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WM18 - Broken it again :(

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oldvelo22/02/2020 18:49:41
295 forum posts
56 photos

"Note sure where I would fit it ie above the motor and would it suck out heat or blow in cold air?"

If the fan on the motor air flow comes out of the top Then mount the fan on the top of the fibreglass housing to suck out the hot air. Push old air in if the outlet is at the spindle end of the motor.

Fit a duct to fit over the diameter of the motor to the fibreglass cover to get maximum air flow through the motor.

I fitted an auxiliary fan on the mill years ago the motor never gets hot even at slow speed and a heavy cut with 4 AMPS showing on the meter

petro1head22/02/2020 19:10:42
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770 forum posts
152 photos

Had a look at the current setup.

Using a jos stick to see the flow of air, the fan is at the top of the motor and draws air from the bottom of the motor and exhausts out the top of the motor. However what is very telling is until the motor is spinning at about 900 there is little to no air being drawn in.

So basicall the motor is starved of air at low speed, just as you said. So I am going to route out a 120/140 dia 12v computer fan and mount that iside the cover with a suitable hole cut and suck air out. I am also going at add some holes at the bottom of the cover so more air can get in.

All I need to buy is a 12v supply for the fan

Edited By petro1head on 22/02/2020 19:11:12

Martin W22/02/2020 19:27:59
921 forum posts
30 photos

If you use a 12V fan similar to those found in computers then a relatively small wall wart psu will be adequate and they are only a few quid each from the likes of CPC or Ebay etc.

Fitting one directly to the motor could be problematical if there is a motor reverse function as then it would be opposing the air flow from the motor. However being aware of this and not running it for extended periods in this mode would mitigate this problem.

Have fun

Martin

Howard Lewis22/02/2020 19:43:02
6311 forum posts
15 photos

Possibly a few holes at each end of the glassfibre motor cover (So that swarf cannot get in) may help extend motor life.

My lathe used to eat Q H worklight bulbs. Took it apart, and filed, a couple of 8mm dia slots om the rim of the "reflector". Bingo! Lamps last MUCH longer; can't remember when the last one failed

ASKING for trouble!

So a little extra cooling air might work wonders in lowering temperatures below some critical value that divides LIVE from DIE.

Howard

oldvelo22/02/2020 20:26:34
295 forum posts
56 photos

Sounds like good plan with a 120 mm computer fan on the inside of the cover, As Martin points out that running in reverse may be a problem running in reverse,

The computer fan will cope at low speeds. How many times will you be running in reverse at highest speeds if a problem switch off the auxiliary fan.

Cool Running

petro1head22/02/2020 20:29:00
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770 forum posts
152 photos

Can't say I have ever run in reverse but a valid point.

So this is what I have done, 120mm Corsair 12v Fan (140 was just a tad too big) exhausting out at the top of the encloure and several 10mm holes at the bottom

motor enc fan mod 1.jpg

motor enc fan mod 2.jpg

I remembered I already have a 12v supply going to the Angle Eye LED around the quill so can tap into that. Jobs done

Edited By petro1head on 22/02/2020 20:31:11

oldvelo22/02/2020 20:54:12
295 forum posts
56 photos

Looks good make sure that the fan has a duct to the top of the motor to get the full airflow over the motor and not bypass it by just ventilating the cover.

petro1head22/02/2020 20:57:22
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770 forum posts
152 photos

Tbh I suspect the fan is probably only a few mm from the top of the motor but will check

Enough!22/02/2020 23:28:29
1719 forum posts
1 photos

When BusyBee in Canada first imported the WM16-type mill, it had no agency approvals. The usual approach in that circumstance is to have it directly approved by the local electrical authority - Ontario Hydro in this case.

Ontario Hydro approved it, subject to a reduced rating-fuse being fitted. I bought one of these and it was something of a nightmare. The fuse would blow during any operation the tiniest bit severe.

After many fuse replacements (and stop-works for lack of a fuse). I decided to switch back to the original fuse but supplied power to the mill via an external, local circuit-breaker - rated as the smaller fuse but with a delayed response. This cleaned up the act quite nicely. I haven't replaced a fuse in years, though I have reset the circuit breaker occasionally.

Since then, I also converted the mill to a belt-drive. This removes the box around the motor and leaves the motor standing up in free air which has also improved it considerably (not to mention being an order of magnitude quieter). The only time the CB trips now is when it's not entirely unexpected (tut tut).

Edited By Bandersnatch on 22/02/2020 23:30:02

duncan webster23/02/2020 01:09:52
4122 forum posts
66 photos
Posted by Martin W on 22/02/2020 19:27:59:

If you use a 12V fan similar to those found in computers then a relatively small wall wart psu will be adequate and they are only a few quid each from the likes of CPC or Ebay etc.

Fitting one directly to the motor could be problematical if there is a motor reverse function as then it would be opposing the air flow from the motor. However being aware of this and not running it for extended periods in this mode would mitigate this problem.

