Speedy's "Bump Steer" Lunch Box Build Thread

[StrokerBoy]

Can't believe I've never seen this thread before.  Love it, nice work.

[speedy_w_beans]

Thanks!

So I did some work on the aquarium/air pump tonight.  First, a little adhesive felt to wrap around the motor...

Then, some scrap aluminum bent to form a bracket...

And there we go; the pump is now wedged in the chassis tub and clamped down with the bracket.  The self-adhesive felt cushions the pump so there isn't any chattering while it runs.  There was a spare screw boss molded into the tub, so I took full advantage of it.

[speedy_w_beans]

Next task was sorting out the wiring.  Originally the motor was powered by an alkaline 'C' cell (1.5V), but with the typical voltage of a LiPo somewhere around 7.4V, it's necessary to reduce the voltage so the motor runs at a normal speed.  I measured the running current at about 200 mA (0.2A) at 1.5V, so to drop about 6V (7.4V - 1.5V) at 0.2A requires 30 ohms of resistance.  I had some 10 ohm, 1 watt resistors, so three of them will do.

I replaced the original wires with some servo wiring, removing the extra white wire.

Joining three 10 ohm resistors in series...

Splitting the positive wire so the resistors can be inserted...

[speedy_w_beans]

One end connected...

Other end connected...

Heat shrink added for protection, and the wire ends tinned for later...

Pump, resistors, and wiring installed.  I did a quick test with a LiPo battery and it ran the correct speed with no rattling in the chassis.  So far so good.

[speedy_w_beans]

With the pump ready to go, I worked on the smoker/atomizer tonight.  The main idea is to cut holes in a small box and use grommets to hold the air inlet nipple and two atomizers in place, then mount the box to the chassis.

Locating the grommets and marking holes with a body reamer...

I had cut a small segment of styrene pipe using a pipe cutter and pressed it into the grommet to begin with, then measured the OD of the grommet channel with calipers to come up with a hole size.  Then I used the body reamer to cut the hole to size, pressed in the grommet, and pressed in the pipe.  One air inlet nipple ready to go...

I used the same process to mount the atomizers as well.

[speedy_w_beans]

With the inlet and atomizers mounted to the box lid, I focused on the bottom of the box next.

You can see there are slot and hole features in the chassis tub already, so I just marked and reamed a hole, then secured it all with the screw, spacers, and nylock nut.  The side of the box is resting against the side of the chassis tub so it won't rotate.

Just a test fit of the two box halves and the tubing connecting the air pump to the atomizers.

I did have to cut the ends off the atomizers so the silicone tubing would fit properly.  I don't see any issues with the tubing popping off; there's a lot of stiction between the tubing and the plastic mouthpiece.

How they look now...

[speedy_w_beans]

So I soldered the two atomizers in series and put heat shrink tubing over the joints to avoid short circuits.  Unfortunately I had to poke another hole in the box to let the wiring out, but I figured I could seal that later.

I used some hot melt glue to seal the wiring hole.  Since the heat shrink tubing didn't quite grip the wires tightly, I added a little glue just to keep the tubing in place.

I tried an air leak test by snapping the box top onto the box itself, blowing into the tubing, and plugging the atomizers with two fingers.  I found out immediately there was a sizeable air leak between the two halves of the box.  I thought about wrapping the box with electrical tape or running a bead of hot melt glue on top of the box edges, but settled on some black RTV silicone smeared on the box top instead.

The finished assembly...  I did a gentle air leak test with the RTV in place and found no leaks when blowing into the tubing and plugging the atomizers with two fingers.  I need to let the RTV cure completely before doing a trial run with a battery, but for now it's looking promising.

Hopefully I can fill the atomizers with liquid tomorrow and give it all a try with a LiPo battery. 

[novicelad]

This looks awesome! 

[Baddon]

when do we get to see the video clip of it smoking?

[speedy_w_beans]

2 hours ago, Baddon said:

when do we get to see the video clip of it smoking?

Soon!

I couldn't resist trying the smoke unit this morning.  A quick check showed no air leaks thanks to the RTV sealant, so I filled each atomizer with liquid.

Then I wired both the motor and the atomizers to a 2S LiPo battery, and got some great initial results!

Attaching some tubing to the atomizers worked well, too -- the smoke travels the length of the tube and still looks very white and full-bodied.  This should be a good representation of steam coming out of a bull's nostrils.

So this is really good; it's much better than the first attempt I made years ago.  The smoke smells like strawberry/banana, not some model train oil, and I don't have any problems with heating elements melting stuff because these parts are engineered for safe handling by people.

Next steps include wiring in the receiver-controlled switch and running some tubing to the front grill of the body.  Then I should be able to see the model work fully as imagined!

[speedy_w_beans]

I cleaned up the wiring this evening.  The air pump and the atomizers were combined in parallel first, then a separate ground wire was run to combine with the ESC ground.  The power to the loads was connected to the output of the receiver controlled switch, and the input power to the switch was combined with the power input to the ESC.  The switch is plugged into channel 3 on the receiver.  I attached some extension wires and bullet connectors so I can use a LiPo.  A few zip ties help hold things in place and keep it relatively clean.

