Start capacitor failure?

[Jo]

What you are measuring for is a short circuit 

How do you power your machine tools Jo ?

I have a Transwave Rotary (transformer) three phase converter to power all of my 3 phase machines. It is rated to enable me to run two machines at once if required - not that I ever have 

The cheapest way forward for you would be to put the original 3ph motor back and run with a VFD.

Personally I would keep the Variator: Because motors are designed to run at a specific speed and if you slow them down you are fiddling with both their cooling and their power output. It has the advantage that the Variator is already plumbed in and you will only have to replace the one belt with its original. You then have the option of modifying the speed on the VFD (if you really must  ) or on the control that you are already used to.

Jo

[Vixen]

+1 for keeping the Variator. 

The other major advantage of the Variator is that the shaft torque doubles as the spindle speed is halved. With a VFD the torque is reduced as the speed is reduced.

If your Variator is in good condition, keep it. Buy yourself another single phase motor.

Thats what I did with my Chippie

Mike

PS I had trouble with the original stop/ start /reverse switch contacts and replaced it with a contacter.

PPS It may be an idea to remove and get the duff motor checked out by a motor repairer.

[Chipmaster]

Ok the variator is sound so I'm halfway though removing the motor, it's quite a struggle.

 IMG_3504 by Andy, on Flickr

IMG_3505 by Andy, on Flickr

I had to slide the assembly out, couldn't lift it as I did 31 years ago. Another problem has surfaced, one of the three anti vibration motor mounts had become a mush and fell apart.

IMG_3506 (2) by Andy, on Flickr

Here's one that's ok

IMG_3511 (2) by Andy, on Flickr
IMG_3512 by Andy, on Flickr

Problem is the mounts are threaded 1/2" UNC into the base of the lathe and I think I won't be able to find a replacement, may have to do without the rubber or bodge it!

I hope to remove the variator and motor from the frame this evening and take the motor to the local motor repairer tomorrow.

Andy

[Chipmaster]

Variator and motor removed, the variator is incredibly heavy, my hydraulic lift table was key to moving these things about.

 IMG_3518 by Andy, on Flickr

Ready to take to the motor repair folk tomorrow.

Andy

[Vixen]

Andy,

I hope the motor man says there is nothing wrong with your motor, it's is a goody. That would narrow it down to the fwd/rev/on/off switch or the wiring connections. I have had problems with that old fashioned Dewhurst switch before and replaced it with a contacter.

Good luck

Mike

[Chipmaster]

Thanks  Mike. When I converted my Chipmaster to single phase I replaced the original three phase starter with a Crabtree starter which is controlled remotely by the original Craig & Derricott rotary switch on the end of the chrome on off forwards backwards lever with the illuminated knob. I visited the Craig & Derricott works in Walsall Wood and they gave me the necessary cams to modify their switch to reverse the single phase motor. So my motor has the three power supply leads plus a four core cable for reversing. I was far more resourceful then. Putting this lot  back together is going to be a struggle.
Andy

[Chipmaster]

Hi Mike, the motor man took my motor apart while I waited and showed me how the centrifugal switch contacts are very dirty. He said the rest of the motor is in beautiful condition, “just look at those windings and the rotor, we don’t see motors like it these days”, it was becoming quite emotional !

So the motor will be repaired by cleaning or replacing the centrifugal switch  .


Gosh I haven’t had this much tension since one of my library books was overdue.

Andy

[Jo]

Did he give you a price 

Jo

[Vixen]

Hello Andy,

If the motor man can find brand new replacement centrifugal switch contacts then you should be good for another forty years.   

Now all you have to do is get that heavy lump back into the machine. BTW I have wooden spacers in place of those rubber vibration mounts. OK it's a bit noisier but I dont care as I have become deaf.

Cheers

Mikw

[Chipmaster]

Hello Jo and Mike,

I asked about a price and was told it wouldn’t be much, it will depend on whether the centrifugal switch has to be replaced and whether a like for like replacement is obtainable. The motor man said modern motors have something other than centrifugal switches and he would fit one of those if necessary. I didn’t take all the details on board.
To me it’s worth paying out to have the lathe working again.

Mike Re the rubber mounts: two of the three are good and like you I’ve had a block of wood wedged alongside the mount at the front which I knew was rather soft and soggy for a couple of years

Andy

[Vixen]

Hello Andy

While you have the Variator out, now would be a good time to change the special oil inside.        I cannot recall the spec (Google it)  but I got a bottle off e-bay.

Cheers

Mike

[Alyn Foundry]

Hi Andy.

The virtues of being close to what was known as the " Workshop of the World " eh? You'd be hard pressed to find such firms in my locality these days.

My Denbigh was converted to single phase nearly 40 years ago. I fitted the bigger and older brother to your motor. It's a 4 HP Brooks with the centrifugal switch mounted in a little domed housing at the rear end. Everything is easy to access and it has given Sterling service despite being second hand when I got it.
Everyone knows when she's started, even the neighbors. ( 4 other properties on a 24KVA pole transformer for us all ) It used to put out the fluorescent lights in the workshop every time. Now we have LED lighting the problem isn't so noticeable.

I didn't really have any doubts about your motor being burnt out, they're really well made and as you didn't mention a smell, the smoke never left the box!!

Good luck with the refit.

Cheers Graham.

[Chipmaster]

Hi Graham,
At 14.25 this afternoon I received the phone call telling me that my motor was ready to collect, how about that for service?
They demonstrated the motor working for me and showed me pictures they had taken of the centrifugal switch before and after, it looks immaculate now.
The original capacitor had also been checked and passed the test. The motor will probably outlast me 

Jo - The cost was £60 for two hours work, I'm ok with that.

Mike - yes I'll change Variator oil, it was Shell Tellus R10 when I bought two five litre flagons of it 30 years ago. Draining the oil is rather a messy affair so I will take the opportunity to do some plumbing to avoid the Variator oil pouring out all over the cradle and motor in future. In the past I have cut up plastic ice cream cartons to catch most of the oil.

To refit the motor and variator I will buy some square steel tube to act as rails so the whole assembly can be slid along into place. I'll also take the opportunity to clean the oily mess off the interior of the lathe base.

Andy
 

[Jo]

£60 

Not long now and the swarf will be flying again 

Jo

[Vixen]

Mike - yes I'll change Variator oil, it was Shell Tellus R10 ...............
Andy

Great result Andy

Oh! Thanks for the reminder. Now I know (remember?) what that grotty old plastic bottle of Tellus R10 was being kept for.

Cheers

Mike