3D Printing Metal Gears

I have spent a few years now playing with metal gears that are additively manufactured so I decided it was time to show something neat. Below are 3 different gears that are printed with different methods and/or finished differently. Two are 20dp and the other I forgot but just wanted to show something after polish. Material is 17-4ph on all 3 gears. The two binder jet gears are solid but the extrusion based gear is 15% dense from 5mm below gear dedendum to 5mm outside of hex.


Binder Jet and BMD printed gears. The third is a not a 20dp gear but shows a Binder Jet gear after several hours in a polishing system.


Top down view to show surface finish differences between extrusion based and Binder Jetting. Both gears are direct from furnace.


Closer look at a project with @zsm150 for a new rev of swerve. He can deep dive but allows azimuth rotation and power transfer to occur on the same axis.


Gear highlighted in blue.

General tolerance on Binder Jet one-off parts I am seeing ~1% for the first print attempt. This is then tuned in to get much better for the final part. BMD will see 1-3% if you are running things correctly and rescale a few times. I am probably going to use this thread to continue to upload cool little parts as I continue to explore printing with robots. I do a lot of plastics too but those are boring, everyone does that. If you guys want to know more on the process, part design, etc just let me know.

-Ronnie

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Definitely interested in this and whether it is good for things like bevel gears in swerve drives. Are you able to share information on what printer you used and how your team has access to it.

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The large, hex-bore gear looks to be the one printed with Bound Metal Deposition, which is a trademarked term for the process Desktop Metal uses in their Studio System printers.

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For access, I do this for a living via Azoth 3D and as a hobby via DesignFlo. My entire life is pretty much robots and additive now. We sponsor my team (SPEED), 503, and also 27.

Our metal printers are from digital metal and desktop metal for now with more coming soon. We have a few furnaces (debinding and debind/sinter) but our main furnace is from Elnik.

The largest of the 3 gears was done on a 3 step studio system. The other two are done on our digital metal. The one gear was finished on our REM system.

The process is very similar for both systems but it is pretty much a 3 step process no matter how you slice it. Step 1 being printing which is generally ~20% oversized into a clay-like part that we call green. This is a mixture of binder (glue) and metal particles of different micron level sizes. This then needs to be debound (removal of the binder) via oxygen or different gas environments. Each binder varies so this is where we develop IP around our process for the best parts. After these are debound, the 3rd step is to sinter it into the metal part. This is where you bring down the part to net shape to increase density.

As you can imagine, this process is not as simple as FDM. There are a lot of variables that can alter the tolerance, density, shape, etc. Beyond these, you have millions invested in equipment to get things running so it’s not something I can recommend teams go dive into. I will recommend finding companies that will sponsor you to get parts in your hands as this technology grows and becomes more affordable. You could get into a studio system for ~250k but quality isn’t there for most stuff.

As to bevel gears and such…yes. I will use this thread as a running blog to post up all the parts we are doing, going to do, and parts I struggle with. Hope this helps!

-Ronnie

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Do you have an estimated printing cost for parts like these? Curious how cost compares to products available from vex and andymark.

I don’t know the cost to customer off the top of my head but material wise on this but you are in the $4-6 range for material. Think of this as a tool to enhance designs/do things you can’t do with traditional gear manufacturing. It is not a cheaper method of manufacturing even though that is what major machine manufacturing companies say.

I have a 1/2 done paper on design for additive manufacturing with polymers and metals that I should finish. It highlights the key characteristics that make good parts and how to enhance design via all additive manufacturing.

-Ronnie

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I hope you’ll find time to finish that paper. Please link it here when ready.

This is a great topic. Now we will have to be more explicit on CD when referring to AM gears – up until now, the reference would have meant AndyMark. Now it might mean additive manufacturing.

Cheap additive metal parts remain an aspirational idea, and one that is driving a lot of investment. Who has a clear enough crystal ball to foretell when the aspiration will be made real?

tbh probs some rich dudes in suits that control a bunch of patents and supply chains

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I’m going to go out on a limb and say 10-20 years.

I hear that someone figured out how to do 6061 aluminum just in the last year or so…