Let me tell you about me Gear Fabrication Syndrome

Happy to! I use a woodworking CNC router (a stock xcarve) to cut the gears out of brass sheets. It is absolutely not the “right tool” for the job, but already had access to one and it seems to work.

The gears are mod0.8. 40, 20, 12, 10 and 8 teeth. I cut the bevel gears and the pinions out of 3mm brass sheet stock while the larger wheels are cut out of 0.7mm brass stock. (Why this modulo? That was the smallest gear family my prusa 3d printer could print reliably, and i guess i just stuck with it as i transfered to cutting brass) (Why this stock thicknesses? That is what amazon had in next day delivery :))

I design the mechanism and create the cutting toolpaths in fusion 360. The paths are 2d profile cuts for the straight pinnions and wheels, and 3d profile cuts for the bevel gears. For the bevel gears I have a “roughing pass” with a 1.7mm bit followed by two passes with a 0.8mm bit. This seems to be needed otherwise as the tiny bit steps “down and out” it encounters too much depth on the “outside” of the cut. At least that is how I explain it. What is certain that when i tried to cut the bevel gears with a single pass the 0.8mm bit broke all the time, and with this strategy I can cut all four of my bevel gears with the same two cutters. :) The pinions and wheels with straight walls I cut with a single pass.

I take 0.1mm deep cuts with 45mm/min feed, altough truth to be told I have tried 250mm/min feeds also and that seemed to be fine too. 350mm/min broke the bit too often.

I run the spindle at a constant max speed, which I have measured to be 27000rpm unloaded. Haven’t measured during cutting but somehow I doubt the dewalt with all its 900W slows down at allwith these tiny bits and cuts.

For work holding I use the following “sandwitch”: a 6mm thick aluminum plate is toe clamped to the bed of the CNC. There is blue painters masking tape glued on the aluminium waste board, super glue on that and the brass stock is held on by that super glue.

I start the cuts 0.3mm above the stock and finish it 0.3mm bellow. I probe the stock’s surface, back the bit up until it breaks the contact and zero it there. The gears I cut are small enough that i don’t seem to benefit much from z-scanning the surface of the stock. I use Universal GCode Sender to send the gcode generated by fusion.

Sorry for the lot of detail, just wrote what I wished have known a few months ago. Let me know if there is anything else you are currious about.

That's super interesting, thank you! I build furniture, mostly more traditionally, but sometimes use a CNC for making jigs. I have access to a 1200mm x 2400mm ShopBot, which has the worst software I've ever used that I didn't write myself. But with care and enough test cuts it gets the job done.

It's fun reading what other people are using these for in practice, and not just the sunny days version. If I ever try cutting brass with this level of detail and scale, this is exactly the kind of thing I'd want to read first.

I look forward to seeing your next project come to life!

Incidentally, your workholding is called a paper joint in woodworking, and is used to make split turnings and sometimes to attach clamping cauls :-)

Yes there can be a social thing, I had a friend who collected Starbucks city mugs, so people would bring them to her from all over the world.

On the “associated” thing - not so much about collections but there was an interesting article on the guardian website a few months ago, about a woman who came to realise that ‘I like Prosecco’ was not a substitute for a personality, but she had run with it for so long that that was all she ever got as a gift, and she discovered her friends knew very little else about her. A one-dimensional character trap.

Late reply, but... I'm with you on this one! Reduce/Re-Use/Recycle, washing glass spaghetti jars, etc. What I've come to the conclusion is the following guidelines/rules:

1) "Save _all_ the things!" Yeah, save them, use them, etc.

2) Use it or lose it: I have a space under the sink for washed/clean plastic containers. If that gets too junky, it's time to throw them out in the trash, offer them "free" on craigslist/facebook marketplace, your neighborhood group, whatever.

3) Regularize: we've ended up with strict "use cases" after saving "_all_ the things!". Sour cream containers become waste-grease-buckets for the freezer. Glass spaghetti jars become candy/cookie containers. Peanut-butter-jars become nail/screw holders in the garage.

4) Limit the flow: Once you "run out of space", keep only one or two "on hand" if it's a particular type of jar that you know you will "flow through". Basically you should reach a steady-state of using the stuff you're saving rather than growing your "cache" unbounded. Unless it's a really useful/valuable/unique type of box/jar/product, get rid of it! Even if it's awesome (but unique), probably get rid of it, b/c it'll end up being "the odd one out" unless you have a really specific need for it.

5) re-Regularize: is there a certain type/brand of spaghetti-jars that are soooo awesome, because they fit on a shelf, have the right size opening, etc. etc.? Start consolidating around one particular type (as you "flow through" them) and getting rid of the oddball ones.

6) Front-door, back-door: Put things by the front door if they're going to be given away, sold, donated, etc. Put things by the back door if they're destined for the trash. Make those decisions and then take action on them as you can.

There's a lot of value in saving some of this "stuff" from the waste-stream, and lots of pleasure to have all your other "stuff" organized in solid plastic containers (that you ended up kindof paying "nothing" for)... just don't fall victim to the "save everything", instead know that you can just "stretch out your hand" and grab the things you need _when_ you need them, not _if_ you need them. :-)