Metalwork - Lathe and Mill topics

Tuesday, 5 September 2023

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

The commutator should have an even chocolate-brown color with no nicks, gouges, high spots, etc.

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

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

Thanks Jeff! First photo, last two digits 82 is the motor we've been talking about mostly. #83 is the other motor. They don't look too bad to me. ;) I'm also having a wiring or relay problem... I can hear the relay click. Nothing else happens. There are also a couple of limit switches in there, and a pair of momentary contact switches that are the Up & Down buttons. . Could be wiring, relay (which I have replaced because the original relay has a cracked open case) or switches. Could simply be corrosion, as this thing sat in an unconditioned shed for most of 20 years. I've got some wet or dry silicon carbide paper, and flint paper, not sure I have aluminum oxide paper... Emery is aluminum oxide. Do you know why it shouldn't be used? Too coarse?

Got plenty of X-Acto knife blades, And I'm sure I could find a broken hacksaw blade. I mostly don't throw stuff like that away! I do not own a growler. Currently, doesn't look like I can afford one that I know works, either. ;)

Funny thing, found a cheap ladies nail care file/buffer thing in drawer under my desktop. Think I'll be using that to polish the commutator. Just the couple of strokes I took with it made the segment I used it one nice and shiny!

Got to drop all that and get us ready for her doctor's appointment this afternoon. More later!

Bill in OKC

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Monday, 4 September 2023

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

Bill,
Commutators once were made differently. Most in the last 25 years or more are injection molded, and have sub-flush mica. This was so that they didn't need to be under-cut when manufactured. They were trued using a diamond bit, spinning at 2000+ RPM. If you attempt to face/true, you quite likely will smear the copper into the slots, instead of actually cutting it. Copper is too soft to satisfactorily machine on an interrupted surface. In the old days, one might just cut down to the mica and undercut anew. Loses comm life, but saves time. Unless it is badly grooved, polish with 200-240 grit aluminum oxide. (don't use emery cloth). Light grooves, irregularities can be polished out. If the brush track is significantly lower than the rest of the bar(s), it will need to be turned. Then you will need to use the ground hacksaw blade or an X-Acto knife to clean the slots. Then it should go on a growler to check for shorts between the slots.
Post a before pic...
Brush caps and brushes (which you already have) Arrowhead Electric. Here is their brusholder/cap page:
http://www.carbonbrush.com/roundholders.htm
Here is their main page:
http://www.carbonbrush.com/
Jeff in Lone Star, TX

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Sunday, 3 September 2023

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

MSC is also useless. Don't have brushes that fit at all, and don't seem to have brush covers at all. Don't carry Leeson motors, apparently, which may be why, these were used on Leeson motors.

All the 3D printed caps I saw were metric sizes, and these are old SAE/ANSI sizes. Might also have to do with why they're so hard to find parts for.

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 Sunday, September 3, 2023 at 02:32:33 PM CDT, mike allen <animal@psln.com> wrote:

I have a armature lathe , a old " Trucut" & on small motors its probably faster to do the hacksaw trick . As far as the brush covers go , if Grainger has them I wonder if MSC does also . If MSC does have them there may be a CAD drawing that ya can DL & try printing them on the 3d printer . I know they used to have cad drawings for their stuff , don't know about for these days . A quick google shows that folks have printed covers/caps & put the files online .

https://www.google.com/search?q=3d+printed+motor+brush+caps&oq=3d+printed+motor+brush+caps&gs_lcrp=EgZjaHJvbWUyBggAEEUYOdIBCDg4NjNqMGo3qAIAsAIA&sourceid=chrome&ie=UTF-8

animal

On 9/3/23 11:59 AM, Bill in OKC too via groups.io wrote:

H
I'm also considering skimming both commutators, Just because I have them apart enough to do it easily. What I don't have is the special tooling to do that. Does not look like there is any mica to undercut. Have seen a ground hacksaw blade used
Somebody stop me before I eBay again! ;P

