Atlas 618 Lathe Progress - Part V: 3D Printed 40t Gear

I never did get immersed in CAD/CAM software up to this point in my life, as I never really needed the skill at work or home. That was for the younger folks, don'tcha know. Well, times change. My daughter bought herself a 3D printer a year or so ago and has been making things. Hmm, that looks like fun. But I have no idea how to even start to learn the skill. But then Mr. Pete (Tubalcain), "your YouTube shop teacher", put out a few recent videos on how he learned to make things on a 3D printer, specifically lathe change gears. And my 618 lathe was missing a 40-tooth gear. If he can do it, so can I. And by jove, it wasn't that difficult.

While purple wouldn't be my first choice in colors, it was the color loaded into DD's machine and I wasn't about to try and change it. The color doesn't bother me at all. The material is called PLA (Polylactic Acid). Since it is biodegradable, I don't expect any gears made from PLA to last very long. Maybe if this 3D printing stuff pans out, I'll actually spring for a roll of ABS or Nylon filler.

Another peg that fell into place was that someone had uploaded STL files (3D printer files) of all the Atlas 618 change gears to the "atlas618lathe" Yahoo group. He mentioned that he had not tried the files but they were there for folks to try. I downloaded the Zip file and did a 40t gear test run on the printer. I used a 20% fill since this was basically a test run. Wow, I'm impressed.

Cool, it worked. So then I thought of trying my hand at actually drawing my own gear in CAD software. I downloaded Autodesk Fusion 360, which if I'm reading the usage agreement right, is free for hobbyists to use as long as they like. The software has an add-in that creates a gear if certain parameters are known, specifically: diametral pitch, number of teeth, center bore diameter, and gear thickness. For my gear, those values were 24, 40, 0.50", and 0.375".

Here is the start of the gear in Fusion 360.

This is after a few hours of fiddling with the software and asking my DD how to do a couple things. Incidentally, the "40" on the gear didn't turn out too well. The font was too small to read on the finished product. Next time I'll do better.

Fusion 360 can then send the finished part to what's called a slicing program to get the data in the right format for the printer (STL file). The slicing program I use is Cura, which is also free. I'm really liking this. And to think 3 days ago I knew nothing of this.

Below is my finished gear, created in Fusion 360, sliced in Cura, and printed on a $150 3D printer. The printer isn't as precise as I thought it would be so I needed to trim up the center bore about .015" and remove some thickness from the gear. With practice though, I'm sure I could get it dialed in pretty closely to not need rework.

I had to use the 4-jaw chuck so I could center the gear bore along the axis of the lathe. If I'd used the 3-jaw, the bore would have been offset since 40 teeth doesn't divide evenly into thirds. That would make for an offset gear - not good.

Here is a photo of the gear in place on the lathe.

Let's try to embed a video, shall we?

I suppose the next step is to actually try to cut some threads using the new gear...