How to draw spur gear which is to cut on laser cutting machine?
Hello all,
I need a internal gear of module 9, teeth = 336, PCD 3024mm, face width of gear is 12mm, and 20° pressure angle.
hence i am planning to cut gear on laser cutting machine,
for that i need a perfect gear tooth profile.
How can i draw a perfect tooth profile, & what clearances req for cutting
2 Answers
That's a very unusual gear.. but here it is:
The internal gear has the exact profile of the external gear, so any textbook about gears will have the exact involut profile equation and others.
Or just punch in the values in the vast selection of gears generators online like here https://khkgears.net/new/gear_calculator.html or https://geargenerator.com/ or https://woodgears.ca/gear_cutting/template.html and many others. Google after gear calculator, gear generators, etc.
I have a parameterized model of a spur gear in CATIA with exact involut 20degree pressure angle. And customize it for 9mm normal modulus and 336teeth and thikness of 12mm and zero profile shift. This is without any backlash and without any tooth grinding for interference (for when the inside external gear has many teeth similar to what the internal gear has.. there was a formula for interal gears interference somewhere)
I have attached an stp file for this internal gear real dimensions.
For laser cutting i assume the opperator knows the kerf of the laser to make an offset on the waste side to ensure proper dimensions.
LE: I bet a laser cutter for mdf is 2D so you need the vector dwg/dxf file so here it is in 1:1 scale
Just my thought about the process:
Make the wheels out of plywood birch (the hardwood type) way more durable. Even construction grade plywood is better than mdf (but construction type of plywood has lots of voids in it and it splinters a lot but alternating plys ensure a great stability)
IDK where do you find a laser cutter that big or a sheet of plywood that big. So print it in sectors. It reduces waste a lot since multiple sectors could be cut out of an ordinary sheet.
To align the sectors I'd strongly suggest making the wheel double layer. To get 12mm of total width, go with two layers of 6mm plywood.
Offset the sectors on top with the sectors on the bottom. The cut part (that needs to be spaced out exactly to maintain the tooth spacing) will be alligned by the top layer that has a continous tooth profile above the bottom layer. Good luck with the project.
