RE: (ET) $15.00 chainsaw....

["Markus Lorch" <mlorch vt edu>]

Chris,

I like your idea. Maybe instead of getting a dc-dc converter you should get
a small variable speed motor controller. You could govern the motor 
voltage/amperage at a level where the motor doesn't overheat. What do 
cordless drills use to get variable speed?

Markus  

> -----Original Message-----
> From: elec-trak-bounces cosmos phy tufts edu
> [mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of 
> Chris Zach
> Sent: Sunday, June 13, 2004 1:42 PM
> To: Elec-trak list
> Subject: (ET) $15.00 chainsaw....
> 
> 
> Ok, in a new quest to make things work with the Elec-trak,
> I've started 
> with a portable chainsaw.
> 
> Ryobi made a line of 18 volt appliances that run on little battery
> packs. One of the failures apparently was a cordless chainsaw. It's a 
> really attractive device, with a chain, oiler, and a 10 inch length. 
> There are *hundreds* of them being auctioned on Ebay right 
> now, all new, 
> all with the little oil containers un-opened. My guess is Ryobi made 
> them and is now getting rid of inventory.
> 
> So I bought one. $15.00 without battery, can't beat that. It's really
> nice actually: Small and red and actually cute. It's plastic, 
> but seems 
> to be rather well made with modern features. It's also very 
> light, which 
> is nice.
> 
> I admired it for about 5 minutes, then took it apart. Screws,
> it's easy 
> to take apart. The motor is a little thing with a geardown for the 
> blade. Bar and chain of fine quality with a little 
> anti-kickback shield.
> 
> Inside it's 16 gauge wiring, small but there. I have to look up the
> specs on the battey pack, my guess is it's a 3ah pack and 
> they run it at 
> around 12-15 amps. So it's an under 200 watt motor.
> 
> So I pulled out the little battery connector, and replaced it with a
> nice AMP plug. Attached another plug to a 14 gauge 50 foot extension 
> cord and wired it into the rear 3 batteries on my Elec-trak. 
> Off we went.
> 
> Oh the chain spins slowly at 18 volts. Must be the gearing
> and the fact 
> that the pack had to be small. I see why these didn't do too 
> well in the 
> world. But we have Elec-Traks, so I went up to 24 volts.
> 
> Better, but still slower than my 14 inch electric. I wonder
> how it would 
> work at a full 36 volts; I hate the thought of imbalancing my pack.
> 
> Still, it cut down a small tree without much difficulty. Just takes a
> bit of time. I'll try wiring it up for 36 volts and see how it works 
> later, from what I remember you can run DC motors at higher voltage 
> without wrecking them as the amps stay the same. Correct?
> 
> Only issue there would be the switch: It would have to clear
> a lot more 
> voltage and might melt down. I recall that the Elec-trak 
> chainsaw used a 
> contactor in the line that was triggered by the saw switch. 
> Makes sense.
> 
> It's a bit of a throwaway, but still I am thinking that instead of
> buying an AC inverter I could build a 36-24 volt DC-DC 
> converter and get 
> a few of these tools from Ebay.
> 
> Chris
> 
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