Let's Make Robots!

"Wild Thumper" 6WD all terrain robot chassis


Vendor's Description: 


It's Here! Now with Video of it in Action on dirt using 34:1 gearboxes and new videos going down and up stairs and over snow with 75:1 gearboxes.

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Now available in silver!

Designed originally here on LMR specifically for robots, this 6WD chassis has wicked spiked 120mm dia. wheels and an anodized aluminium chassis made from 2mm thick plate. The chassis has 4mm dia. holes punched every 10mm to allow easy mounting of PCBs, servos etc. All nuts, bolts and screws are stainless steel. Brass fittings and suspension springs are nickel plated.

Two chassis segments between the wheels have been designed to hold 7.2V sub C battery packs (not included) as used in many RC cars. A total of 4x 7.2V battery packs can be fitted if necessary. These batteries are ideal for driving the 6V motors as well as inexpensive linear regulators to supply 5V.

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These photos show how even with one wheel resting on a large LMR mug (115mm high) all wheels are still touching the ground. It may not be a rock crawler but that's awesome for an off the shelf robot chassis.

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Ground clearance with the suspension lightly loaded is 60mm which is almost half of the total 130mm height when the topdeck is mounted on 25mm spacers.

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As you can see in this photo, with the top deck fitted you have a smooth deck to mount equipment on even when the chassis is flexed. Mounted on brass hex spacers, the top deck gives you room underneath to hide cables and PCBs to give your robot a cleaner more proffesional finish.

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The suspension for the front and rear is a single torsion spring. As the motor housings are connected to each other and not the chassis the front and rear can roll freely with the spring supporting weight and absorbing shock.

The steel cable is used to limit spring travel. The motor housings have 3 holes for each allowing spring tension and travel adjusment depending on the weight of the robot. Rubber grommets are fitted in the spring mounts to eliminate play while allowing the motor housing to roll.

The center suspension is similar but has 2 springs. Each spring connects from the motor housing to the chassis keeping the robot upright.

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The 6 powerful geared motors have steel gears and are fitted with powerful magnets to provide high torque. Top speed is about 6.6km/hr. These motors have a maximum stall current of 5.5A each so with 3 motors per side wired in parallel a dual "H" bridge rated for at least 17A per channel is required.

Rated voltage: 6V DC (min. 2V Max. 7.5V)
Stall current maximum 5.5A
No load current per motor is 350mA
Motor RPM is 10000 +/- 5%
Gearbox ratio is 34:1
Output shaft speed is 295rpm +/- 5%
Stall torque is 4Kg/cm

A 75:1 gearbox is now available!
This gives a top speed of about 3Km/hr and a massive stall torque of 8.8Kg/cm per wheel!!!

The chassis comes pre-assembled and weights 2.6Kg. Shipping cost to America or Europe will be approximately $48 USD.

Now available in 2 colour schemes:
Black with metallic red rims
Silver with chrome rims

Here is a preview of the 4WD version:

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Hi,

On my 4WD, the springs are kind of binding on one end.  The legs that attach to the motor mounts rub against each other as the mounts flex.  I tried prying each one up over the other like on the other end, but they don't stay.  Have you seen this?  Is there a quick fix?

Thanks,

Colin

Can you please post a photo or 3? I am having trouble following your explanation of the problem.

Hi,

I just got my Thumper 4WD.  I'm a very happy camper.

I was just wondering, is there any chance of getting 1 or 2 additional centre segments -- the one that doesn't have wheels.

Thanks a lot,

Colin

Sorry, once again I am having trouble understanding your explanation. Do you mean the brass adaptors that mount the wheel onto the gearbox shaft or the plastic rim inside the rubber tire? The brass adaptors can be bought seperately but the wheels (tire and rim) are sold together in packs of 4..

Sorry, by centre segments I mean:

"Two chassis segments between the wheels have been designed to hold 7.2V sub C battery packs"

I thought if I could get another one of those I could lengthen the wheelbase.

Thanks,

Colin

 

Those are not sold separately. If you lengthened the wheel base then it will not turn as easily.

OK, thanks.  Down the road, maybe parts could be made available.  I can see where an extra top plate might be useful, or maybe a half-plate.

Colin

Hi, I just got the wild thumper 6WD and I'm wondering how am I going to measure the speed in a direct form?... could you help with some ideas? or How do you do?... thank you.... P.S: I haven't bought the motor controllers yet, but for the application I'm building a good velocity measure for each wheel is very important

 

Thank you 

The easiest way would be to glue one or more small neodynium magnets on the inside of the wheels (inside of the tire, between the plastic rim and the foam insert) then use a hall effect sensor mounted on the gearbox to monitor the revolutions of each wheel.

Measuring the time between pulses will give you a direct measurement of speed.

When will the 4 wheel version come out