How do we sketch an accurate cam form?

[vworpi]

I have a customer drawing that would be beneficial to us if we converted it to a solid model.

Any suggestions for the best method for doing this? My first though is splines, but is there any way to automate the dimensioning of the points? Use expressions to generate the points?

Ultimately the model would be used to produce a CAM program.

[MRWakefield · Accepted solution]

I'm not aware of a cam profile generator add-in for Fusion so you could knock up a spreadsheet like the one I've done for your cam. It might not be the best solution but it's what I could come up with in the time. I've attached the spreadsheet and the CSV generated from it. You'll just need the ImportCSVPoint add-in script to generate a spline from the points. I'm sure you could get away with fewer points but I'll leave that up to you .  I'll also leave it up to you to add the rest of the profile. I hope this helps.

Here's one I did earlier.

[vworpi]

That looks like a good point in the right direction. Normally I'd manually bang the g code together with a bunch of points from an excel sheet, so I think our baseline method is very similar 🙂

I've just had a quick play with projecting the edge of a coil, but can't seem to get the angle relationship of the coils close enough for the part.

I'll have a look at ImportCSVPoint over the weekend.

[vworpi]

I used ImportSplineCSV. Couldn't find ImportCSVPoint, ignore me, just found it on github.  

I had to add z co-ordinates the csv to get it to work, and it scaled the points up by x10(!)

So, scaled everything down, added my missing arcs, extruded and CAM'ed out my program. All worked, machined the job friday morning.

Thanks for the help.

Quick update since typing this 5 mins ago. ImportCSVPoint works much better than the built in ImportSplineCSV.

[MRWakefield]

That's great, I'm pleased it all worked out

I think the ImportSplineCSV works in cm so that would explain the x10 scaling. As I'm sure you found out, the ImportCSVPoints lets you choose the units and it doesn't require Z values.

Way back when I was a CNC Programmer/Setter I developed a CNC editor/comms application in VB (later ported to Delphi) which had various point/contour generating features such as bolt-hole circle, parabola, involute and helix/spiral. This was 30 years ago or thereabouts and there wasn't much in the way of CAM software around then. It made life easier and programming a bit quicker. I also developed an engraving utility that would take a PLT (HPGL plotter file) and convert it to G code. It could 'wrap' the 2D geometry around a (partial) spherical surface for engraving on top of a gear knob for instance. It would also work with a 4th axis so you could engrave around a cylinder.

Anyway, since using Fusion 360 I've been meaning to learn some add-in development stuff so I thought this might be a good opportunity. Spurred on by your post I've developed an add-in that I've been working on for the past few days for creating spirals (for cam design or whatever). It's a bit rough & ready and it could be improved in various ways but it's a first iteration and it seems to work ok.

This is my first foray into Python and Fusion 360 add-in development so it's been 'interesting'!

So give it a go if you want and see how you get on with it. You just need to unzip it into your add-ins folder. If you do give it a go let me know how you get on with it.

Edit:

I forgot to say that when you run the add-in it will put a new entry 'Spiral Generator' at the bottom of your sketch menu. You'll need to be in an active sketch when you invoke the command.

[vworpi]

I like it.

I managed to replicate my cam part using your spiral generator. It's certainly quicker than calculating the points in excel and importing the csv.

[MRWakefield]

That's great, thanks for letting me know, I'm pleased it works ok. Yes, the spreadsheet method is alright for a quick one-off but a bit cumbersome if you need to do it with any frequency. I'm thinking of developing the add-in further so that you can enter multiple segment definitions in one go, so stay tuned!