Re: [atlas-craftsman IO] OT-how to test and repair DC brushed motors.

Not where I grew up. We had another phrase for that, and I'm too inhibited to use it anymore. I guess we could call it red-neck engineering. Sort of thing farmers do to get critical equipment to operate when they need it and the only folks that can be hired to fix things have a long wait time and harvest is due RFN. 

Not really a redneck, just a wannabe. Though my other grandma was from Beckley, WV. So I have some redneck ancestry! ;)

Bill in OKC

William R. Meyers, MSgt, USAF(Ret.)

Aphorisms to live by:

Good judgement comes from experience. Experience comes from bad judgement. 

SEMPER GUMBY!

Improvise, Adapt, and Overcome.
Physics doesn't care about your schedule.
The only reason I know anything is because I've done it wrong enough times to START to know better.

Expect in one hand, expectorate in the other. See which one gets full first.

On Friday, August 11, 2023 at 09:53:35 PM CDT, mike allen <animal@psln.com> wrote:

        no " micky mousing " is when you do something halfassed that  you know in the back of your mind can possibly injure someone .

        animal

On 8/11/23 5:31 PM, Bill in OKC too via groups.io wrote:

Yep. That's what we call "micky-mousing" something. I grew up not too far from Disneyland! Dad and Grandpa were great at it!

William R. Meyers, MSgt, USAF(Ret.)

Aphorisms to live by:

Good judgement comes from experience. Experience comes from bad judgement. 

SEMPER GUMBY!

Improvise, Adapt, and Overcome.
Physics doesn't care about your schedule.
The only reason I know anything is because I've done it wrong enough times to START to know better.

Expect in one hand, expectorate in the other. See which one gets full first.

On Friday, August 11, 2023 at 06:49:02 PM CDT, mike allen <animal@psln.com> wrote:

        push comes to shove , ya can gut the motor take the armature off the shaft & put the shaft back in & power the shaft from another motor .

    You'd be surprised at some of the things we've done to keep things workin . Years ago my bud scores a 4 cylinder compressor from his wife's boss , he was a dentist . The motor had burnt up in this compressor so they bought a new one & passed the burnt on over to my bud . Did the same thing here ,  tore the motor apart emptied the armature shaft & then installed a pulley in the shaft & cut a notch in the motor housing .

Then I found a nice piece of scrap plate in my someday pile & mounted a motor on it & bolted the plate under the old motor , ran a belt from new motor to new pulley on the shaft from the old motor & the rest is history .

        Yer half way there already with the bad motor .

    anmal

On 8/11/23 3:55 PM, Bill in OKC too via groups.io wrote:

Unless I want to completely redesign it, I need the right-angle gear box. I'm not qualified for that! I could probably put a different gear box on it, but none of the ones I've found are near the right size. Too big, or too small, nothing in the Goldilocks zone. I do have a Leeson DC motor and probably some spare brushes for larger motors from my former work, that they trashed. All I have to do is find them. IF I can find something, I can probably cut it down if it's not the right size already. I am good at micky-mousing something... 

Bill in OKC

William R. Meyers, MSgt, USAF(Ret.)

Aphorisms to live by:

Good judgement comes from experience. Experience comes from bad judgement. 

SEMPER GUMBY!

Improvise, Adapt, and Overcome.
Physics doesn't care about your schedule.
The only reason I know anything is because I've done it wrong enough times to START to know better.

Expect in one hand, expectorate in the other. See which one gets full first.

On Friday, August 11, 2023 at 01:39:17 PM CDT, mike allen <animal@psln.com> wrote:

        Just tossin this out there , with no load on the motor you will not get the actual amp reading . Also unless  you have a good DC clamp meter most DVM that do amps top out at 10 amps .

       I thought there was a guy in this group that had a motor shop ?  Does the motor absolutely have to have the right angle gear box or can it be a straight gear reduction motor ?

        animal

On 8/11/23 9:02 AM, Bill in OKC too via groups.io wrote:

SWMBO' s power wheelchair lift crapped out the other day. New motor is no longer available since the lift is ancient. Manufacturer of the lift removed any OEM markings. It's a right- angle gear motor, which I'll eventually have some photos and dimensions for. This is the in-and-out motor for a Harmar AL-600 lift that fits in the back of a van. Near as I can remember it was made about 2007 or so. 

There is no continuity in the motor, but  othinf seems burned. I pulled it apart and fiddled with it, and got continuity back. Hooked it back up to power trying to get a current draw reading and it spun up and  rapped out again. No continuity again. Brushes look good. 

I have a megger for testing  insulation, and an assortment of DVMs and at least one analog voltmeter. Somewhere in the library are a couple of older books on motor testing and repair, but haven't found them yet. Any suggestions for resources? I looked at Grainger & McMaster-Carr, also Amazon & Surplus Center. They have similar gear motors but nothing that looks exactly  right. Most are either way too light or way too heavy. This is a 12vdc motor, could draw as much as 20amps, but probably closer to 10, and could less. There is another motor on it with a different gearbox. Looks to be about the same motor. May fiddle with that, and get a current draw.

Found one of these motors for sale on the knoppix site for $600, was $400 from Harmar at one time. Seems a bit fishy to me, and can't afford it anyway. 

Gotta get ready to take SWMBO to get fitted for a new CPAP mask, and for both of us to get new CPAP machines. Hope someone can point me in a useful direction. Used to be a bunch of folks whe rebuilt motors & alternators/generators around here. Called one and they don't do DC motors at all, and don't think there's anyone left who does.,

Any help will be appreciated!


Bill in OKC