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Re: Mini lathe DC motor longevity

 

Interesting replacement.

I do not here of any one changing brushes.

I do know the type and size of brushes the use on mini lathe motor will last 1,000 to 3,000 hours. Items like sewing machines and treadmill mills usecsamevtype motor.

A squire cage motor has life of over 20,000 because of the ball bearing. Most found on older mini lathes.

The industrial DC motor brush life between changse is 7,000 to 10,000 hours. Probably to costly for mini lathes

FYI on oil run motors like the homes AC will last about 20 years and has a Chinese made oil capacitor needs to change every 5 to 7 years American will last 12 to 20 years. This is available and can be same category as a AC motor. Do have number of hours just years

So I look at the problems member are having and wonder why and can be fix and low cost.

Dave

FYI
On electronics control boards
Most time it is a manufacturer error, over heating, voltage stickers or drit on the board.
My example is clock my wife and self purchase 32 years ago and use everyday is still running or 280,000 hours and still going


On Sun, Jul 14, 2024 at 06:25 AM, <jtpikitech8@...> wrote:
On my HF mini lathe the controller failed but I had been saving a treadmill motor (110 DC permanent magnet motor with a large flywheel and small diameter poly groove belt pulley) to provide more overall torque. This motor did require a mounting bracket as it is to large for the under bed location. I also drilled a small hole parallel to the motor shaft half into the pulley and half into the shaft and drove a pin in to prevent the flywheel coming off when the motor started. It was only secured with a bolt thread in the treadmill. I have a shop made poly groove pulley on the spindle instead of the OEM toothed belt input pulley. The DCPM motor maintains high torque with low RPM when it receives less DC voltage. It's range is 0-110 VDC and this is provided by an inexpensive SCR based AC lamp dimmer circuit and a full wave bridge rectifier (Amazon) and a DPDT (6 terminal) switch provides reverse. This setup does not use the change gears and does not drive the lead screw so I feed the cross slide manually. I do plan to redesign it soon to include a jack shaft with a toothed belt to drive the OEM input pulley and therefore the change gears, the lead screw, and the hi/lo range gears and this should allow much slower RPM with high torque. Since I acquired the motor for free and built the hardware to mount it my only cost was for the SCR dimmer, the rectifier, and the DPDT switch.
--
JTPIKITECH
Re: Mini lathe DC motor longevity

 

On my HF mini lathe the controller failed but I had been saving a treadmill motor (110 DC permanent magnet motor with a large flywheel and small diameter poly groove belt pulley) to provide more overall torque. This motor did require a mounting bracket as it is to large for the under bed location. I also drilled a small hole parallel to the motor shaft half into the pulley and half into the shaft and drove a pin in to prevent the flywheel coming off when the motor started. It was only secured with a bolt thread in the treadmill. I have a shop made poly groove pulley on the spindle instead of the OEM toothed belt input pulley. The DCPM motor maintains high torque with low RPM when it receives less DC voltage. It's range is 0-110 VDC and this is provided by an inexpensive SCR based AC lamp dimmer circuit and a full wave bridge rectifier (Amazon) and a DPDT (6 terminal) switch provides reverse. This setup does not use the change gears and does not drive the lead screw so I feed the cross slide manually. I do plan to redesign it soon to include a jack shaft with a toothed belt to drive the OEM input pulley and therefore the change gears, the lead screw, and the hi/lo range gears and this should allow much slower RPM with high torque. Since I acquired the motor for free and built the hardware to mount it my only cost was for the SCR dimmer, the rectifier, and the DPDT switch.
--
JTPIKITECH
Mini lathe DC motor longevity

 

Look at improve the longevity of the mini lathe motor.
I see a lot members having motors problems. Now is from environmental , operator , motor control board or motor errors?

FYI There are two basic type use on mini lathes DC motor and brushless aka {electronic 3 phase} motor.
This only on the DC type.

Please post how fix or you replace motor.

Dave
Re: how to.inspect.motor?

 

Under some conditions a motor can get starting a lot .
The motor under no loal it about 2 times or 3 time running amperage just second.
If air compressors is higher but longer too.
Most mini lathe uses soft start.
That where power is incress over a few seconds.
They do this to protect the electronics from overload.

