New-to-me LT14 SUV - old LT18 problem

[David Utterback]

Years of doubt about the performance of my LT18 (an old olive green variety from about 1994) led me to long covet a better cutting saw. A local hobbyist woodworker who had a shop too big to move sold me his LT14 SUV. I love it. It resaws hardwoods many times faster than with the old saw.

The difference leads to the question-- What is wrong with the LT18? It is clearly underpowered yet seems to run full speed when not under a substantial load. The motors on the saws are both rated at 3 HP. Even when resawing 8" cherry with a new 3/4" Lennox 3 tpi blade, the old saw could be made to completely stall even with a very, very slow feed rate.

Can a motor partially fail? Is there a simple test to determine the nature of the problem? I would like to sell the bigger saw to free up limited shop space but do not want to stick someone else with a faulty machine. Your insights would be greatly appreciated.

Thanks
David

[richard poitras]

How's the belt on the saw?

[Andrew Hughes]

Sounds like a power problem to me. Belts or motor maybe wired for 240 and your feeding it a 120 circuit?

[David Kumm]

Those were Sagitarius ( sp? ) saws and not top of the line. I had an ACM LT18 that replaced the Sagitarius and it had a 3 hp motor that tended to stall under heavy load as well. I don't know if the motor was the same on both saws but it ran warm and seemed weak for its size. The 3 hp on my old Oliver has way more torque. Dave

[Geoff Crimmins]

Could be a slipping belt or pulley. The motor could be wired wrong. If it has a run capacitor that has failed, would that cause this problem? If you can't hear the motor bogging down but the cutting stalls then the tire could be slipping on the wheel, or maybe there's something wrong with the blade-tension mechanism that's allowing the blade to slip on the tire. Or maybe if the bearings in the motor or wheels were really trashed. Even if that's not the best saw Laguna sold, it sounds very strange to be able to stall a 3hp motor with a light feed. I have an old Jet 18" saws with a 1.5hp motor on it and have never even come close to stalling the motor. Ditto with my Delta 14" saw with a 1hp motor. Granted, neither saw cuts as fast of my friend's saw with a 4hp motor, but they don't bog down and stall with normal cutting either. BTW, congrats on the 14" SUV. I have a friend with one who really likes his.

[David Utterback]

Thanks for the responses. Belt appears to be in good shape. I will try tightening again.

The motor does get warm but not too hot to place hand on surface. The saw is a Sagittario model with an ELD brand motor, Type M90LB 2, 3HP and Serv S6/60. The motor is dated 1994. It is definitely powered with 220 VAC since it is the same circuit used for four other machines. Those are not operated simultaneously.

Any ideas on where to get replacement motor, if needed.

[David Utterback]

Geoff suggested a problem I had not considered. It may be the motor wiring is for 110. The previous owner had it set up in his garage and may not have had 220 outlet available. I will check it later this morning. Thanks!

[Tom Trees]

If the tires are not right it can cause the blade to twist slightly when running...
I've noticed this on my 24 ACM star that has flat tires.

You wont really see it happening that clearly though, but it can render the saw unusable.
Does you saw run smooth (hand turning the top wheel) with most off the tension off the blade...i.e just enough to stay on the saw?
Obviously doing these tests with all guides backed off to ensure no contact with the blade.

If you do notice this you might try seeing if your saw wheels are coplanar, or if one needs shimming out with a washer or by adjustment.

Good luck
Tom

[David Utterback]

I opened all the wiring to view. Several past SMC posts on this issue indicate that the power supply is low since the motor does start slowly and recovers slowly after lower speeds due to feed rate. The mag switch is variable amperage with settings for 10, 13 and 16 amps. It is set at 10 as can be seen in the photo at the left. Would this limit the output to the motor below its rated capacity and create the problem?
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Also, the use of red wires for most connections on the thermo switch (along with a couple of extra screws and a washer free in the panel) make me believe this was replaced at some point. Not shown but there appear to be fuses(?) labelled A1 and A2 under the connections for 3 and 14 respectively. 14 is connected with a red wire to A1 which is also connected with another red wire to the main switch. 3 is connected with yet another red wire to A2 which does not have a second connection.
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Also, the tires were replaced last year and trued up on my lathe. The blade runs true with appropriate settings for the guides.

