25# Sprockets

[AdamHeard]

Originally Posted by Akash Rastogi

I've been meaning to run plate sprockets and gears on a sponsor's laser, do you have experience with any pros/cons of having them waterjetted vs laser cut?

Thanks,
Akash

It really depends on the specific machine, and the knowledge of the person operating it.

First I'd say get some samples cut, and see for yourself. That trumps all advice I'm about to give.

We've had gearing water and laser cut on multiple different machines and different sponsors.

Most waterjets take a real quality hit on curved teeth as the cut is slowed down and excessive blowout seems to happen. The lower the toothcount, the more the teeth are curved. Even with this, pretty much every gear we've cut at 16DP or larger (including a 9T pinion) has run fine after some wear in. Our swerve also ran a 50T 20DP gear that ran fine.

When you get into huge gears, like the 300ish toothcount 24DP turret gear for Encore, the teeth are essentially straight and the smaller toothsize isn't really an issue.

Every waterjet gear we've cut has required some run/wear in, but has performed fine and lasted the season.

For Lasered gears, if they know how to run their machine right, you should get far better results that allow much more freedom in terms of small teeth and small toothcount. I did have one laser run that was just too gummed around the edges and was a total failure; this however was from a company that primarily worked in steel, and never worked on parts with fine detail.

As for sprockets, pretty much everything should work. For some waterjets you may want to artificially shrink the sprocket a few thou. Wear in will also be necessary (but can be done on the final vehicle of course) unless they are nicely tumbled or something. Laser should make beautiful sprockets.

In summary, we love it as a process. It's not the greatest method for small gears, and small teeth; but these are the easiest gears to cheaply get premade, so it isn't really an issue.

[ajlapp]

We routinely make our own #25 sprockets from 0.09" plate aluminum on the waterjet. 6061 works fine.

We also used custom sprockets in our drivetrain this season using the same process....no maintenance and no failures.

[Akash Rastogi]

Originally Posted by AdamHeard

For Lasered gears, if they know how to run their machine right, you should get far better results that allow much more freedom in terms of small teeth and small toothcount. I did have one laser run that was just too gummed around the edges and was a total failure; this however was from a company that primarily worked in steel, and never worked on parts with fine detail.

As for sprockets, pretty much everything should work. For some waterjets you may want to artificially shrink the sprocket a few thou. Wear in will also be necessary (but can be done on the final vehicle of course) unless they are nicely tumbled or something. Laser should make beautiful sprockets.

In summary, we love it as a process. It's not the greatest method for small gears, and small teeth; but these are the easiest gears to cheaply get premade, so it isn't really an issue.

Thanks for all the input and feedback!

One more item: Would the heat from the laser make the teeth brittle or anything?

[nathan_hui]

If anything, should anneal the metal, unless you quench the part after fabrication.

[AdamHeard]

Originally Posted by Akash Rastogi

Thanks for all the input and feedback!

One more item: Would the heat from the laser make the teeth brittle or anything?

Don't take this as fact. I would wager it anneals the material, but I've heard that if the settings are correct it can locally harden.

I'd ask the shop to be sure.

[Akash Rastogi]

Originally Posted by AdamHeard

Don't take this as fact. I would wager it anneals the material, but I've heard that if the settings are correct it can locally harden.

I'd ask the shop to be sure.

Will do!

Thanks,
Akash

[Garrett.d.w]

As mentioned above, most teams don't do it due to the fact that AM (and similar) sprockets are so readily available and cheap. I am sure, however, that there are a few teams out there that do it just for giggles.

It is relatively light on the design process. Drawings for the sprockets are readily available online from various sources. Drawings can also be done easily with a tool in inventor (don't ask me how, but I've seen it done).

Once you have your design, you have to choose your manufacturing process. A popular method is to use a waterjet to cut them out of a sheet of 6061 aluminum that is .125 of an inch thick. I prefer the waterjet idea as it allows you to make a lot of them at one time and minimizes machine time.