Re: Cordless drill motors

[Joe Sommer <anvilus9-at-adelphia.net>]

Marc,

At 06:00 PM 9/3/2004 +0200, "Marc en Wendy" <marcmethorst-at-zonnet.nl> wrote:
>Is there anyone out there who is still using cordless drill motors instead 
>of changing to EV Warriors?

I originally used 12VDC Makita 6216D cordless drill motors
for Hetzer #T010 using a 1:1 drive ratio from the motors to
4 inch diameter drive sprockets.  They provided 400 rpm
for low speed and 1300 rpm for high speed.  Makita specified
320 in-lbf maximum torque.

The Hetzer was very fast but slightly under powered.  I could
do full-skid turns (e.g right track forward, left track reverse)
on pavement and short grass, but could only do half-skid
turns (e.g. right track forward, left track off) in heavy grass.

I recently switched to 24VDC Makita BDF46 cordless drill
motors with the same 1:1 drive ratio and sprockets.  They
provide 460 and 1500 rpm with 476 in-lbf maximum torque.
Hetzer #T010 is now very fast and very powerful.

>If there are, I would like to know:
>- how they perform,

I have not yet tried the 24VDC motors in battle,
but I am very pleased so far in field trials.

However, remember that Hetzer #T010 has the shortest
ground contact length (18 inches) and is the lightest
tank (75 pounds) that has been in battle.

Heavier tanks and those with longer ground contact
length will require more torque.

>- if they use the max torque safety system of the drill for when the 
>tracks lock up,

I have never locked a track.

I have stalled the tracks in heavy grass.  The max torque
adjuster did not engage.

>- do they generate a lot of heat.

Not really - The Makitas have tiny cooling fans in the back.

Almost all tankers are now adding cooling fans even
to their EV Warriors.

>Also, I noticed there are lots of cheap cordless drills for sale that run 
>on 14,4 V. These will probably also do fine on 12 V, but does anyone have 
>experience with this?

Operating a 14.4VDC motor at 12VDC will reduce
the torque considerably.

Also you will need to get cordless drills that have 2
or 3 speeds and use the lowest speed for 1:1 drive.
Otherwise you will need to provide external speed
reduction ratio of about 3:1 from the motor to the
drive sprocket.

Personally, I recommend 24VDC drill motors
or 12VDC EV Warriors.  If you really want speed
and power, you can run EV Warriors at 24VDC.

>I have now put through some modifications (a different rubber liner on the 
>drive wheels, a stronger tensioning system and reinforced motorframe) and 
>will hopefully be able to test this during this weekend.

If your guide horns on your inner track links are
strong enough, you can actually drive the horns
using a sprocket with rollers similar to the
original T-34 drive system.
http://www.gjames.com.au/chris/t34/fullsizecad.html
http://www.battlefield.ru/t34_76_4.html

Best wishes,
Joe


**********************************************
Joe Sommer
2378 Nantucket Circle, State College, PA 16803
814.234.4773     anvilus9-at-adelphia.net
http://www.anvilus.com