induction motor getting hot help!!

[Rorschach]

Is the motor original to the machine?

 

[dzj]

i can't see a company a german one at that manufacturing a saw underpowered for the blade that it is designed to use especially one from back in the day machines used to be built like tanks back then haha

If you check the specs of modern and not so modern table saws that can manage a 16" blade, you'll see they all
run on 3 phase and have at least 4-5 KW of power.
The Austrians and Germans once sold table saws with such large blades directly mounted on the motor shaft,
but these were only used for crosscutting smaller logs and they were single phase. Perhaps this is what you have?

 

[accyjoiner]

https://www.ebay-kleinanzeigen.de/s-anz ... 6-84-15355
this is the saw i have

 

[dzj]

Yes, that's it. For domestic use, around the garden and so on.
Most likely the bearings have been worn out . 400mm was optimistic. Just revert to 12" and you'll probably be fine.

 

[accyjoiner]

there is no play in the shaft and like it says on the label its designed for 400mm blades i want to use them for thick rips resaws and such

 

[dzj]

Ripping/ resawing requires more power than this motor can muster.
The 400mm blade was intended for crosscutting green wood which is not so taxing.

 

[accyjoiner]

even if i did it in small steps say an inch or 2 at a time

 

[Myfordman]

Is this motor running on a normal 13 amp fused plug?

 

[accyjoiner]

yep

 

[Myfordman]

Right in that case it is likely to be no more that 3hp (2.2kW)

My table saw is 10" and has 3 hp motor. In my opinion there is no way a 16" blade can be powered by such a small motor even if it is a low tooth count ripping blade.

 

[accyjoiner]

the motor is really heavy i took it off once to flatten the top i can barely lift it

 

[heimlaga]

The ad you refered to says "starkstrom" which should be German slang for three phase.

I am prett convinced those saws were built to use a 350-400 mm blade. My Stenberg combination machine uses a 400 mm blade and it has a 3,7 kW (5hp) motor.

I also think you have a 380 volt three phase motor wound for use in star configuration. The plate on those usually says 220/ 380 volt. That means they are intended to run on 380 volt three phase but due to the pattern of winding they theoretically would work with 220 volt three phase if there was such a power source around.
Usually the power output is given only for 380 volt as that is the power it is supposed to use.

By adding a capicitor it should be possible to run such a motor on single phase but you loose a lot of power and get a lot of superficial heat.
If that isn't the sole cause of your problems I suspect some fault with the insulation inside the motor. The insulation could be tested using a Megger without dismantling the motor.
If the Megger says there is i current leak the only possible fix is to take the motor apart and rewind it which is a job most hobbyists cannot do at home and which will cost from 400 euros and upwards when you pay someone for doing it.
If the Megger says that the windings are okay you should discard the capacitor and get a proper phase converter or some other source of three phase power. In this case you should dismantle the motor carefully and shift them and put in good quality rubber sealed deep groove ball bearings class C3. *** is my favourite brand. SKF are also good. When the motor has been run hot that way the bearings will start to overheat as the grease has dried out.

 

[Chrispy]

if you really must use a 400mm blade you may find an old plate saw well filed that is, will need less HP to cut with than a modern TCT blade, of course it won't stay sharp as long though.

 

[accyjoiner]

there isnt a plate to change it from star to delta the only place i can see for wiring is the button and a plate to the cap but neither of those are for altering the winding configuration

 

[dzj]

Regardless of adequate/ inadequate power issue, did you figure out the trouble with over-heating?

 

[accyjoiner]

i had another go with it today doing a small job including some resawing was on about 10 mins 15 mins and it didn't get warm maybe i had my saw running a bit longer than i thought yesterday? anyway im gonna put a fan on the second arbour on the motor that should keep the motor cool in future i think and if i put an ammeter on it permanently i can keep an eye on the current draw i had one on a wide belt sander and it was useful for making sure i never pushed the machine too hard

 

[wallace]

Do you know how long it was not used before you got it? Maybe the grease in the bearings is bad

 

[accyjoiner]

maybe but if that was the case the arbour would get hot quick regardless of blade size i only noticed when i changed the blade and had a hold of the arbour on some jobs i change the blade a lot from dado to large blade to small blade etc

 

[accyjoiner]

used it again for a larger job and it din't get warm til i turned it on and off a few times so it must draw more to get it going and warms up seems like its just a normal feature panic over and just to settle the debate it handles rip cuts using the 16" blade no preoblem no bogging down or slowing down at all seems they dont make saws like that anymore

 

[Fitzroy]

Starting a motor makes it heat up, and does other stressful stuff to it. Some of our big drives in work (1MW+) can only be started twice per 24hr period.

F.