HELP warco 250vf spindle stalling

Hello all.

I have an issue with my lathe. Warco 250vf.

I can turn it on. Ramp up speed from 50 rpm part past 2000 rpm with out an issue.

And the same back down again.

The problem starts as soon as I try and take a cut, the slightest resistance to the material and it looses speed, nor torque at all. even on a 0.05mm pass it either slows down or stalls and blows a fuse.

I've spoken to warco after calling about 20 times before someone answered the phone. They first off asked me to check the bushes in the motor which are around 10mm on each side. After another hour of trying to get through I was told it was a circuit board, having looked inside and seeing 3 circuit boards, and unsure which one would need replacing, I've had to try and call again( another hour of try to get someone to answer ). I've now been told it's not a circuit board problem it's a motor problem.

Does anyone please have any idea on what the issue might be?

Regards

Ask to speak to Mr Warren, the owner I think. I got lots of help when I had problems with mine but it was still under warranty.

My warranty ran out 6 mouths ago unfortunately

Andy,

sorry to hear of your problem....My money is on the motor..,probably open circuit windings....

If you get no joy from Warco, your best bet is going vfd/3phase motor route cash allowing...but be prepared to do some mods...

Just because your warranty "ran out" be prepared to argue as goods should be "fit for purpose"and a motor that fails after such a short time would not fit in that category I would have thought.

It might be worth posting a photo if the wiring including the motor circuit and it's connections. I did have a small mill at one point that used a brushed motor but never had any need to go near it. Bearing that in mind it might use either a permanent magnet motor or one with a field winding. I suspect that the motor speed would vary if there is something up with the field winding or the connections to it. The fact that a fuse blows suggests that one winding, field or armature is ok.

John

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I would politely ask, why just jump to a conclusion so automatically?

Without knowing all the facts about this particular persons problem...which others are trying to help to diagnose, it would be wrong to throw in such a statement at this early stage.

It could be the motor or the circuit board. Reasons for the failure for one or the other or both could be various, to include:

A. Faulty motor or board

B. Bad power supply/surge/blackouts/brownouts in the area

C. Poor wiring in the workshop - especially applies to customers in France where DIY is king

D. User related - i.e. what was the user doing - before the fault developed?..e.g. overloading/abusing the lathe?

Based on the above four points atleast, the 'fit for purpose' card could be applied to more than just the motor.

Ketan at ARC

For info.....

These machines are equipped with a DC permanent magnet motor.....

In my experience, they will run at a fair speed unloaded.....but doesnt prove that the motor or the speed controller are fully functional...

There are tests that can be carried to determine the operability of the controller ( the light bulb test ) but the motor is a little more difficult without appropriate equipment...( a multimeter, megger ar even better a Growler...)

Hope you have some success with Warco...

Maybe there is a web site that goes through fault finding on this style of machine but I can't see any signs of one that does it thoroughly.

John

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If DC what voltage is the motor? Would it run on 12v (car battery) if ok and what would a blown winding stop it running or show some obvious characteristic.

If testing the board with eg a light bulb what bulb is appropriate?

Warco or another user might be able to answer the above to provide some diagnostic info.

From what I know/past experience....Im no expert...

The motors are generally rated as 180V DC....ergo the controller is set to meet this by adjust the Max preset pot on the board ( assuming this is a KB controller or clone)...

The motor will run when a DC voltage is applied but does not mean the windings are intact....if one or more are open circuit, then this will be seen as arcing across the commutator ( due to the switching nature of the comm between normal windings and those that are open ) A simple continuity test with ohm meter will show any open segments....if the winding is shorted to the metal then that is a different scenario...

Testing the controller is best carried out using a known good motor for conclusive results but in the absence of such then a 200 watt domestic light bulb will work as a load to give indication that as the speed pot is advanced the brightness of the lamp follows...this basic test does not take into account the overload functionality of the controller....

Fitting a replacement boards requires some test equipment, ammeter, DC voltmeter. Board adjustments are required to ensure that the motor is matched to the board and vice versa....KB controls have a manual outlining this on their website.

Edited By John Rudd on 10/09/2015 18:22:12

Just a thought, Any grease or oil on the drive belt?

I found that the chain lube I was using on the backgears was getting sprayed on to the belt causing it to slip under load.

Bear in mind that for a given voltage DC is more dangerous than AC, especially as if you grab it your muscles tend to tense up, rather than relax, Lots of amps in these things and as my Dad used to say 'volts jolts, mils kills'.

Neil

How are you managing that as it would need the belt changing between the two speed ranges 50-1000 and 100-2000 or there abouts?

Edited By JasonB on 10/09/2015 19:18:42

Apart from Kv, very high voltages, there isn't really any need to worry too much about volts unless you intend to grab hold of it. Kv is more of a problem as it can creep up probes etc even via grease or dust. Once it breaks down the resistance drops and higher currents can flow - hence being very careful about things like CRT TV's. Mains voltage doesn't have that problem unless people are rather silly.

DC is reckoned to be worse because it's continuous where as AC isn't. Shocks from one arm to another are more lethal as they will pass through the heart. Most of the info in this area is obtained by electrocuting pigs.

John

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Tim, he did mention that a fuse was blowing when he applied a load....( 2 thou cut...) ...dont know if you missed that detail?

Jason's point re the speed is interesting....my SPG lathe has the same speed range which requires a belt/ pulley change...( not when I get my 3 ph motor mounted....)

You will find that to get increased cutting torque you will still need a belt change and that running 3 phase motors at low speed via an inverter for long periods even under the miserable power levels they may provide when used like that can burn the motor out. There aren't any free lunches in this area.

What most people do who convert ordinary lathes is something like doubling the power of the motor. That means that if they run it at half speed they will have the same torque available as they did with the original motor. When run like that in situations where that level of power is actually needed for long periods the motor is very likely to burn out. In some ways it's better to speed them up but the motor manufacturers aren't very happy about that, balance issues and the armature might burst.

There was some one on another forum that became very annoyed when he finally realised what variable speed means. It's pretty simple really HP or Watts in terms of motors is a product of torque and rpm. Torque is set by the current the motor can take so tends to be constant. Reduce the RPM by 1/2 and loosely speaking the power is reduced by the same amount as the torque is the same. Do it with a belt etc and loosely speaking again torque is doubled.

John

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Edited By John W1 on 11/09/2015 00:17:53

Edited By John W1 on 11/09/2015 00:19:03

Have you checked the shear pin? I had a problem once when the lathe turned ok but wouldn't cut and I found that although the shear pin had indeed sheared, a piece of it, or something else, had got jambed in between the two sleeves that the pin connects them.

Might be slightly tight bearings. This can cause fuses to blow easily at top speed with variable speed machines.

Run at top speed for ten minutes and see if the headstock starts to get over-warm.

Neil