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12-03-2011, 11:04 PM #1
Need power switch for Bridgeport Mill
I just bought a 1978 Bridgeport Mill, The power switch(forward/reverse) is bad. I have found many parts suppliers on line. Any comments on who to purchase from.
12-04-2011, 09:29 AM #2
i had to replace one on my bridgeport clone. (JET)
so take a deep breath when they tell you the price.
mine was $187.00, and that was several years ago.
good luck with your project.
12-04-2011, 01:19 PM #3
Check with High Quality Tool. The original switch is no longer in production but they have a replacement switch that is very similar. Beware of the all plastic ones, they suck. They can be identified by the big metal outer case with a small switch assembly inside. Bridgeport started using them in the last years of production and they fail rapidly.
12-04-2011, 01:48 PM #4
I have always considered that just the direction selection switch. On, off and the associated arcing i leave to the nice big fat ugly contacts on the relay in the control cabinet! Slows power tapping a bit, but that switch is nothing like big enough for a live reversing switch!
12-04-2011, 03:05 PM #5
The innards are just a straight forward industrial cam switch as supplied by Klaus and Naimer et al. Should be able to obtain the switch block and keep the actuator end as these have been standard / interchangeable for many years. Alternatively get the whole kit and caboodle from a proper industrial switch supplier. Hardest part will be identifying the proper switch block code with appropriate switching current ratings. Assuming correctly switch rated contact sets are available at all. Which I seriously doubt given that such switches are inevitably slow make-break so switching loads are far lower than carrying ones.
Certainly UK machines have always had proper electro-magnetic NVR contactor controls with the switch used, as intended, for hard stop and direction selection. At UK voltages they soon burn out when some dinkle brain uses them as power switches.
Frankly given the relatively low cost of NVR units with reverse, heck even in Rip-Off UK we can get "hobby rated" ones for £30 ish, it makes more sense to ignore the OE system and fit one of those with an additional isolator for hard off. Might as well copy UK practice and put the thing where you can safely get at it when a job blows up in your face. Standard site made some sense when Bridgeport made heads to bolt on "any machine" but that's about all. OEM original is fine in a museum but the chips don't care.
12-04-2011, 03:25 PM #6
We ran an Induma with a 2HP motor with an Allen Bradley 800T-J2 with 3 800T-XA contact blocks as the only motor control for years. It never failed.
I might even have an old one in the junk box.
Last edited by WHHJR; 12-04-2011 at 03:29 PM. Reason: add source
12-04-2011, 04:57 PM #7
12-04-2011, 05:16 PM #8
You're looking for a "drum switch" most likely. It's a plain old lever operated switch without overload protection. It reverses and, by the way you connect the motor leads following the circuit diagram that comes with the unit, will serve single and three phase motors. I like the kind that uses cams and double break contacts but the really old technology works too.
Here's a whole eBay listing: http://www.ebay.com/sch/i.html?_from...h&_sacat=12576
Look for one having 50+ Amps capacity.
The big box store people will give you a blank look. Check with your local electrical wholeseller, motor repair shops. Expect to pay $20 to $60 depending on quality and that the traffic will bear.
A drum switch is pretty basic technology dating from 1870. Don't let a rubber mouth salesman up-sell you to a protected reversing motor starter ($$$) if a drum switch is what you want. Code does not enter into the picture provided the drum switch is correctly rated and the curcuit feeding the machine is proteced with over-currect protection. A fused or circuit breaker disconnect on the wall near the machine is the usual remedy.
12-04-2011, 10:28 PM #9
I paid about $100 for a A-B drum switch on ebay a couple years ago. At the time that was the best price I found. It wasn't a OEM direct replacement on a tree mill but I mounted it lower and easier to reach anyway. I don't have the seller name anymore, but it was out of ohio selling new old stock.
12-04-2011, 11:56 PM #10
Check with these folks
Machine Builders of New England, LLC
33 Hull St.
Shelton, CT 06484
ex factory people. They have take offs from rebuilds and will be able to supply OEM used switch.
12-05-2011, 12:59 AM #11