Nothing but Dewalts???

Hasn’t anyone used http://www.chiefdelphi.com/media/papers/1592 lately??

It looks like a relatively easy-to-make two-speed gearbox. And for the price it definitely beats any COTS shifter.

Any thoughts??

The specific transmissions have been close to unobtanium for several years. With AM and VEXPro 2-speeds on the market, there hasn’t really been a need for someone to retool the NBDs to currently-available transmissions.

3620 used a DeWalt transmission to power the floor pickup roller in 2012. Drill parts are not hard to get.

However, several much more convenient alternatives have become available recently. Check out what VEXPro and AndyMark have to offer.

Last time we used a Dewalt gearbox was in 2006 and it worked fine (no shifting), but with today’s offerings from Banebots, Vex Pro, and AndyMark, I wouldn’t even consider it. Oh how times have changed. I still remember the Bosch drills of 2002, and trying to get the darn clutch to not slip, and the Bosch drills of 2003 and 2004, trying to get them to not totally fall apart. We still have the parts from the Dewalts if someone needs them for a specific project.

We haven’t used them on Spectrum but I was on 647 when we wrote the paper. This thread has got me thinking, making a VersaPlanetary output to DeWalt adapted could be really useful. One of the main problems with DeWalts is the sun gear has to be modified and pressed on. If you press it on to a VP CIM output shaft, you could replace motors and change up gear ratios easily.

So adding the second stage (dewalt transmission) to the versa would allow the user to choose the versa ratio and the motor to fine tune their ratio and rpm for their application??

That was the idea, shifting VP. It does limit the output shaft and mounting options.

I know people have been weary of shifting with servos on the AM shifters, do the servos perform well with the Dewalt’s?

We (647) used them in 05 and 06 and they worked well. The DeWalt shifting mechanism is rotary so it is easier for the servo to shift. They weren’t instant so it was impossible to shift and keep a strait line but you could shift underload most of the time.

So I guess the real question is: is it worth the effort? Would they be successful servo shifting gearboxes for drivetrain for only $120 each…especially for our team that likes to stay away from pneumatics?

Wouldn’t you need two gearboxes per side (One Motor Per)? 4 total?

Oops…my fault there. So that’d put at the same price (roughly) as a comparable servo shift for a drivetrain.

But on another note they could be used for mechanisms where you might need shifting.
Ball indexing example: high gear for moving, low gear for unjamming.

Seems like they’re a lot of possibilities

If you need shifting on a mechanism, it would be easier/cheaper to probably just get a DOG/Ball Shifter shaft and some DOG/Ball gears.

I know your wanting to stay away from pneumatics, but they rock for linear motion such as shifting.

FRC 33 has used a lot of Dewalts, but not in the drive train since 2006. In 2008, we talked about a dual CIM into dealt XRP, but I found a component in the XRP that likely would fail. FRC 27 ran dual CIM into Dewalts and had dome issues (different component but similar failure mode).
In 2010 FRC 33 ran a cim through a dealt into an andymark gearbox and then a big chain reduction for the robot lifting arm.
In 2012 we switched to a small Milwaukee electric screw driver for a winch. High torque and anti back drive. This tool used a 550 series motor so the conversion was much simpler. Bosch has a nice 2 speed unit but the pinion swap is pretty tricky as the pinions are prone to break.

Ike, it looks like autocorrect is messing with your post. :slight_smile:

For drive trains, I don’t think they are a great option.

However for manipulators, they have a lot of nice features (anti backdrive, built in clutch).

I saw http://www.robotmarketplace.com/products/0-DEWUT.html in servo magazine this month. They don’t list anti-backdrive as a feature, but I bet it is. Could be retrofitted with an FP or RS 550/775 fairly easily I’m sure.

We used them in 2010 and 2011 with FP motors for various mechanisms, but have not used them for driving.
They work great and allow some nice tuning of speed and torque as needed.

That said, with all the different options out there now, we most likely will not be using them in the future.

I think the best thing we learned from using them is how to modify transmissions to work with different motors.

For example, in 2012, we used a 395 motor and a transmission from a “Globe Motor” to control the rotation of our turret.

From what I have read in the rules you can use any drill for a transmission as long as you use a First motor. 192 used a Harbor Freight angle drill 3 years ago. It made a quick angle gear box with correct reduction that was needed. As long as other teams can buy the drill you use it should be legal.

To echo what everyone else has said, the recent offerings from AndyMark, VexPRO, and others make Dewalts a poor choice for a drivetrain. I built a drivetrain with them back in the summer of 2007, and we competed with it at a couple off-season events. They were nice solid transmissions, but there were a number of little issues (size, mounting, manufacturing) that make them less attractive today. Shifting with a servo worked, but wasn’t particularly smooth. In my experience, using a servo to shift a DeWalt isn’t better than an AM. In both cases, the servo moves slowly and with relatively little power (relative to pneumatics, which go, “Bang. Done!”).

Dewalts may still be a good choice for a manipulator of some type because of the anti-backdrive or clutch. However, given the effort involved to actually make them work, don’t make the decision based on cost. In FRC, spending three or four days to save $50 is rarely worth it.

The dewalts couldn’t really shift on the fly. If you were driving, and you shifted, you first heard a screeching noise, one side of the robot stopped moving, the robot started turning, then one side made a crunching noise, shifted into gear, spun the robot, then (if you were lucky) the other side would fall into gear a second or so after. If you’re interested, check out 118 in 2007. They used a dewalt gearbox, and were really successful.

However, there are a TON of things out there that use motors really similar to the RS 550 and 775. You can grab gearboxes from these all you want. You can find leaf blowers, circular saws, drills… Who knows, maybe you’ll find something better than the drill!