Dave




On Fri, Jul 12, 2024 at 05:37 PM, Roy wrote:
Don't forget about the difference in expected running times. Starter motors only run for a few seconds under a heavy mechanical load - most common motors run for much longer times under lighter mechanical loads.

Roy
Re: how to.inspect.motor?

 

The problems you can run into with mini lathe is more just single speed motor.
The mini lathe motor top speed is around 6,000 rpm
Now we slow motor down 300 rpm remember the cooling fan is now run at 300 rpm too.
The manufacturers of mini lathes do not say anything.

This also be a problem with motor over heating too. Now let's add hot temperatures of summer too.
In this case some add a cooling fans.
I add a temperature gauge and if problem next step is a cooling fan.

When work on drill motors it was bugs dieing on brush was big problem or sometimes coke , coffee and beer. Heat problem was next one.

Dave


On Fri, Jul 12, 2024 at 05:37 PM, Roy wrote:
Don't forget about the difference in expected running times. Starter motors only run for a few seconds under a heavy mechanical load - most common motors run for much longer times under lighter mechanical loads.

Roy
Re: how to.inspect.motor?

 

Don't forget about the difference in expected running times. Starter motors only run for a few seconds under a heavy mechanical load - most common motors run for much longer times under lighter mechanical loads.

Roy
Re: how to.inspect.motor?

 

When modified brushes to fit I did find some harder file that other.
Most it was grab bag of different sizes that easy to file than Black and Decker aka Dewalt.

I do know some read on subject did say a ligh spring pressure would longer life but may not give good electric contact for running.

I did find a start motors in cars and truck are at higher spring pressure. They short live motor.

Dave


On Wed, Jul 10, 2024 at 06:58 PM, Tony Smith wrote:

And if anyone isn’t aware, brushes have different hardness grades.? The trade off is soft brushes need replacing more often but don’t wear the commutator, and the opposite for hard ones.

?

Of course our mini-lathes get so little use it doesn’t matter, ?as shown by Ralph’s 30 year old example that has plenty of brush left and zero commutator damage.

?

Spring tension matters as well, as Jon pointed out it had failed in Ralph’s picture.? If it doesn’t press hard enough you get arcing & heat build-up which cascades until it all goes pear-shaped.? As happened.

?

Tony

?

?

?

From: 7x12MiniLathe@groups.io <7x12MiniLathe@groups.io> On Behalf Of davesmith1800 via groups.io
Sent: Wednesday, 10 July 2024 12:24 AM
To: 7x12MiniLathe@groups.io
Subject: Re: [7x12MiniLathe] how to.inspect.motor?

?

When doing a lot motor repair it hard to get the parts.?
I even took brushes and file down to fit.?

I had older motors for parts.
Getting parts has always been a problem. FYI Ebay can easier to find parts. Today if I have problem with motor I just replace the motor only because of size.?

Dave?

On Mon, Jul 8, 2024 at 06:48 PM, Ralph Hulslander wrote:

Here is the adjusted brush holder:

?

?

It's not straight so maybe I'll try to adjust. I'll try to get the wood closer to actual dimensions.

You can see what happened to the set screw. Also the holder is no longer set; it can slide in and out.

Possibly the brush will hold it in place.

?

Ralph

?

On Mon, Jul 8, 2024 at 9:32?PM Roy via <roylowenthal=yahoo.com@groups.io> wrote:

Here's more detail than you probably want about testing ball bearings;

?< >

Realistically, on these small bearings all that's needed is a visual inspection for obvious damage & checking that they rotate smoothly with thrust applied in both directions. If you decide to replace one, make sure you don't apply pressure on the outer race while pressing the inner race onto the shaft. Putting pressure across the balls damages the bearing by making little dents (brinelling) on the contact surfaces.

Roy

?

?

?
Re: 7x12 Motor Won't Turn On

 

I had problems with motors in 1970's when hot like is today.

The way was resolved was to add more cooling.
Either do not use your mini lathe over 90°F or add cooling fans.

I even had running water on some motors outside so could use motor in heat.

I know does not help after you problem by can help others before they loose there motor.

Hand drill motors was problem no way to keep them very close to the mini lathe motor. I could only repair them and hope coils did not burn.

