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These things are a thermal switch. ?They open an electrical circuit if the temperature is above their set point. ?So you would bolt them firmly to any object that you do nopt want to be very hot. ? That might be the motor

But our mini-lathes are usually hand operated so the operator would be close by and if the spindle jammed, he’d see it and shut off ther power manually.

There switches are mostly used on automated equipment where the operator is not present. ?It might be good to have one on a CNC lathe or mill because you might not be nearby while it is running. ? I have one on the heated baed of a 3D printer as a backup shutdown in case the primary controller fails to detect an accidental overheating. ? ?THese are almost always used as a backup system to a primary controller.

You see them mounted inside domestic water heaters too, If the heat ever gets to 125C, there is obviously something wrong (water can’t be heated over 100C) and the system needs to shutdown. ?Same with cloths driers, they use these thermal switches to shutdown power if the unit gets too hot, which would only happen if the primary controller failed.

Modern equipment of all kinds is usually designed so that it remains safe even after a major failure happens, ?So they use these on anything that can overheat and catch fire. ? But again, do you need one on a manually operated lathe? ?If so then why not on a drill press, table saw or bench grinder?

Show quoted text

On Apr 8, 2024, at 12:25?AM, DAVID WILLIAMS via groups.io <d.i.williams@...> wrote:

Dear All,

First, thank you for the information.

Sorry for my ignorance, but where exactly do you fit these resettable thermal fuses on the lathe. Anywhere on the live power line input? ?As they are resettable, then presumably they must be relatively easily accessible.?

Thanks in anticipation.

David (UK)

On 8 Apr 2024, at 06:54, Tony Smith <ajsmith1968@...> wrote:

?
Those are “last resort” fuses, you really want a resettable one like these:?, or these:?
?
Replacing those fuses is a PITA, especially since they need to be crimped, not soldered.? (Everyone makes that mistake at least once.)
?
No harm having both, just make sure the resettable one is a lower temperature.
?
Tony
?
?
From:?[email protected] <[email protected]>?On Behalf Of?davesmith1800
Sent:?Monday, 8 April 2024 3:24 PM
To:?[email protected]
Subject:?[7x12MiniLathe] Motor protection
?
Using time delay and thermal overload?
Will save a motor?

This is a thermal over load set at 200°F or 93°C.?

Time delay gives a over load for starting to 10 time rate ampage for very short time.

Dave??

#119362

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Most quality drill presses , table saws & even some bench grinders have those built into the motors . Look for the little red button .? Their real handy units to have a couple laying around . The pellet stove in my other shop has 3 inside . Having no manual it took me a while to find all of them . I like the idea of one on the printer bed . Been thinking about something like this , last week the thermocouple on my print head came out of its place on the print head I knew something was up I could smell it & hit the emergency shutoff & after some diggin I found it's little head out in open air instead of its hole it lives in .

thanks

animal

On 4/8/24 9:04 AM, Chris Albertson wrote:

Show quoted text

These things are a thermal switch. ?They open an electrical circuit if the temperature is above their set point. ?So you would bolt them firmly to any object that you do nopt want to be very hot. ? That might be the motor

But our mini-lathes are usually hand operated so the operator would be close by and if the spindle jammed, he’d see it and shut off ther power manually.

There switches are mostly used on automated equipment where the operator is not present. ?It might be good to have one on a CNC lathe or mill because you might not be nearby while it is running. ? I have one on the heated baed of a 3D printer as a backup shutdown in case the primary controller fails to detect an accidental overheating. ? ?THese are almost always used as a backup system to a primary controller.

You see them mounted inside domestic water heaters too, If the heat ever gets to 125C, there is obviously something wrong (water can’t be heated over 100C) and the system needs to shutdown. ?Same with cloths driers, they use these thermal switches to shutdown power if the unit gets too hot, which would only happen if the primary controller failed.

Modern equipment of all kinds is usually designed so that it remains safe even after a major failure happens, ?So they use these on anything that can overheat and catch fire. ? But again, do you need one on a manually operated lathe? ?If so then why not on a drill press, table saw or bench grinder?

On Apr 8, 2024, at 12:25?AM, DAVID WILLIAMS via groups.io <d.i.williams@...> wrote:

Dear All,

First, thank you for the information.

Sorry for my ignorance, but where exactly do you fit these resettable thermal fuses on the lathe. Anywhere on the live power line input? ?As they are resettable, then presumably they must be relatively easily accessible.?

Thanks in anticipation.

David (UK)

On 8 Apr 2024, at 06:54, Tony Smith <ajsmith1968@...> wrote:

?

Those are “last resort” fuses, you really want a resettable one like these:?, or these:?

?

Replacing those fuses is a PITA, especially since they need to be crimped, not soldered.? (Everyone makes that mistake at least once.)

?

No harm having both, just make sure the resettable one is a lower temperature.

?

Tony

?

?

From:?[email protected] <[email protected]>?On Behalf Of?davesmith1800
Sent:?Monday, 8 April 2024 3:24 PM
To:?[email protected]
Subject:?[7x12MiniLathe] Motor protection

?

Using time delay and thermal overload?
Will save a motor?

This is a thermal over load set at 200°F or 93°C.?

Time delay gives a over load for starting to 10 time rate ampage for very short time.

Dave??

#119364

I learned this in? college from an old time machinist. Foremen would walk among the machines putting their hands on the motors. If you could leave a hand on the motor?then it wasn't working hard enough. Likewise I surprised a PhD friend with a sample and hold ammeter showing him that his lathe motor drew 6 times the running current?when starting unloaded!