Thanks for your valuable information.
David

[Tom Trees]

It does sound like its setup fine from what your saying, just wondering though, does it run with no blade vibration when there's barely enough tension for it to stay on the wheels?

And are they coplanar ?..might not matter so much if they're crowned though

[scott lipscomb]

I have the same saw, but with the 1.9hp original euro motor. I resaw 12" doug fir with a 1" blade regularly and 8" hardwood (biggest I have cut) works fine. But then, I have never had a bigger and more powerful bandsaw, so maybe ignorance is bliss in my case.

[Bill Orbine]

I'm curious to what comparisons the blade speeds between the two 14 and 18 bandsaws. If the 18 has a significantly higher speed rate, then that could be likened to starting uphill on a bicycle in higher gear..... you see what I'm thinking?

[Geoff Crimmins]

I opened all the wiring to view. Several past SMC posts on this issue indicate that the power supply is low since the motor does start slowly and recovers slowly after lower speeds due to feed rate. The mag switch is variable amperage with settings for 10, 13 and 16 amps. It is set at 10 as can be seen in the photo at the left. Would this limit the output to the motor below its rated capacity and create the problem?

Is the motor amperage listed on the motor tag? I know that's listed on a US-made motor, but I don't know for sure with a metric motor. I just Googled a Leeson 3hp Unisaw motor, and it's a 13 amp motor. You mention that it looks like the starter has been replaced. I wonder if it was wired correctly. Maybe the motor is only connected to one of the two hot wires in the 220v circuit. It would certainly lack power if that's the case. Is there a wiring diagram diagram on the starter that would help you trace the wiring?

--Geoff

[Bill Dufour]

The wiring on the contactor does not look correct to me. There should be two hots in and two hots out straight across. it looks like the red wire on the right is not connected to anything? I think 3 should go across to 4, 5 to 6 when the coil is energized.
I may be wrong as I do not see the control wiring. Is there a neutral supplied to the control box? I would disconnect the ground and see what happens. This is because the only way to run on 120 volts is one hot to ground or neutral. If the ground and neutral are not connected the motor must be supplied by 240 volts or nothing.
regarding the amp setting it will just trip out at a lower amp draw and stop the saw until reset.
Bill D.

[David Utterback]

Thanks for all the responses. On the MS 25, the two 120V lines are connected to 1 and 5 with a jumper from 3 to 6. MS 25 connections 2 and 4 go to the KN 12 connections 3 and 5, respectively. The green lead from the plug is attached to ground. As best as I can do, here is a schematic of the bandsaw wiring. Other than the green ground for the plug, no other ground connections are in the schematic.

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The motor is labeled as 3HP and 2.2 kW.

[David Utterback]

The schematic may not be clear. It only shows the wiring that runs from the power source to the motor starter (MS 25), the thermal overload (KN 12), lockout (or reset button), the switch, and then the motor wiring panel. I do not know the internal connections for the various components. I have searched the manufacturers information but have not found the diagrams.

It seems to me that both 120 legs are connected to the lockout from poles 5 and 13 on LN 12. (The connections for the lockout are not as drawn but actually are wires from poles 5 and 13 attached to one side and the wire on the other side going to the main switch.) The switch when closed then feeds the power through pole 14 on LN 12 and out through 4 and 6 to the motor wiring panel. But this seems incorrect because the switch would only activate a single leg (one wire) running to 14. Then again, maybe the internal wiring of LN 12 activates both 4 and 6 when power is received through pole 14.

Here are 2 more pictures of the wiring for the lockout and main switch
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and the motor wiring panel.
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I will test for continuity and power through the components and see if I can add information. For now, it seems very likely that the motor is only getting one leg of power because of the reduced output and the slow start up.

Thanks again for the input.
David

[David Utterback]

Well I got the lockout wiring incorrect in the post above. Pole 13 is connected to the same side as the wire going to the switch and pole 5 is connected to the other side of the lockout. Need more coffee.

[David Utterback]

The electrical measurements checked out with 240V to the motor. After reassembly, the start speed was back to normal but it still had insufficient power during resawing. All other aspects of the saw work well including a new sound with start up like the switch engaging. It may be that the loose washer or nut was interfering with a pair of contacts or something like that limiting the current on one side. Also, my guess is that the motor is a little short on torque.

Thanks for all the help.
David