Dave


On Wed, Jun 12, 2024 at 06:18 PM, Arthur Coe wrote:
Had a crash awhile back while using a milling bit on my Grizzly 7x12 mini lathe.? Motor stalled and fuse blew.? I put in a new fuse, but motor won't run.? Are there any other circuit breakers/fuses that could be the problem?? Or, am I looking at a blown motor?
Locked Re: Off topic just FYI

 

Just checked at 11:30 the temperature in where mini lathe and it is 104°F [40°C]
Hot?
Not good day to running a mini lathe?

Dave?
Locked Off topic just FYI

 

This just FYI.
My temperature for this month was 79°F thank God for AC?
My mini lathe is a small shop without AC so have to other things.

I only bring up heating because it can have a effect on your? motors and you.??
?
I know some think humans are powerful.?
The last time I saw heat like this was 1972 when I was working as a iron worker. I did Iron work? when I in high school? and college.? It paid for college and a nice machine shop tools. But outside in the heat.?

So if born after 1972 you think it is hot. You have to go back 1905 for hotter days.??
To cool off earth try a few big volcanos this lower to earth temperature by few degrees.

I did not know if humans has any thing to do with the temperature increase is about all say on subject. I look pass?

Dave?
Locked Re: OT Hot Hot Hot

 
Edited

The good news this heating of earth has happen before.? Last time was around 1905 it did get very cold in 1944.?
We have not broken any records from 1905.?

It is not ever x number of years it has to do with earth orbit and other things I for got.?
This what happened with ice age.?

I have not to the words G#%%# W#%^$$.?

The best violin was from had a 75 on a earth cool down.?
England had great wine grapes when had a global temperature increase.?

My grandparents live here in 1905 Fresno when 115°F and some parts of Valley got to 116°F. Back then thd call it G [b] [/b] in 1940's they call it G C.

FYI? both polar ice was hot too in earth history. All we are is in a up cycle
Locked Re: OT Hot Hot Hot

 

Possibly. But my running time may not produce the kind of dangerous heating that we think. I do mostly small stuff. My motor is also a brushless one.?

george

On Thursday, July 11, 2024 at 08:12:21 PM PDT, Roy via groups.io <roylowenthal@...> wrote:


Intermittent operation may actually make the motor internals hotter than continuous running! With intermittent running, the motor's internal fan is stopped while the heat generated internally is still trying to travel to a cooler area without the fan helping it to flow. An easy fix is adding an external fan, which can also be arranged to cool the electronics at the same time.

Roy

Locked Re: OT Hot Hot Hot

 

Nope. Just a remodeled two car garage without insulation. No ac, just a small fan. Today at my house it was 114.

george

On Thursday, July 11, 2024 at 09:26:38 PM PDT, davesmith1800 <davesmith1@...> wrote:


It more likely to do with air compressor sitting outside for shop air. The mini lathe should be in a cooler room. Maybe the AC keeping the you mini lathe and you cool

Dave?


On Thu, Jul 11, 2024 at 12:56 PM, gcvisalia@... wrote:
?
I do at times but it's never long running stuff. A bit here and there. So I seriously doubt there would be any issues doing it that way. And it's not often. For sure I do more in the upper 80s so i don't think it bothers the motor much if it's a few degrees higher. Nothing I do is ever long running.
?
george
?
On Thursday, July 11, 2024 at 07:54:44 AM PDT, davesmith1800 <davesmith1@...> wrote:
?
?
Using a mini lathe and other tools in 2004 most of time temperature of 105°F and maybe spikes to 108°.?
Today the temperature is over 108° and days to 113°F?
So odds of burning the mini lathe motor today is greater because of Global warming.??

But do not know any here Using a mini lathe over 90°F

Dave?
Locked Re: OT Hot Hot Hot

 

It more likely to do with air compressor sitting outside for shop air. The mini lathe should be in a cooler room. Maybe the AC keeping the you mini lathe and you cool

Dave?


On Thu, Jul 11, 2024 at 12:56 PM, gcvisalia@... wrote:
?
I do at times but it's never long running stuff. A bit here and there. So I seriously doubt there would be any issues doing it that way. And it's not often. For sure I do more in the upper 80s so i don't think it bothers the motor much if it's a few degrees higher. Nothing I do is ever long running.
?
george
?
On Thursday, July 11, 2024 at 07:54:44 AM PDT, davesmith1800 <davesmith1@...> wrote:
?
?
Using a mini lathe and other tools in 2004 most of time temperature of 105°F and maybe spikes to 108°.?
Today the temperature is over 108° and days to 113°F?
So odds of burning the mini lathe motor today is greater because of Global warming.??

