[FTC]: [FTC] Looking for input on mounting NXTs

[CENTURION]

Hiya everybody!

So in the most recent season, my team and I ran into a bit of trouble with mounting the NXT to the robot. We did use the supplied Tetrix-to-lego adapter pieces, and it did work, but we concluded that this is not a very good mounting solution.

The two biggest issues I can see are:

The spacing of the bolt pattern on Tetrix rails doesn't seem to mate too well with the spacing of lego parts.

Lego attaching pins (Don't remember the actual name for them) don't hold too tightly, we had to zip-tie part of it down.

So I figured; why mess around with all these lego pieces at all?

I had some down time and started messing around in Solidworks, and this is what I've come up with:

(Sorry for the large images )







Essentially There's a cradle around the NXT, that has cutouts to allow access to the connectors on the ends, the battery compartment, battery compartment clip, and charging port. And it has tapped holes in the same pattern as Tetrix extrusion. The cradle is large enough in width to fit right between two Tetrix rails at proper spacing.

Then there's a lid that bolts down over the cradle, holding the NXT in place.

My question for you, CD, is this: Is this a useful design?

We're a rookie team, so we have some knowledge of how this enclosure would be implemented in future robots, but we don't have the experiences some of you have. Do you generally mount your NXTs from the side like this, or is it more from the bottom?

Oh, and yes, I've heard that the Ev3 will be put into FTC use for the 2014-15 season, so a new enclosure will need to be designed for that brick, but that's another matter, this design could still be used for the 2013-14 season.

So, your thoughts?

[Andrew Rudolph]

Very cool. Most of the teams I have worked with this year have just mounted the NXT to a piece of wood or lexan then bolted it to the textrix. This thing takes it to another level!

One thing you need to be mindful of in your design is how to change batteries easily, if its just connected with lego to a piece of wood, its easy to pull the lego out of the wood, leave the wires all plugged in, and swap batteries. Your four screws aren't difficult, but not nearly as easy as snapping lego.

This would be neat if you could somehow get LEDs in it to light up the screen.

One thing I have all the teams I interact with do is provide good support to the USB connector both on the NXT and more importantly the Samantha Module. The samantha module has a very flimsy usb connection so I make sure everyone puts something under the usb cable to support it.

[CENTURION]

Good point on the battery, but already taken care of

For some reason I didn't think to put in a photo of the underside, D'oh!

The cradle is open on the bottom, and I put in symmetrical cutouts so you can access the battery compartment clip, and charging port (We use the rechargeable batteries, so it can actually be charged in place), no matter which way you put the NXT in.

Oh, and I added some cutouts for weight.



I wasn't aware of the USB connector issues, thanks for the heads up on that!

I'll see if I can work something into this enclosure for that support.

LEDs might be possible, but that top panel is only 1/8" thick as it is.

[DanielH]

One thing that our team has done when mounting the NXT and SAMANTHA is to shock mount them. I believe that this helps keep disconnects from happening. Our shock mount is basically horizontal surgical tubing going between two tetrix beams, and then mounted to that surgical tubing is the NXT.

[CENTURION]

Yeah, I've been thinking about building in some sort of rubber shock-absorption, we'll see.

My team actually didn't run into any issues with disconnecting cables. How often does that happen?

[FTC-5648]

First off, this idea is amazing! Our team has had continuous problems mounting the NXT. We constantly get asked what the best mounting practice is and we never have a good, solid answer. This design would be extremely helpful! I was wondering if you had a 3D model file that you would be willing to share, so that teams could print their own cradle.

Congrats on the amazing design and good luck this season!

[CENTURION]

Sure! I've attached the two parts as STEP files, let me know if you'd prefer a different format.

Keep in mind that these parts were designed for machining, not 3D printing, so there may be things that require tweaking, I don't know much about designing for 3D printing, so I don't know for sure.

I made all the holes to the tap-drill size for #6 screws, so once it's printed, running a screw into them should self-thread them.

You should be able to edit the sketch for the team number on it to your own pretty easily (I hope). If not, let me know!

Also keep in mind that I haven't actually made this thing, so I'm not %100 sure that it will actually work, but I'm pretty confident.

[FTC-5648]

Thank you for the file! We had a SolidWorks pro create the case for 3D printing. Thank you so much for posting the information about the case and I will be sure to post pictures of the completed object.
Our team would like to credit yours with the idea and design, what team name and number can we put in our engineering notebook?

Best Regards,
Todd N. Farschon II
FTC Team 5648
Tek Twisters 2.0

[CENTURION]

Awesome, I can't wait to see the finished part! And please let me know if there are any issues you run into, or new design considerations. We'll have to be designing a new one of these for the EV3, and I'd like to integrate those things.

We'll hopefully be getting a printer soon too, so I'll have to crank one out as well.

We are Team 6806: Ratchet Robotics. Thanks!