right angle.

What I am lacking is the information on how to cut the teeths. For example:

1. Do I use a fly cutter, slit cutting saw, or a round/ball end mill?
2. Should I use waterline roughing/finishing, or complex?

When it comes to teeth with an angle, I have never been able to get the exact cut out of sprutcam. And I have not been able to find a tutorial on how to optimize this process.

I know there was a blog posting on Tormach of a guy using the fourth axis to do bevel gears, but the CAMing was done in Visual Mill. Plus that was the only information offered.

JIQ

[scottsss]

If you go to youtube and do a search for "sprutcam gears", duke4monny (think I have the spelling right) has a two video's. I've only watch one of them but I believe it covers what you want. See link http://www.youtube.com/watch?v=wG8DQAH0M94]SprutCAM 7: Cutting an Involute gear on a 4th axis CNC mill - YouTube

[avayan]

Thanks to everyone for your great suggestions! I have definitely learned quite a bit on the process. Unfortunately, I am still missing the step to successfuly perform this job. I am attaching my project so you can see what I am trying to do. As of today, nothing works. Have in mind that I do not have a cutter like the ones suggested by Dukes4monny, which are excellent to cut gears. I am thinking about using a conventional mill, whether it is cylindrical or ball.

Here is what I have tried:

Waterline: Cuts a perimeter around the cylinder, even when I am programming the teeth faces, and not the pulley itself.

Pocketing: expands a square around the line edges that form the teeth and completely ignores the teeth.

Complex: So complex I don't even know what the hell it is doing, but simple enough to realize it is light years away from what I want it to do.

Rotary machining: Uses a gigazillion passes to carve one miserable teeth and disregards the other 18, even when I programmed the transformation around the A axis to fo 19 passes at 18.95 degrees.

The only other thing that I have not tried is to submerge the computer in a pond of sulfuric acid out of utter frustration. Could it be that $16K worth of equipment are useless at building something that should be so simple? The videos surely make it look like a kindergardener should be able to program this while at their sleep...

Any other suggestion? I bet I am one meassly click away from getting this done. All I need to know is what that click is!

[Scott_M]

I looked at your file. My guess is that you were not picking faces for your job assignment. I just quickly tried a couple different operations and picked the faces of one of the tooth cuts and they both ran and simulated fine. I will attach the file. BUT this is just for you to get some ideas from. I used an 1/8" ball end mill and I don't think it will cut the bottom radius correctly. You may want to play with other settings like "Scallop" and number of passes and others. This is just for toolpath.
The first one I applied the rotary transformation.The 2nd one I did not.

I am not saying it is right or anything... just to give you some ideas.

Also if you have to make very many of these I would look into a form cutter. One pass and done. With the little ballmill it is gonna take some time.


Scott