Member postings for TIM RALPH

It doesn't necessarily suggest a field coil fault Dave.

My switch melted as oil got in it, causing arcing which melted parts of it and causing it to short. This could be the same problem. The new switch 'either does nothing or trips the overloads' depending on how it's wired up. It needs to be wired up correctly! It it's connected incorrectly then it is likely to either not work or trip something depending what is connected to what. 1st thing MUST be to ensure that the new switch is making the correct connections in the various positions. Unless you've got that it will never work. Once wired correctly if still not working then yes check the motor. The motor could be checked 1st but it still won't work unless the switch works correctly.

Do you have a manual with a wiring diagram in it? Sure it is a simple switch but with specific connections on each setting (ie FORWARD - OFF - REVERSE). You definitely need to have the connections correct straight away not trying different combinations! I don't know if your switch will be the same as on my Mk2 800. The problem I had when trying to source a replacement switch was that there are plenty of forward/reverse switches out there which simply make the connection for the 3 separate phases in FORWARD and swap over 2 of the phase connections in REVERSE but in the OFF position there is no connection at all. However on my lathe Colchester also used the same switch to pull in the contactor when in the OFF position. This means that the switch has a separate pair of contacts that are only made in the OFF position and are open in the Fwd/Reverse positions. I could not find that on any of the replacement switches that I looked at. Assuming the wiring is the same as for my lathe, unless your new switch has the 4th set of contacts to be made in the OFF position you will never be able to get it to work without modifying the lathe wiring. I did not want to do that as the safety feature it provides works brilliantly with the standard fwd/reverse lever.

It took a few months but I finally got there. I couldn't find a suitable switch anywhere. I did eventually manage to get another switch on ebay from a Colchester Student that looked similar but internally it was quite different and the connections were completely wrong. I did however manage to salvage enough from mine to build one out of the two, modifying some parts as necessary. I thought I had some photographs but can't find them and my memory's very hazy about what I actually did. It works absolutely fine now.

I found the problem had been caused by oil getting into the switch causing the arcing.

If I had to fix it again I would search for klockner moeller t2b on ebay. A switch with 3 or more segments would do. I would then hope I could make one out of the 2. When I was searching I did find a few on ebay that were from abroad but the only one that wasn't stupidly expensive kept refunding my money when I tried to but it. I wasn't prepared to pay a great deal of money for something that might instantly have proved to be totally unsuitable when it arrived.

Good luck.

Thanks Simon.. If I don't get any joy I will try somewhere. The switch is awkward to get to and took ages for me to get it off. As you say the funcitonality of it is fairly standard. The problem I envisage is that for a direct swap it must mate up with the operating mechanism and needs to turn by the same amount (about 30 deg in each direction).

Here are a couple of photos of it

If I don't get any joy I may be able to strip, clean and rebuild the switch so that it only uses the 1st undamaged segment. and only for feeding a contactor to bring in anothe FORWARD/REVERSE switch. That way the lathe will still be started and stopped in the same way and the rebuilt switch will only be operating on 110v and with minimal current to operate the contactor.

Tim

Yes thanks I emailed them last night but they replied this morning that they don't hold any electrical items. The original manufacturer of the switch Klockner-Moeller still exists in USA so I've emailed them about it.

Hi. I have a Colchester Bantam Mk2 800. It's a 3-phase machine running off a Transwave converter. Recently it won't start and I've now discovered why. The foward / reverse electrical switch mustb have developed and fault and has been arcing and burnt away part of the switch. No wonder the overloads kept tripping. Does anyone have a spare switch, know where I might obtain one or got any other suggestions? I realise I could fit a straight forward FORWARD/OFF/REVERSE switch and may have to go that route if I can't obtain one but it will be so much better and safer to use the standard operating lever as I have been for the past 20 years. Thanks. Tim