Dewalt gearboxes?

My team has not made a shifting drivetrain before so I was wondering if someone could give me some advice. I recently found some old dewalt gearboxes in our team’s cabinets. I know there was a white paper on how to modify them for shifting, but I haven’t seen anyone use the gearboxes in any of the years that I have been involved in FIRST (starting 2008-09). I was wondering if there is a reason nobody uses dewalts anymore. Is there a hidden flaw, or are the shifters from Andymark just cheaper/lighter/better?

If there are any other things we should keep in mind while designing a shifting drivetrain, please let me know. Thank you.

We got our AM Shifters in 2005 and used them on every robot since except 2009. The andy mark trans are light, easy to change the gear ratio, and they just look good :). The $350 price tag is totally worth it.

Dewalts are still very much in use. Las Guerillas, Rush, Wings of Fire and other well known teams have used them.

The benefits: they are light weight and cheaper than Andymark and can allow 3 gear shifting. The drawbacks: They require machining.

It would be awesome if Andymark started selling just the machined components necessary to convert the Dewalts. It would probably be cost prohibitive though considering the labor involved to tear them down and machine them.

We used Dewalts exclusively from 2005-2009. (And built our own completely custom shifters prior to 2005.)

In 2010 we made the decision to take the weight penalty and use the completely COTS AM Supershifter components…to make a long story short, we had lots of problems with our Dewalt setup in 2008.

We were constantly liquefying the guts of the transmission itself. My theory is that we had gotten to a truly rigid setup where the loads from the wheel on the carpet traveling back up the direct drive shaft were just too much for the transmission to handle. (Prior to this we had chains and other load absorbers in the loop) I cannot recount every modification that we made, but it’s safe to say that by the end of 2008 we had more or less re-designed/re-built the entire Dewalt assembly.

In 2009 we debuted a version of the Dewalt based on their 36v drill transmission. 36v Dewalt Trans in MuleBot This setup survived 2009 for obvious reasons (regolith), but started to show signs of weakness by the start of 2010.

Somewhere in this evolution we decided to accept the small weight penalty of using an AM Supershifter over the stress of building completely custom assemblies…to date we have never had a failure or open issue with the AM components. FYI…we are one of the rare teams that servo shifts! I believe it works flawlessly, though Andymark states on their website that servo shift is inferior…it deserves a second look.

All of this aside, we still use Dewalt transmissions all over our robots. They are super light, easy to implement and have handy built-in clutches that make them friendly to use for all sorts of scenarios.

We used a dewalt this year for our lift, the anti backdrive is great. I would never want to use one in a drive-train after seeing the innards of it, the only thing that makes it durable enough is the metal casing that comes with the drill. The gearbox itself while durable enough to be used in a high power system, would not handle shock loading well without the outer case.

Do a search on this web site for teched3 and white papers. I posted some info on the DeWalt/CIM mating of these components. We have not had bait of trouble with the through a season of competition, and did a teardown post season. I posted pics of this on CD a few years ago. We dropped the lowest stage per Joe Johnson’s White Paper, and only shifted 2 speeds. Shifting on the fly is not recommended. We are looking at a newer model which appears beefier and more available than the older model. PM me if you need more info.:slight_smile: :slight_smile:

Many, many teams have used Dewalts in drive train applications for years with little or no issue. They are more than robust enough.

We used Dewalts in 2007 (before my time, so I don’t know much about that) and then used it again to power a winch for the 2010 pull-up. It survived pulling around our 140-lb robot all by itself for three competitions, and we were quite happy about the small size relative to AM gearboxes, since we had a very crowded robot that year.

The shifter was this little rubberized tab that clicked through three positions, and in order to use it, we had to mount a servo with a little arm that actuated it.

I know that they are robust enough with the metal dewalt housing, we built a custom housing to mount our fisher price this year, and had only the white plastic gearbox itself. I would not recommend this for anything that will be exposed to shock loads.