Ultra light Motail

[John Doe]

Just tested an ultra light version of a push stick.

The inline skating push stick weighs in at a lean 6.3 pounds. The
DeWalt 18 V motor is small but surprisingly powerful. I sort of
messed up the right angle drill controller, currently using
another controller from a standard DeWalt 18 V drill, it seems to
work. The wheel is a 125 mm Razor scooter wheel, it is hard but
small and light. Not good for rough terrain, but that is usually
avoided. The push stick is unwieldy and unnecessarily stressful
when held by hand against the ground. Will attach a hook to the
stick that will press against my rear thigh. And the controller
needs to be attached properly so that the stick can be held while
the controller is used, with one hand. Next up is to determine how
long one 18 V XRP battery lasts. Using lithium-ion, later, the
weight will be reduced.

Concern about abrupt starting could be in theory eliminated by a
clutch that is included with most cordless drills. Unfortunately,
the DeWalt right angle drill happens not to include a clutch.
However, it is small and light, and the chuck can be hacked and
ground so that the skate/scooter wheel is secured right on the
chuck extremely close to the large right angle gear bearing. The
wheel being so close to the bearing, hopefully the unusual torque
will not prematurely destroy the bearing and the right angle gear.

In short, the damn thing works, yea.

[John Doe]

Solidified the controller on the push stick so that the stick can
be held and the controller used at the same time. Stuck a hook on
the push stick so that it pushes against my rear thigh. That is
partly to eliminate unnecessary stress from holding the thing by
hand. However, there is not very much stress when I crouch and
hold the front end of the push stick with my arms extended.
Similar to being pulled by a vehicle.

Will figure out how long does a 2.4 amp hour battery last and what
is the top speed. Using the DeWalt 18 V right angle drill with a
125 mm scooter wheel, low and high speeds are both usable. Low
speed is definitely slow enough to hopefully get me up hills. High
speed is not too fast for the sidewalk with no pedestrian traffic.
Seems the controller does not get hot. The motor gets somewhat
hot. From a standstill, acceleration can be a bit jerky, but that
is the fault of the controller. Takeoff should become much
smoother with practice. The scooter wheel bounces around some,
but rough treatment is what power drills are made for.

[John Doe]

Needs a softer or an air filled wheel.

[John Doe]

Needs a softer wheel, but otherwise it rocks. The first push stick
for inline skating that uses AutoGrip. When the stick pushes from
behind, it tries to ride up the skater. Doing so, the stick angle
becomes greater and the counterforce pushes the wheel into the
ground, thus causing traction. That means the push stick can be
light as possible, it does not require static weight to hold the
wheel against the ground. So far, besides going up hills,
providing short bursts of speed is fun and useful for street
skating. Battery life is okay.

[John Doe]

Charged up both DeWalt XRP 18 V batteries and took my ultralight
Motail (with AutoGrip) out for a more exhaustive test ride today.
It was fun, I need to get used to the fun. Now I am not sure about
needing a softer wheel. With practice, the thing bounces less.
Also, I can sense bumpy pavement with my skates and remove the
thing from the ground. Somewhat concerned about the abnormal
strain on the right angle gear, but I might just use the thing
until the right angle gear fails or proves itself to be
surprisingly durable. The trigger throttle is still a bit
unwieldy, but it does fine with careful use. Since a cordless
drill controller at full speed shorts the battery to the motor,
full speed is the most efficient position to be in. I only used
high gear this outing, that's probably between 10 and 20 mph. I
will measure speed later, maybe. The batteries got hot, but that's
probably not very unusual for cordless tool batteries. I might go
for a lithium-ion battery soon, but it's only a reduction from 2.1
pounds to 1.5 pounds per battery. The total push stick weight
using a DeWalt XRP NiCad is 6.5 pounds, without an extra battery.

[John Doe]

Post by John Doe
Just tested an ultra light version of a push stick.

Put a picture on my page.

http://www.flickr.com/photos/***@N04/

[John Doe]

There are many possible modifications/improvements/upgrades.
Making the thing lighter is obvious. Improving the battery
technology is obvious. Also possible is hook the battery on my
belt and connect it through a wire to the controller on the push
stick. That would make the stick much lighter and maybe easier to
handle. Then again, since the stick is a force capable of pushing
me, there probably is no stability improvement by doing that.
Using a cordless drill motor part that includes a clutch still
sounds like a great improvement over my current DeWalt right angle
drill that has no clutch, slightly increasing the weight. Also
possible is to just use an ordinary drill motor part, with a seven
or 8 inch wheelchair wheel. The DeWalt right angle drill includes
a very large bearing at the output of the angle, that's a plus.

http://www.flickr.com/photos/***@N04/
http://www.flickr.com/photos/27532210 N04/ (sign removed)

[John Doe]

It is fun. On slight hills, no more pushing, I zip along at it
least 15 MPH. Planning to make another one, the same power, maybe
better functionality, and lighter than the current 6.5 pounds. The
fact it can be carried instead of towed makes some street skating
operations (like going up curbs) easier. It's also smaller and
easier to put into a store cart, or carry onto a city bus, etc.

http://www.flickr.com/photos/***@N04/
http://www.flickr.com/photos/27532210 N04/ (sign removed)

I might end up using NiMH 3.5 amp hour batteries, or maybe 3.0 amp
hour lithium-ion.