I recently moved shops, and am trying to figure out what’s up with my Laguna bandsaw. In the old place, when I turned it on, I’d hear a slight “thunk” and it would spin up to speed in about 3-5 seconds. In the new shop, when I turn it on I don’t hear a “thunk” and it takes 14-16 seconds to spin up to full speed.
I’m trying to figure out what’s going on, because my table saw doesn’t behave any differently in the new place and the old place.
I only have one 240v receptacle. It is a 20a three-prong round (locking). I checked the wiring inside the receptacle. It’s a 12/3 wire, with the black, red, and ground attached to the plug. Ground attached to the green screw as expected, and red/black wired to the other two screws. The white is bent back out of the way. Checking in the sub-panel, the red and black go into both halves of a double breaker (240v/ 20a) and the white and ground go to the neutral/ground bus.
Does anyone have any suggestions? Am I hurting my bandsaw by running it this way?
“Honey, will you please make some sawdust and track it across the carpet?”
“Yes, dear…”
Replies
You didn't give the HPs of the 2 saws. Even at the same HP a TS blade is unloaded compared to at least some load in a bandsaw. Just the same check the voltage you should have 240 L1-L2 and 120V from L1 & L2 to Gnd. If the voltages are within +/- 10% of nominal, everything should be fine. Something may have rattled loose in the move. After eliminating any mechanical causes disconnect the supply and check the motor and starter for loose connections. Since you still hear the same 'thunk' I'm going to guess that the centrifugal starting switch in the motor is OK. Barring anyother findings I'd suspect the capacitors. At that point unless you're very electrically inclined you should take the motor to a motor shop.
John O'Connell - JKO Handcrafted Woodworking
The more things change ...
We trained hard, but it seemed that every time we were beginning to form up into teams, we would be reorganized. I was to learn later in life that we tend to meet any new situation by reorganizing; and a wonderful method it can be for creating the illusion of progress while producing confusion, inefficiency, and demoralization.
Petronious Arbiter, 210 BC
The T/S is a 3HP. It's the one that has always gone "thunk".
The B/S is als 3HP. IN the past, it used to thunk or "click" when it came on, and took ~4-5 sec to get up to speed.
L1- grnd = 122 vL2- Grnd = 123 v
L1+L2 = 245v
"Honey, will you please make some sawdust and track it across the carpet?"
"Yes, dear..."
These voltages are spot on. If everything is wired right then I think it's the motor starting switch or caps. Even with a #14 extension cord at 17 amps which is the full load current for a 3hp induction motor you'd need a 67 foot extension cord to get to 3% voltage drop. Unloaded start-up acceleration should be a snap.John O'Connell - JKO Handcrafted Woodworking
The more things change ...
We trained hard, but it seemed that every time we were beginning to form up into teams, we would be reorganized. I was to learn later in life that we tend to meet any new situation by reorganizing; and a wonderful method it can be for creating the illusion of progress while producing confusion, inefficiency, and demoralization.
Petronious Arbiter, 210 BC
Assuming no mechanical resistance (spin the wheel by hand), the symptoms suggest you're not getting enough amps. The wire sounds ok, though you don't mention what else is on this circuit. Is there something else on it, like a vintage refrigerator? Are you using an extension cord? I can also imagine that maybe the breaker is no good or improperly connected.
I'm going to guess that the thunk you're used to is the motor taking a little hop from torque when the juice hits it. A centrifugal switch generally goes "click" and is hard to hear on startup.
I wouldn't run it much until you get it figured out.
Pete
The shop is about 25' from the house, with a subpanel professionally installed (4 ga or 6ga wire feeding into it. The plug is another 30' on 12 ga romex. From the outlet to the saw I used an extension I created from 12ga stranded (15'). I haven't calculated the resistance, but the bandsaw neeed 7.3 amps, so it ought to be OK. This is a dedicated circut, so there's nothing else sucking juice away.
The tablesaw definitely makes a more pronounced thunk, but the B/S used to make a very slight one. Now I don't hear that at all, and as I mentioned, it takes 14-16 sec to reach dulll speed. There's no resistance on the B/S when I spin the wheels free-hand."Honey, will you please make some sawdust and track it across the carpet?"
"Yes, dear..."
I suspect that you are getting only 115 volts to the motor. The problem may be in the saw or your wiring. I doubt that it can be analyzed here or without a voltmeter. To test my theory, turn the saw on and attempt to cut through a thick piece of hardwood with a high feed rate. If the saw nearly stops cutting, I am probably correct. A 220-v motor will run on 110-v current. Don't ask how I know.Cadiddlehopper
I'd certainly try it w/o the extension. Cadiddle's thought is a good one, though your description sounds like the wiring is right for 240. One potentially dangerous possibility is that the plug, extension, or outlet is miswired so you're getting a hot and a ground wire instead of two hots. This would give you 120 at the motor with the potential that the machine body is hot also.Pete
Edited 4/2/2007 10:30 pm ET by PeteBradley
It is tempting to presume an electrical problem, but it does sound like the power at the outlet is good, and a capacitor failure because of the the moving is hard to make sense out of. Did you move to someplace, a different country, where the frequency would be different by any chance?
Take a look at the belt tension, the motor or the saw could easily have shifted if the machine was jostled while being moved. A loose belt would cause exactly the symptoms you are describing.
John White, Shop Manager, Fine Woodworking Magazine
Problem solved. One of the hot wires had pulled loose from the terminal block on the bandsaw frame. I discoverd this because I opened the cover on another access panel and checked the voltage and found it to be 122v.
Thanks to everyone for your help.
-DJS"Honey, will you please make some sawdust and track it across the carpet?"
"Yes, dear..."
This forum post is now archived. Commenting has been disabled