Graziano SAG 12 shuts off @2K rpm the heat fix

My Sag 12 keeps shutting down @2K rpm. I am running my SAG 12 from a balanced rotary converter from single phase 220V I noticed that when the temperature in my unheated shop is >65*F that the shut down does not occur. Today it's 66*F when it would normally be about freezing with snow on the ground here in the southern California mountains @6K ft elevation this time of year but the climate has changed in recent years. I usually just reset the motor contractor when the lathe shuts down, however if it is colder than 65*F the shutdown will occur again. I tried heating the motor contactor with a heat gun and no shut down.

Hi Don, do you have a infrared digital thermometer ? Just a wild guess that thermal cycling of some of the contacts and wire connection points have "cycled enough times to get loose. The temp gun will read higher temps at the points w/ resistance/ looseness...

Regards,
Chuck

I would check the amps on each phase at 2000 RPM Perhaps with different outside temperatures

Peter from holland

Thanks for the ideas guys. I did check the current on each phase when balancing my DIY rotary converter, however didn't correlate with temperature. My grandson got a FLIR camera for his I-phone for Chistmas. When he was up last week we looked at my home for thermal leaks. Using the FLIR camera on the SAG12 electrics would be a good use for I-phone camera.
BTW it was 75*F yesterday and with my shop doors open the lathe was working great @2K rpm having turned many 1-1/16" diameter 6061-T6 parts. Yeah there ain't no global warming.

Hi Don,

I`m just experiencing a problem with a controller board of my BP mill and one member here helped me out immidiately with a very extensive diagramm, descriptions.

Anyway, the despcriptions says: Operating ambient temperature :- +10 degrees C to +35 degrees C.= 50-95 Fahrenheit.
Such a high operating ambient temperature I didn`t expect, despite it`s age of some 30 years.

I used to work on tower and shipyard cranes where temps easily drop below -5F and raising above 120F inside the electrical cabinet. We experienced plenty problems particular in SE-Asia where the temps exceeded some 180F inside the cabinet. But not the contactors gave up but the PLC boards.

I`m still working on my problem with the table feed controller board but one fault I found being three cold solder joints of one coil. I discovered it only cause I could feel a shaking movement when handling the circuit board. I guess it`s showing its age.

I know that the SAG12 is having this speed joystick at the apron and some microswitches which control the electrical magnetic clutches. Wether your problem is with your old electrical/electronical system or with your RPC I cannot say. I know that these clutches may fail and I heard that some owners simply swapped them when the faulty clutch was in a low speedrange because they are horribly expensive to buy. However without knowing the full story and being anything but an expert I`d look at the plan what`s happening when the RPC and the lathes` system is drawing full current. I don`t envy you.

Rainer

Could your problem be in the motor contactor? I'm not familiar with american systems, but in Europe we normally have an adjustable current overload trip switch with a pretty long time lag in the motor contactor. These tend to be adjustable for current. If your motor does not run hot, you could try to increase the trip current some, and possibly clean/ check/ replace the contactor if this doesent help.
Ole