Banebot 56mm gearbox - double D - RELOADED

[Dick Linn]

1018 and 1020 steel can be hardened somewhat. The critical part is the rate of cooling, which is the reason for the salt and surfactants. The vapor barrier between the hot steel and the quenchant must be minimized. The Manganese content of the steel may also be a factor.

Another method is to use a high-pressure stream, as in the case of the process in U.S. patent # 3294599. This patent claims an increase in strength from 40-60,000 PSI to 155-250,000 PSI in steels having from .08 to .25 percent carbon content.

[esquared]

Originally Posted by Billfred

Keep reading.



That said, a competition-day switch wouldn't faze me in the least. I have empirical evidence that shows even a marketing major can tear a pair of these down and rebuild them in well under an hour with one allen key.

It's not the time required to disassemble the tranny to replace the plate. It's the time required to disassemble everything, get to, and remove the tranny that is a concern. Considering the number of teams who will still be getting their robot working during the day before/during practice rounds at the regional, having them at the regional will definitely cut into their time to get finished.

[travis]

Before I could tell them not to bother, our (lockheed) lab guys snuck a carrier plate in between shooting space shuttle parts. I cast another vote for 1010-1020 series.

They used an X-ray fluorescent (XRF) machine to determine the alloy:

http://en.wikipedia.org/wiki/X-ray_fluorescence

The reson you need to put detergent in your quenching liquid, and that you can firewalk, was discovered by this stern looking indiviual:

http://en.wikipedia.org/wiki/Leidenfrost

My edition (27) of machinery's handbook lists this series in the carburizing heat treatable alloys table at 900C (that is 1650F in christian units) follwed by plunge in water/brine with 170C/325F optional tempering. So if you want to do some mad science, and get yelled at by mom for experimenting in the kitchen (for the tempering anyhow), boldly go, the replacements are in the mail if you wreck them.

Travis

[grantf]

My team is experiencing 2 issues with the BaneBots 56mm transmissions.

Here's our setup:

• 4 56mm 16:1 BB Transmisions
• 4 CIM motors
• Each motor/transmission combination directly drives an 8-inch wheel.

Here are our problems:

1. Carrier plate issue.
   This is well understood so I won't take up space here.
2. Brass dust from the planetary gears.
   We drove our robot around for about an hour and had no problems. After that first hour we noticed that our robot was "swerving" a bit. After about 2 hours, we noticed that 2 of our wheels were very reluctant to rotate. After reading this thread, we disassembled our BB transmissions and found a lot of brass dust inside. We cleaned out all of the grease (brass paste at this point) and re-lubricated the transmissions with all-purpose automotive chassis grease. This seemed to improve our situation. However, one of the transmissions rotates well, 2 rotate fairly well, and 1 is still pretty tight.

Our next steps:

1. Break in the transmissions (no-load duration test)
2. Check for more gear dust
3. Monitor current draw from the CIMs

Any advice would be greatly appreciated.
Thanks.

Editor's note: I (Joe J) have closed this thread, but the Second Stage Sun Seizing discussion continues here.

[MrForbes]

Did you find any obvious wear points on the planet gears to indicate where exactly the brass was coming from?

What stage was most of the brass in?

Do you have the black steel wear plate installed between the 2 motor adapter and the first stage gearset?

[ZZII 527]

Originally Posted by esquared

It's not the time required to disassemble the tranny to replace the plate. It's the time required to disassemble everything, get to, and remove the tranny that is a concern. Considering the number of teams who will still be getting their robot working during the day before/during practice rounds at the regional, having them at the regional will definitely cut into their time to get finished.

If this does wind up being a Thursday fix at the regionals, teams should prepare by making sure that they have a process for getting out the gearboxes. Something to press the pins out will be useful too...a table top drill press can probably work. And don't rush the job...it's better to spend an hour or two making sure the alignment is good and the gearboxes are broken in than to find out on Saturday that you have nothing but rounded off brass cylinders where your planets used to be.

That being said, if you are a team using 12:1, 1 CIM (like many rookies, I'd imagine), have been driving around for a while and haven't notice any major backlash problems, and have taken appropriate software measures to reduce shock loading, would you still repair these on Thursday at a regional? I'm not sure that I would.

[MrForbes]

Originally Posted by ZZII 527

Something to press the pins out will be useful too...a table top drill press can probably work.

If the new plates don't have pins in them, you can quickly remove the pins from the old plate with a 1/8" pin punch (or a 16d nail with the point ground off), a hammer, and a small socket from a socket wrench set.

Installing them can be done with a vise or the hammer, but it would be nice to have a guide, such as a chunk of 1/4" or so thick aluminum with a slightly oversize 4mm hole in it, drilled as close to 90 degrees as you can get it.

[Joe Johnson]

Concerning the pins. The new harder carriers from Banebots will have pins installed in them so removing them should not be required.

On another note, I am going to close this thread and start a new one here:

Banebot 56mm gearbox - double D - V3 - It's Show Time.

I will also start a new thread about the second stage sun siezing on the output shaft.

Joe J.