Have fun

Martin

If it's a centrifugal fan then I think it blows the same direction whichever way it's running. It might blow a whole lot better one way than the other

clogs23/02/2020 06:09:51
626 forum posts
12 photos

I nearly bought a WM mill......

after reading this and other problems with the brand.......RATHER glad I didn't.....

with all the world sales I would have thought that the factory should have got it right by now.......

Overpriced and over comes to mind.......

petro1head23/02/2020 09:00:30
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770 forum posts
152 photos
Posted by clogs on 23/02/2020 06:09:51:

I nearly bought a WM mill......

after reading this and other problems with the brand.......RATHER glad I didn't.....

with all the world sales I would have thought that the factory should have got it right by now.......

Overpriced and over comes to mind.......

I would not be so quick to dismiss the wm18. It’s a fab mill and any problems I have had have been down to my own fault not the product

Martin W23/02/2020 10:02:22
921 forum posts
30 photos

Duncan

The fans on these motor are standard bladed fans that are pressed onto the motor shaft and are internally mounted. Change motor direction and this changes air flow direction unlike some of the fans that can be seen on power hand tools etc. which are centrifugal and can shift a lot of air through the motor when running at a reasonable speed

Martin

Edited By Martin W on 23/02/2020 10:04:30

mgnbuk23/02/2020 10:54:21
1207 forum posts
72 photos

Usual practice on industrial DC motors is to have a separate blower mounted at the non-drive end forcing filtered air through the motor to exit through louvres at the drive end (should be a picture below)

**LINK**

The airflow is usually substantial & is frequently monitored using a flow switch downside of the filter to check for filter blockage. The centrifugal fans are directional - they will move air when running in reverse, but at nothing like the output when running correctly - think summer breeze versus winter gale !. A Gildemeister lathe at work had to have the 22Kw main spindle drive motor rewound due to the previous owner having changed the blower motor bearings & wired it running reversed when replaced - both the armature & field windings cooked at the drive end due to inadequate airflow & the rewind cost £5K 10 years ago + £1k for the Baumueller drive repair, as the failed field windings took out the field controller.

On your machine the airflow needs to be through the motor, not over the casing - the heat is generated in the armature windings & they are what fails. I would look to removing the internal armature "fan" altogether to reduce resistance to airflow though the motor & duct the external fan airflow into the non-drive end near the brushgear. to maximise air through flow.

Nigel B.

Michael Gilligan23/02/2020 11:03:04
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20289 forum posts
1064 photos
Posted by mgnbuk on 23/02/2020 10:54:21:

[…]

On your machine the airflow needs to be through the motor, not over the casing - the heat is generated in the armature windings & they are what fails. I would look to removing the internal armature "fan" altogether to reduce resistance to airflow though the motor & duct the external fan airflow into the non-drive end near the brushgear. to maximise air through flow.

.

That seems very sound advice, Nigel star

You might be the saviour of a good few hobby-machine motors.

MichaelG.

petro1head23/02/2020 11:32:17
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770 forum posts
152 photos
Posted by mgnbuk on 23/02/2020 10:54:21:

On your machine the airflow needs to be through the motor, not over the casing - the heat is generated in the armature windings & they are what fails. I would look to removing the internal armature "fan" altogether to reduce resistance to airflow though the motor & duct the external fan airflow into the non-drive end near the brushgear. to maximise air through flow.

Nigel B.

So are you suggesting blowing down as opposed to sucking up

Re the fan I may invest in a better fan, the one I have runds at 1200rpm and 70cfm.  Noctua do one thats for industrial use ie servers, that runs at 3000rpm and 110cfm

Re ducting the gap between the top of the motor and the fan is 4mm so think ducting would prob not held and be a bugger to design

Edited By petro1head on 23/02/2020 11:35:07

mgnbuk23/02/2020 15:12:01
1207 forum posts
72 photos

All the force cooled industrial motors I have worked with take ambient temperature air & blow it through or around the motor (depending on motor type). I cannot recall a motor failing through being "over cooled" - more airflow is definately better than less.

Could you introduce an internal baffle part way down your cover that would reduce the air blowing around the outside of the motor casing & force more of the airflow through it instead ?

Nigel B.

Edited By mgnbuk on 23/02/2020 15:12:29

petro1head23/02/2020 15:24:00
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770 forum posts
152 photos
Posted by mgnbuk on 23/02/2020 15:12:01:

Could you introduce an internal baffle part way down your cover that would reduce the air blowing around the outside of the motor casing & force more of the airflow through it instead ?

Nigel B.

Well I suppose I could use a piece are cardboard

not done it yet23/02/2020 17:25:01
6888 forum posts
20 photos
Posted by petro1head on 23/02/2020 15:24:00

Well I suppose I could use a piece are cardboard

Well, that would be a good permanent/long lasting modification🙂.

oldvelo23/02/2020 17:49:51
295 forum posts
56 photos

Re ducting the gap between the top of the motor and the fan is 4mm so think ducting would prob not held and be a bugger to design.

Just an Idea Plywood 10 mm thick say 120 mm x 120 mm bore a hole in the centre to fit over the motor bolt to the underside of the fan.

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