Help with Graduate please

Hi Hotfoot,

I'm no Graduate lathe expert but I don't believe they were originally sold with variable speed drives. Therefore, it's likely to have been converted at some time after its manufacture. LRE Machinery[1] make (or maybe just market?) the Variturn system of speed control for these machines; it may be worth contacting them if it is one of theirs, as they should be able to advise what may be wrong.

Alternatively it could have been done as a one off conversion by a previous owner. If it's got a 3 phase motor and a normal mains plug then there must be an inverter included somewhere to achieve the variable speed operation. You should proceed with the following only if you are appropriately qualified and understand where the risks may be. If not, then any competent firm of industrial electricians should be able to sort it out for you. If you locate the inverter[2] and note its make/model you should be able to find documentation explaining what its required inputs are and what its output is. Then you can trace the wiring and use a multimeter to check which of the switches is open or closed, and work out if any need switched to the other position or replaced. Methodically tracing the appropriate control circuits should locate all the microswitches (if they exist) that are in the machine. In this manner you should be able to eliminate the problem.

This, of course, assumes the inverter is working and that may not be the case. If it's faulty first check it for fuses or resettable trips, then look at getting a new one. RS[3], Farnell[4], or an electrical wholesaler/electrician should be able to supply a suitable inverter.

Hope this is of help to you.

Neil

[1] http://www.woodturn> Hi, Hotfoot here, the arts centre at Milton Keynes has recently had a

i would suggest that you check the following and only if suitably conpetant.

if the graduate is fitted with variable speed it probably works with a dual phase motor powered through an invertor.

1. check the mains plug fuse
2. is there 240V going to the invertor
3. the invertor should make a noise (the cooling fan) when working (if it is a modern one)
4. is there a digital display on the invertor - is it showing anything if there is a display the invertors programming may have been altered by mistake.
5. if invertor working check there is 4 wires leaving the invertor (1 earth) and check the voltages of these.
6. aparently invertors should not work of separate on/off switches in the power circuit . ie the switch is through the control panel of the invertor not on the power circuit. so if there is power coming out then check the power after the switch that you are using. if there is no power after the switch - obviously the problem is in the switch which you could try by passing or changing.
7. also if there is power in and none out of the switch - old pull in switches have a max current setting which means the trip on the switch could have gone off and need resetting.
8. check that you are using a suitable dual phase motor and you have wired the motor the correct way (star or delta)

if you have a multimeter it shouldnt take long to find the problem...

good luck

Having read some of your helpful replies I have come to one conclusion about our non running Graduate lathe. It has a socket on the back of the head, and it would seem that this socket is live, my thoughts where that is might be for a light attachment but then I suddenly thought what about an emergency foot switch. so what do you think? could it be for a foot switch, that might explain why I am not getting any action from the lathe, because the circuit is broken until the foot switch is plugged in. If this is the case, there is no sign of any foot switch or lead left in the workshop where I picked it up from so I am going to have to get something to close the circuit if not a foot switch then some other plug. Any thoughts on this idea, does it make sense? Does anyone know what companies deal with the graduate lathes, and might have fitted the varispeed. Thanks for you input, Hotfoot.

This is a VERY bad idea! If you are wrong you could be badly burned when you plug in the lathe. You could start a fire. You could destroy the motor controller. Or you could save a few bucks. Please find someone that knows what they are looking at.

Walt A

aaah, I don't think just shorting that plug is a good idea. Just trace out the wires and see where they go. Draw a schematic and then it will be clear - if you don't know how to do that, find a high school student that knows how to use a VOM and let her help you.

Bill

to contact me, do not reply to this message, instead correct this address and use it

will iam_ b_ No ble at msn daught com

I am sure it is a bad idea. Can I just say that at no point did I say I was going to put a link over the socket. Although I cannot figure out what this socket is for yet I am not stupid. I am trying to find out which company did this refit. Way back in my memory I am sure I remember seeing a Graduate at one of the woodworking shows with an in built light attachment, but cannot remember which firm was showing these lathes.

Hotfoot