Unisaw Mod. 34-802 Elec. Prob. Advice Please

My Unisaw is equipped with a magnetic stater (as were all of this model). It has a push-button switch mounted on the front of the case for turning it on and off. In order to get the saw to run I must hit the on button as many as 40 or 50 times to get it going. No problem shutting it off, only starting. I have taken the cover off the starter (mounted in back), blown it out with compressed air, sprayed with an electronic cleaner and done the same thing to the on-off switch. It has not helped. This means I must have either a bad starter or a bad on-off switch. The starter is around $200. The on-off switch is about $100. Has anyone else had this problem? Any ideas of what part might need replacing? There are a number of parts within the starter which look as though they might be replaceable without having to buy a whole new starter. Again, anyone had this problem and found an inexpensive solution. Grizzly sells a mag. starter for $69.00 with an integrated on-off switch. I am a bit hesitant as I do not want to risk burning out my motor with a cheap starter. Any ideas, suggestions appreciated.
Joe
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Joe Bleau wrote:

I'll have to go look; I've got a bunch of old Delta/Rockwell starters on a bunch of different gear--they're actually built for 3-phase but I'm using them on single. Same box/geometry just w/ the 3-wire guts instead of one at least at that age. Anyway, seems to me there's a push start button inside the box as well as the remote start button--check for that and if so, that would isolate it between switch and starter.
Is the starter in metal box of about 8x12" by 3-4" deep or thereabouts? If so, may be same/similar...
My money would be on a set of burnt relay contacts (like burnt set of old ignition points, in essence) if I were betting. Again, I don't recall for absolute certain whether these were replaceable but I think they were. Of course, parts for that old a starter may no longer be available, I don't recall.
As for the Grainger/Dayton/Atlantique starters; they're fine. All you have to do is size the "heater" for the proper motor current. I've got a couple of them as well that I put on stuff that originally came w/ mechanical switches.
--
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cheapest place i've found for relays is http://www.newark.com/ if you can get a part # off it, they're about the lowest on the net.
no interest in this site; just that i've used them before.

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I have a couple of 3 ph. starters around the shop but I did not realize they can be used with single phase. Can you give me a better idea of what I would have to do to make a 3ph starter work on single phase? Thanks.

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Check the motor starter for a reset button. Many starters have these to prevent accidental restart of the equipment if there was a power interuption.
Mike
wrote:

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If the saw doesn't start up at all when you press the ON button, then you probably need to clean up the contacts for the ON button (shut the power off to the saw first.)
If the saw starts up, will it stay running if you hold the ON button depressed? if so, you may need to clean the STOP button contacts or the 'holding' contacts on the motor starter.
Doug

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wrote:

Yes! If I keep the start button depressed the stall runs but as soon as I take my finger off it stops. Can you give me an idea of where are the contacts inside the starter case? They are not visible and it does not look as they the phenolic(?) cases can be opened? I know how to clean elec. contacts but I have to gain access to them first. Thanks, Doug.
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I don't know about that specific brand of motor starter, but most magnetic starters work the same way. The ON contacts are connected in parallel with a set of 'holding contacts' on the starter itself. You will have to follow the two wires connected to the ON button and see where they lead to on the magnetic contactor. When the magnetic contactor pulls in, the 'holding contacts' basically take the place of the ON button and allow the contactor to stay on.
Doug

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Joe Bleau wrote:

Take at look at Grizzly Tools magnetic starters. An example would be their G4573 Magnetic Switch, Single Phase, 220V Only, 3 HP, 17-24 Amp at $69.95.
http://www.grizzly.com/products/G4573
--
Jack Novak
Buffalo, NY - USA
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"Joe Bleau" wrote:

Based on the above, you have a defective "start" button.
Again, based on the above, "stop" button and "holding" contact are operating properly.
Replace "start" button as a starting place.
Lew
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AND, If you replace the switch first and end up replacing the starter to solve the problem you will have only spent $100 too much. If you replace the starter first and end up having to replace the switch to solve the problem you will have spent $200 too much.
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I have an elderly "Progress No1" drill press, which I bought on ebay, which appeared to have a similar problem. Then I discovered the secret was to make sure I pushed the button in firmly, all the way in, and pause for a moment before letting go.
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Stuart wrote:

Weak/intermittent transformer coil maybe so the LVC is flaky???
--


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Dunno really - as long as it continues to work, which it does every time as long as I treat it as above, I'll leave well alone. Plenty of other things to do with my time :-)
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