Here are the atomizer hoses connected to the nostrils in the front grill.  The headlights are connected to channel 4 / battery on the receiver.

A quick bench test, and it works beautifully!

And a nice dramatic teaser taken in the hallway!

So, four and a half years later, it's finally done!  Time to make a quick video and have a little fun with it!

[Grastens]

Simply stunning! I am so happy to see the Bump Steer brought to life, and with such care and effort, too. Your work is superb!

I am sure this model will, to quote the original Bruiser promo video: "delight those who see and operate it"

[scollins]

Paul, I have to say- your commitment to getting this to work as you imagined is truly impressive!  You are a true Jedi!!!

I am in awe of your electrical skills, from now on I will consult with you on any electrical challenge I face on my R/C projects.

As for the Bump Steer truck, it is really really cool.......Movie worthy as a cameo in something maybe related to Dumb and Dumber-er-er part 3.. ;-)    (thought there were two movies already ,lol)  First one was the best.

My god I love this thing!!!!   You really could go further and do this same idea for a Pro Street project or a muscle car project,,,smoke from the tires??? 

I've got a NIB HPI Cuda body that would love to have smoke coming out from under the rear quarter panels!!

 

[speedy_w_beans]

Thanks for the kind words, guys!

Grastens, can you believe we were talking about this as a concept *six* years ago?  Back then you were doodling ideas in a notebook at school!

[Crash Cramer]

On 11/27/2017 at 7:57 PM, speedy_w_beans said:

Thanks!

So I did some work on the aquarium/air pump tonight.  First, a little adhesive felt to wrap around the motor...

Then, some scrap aluminum bent to form a bracket...

And there we go; the pump is now wedged in the chassis tub and clamped down with the bracket.  The self-adhesive felt cushions the pump so there isn't any chattering while it runs.  There was a spare screw boss molded into the tub, so I took full advantage of it.

 

UHOH, somebody call the press, there was something taken advantage of. ?@!@?@!

On 11/27/2017 at 8:16 PM, speedy_w_beans said:

One end connected...

Other end connected...

Heat shrink added for protection, and the wire ends tinned for later...

Pump, resistors, and wiring installed.  I did a quick test with a LiPo battery and it ran the correct speed with no rattling in the chassis.  So far so good.

Am I being too picky or is one of those resistors turned around backwards or does it matter with those type??? I think my only electronics lesson was the fact that LEDs don't just go on anyway you like them, there is an anode and cathode(I think that is what they are called) and you have to get the right end on the right polarity to get any result and hopefully you haven't applied too much voltage to the said LED or it blew up when you got it wrong. LOL

MASTERFUL work with the micro electronics work, but I do wonder if those 3 resistors won't get a little hot under the collar and end up melting the neigbor wire then the heatshrink before long??? I guess it might depend on how long you run the smoker motor.

VERY cool work and I should have made a point to come visit a few weeks ago when I went to Ft Myers to visit my brother and father. Next trip for sure if you will have me over.

 

[speedy_w_beans]

Hahahaha!  Yeah, I was looking at the pictures later and realized one of the resistors is backwards compared to the others, but it doesn't make any electrical difference at all.  Only certain parts like diodes, LEDs, transistors, integrated circuits, and some capacitors have polarization.  Resistors and inductors aren't picky.

As far as the resistors getting hot, I don't think that will be an issue.  Running current for the motor is about 0.2A, so power is P = I^2 * R.  In this case, P = 0.2A * 0.2A * 10 ohms, or about 0.4 watts per resistor.  The resistors are rated for 1 watt each, so there's some margin.  Plus, I only run the smoker in short bursts for a "snort" effect.  The circuits stays off most of the time.

Yeah, next time you're in NC and in the Charlotte/Greensboro/Winston-Salem area give me a shout.  Happy to have you for a visit!

[Grastens]

35 minutes ago, speedy_w_beans said:

Grastens, can you believe we were talking about this as a concept *six* years ago?  Back then you were doodling ideas in a notebook at school!

I hardly can 

If I recall correctly, it was not one of my initial ideas, but somebody brought it up and I drew it. From there, it was all your handiwork and creativity to make it a thing, and it truly is far better than anything I could have dreamed of 

I never would have guessed that vaping entering the mainstream would give the project the momentum it needed, either, so a lot of blind spots there for me

Anyway, congratulations on a fantastic project well-done!

[speedy_w_beans]

Go back to the first post in this build thread -- I still have a link to your "modern classic" RC thread for reference!  Do you still have the images from that thread? Such fun!

[Grastens]

I do - here is the original Bump Steer sketch:

I did not draw wheel arches because I really did not know what a Lunch Box looked like  Clearly, I was inspired by The Boogey Van:

One fuzzy Lunch Box later, here we are

[Crash Cramer]

OOOOOOOO, FUZZY LUNCH BOX, does that have any innuendo to it??? Like do I need a penicillin shot to eat my lunch out of the FUZZY LUNCH BOX????