Never found the missing parts, so I'm headed out to the shop to see If I can make a couple of matching brass brush covers. The two Themac J-3 tool post grinders I wound up with both have more complex brush covers: One on the left is the other one of what I lost. The other two will screw down into the brush holders, but are slightly different in size. I'm going to try ordering some that should be the correct one from Grainger, where they're $2.29 each, which isn't bad, and I can pick them up so not pay shipping, but the earliest they could be here now is after 4PM on Friday. $4.98, so I went ahead and ordered them. The brushes, if I got them from Grainger would be $26.76 each. DC Motor sold them to me for $5.13 each. Probably should have asked if they had the brush caps, but didn't think of it then. ;)

Got a package of 50 of the 8-32 kep-nuts from amazon for under $8 last weekend. I now have LOTS of spares! :)

Bill in OKC

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

https://www.google.com/search?q=3d+printed+motor+brush+caps&oq=3d+printed+motor+brush+caps&gs_lcrp=EgZjaHJvbWUyBggAEEUYOdIBCDg4NjNqMGo3qAIAsAIA&sourceid=chrome&ie=UTF-8

animal

On 9/3/23 11:59 AM, Bill in OKC too via groups.io wrote:

H
I'm also considering skimming both commutators, Just because I have them apart enough to do it easily. What I don't have is the special tooling to do that. Does not look like there is any mica to undercut. Have seen a ground hacksaw blade used
Somebody stop me before I eBay again! ;P

Never found the missing parts, so I'm headed out to the shop to see If I can make a couple of matching brass brush covers. The two Themac J-3 tool post grinders I wound up with both have more complex brush covers: One on the left is the other one of what I lost. The other two will screw down into the brush holders, but are slightly different in size. I'm going to try ordering some that should be the correct one from Grainger, where they're $2.29 each, which isn't bad, and I can pick them up so not pay shipping, but the earliest they could be here now is after 4PM on Friday. $4.98, so I went ahead and ordered them. The brushes, if I got them from Grainger would be $26.76 each. DC Motor sold them to me for $5.13 each. Probably should have asked if they had the brush caps, but didn't think of it then. ;)

Got a package of 50 of the 8-32 kep-nuts from amazon for under $8 last weekend. I now have LOTS of spares! :)

Bill in OKC

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

Had to order brushes. https://www.dcmotorparts.com/ in Princeton, WV, is a good place for motor brushes, and you can search by size. Got 4 brushes, shipped, for about $30, and here in three days. Would have been faster if USPS hadn't lost the package for a day. First motor is running. Looks like I need to create a wiring diagram, and make sure the replacement relay I bought for it is the right one, because the controller isn't working, thought the motor spins on the bench.
https://www.dcmotorparts.com/
I'm also considering skimming both commutators, though the one I've already seen doesn't look all that bad. Just because I have them apart enough to do it easily. What I don't have is the special tooling to do that. Does not look like there is any mica to undercut. Have seen a ground hacksaw blade used for that purpose, so don't know if I need the specialty tooling. And no idea how many more motors I might need to work on...

Somebody stop me before I eBay again! ;P

Never found the missing parts, so I'm headed out to the shop to see If I can make a couple of matching brass brush covers. The two Themac J-3 tool post grinders I wound up with both have more complex brush covers: One on the left is the other one of what I lost. The other two will screw down into the brush holders, but are slightly different in size. I'm going to try ordering some that should be the correct one from Grainger, where they're $2.29 each, which isn't bad, and I can pick them up so not pay shipping, but the earliest they could be here now is after 4PM on Friday. $4.98, so I went ahead and ordered them. The brushes, if I got them from Grainger would be $26.76 each. DC Motor sold them to me for $5.13 each. Probably should have asked if they had the brush caps, but didn't think of it then. ;)

Got a package of 50 of the 8-32 kep-nuts from amazon for under $8 last weekend. I now have LOTS of spares! :)

Bill in OKC

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