But do not know any here Using a mini lathe over 90°F

Dave?
Locked Re: OT Hot Hot Hot

 

Intermittent operation may actually make the motor internals hotter than continuous running! With intermittent running, the motor's internal fan is stopped while the heat generated internally is still trying to travel to a cooler area without the fan helping it to flow. An easy fix is adding an external fan, which can also be arranged to cool the electronics at the same time.

Roy
Locked Re: OT Hot Hot Hot

 

I do at times but it's never long running stuff. A bit here and there. So I seriously doubt there would be any issues doing it that way. And it's not often. For sure I do more in the upper 80s so i don't think it bothers the motor much if it's a few degrees higher. Nothing I do is ever long running.

george

On Thursday, July 11, 2024 at 07:54:44 AM PDT, davesmith1800 <davesmith1@...> wrote:


Using a mini lathe and other tools in 2004 most of time temperature of 105°F and maybe spikes to 108°.?
Today the temperature is over 108° and days to 113°F?
So odds of burning the mini lathe motor today is greater because of Global warming.??

But do not know any here Using a mini lathe over 90°F

Dave?

Locked Re: OT Hot Hot Hot

 

Here calculations for mini lathe in ambient temperature 104°F? [40°C]?
Motor rize in temperature 60°C
Hot spot 5°C?
Total is 105°C?

Then check your insulation temperature along below you good shape.?

Now with global warming to 115°F [46°C]
ambient temperature 115°F? [46°C]?
Motor rize in temperature 60°C
Hot spot 5°C?
Total is 231°F? [111°C ]

Your insulation mat not hold up or short Motor life

Dave?
Locked Re: OT Hot Hot Hot

 

Using a mini lathe and other tools in 2004 most of time temperature of 105°F and maybe spikes to 108°.?
Today the temperature is over 108° and days to 113°F?
So odds of burning the mini lathe motor today is greater because of Global warming.??

But do not know any here Using a mini lathe over 90°F

Dave?
Locked Re: OT Hot Hot Hot

 

A few months I add a temperature gauge to my lathe and the Calc on how down does a mini lathe motor gets.

If go on internet you all garbage formulas on this subject for just few degrees.? But electric hand book it is simple ambient temperature + motor rize = running temperature?
Then you look at the max insulation temperature.?
Most ambient temperature is set 105°F? ,[40°C]. Because of Global this temperature maybe increase.?
Air conditioner was in 1970's 120°F??

I will say I do not know anyone using a mini lathe over 100°F Most likely under 90°F so Global warming is not a problem.? But check AC temperature.?

FYI
I look at mini lathes back around 2004 I look at mini lathe for work in line boring.? So on truck it would bun at 114°F

Dave?


On Thu, Jul 11, 2024 at 12:54 AM, Chris Albertson wrote:


On Jul 10, 2024, at 5:44?PM, BuffaloJohn via groups.io <johndurbetaki@...> wrote:
See responses below

On Wed, Jul 10, 2024 at 4:54?PM davesmith1800 via <davesmith1=sbcglobal.net@groups.io> wrote:
If remember NEMA ia at sea leave I think at 40% humidity.
?
No, there is NO humidity, it is 40C which is 104F.
?
We feel humidity as making the heat worse because our bodies are cooled by evaporation. ?humidity slows down the evaporation process. ?But this does not apply to motors.
?
The more modern way to use a motor is to embed a tempature sensor into it and have the controller reduce the power so as not to overheat the motor. ? But years ago sensors and the computer needed would cost more than the motor. ?But today it costs almost nothing so “temperature throttling" is common. ?I think our minilathes are too old of a design for this. ?Maybe the ones with BLDC motors have this?
?
In any case this whole problem of brushes goes away with brushless motors. ? The other thing about those motors is they have maximum torque at zero RPM. ? If you must replace a motor, that is the way to go.
,_
Locked Re: Double OT Hot Hot Hot

 

Gerald you are right about Global Warming you can easily debunk it with a little research it is only making someone very rich.
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