Bandsaw MOtor Help

GOt a bandsaw that isn't acting right

The electrical setup has two momentary pushbuttons, a start and a stop. Theses control a latching 120v relay that brings in the hot side of the motor, and starts it up. It also has a limit switch in line witht the latching setup to stop the saw when the cut is complete.

Now for the weird part.

Check the motor stick the leads into an outlet and it spins up fine. I try to start it off the relay and the relay just buzzes.

This is with zero load on the motor just spinning the pully on the shaft. About 1 out of 15 times it will start with the relay.

I replaced the buttons and relay with some surplus but new ones that I had.

THe buttons are rated at 10A and the relay I think is 12.5A

the motor is 550w with a capacitor on the side

please help me. It needs to run so I can sell it, but I want it setup safe and fully functional for time to come, not cool with half way repairs

Mike Miller Please help any ideas ?

Reply to
Mike
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Hey Mike,

Was this yours to begin with, and if so did it run OK at some point in the recent past?

The simple explanation you've given might indicate a 220 volt wired saw trying to run on 110. Or the relay may be faulty. When relays are used, there is very little current draw in the control part of the circuit. Is the relay an "open frame" style, or enclosed? Is it possible to operate the relay by hand, like pushing and holding it in with a stick or something, and see if the motor runs OK them.

Take care.

Brian Lawson, Bothwell, Ontario. XXXXXXXXXXXXXXXXXXXXXXXX

Reply to
Brian Lawson

When you stick the motor leads into an outlet and it "spins up fine" can you tell if the motor's internal centrifugal switch is operating, i.e., do the contacts inside the motor seem to operate normally? This question is based on a guess that the motor has a centrifugal switch inside that starts the motor and then drops out after the motor reaches speed. The internal centrifugal switch may be defective - you can open the motor and repair the switch; usu. by adjusting contacts. Does the motor even "kick" at all in an attempt to start when it is mounted on the bandsaw? There may be chip or notch out of the bakelite disc of the centrifugal switch that somehow always comes to "stop" in the same place, disabling the switch only when the motor is mounted on the bandsaw.

If you eliminate the motor's internal start switch, then take a careful look at the contacts of the relay. They may be burned and/or out of adjustment. The relay may be part of some sort of safety interlock that senses blade position, blade rotation or if the operators hands are out of the way, etc.

Others with more bandsaw experience may have suggestions, also.

Reply to
Robert Swinney

This used to belong to my old place of work. They called me and say it was going into the trash, or I could come and pick it up free. I had been the one to make it work when I worked there. It was off in the corner all dirty. The original switch had burned out when the saw jammed at some point previous. It was a really expensive switch so they went without. Or so they told me.

So I rewired the whole thing. I used to 30mm push button switches for start / stop and an Ice cube relay ( 8 pin - 2 for the coil 2- inputs and their nc/no contacts).

When I stuck the motor leads into the extension cord it starts perfect, even under a load no problem, witht the relay it made the relay chatter and hum and trip out the saws circuit breaker I had put int hte enclosure when I built it.

I had an idea and moved the motor start wire, and combined it with the relay coil hot wire. So when I push the start button the motor gets a direct connection to power and starts right up. THen when the start button is released the relay has latched and now the relay is supplying the motor its power. The limit switch and stop push button will stop the saw at anytime when activated.

The coolant is on a seperate set of contacts on the same relay and only run when the motor is on.

So far if have start/stop the saw at least 100 times in a row perfectly.

I'm guessing that maybe the switch is closing its contacts faster than the relay was. Also ambient temperature outside is about 105'!!!

So it seems to be working good. I still want to know why it hummed the relay when it used to work that way before.

When the saw was given to me I was told it wouldn't cut all the way. The hydraulic cylinder was all messed up, loose and binding plus empty of fluid. GOt it all fixed and then went to fire it up. Hmmmmmmmm...crap opened up the box and the whole wiring had beeen modified since and it had a burnt wire.

Anyhow, thanks for all the input so far and any more info that can be offered up.

MIke

Oh yeah this was the tool gloat last week. Its a Startrite h175

hope its cooler at your house

Reply to
Mike

Trace is with a multimeter, sounds like a bad contactor/relay. Verify it, and if so, replace with a better/bigger unit.

These may not have enough "meat" to run motor loads.

Sounds like the relay has troubles supplying the startup current.

I am positive that these electrical problems will find an easy resolution.

congrats. Do not worry about electrical issues. Likely easy and cheap to fix.

i

Reply to
Ignoramus27404

My bet is that the relay contacts are eroded. The keeprunning contacts will be the major suspects.

-- Why do penguins walk so far to get to their nesting grounds?

Reply to
Bob May

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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

Reply to
William B Noble (don't reply t

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