Spur Gears CNC

[riche543]

Hey Guys.
Ive been trying to cut out some spur gears using my cnc machine,
Now im using emachine software which has a specific part for drawing gears.
my problem is that once ive cut out a gear the gap between the teeth is much bigger than it should be , which is due to the cutting tool im using 1.59mm end mill i presume.
so if i was to cut another one the same there would be lots of slop between the two meshing together, hope ive explained this enough too understand, if anyone has some advice or can point me to a good tutorial , it would be much appreciated.
Thanks guys
Rich..

[wledzian]

In my (admittedly limited) experience with CNC, the toolpath needs to be offset from the part by half the tool diameter. Every CNC package I've worked with has had built-in tools to generate the appropriate toolpath, but if your software simply moves the tool along the part outline, you need to offset the part borders manually. Every CAD package I've ever worked with has an offset tool - select the entire part outline and offset it by half the tool diameter to the waste side.

[riche543]

Thanks Wledzian for the reply,
Im a very slow learner , but normally after time it just clicks & i understand it, Took me long time to figure out how to build my cnc.
With most of my drawings i do componsate for the thickness of the tool, this dosent seem possible with gears unless the gear wizard software i use would have tool offsets. the major thing from what i can see is that the gap between the teeth need to be scaled down but not the rest of the gear, maybe im on a looseing streak tring to cut them on a 3 axis cnc/mill , as there isnt much on the net ive found rgding gears on cnc mill. not small gears anyway. reckon i could make a big wooden clock though LOL. anyway thanks for the reply i will keep searching
Cheers.
Rich.

[mondo50m]

I have been cutting gears on my machine for the last two weeks with some great success. I have been making 48 pitch gears in the following sizes: 60 tooth, 48 tooth, 36 tooth 30 thooth, 24 tooth and 12 tooth. all but the 12 tooth have 1/4" hubs, and the 12 tooth has a 1/8" hub. I did not have the necessary end mill (about .5mm) to do the cutting. I could only find end mills that have a cut depth of 1 to 2 mm in the size that I needed. What did I do you say??? I have a set of carbide micro drill bits that go down to about .2 mm. So I used one of those (but at .5mm) to do the cutting. I do not know what size gears you are making. But, the smaller the gear, the smaller the cutter has to be. I used the .5mm for all of the above mentioneds sizes and cut them out really slowly and with small depth steps. I am now in the process of molding them from resin. Working acceptably. Wil post pics in a couple of days



Milt

[riche543]

Thanks for reply milt.
I have been trying to cut 40mm diameter gears approx 40/50 or so teeth. I will have to work out how to compansate for the tool thickness in my drawings.
I will get there. I have my mind set onit now!!. will keep yas posted Thanks Again.
Rich..