Show quoted text

On Mon, Apr 8, 2024 at 12:13?PM mike allen <animal@...> wrote:

Most quality drill presses , table saws & even some bench grinders have those built into the motors . Look for the little red button .? Their real handy units to have a couple laying around . The pellet stove in my other shop has 3 inside . Having no manual it took me a while to find all of them . I like the idea of one on the printer bed . Been thinking about something like this , last week the thermocouple on my print head came out of its place on the print head I knew something was up I could smell it & hit the emergency shutoff & after some diggin I found it's little head out in open air instead of its hole it lives in .

thanks

animal

On 4/8/24 9:04 AM, Chris Albertson wrote:

These things are a thermal switch.? They open an electrical circuit if the temperature is above their set point.? So you would bolt them firmly to any object that you do nopt want to be very hot. ? That might be the motor

But our mini-lathes are usually hand operated so the operator would be close by and if the spindle jammed, he’d see it and shut off ther power manually.

There switches are mostly used on automated equipment where the operator is not present.? It might be good to have one on a CNC lathe or mill because you might not be nearby while it is running. ? I have one on the heated baed of a 3D printer as a backup shutdown in case the primary controller fails to detect an accidental overheating. ? ?THese are almost always used as a backup system to a primary controller.

You see them mounted inside domestic water heaters too, If the heat ever gets to 125C, there is obviously something wrong (water can’t be heated over 100C) and the system needs to shutdown.? Same with cloths driers, they use these thermal switches to shutdown power if the unit gets too hot, which would only happen if the primary controller failed.

Modern equipment of all kinds is usually designed so that it remains safe even after a major failure happens, ?So they use these on anything that can overheat and catch fire. ? But again, do you need one on a manually operated lathe?? If so then why not on a drill press, table saw or bench grinder?

On Apr 8, 2024, at 12:25?AM, DAVID WILLIAMS via <d.i.williams@...> wrote:

Dear All,

First, thank you for the information.

Sorry for my ignorance, but where exactly do you fit these resettable thermal fuses on the lathe. Anywhere on the live power line input?? As they are resettable, then presumably they must be relatively easily accessible.?

Thanks in anticipation.

David (UK)

On 8 Apr 2024, at 06:54, Tony Smith <ajsmith1968@...> wrote:

?

Those are “last resort” fuses, you really want a resettable one like these:?, or these:?

?

Replacing those fuses is a PITA, especially since they need to be crimped, not soldered.? (Everyone makes that mistake at least once.)

?

No harm having both, just make sure the resettable one is a lower temperature.

?

Tony

?

?

From:?[email protected] <[email protected]>?On Behalf Of?davesmith1800
Sent:?Monday, 8 April 2024 3:24 PM
To:?[email protected]
Subject:?[7x12MiniLathe] Motor protection

?

Using time delay and thermal overload?
Will save a motor?

This is a thermal over load set at 200°F or 93°C.?

Time delay gives a over load for starting to 10 time rate ampage for very short time.

Dave??

#119372

Herd one way use a thermometer like this one.

#119374

I order the thermometer for my lathe?
The advantage is I see the temperature rising and let lathe run higher speed to cool the motor down .

All the other ways only till you?you to hot ?.??

The dial on the thermometer tells me I may have problems.?

Dave

Insulation Class

Insulation temperature (insulation class). The MAX temperature rises so that the winding of the motor can handle normal operation. Below is the Insulation class table. Found the motor name plate

?

Class A.? 221°F? / 105 Degrees C

Class B? ?266°F? /?130 Degrees C

Class F? 311°F? /??155 Degrees C

Class H? 356°F? /??180 Degrees C

#119375

I'm in the process of adding a DC ammeter to mine, inline with the feed to the Fwd/Rev switch.? I bought a 3amp one based on Youtube videos and it looks like it will be a good match in testing, but a 4 or 5 may be better.

On Tuesday, April 9th, 2024 at 7:58 PM, davesmith1800 <davesmith1@...> wrote:

Show quoted text

I order the thermometer for my lathe?
The advantage is I see the temperature rising and let lathe run higher speed to cool the motor down .

All the other ways only till you?you to hot ?.??

The dial on the thermometer tells me I may have problems.?

Dave

Insulation Class
Insulation temperature (insulation class). The MAX temperature rises so that the winding of the motor can handle normal operation. Below is the Insulation class table. Found the motor name plate

?

Class A.? 221°F? / 105 Degrees C

Class B? ?266°F? /?130 Degrees C

Class F? 311°F? /??155 Degrees C

Class H? 356°F? /??180 Degrees C

#119380

The ammeter is great if motor is turning at high speed.
When turning low speed is when motor gets not because the cooling fan is turn at low speed.?

When did research I found most motors would burn up when they where turning at low speed.?
Even a time delay fuse will not protect the motor.?

A thermal fuse would or a thermometer will real time temperature.
Thd best is to have the bub in coil but this not a option. So do next best put on the outside and use a lower temperature for max.

Dave?

#119381

Why not attack the basic problem? If the motor's internal cooling fan doesn't move enough air at low speeds, simply add an external fan to provide clean, cool air. "Muffin" fans are readily ( cheaply )? available from junked computer power supplies.

Roy

#119382

That first way I was going fix the low speed overheating is a axillary fan

But could see or feel the real temp of motor .?

My motor came from factory with slow blow fuse .?

Next was a thermal fuse or breaker

So if know real temperature is then like car or truck ? you know to spot working?

Dave?

Show quoted text

Roy

4:54pm? ?

Why not attack the basic problem? If the motor's internal cooling fan doesn't move enough air at low speeds, simply add an external fan to provide clean, cool