Electric chainsaw motor

I never pass up 25cent pulleys at yard sales, at worst, most come with a set screw.

Reply to
Gerry
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I think chainsaw horsepower is measured by how fast it cuts human flesh.

Reply to
Gerry

Cello.

The Portland HF is selling now lists no-load RPM as 5,500, Tawm.

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pg 8

Reply to
Larry Jaques

That's a 10x start-load! I've read that motor startup uses 4-10x the current, but most I've seen were closer to 4x. That's a biggie.

Have you tried an idler pulley setup to remove the flywheel load from the motor on startup?

Is it time to plumb in an unloader/pressure switch, or does it already have one?

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Any way to wire in a start cap to help with the current onrush?

Have you verified the genset specs under load?

Are you trying to fix this, or is it posted here only as info, since the genset does start the compressor?

Reply to
Larry Jaques

There are various legitimate ways to measure horsepower, but electrical power is being misused in those consumer-product ratings we were discussing.

At stall, all of that power is converted directly to heat. That's power, but it isn't horsepower.

Reply to
Ed Huntress

Without doing the math, I'll guess that's close to the kinetic power measured by torque and rpm, or the ability to lift a load at a specific rate against gravity (the original definition of "horsepower.")

It doesn't appear that they used such a method to measure the "horsepower" of my "4.25 hp" Ridgid shop vac. That would blow any fuse in my house, except for the one on my electric dryer. d8-)

Reply to
Ed Huntress

That's Texas Chainsaw Horsepower (TCH).

Reply to
Ed Huntress

Gerry has been watching too many Texas Chainsaw Massacre movies.

Reply to
Larry Jaques

But that's a gas model. Electrics are much, much tamer.

Reply to
Larry Jaques

The compressor motor has a starting cap.

I replaced the 1970's Load Genie unloader and swapped the copper tube that may have been stressing it for rubber power steering hose rated

175PSI, 302F but still don't hear the hiss of it unloading, however the compressor works fine on grid power. I only noticed the no-start during a long power outage.

If I have to inflate another tire on someone's neglected generator during an outage I can loosen the head outlet fitting or use the 12V compressor from the car.

-jsw

Reply to
Jim Wilkins

es

and on (non electric) motors, it's 550 foot-pounds per second. the picture that makes in my head is this: A motor with a 1 foot radius drum attached, winding a rope. If that rope can lift a one pound weight 550 feet in one se cond, that's a one horsepower motor. If nothing is moving, it's not doing u seful work.

Reply to
rangerssuck

and on (non electric) motors, it's 550 foot-pounds per second. the picture that makes in my head is this: A motor with a 1 foot radius drum attached, winding a rope. If that rope can lift a one pound weight 550 feet in one second, that's a one horsepower motor. If nothing is moving, it's not doing useful work. ======================

Th Harbor Freight 1300Lb electric hoist can give an easily measured demonstration of electrical and mechanical horsepower.

-jsw

Reply to
Jim Wilkins

It was the same guy that measured amplifier output in car stereos in the

70's.
Reply to
Tom Gardner

It really is a good, useful idea, it will be a bit harder to build now that I no longer have a machine shop. But using hand tools is good practice. I will have to farm out a couple of turnings and a bit of mill work.

Reply to
Tom Gardner

I wont be taxing the motor very much and it doesn't need to last long, just long enough to demonstrate the concept for a while. I got the cheapest one with the most "power". It should do the job as I have defines it.

Reply to
Tom Gardner

There is a maker-space kind of operation locally here that has mills, lathes, tools... for use. You pay a monthly fee or some such for access.

It looks like there is something similar in Cleveland. Might be worth checking out if you haven't already...

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The Cleveland Library has a 3D printer and a few other goodies too:

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Reply to
Leon Fisk

I like it ... that's really clever! The only tricky part is affixing something to the chain - there's not much clearance. I'd tack weld, or solder, a bit of wire.

Reply to
Bob Engelhardt

So do you hear the hiss when on grid power? Could the resiliency of the rubber hose bypass the function of the unloader? I haven't seen a crossection of the valve, or had one apart, so I'm not certain how it works. It sounds like there may be a spool in there which opens the check valve to allow filling, and it then releases the valve and covers the orifice/uncovers the vent orifice when the pressure switch turns off the compressor motor.

If it's only affected after a power outage, could the start cap on the motor be leaking down?

I finally bought one of those 12v jobs. Haven't had a flat for 30 years, but the time-before-last when I did, the spare was down. After that, I regularly thumped the spare to verify air. Now, my Tundra spare and the 4 on the ground have pressure sensors. Handy!

Reply to
Larry Jaques

Ayup. Is that a real poncho or is that a Searz poncho?

Reply to
Larry Jaques

It really is a good, useful idea, it will be a bit harder to build now that I no longer have a machine shop. But using hand tools is good practice. I will have to farm out a couple of turnings and a bit of mill work.

***

If you don't mind some shipping costs I can help you out with some basic stuff. I'm not a "real" machinist, but I am perfectly competent at turning stock into a pile of unrecoverable chips.

Reply to
Bob La Londe

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