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Involute of a circle...
andy_morris900
Member Posts: 8 ✭
in General
Hi Peeps,
I shouldn't even be discussing this, seeing as I'm a piping designer by trade and, by rights, I shouldn't even be using a parametric design tool.
Anyway, here I am, getting in far too deep...
I have somehow found myself getting into gear design. At first I was just messing around with a single sketch that contained two simple parts, one inside another. I created parameters which allowed me to change certain sizes on the fly and the outer part also changed so that a clearance was always maintained between the two.
Believe me, and I know you will laugh at this, but I find this fascinating...
Then I came up with the bright idea of, what if I made a very simply two gear train that had a gear box around it that changed size to suit the current gear design.
I could have just messed with extruded circles but I went off and googled "gear design" and a whole new world opened up to me.
Pitch Circe, Base Circle, Module, Addendum, Dedendum... All new terms to me and my brain has been fit to explode!
Eventually I decided to see if I could create an approximation of the involute shape in Onshape. At this point, after a bit of research, I realised how "Trig Lazy" I have become over the years. I started as a designer on the board and trig was essential. But once I got onto CAD (AutoCAD) I found that I no longer had to bother with trig at all. Ever.
Without looking into what other peeps have done with respect to this topic, I had decided that I could use points in Onshape and constrain them with dimensions. Those dimensions were calculated using trig formulae and gave me x and y locations of points on an involute curve. I then drew a spline from one point to another and, as best I can tell, the shape looks okay.
One bad thing I have noticed, as I changed the Pitch Circle parameter, quite drastically, the spline looked a bit weird and I need to have a think about that. Might be something to do with me not knowing how I should fully constrain the spline. It stays blue no matter what I try.
I should post some pictures I suppose, but it's a bit late here in the UK now and I should be hitting the sack.
I could post some of the lines of formula that I came up with to work out the required points, but it would take me some time to explain all the variables. It's not rocket science anyway... Just a lot of cos this and sin that haha.
From the point of view of my model, I've only got the involute curve sorted at the moment and the next thing I have to think about is the important stuff like number/size/shape of the teeth...
I'll end on saying, it sure is fun, but I'm wondering when I am going to get bored and go back to playing DOOM!!!
I shouldn't even be discussing this, seeing as I'm a piping designer by trade and, by rights, I shouldn't even be using a parametric design tool.
Anyway, here I am, getting in far too deep...
I have somehow found myself getting into gear design. At first I was just messing around with a single sketch that contained two simple parts, one inside another. I created parameters which allowed me to change certain sizes on the fly and the outer part also changed so that a clearance was always maintained between the two.
Believe me, and I know you will laugh at this, but I find this fascinating...
Then I came up with the bright idea of, what if I made a very simply two gear train that had a gear box around it that changed size to suit the current gear design.
I could have just messed with extruded circles but I went off and googled "gear design" and a whole new world opened up to me.
Pitch Circe, Base Circle, Module, Addendum, Dedendum... All new terms to me and my brain has been fit to explode!
Eventually I decided to see if I could create an approximation of the involute shape in Onshape. At this point, after a bit of research, I realised how "Trig Lazy" I have become over the years. I started as a designer on the board and trig was essential. But once I got onto CAD (AutoCAD) I found that I no longer had to bother with trig at all. Ever.
Without looking into what other peeps have done with respect to this topic, I had decided that I could use points in Onshape and constrain them with dimensions. Those dimensions were calculated using trig formulae and gave me x and y locations of points on an involute curve. I then drew a spline from one point to another and, as best I can tell, the shape looks okay.
One bad thing I have noticed, as I changed the Pitch Circle parameter, quite drastically, the spline looked a bit weird and I need to have a think about that. Might be something to do with me not knowing how I should fully constrain the spline. It stays blue no matter what I try.
I should post some pictures I suppose, but it's a bit late here in the UK now and I should be hitting the sack.
I could post some of the lines of formula that I came up with to work out the required points, but it would take me some time to explain all the variables. It's not rocket science anyway... Just a lot of cos this and sin that haha.
From the point of view of my model, I've only got the involute curve sorted at the moment and the next thing I have to think about is the important stuff like number/size/shape of the teeth...
I'll end on saying, it sure is fun, but I'm wondering when I am going to get bored and go back to playing DOOM!!!
0
Comments
You can also see the code which was a lot of cos and sin!
Thanks Neil,
I've grabbed that, so thanks for pointing it out. Can't say I understand what I am seeing but it works, of course... I just need to learn more about Onshape.
Kind of took the wind out of my sails but it means I can get on with other things.
I might still see how far I get with doing it the hard way haha!
I've copied it to my workspace so I can examine what is going on. So much to learn, and for what, I'm not sure.. I doubt very much if I will be able to switch to a purely mechanical discipline after thirty odd years as a "piper..."