Laguna LT18 motor start capacitor size.

[Kurtis Olson]

I have a Italian built (ACM) LT18 laguna bandsaw with the single phase Bonora 5hp motor manufactured in 1999, and I have searched high and low for information on the proper sized motor start capacitor with no luck. I've emailed all of the associated manufacturers of the machine, (Bonora, ACM, and laguna) and none of them have been able to give me the size of the capacitor. Laguna says they cant find the info on the capacitor, but would gladly sell me an adapter plate and a new leeson motor, which is totally absurd. The data plate on the motor states the RUN capacitor size which is 100uF 450vac, but nothing about the START capacitor size, and of course the sticker on the capacitor itself has been torn off... I was advised that it "should" also be a 100uf 450v start capacitor, so I tried this and it blew up immediately into a plume of smoke. Soooo...

I was hoping that maybe someone here has the same saw and would be able to tell me the size of the start capacitor on their machine? This is my last ditch attempt on resolving this. Any help would be greatly appreciated.

[Tom M King]

Have you talked to someone at an electric motor repair shop?

[Kurtis Olson]

Yea, I called one and they told me if I didn't know the size of the original capacitor then I'm "hosed".

[Bill Dufour]

Voltage and amps?
Bill D

https://www.bevi.com/about-bevi/knowledge-bank/dimensioning-run-start-capacitors

[Tom M King]

Did you check the windings in the motor? Search that on youtube if you didn't. Is the start capacitor the same physical size as the run capacitor? Wonder if Google translate can search in Italian?

[Aaron Inami]

The starting capacitor is always going to be significantly higher/larger than the run capacitor. I have seen the variance be at least 5x difference. On a tiny motor, I have a 100uf start capacitor with a 20uf run capacitor. If your run capacitor is 100uf, then the start capacitor could be as high as 500uf. I'm not a motor electrician, so it's a guessing game. Here's an example of a 5HP pump motor start capacitor that is sized at 300uf (+/- 10% variance):

https://www.tuhorse.us/parts-and-accessories/capacitors/270-324-mfd-uf-motor-start-capacitor-by-bmi-compatible-replacement-part-for-franklin-275468119-and-tuhorse-5hp-start-capacitor/
(https://www.tuhorse.us/parts-and-accessories/capacitors/270-324-mfd-uf-motor-start-capacitor-by-bmi-compatible-replacement-part-for-franklin-275468119-and-tuhorse-5hp-start-capacitor/)
This also matches what people are finding in a standard Baldor motor:
https://www.garagejournal.com/forum/threads/capacitors-for-baldor-5hp-single-phase.426332/

That being said, you will be starting this bandsaw motor "under load" (i.e. cranking up those really heavy cast iron wheels), so a higher value start capacitor could be recommended here - maybe something like 450-500uf).

[Kurtis Olson]

Voltage and amps?
Bill D

https://www.bevi.com/about-bevi/knowledge-bank/dimensioning-run-start-capacitors

It is a 220v 21.7 amp motor.

[Jamie Buxton]

My LT16 from 1999 has a Bonora motor, and the capacitor size is on the motor plate.

[Kurtis Olson]

My LT16 from 1999 has a Bonora motor, and the capacitor size is on the motor plate.

Yea the RUN capacitor size is stated on my motor plate, but not the Start capacitor.

[Tom M King]

I looked for a formula. I'm sure there is one somewhere. This is the only one Google found.

https://sciencing.com/troubleshoot-electric-motor-capacitor-problem-8001821.html

I would check the windings on the motor before gambling on another capacitor.

But it did find this for single phase:
https://www.electricneutron.com/electric-motor/single-phase-capacitor-sizing/

[Andrew Hughes]

Does your saw have the switch with the manual over load?
Here what my start cap looks like in my Italian saw. I think it’s proprietary but you can get one from Jesse at Eagle tools.
if it looks like this. This start cap has a time delay for the inrush
Good Luck

[Richard Coers]

I've never seen a capacitor that doesn't have the specs printed on it.

[Bill Dufour]

A little research suggests around 300 microfarid for a start cap. For 240 volts use at least 330 volt.
Does it have a mechanical start switch that is not working. I hear many bigger Euro tools use a push button start switch to avoid centrifugal switch problems.
Bill D

[Kurtis Olson]

I've never seen a capacitor that doesn't have the specs printed on it.

Yea it looks like at one point there was a sticker with the data on it but it has been peeled off.

[Steve Jenkins]

My LT 18 only has one capacitor on the motor and it’s a 80 microfarad 450v. The motor is a Bonora 2.2kw,220v

[Kurtis Olson]

My LT 18 only has one capacitor on the motor and it’s a 80 microfarad 450v. The motor is a Bonora 2.2kw,220v
That kind of makes sense as mine is a 3.5 kw, 220v

[Kurtis Olson]

I believe you're suggesting that I should check the windings to rule out the motor itself being bad? I don't think that's the case only because I've tested the capacitors and one of them is certainly bad, and if I spin the wheel before I hit the start switch the saw will operate fine. In fact this is what the previous owner had been doing for years.

[Justin Rapp]

I know you said you talked to someone at a motor repair shop. Have you taken the motor off the machine and brought it in to them?

[Kurtis Olson]

No I have not. The local motor repair shop just said there would be no way to tell what kind of start capacitor it should have unless you have the original capacitor with the specs on it. It's incredible to me that not even bonora was able to help me with this issue. They asked me to send them a picture of the data plate so they could point me in the right direction. I sent them the pic and they replied with something to the effect of "sorry, since this was a custom built motor for ACM we do not have the specs for this unit, you will have to contact ACM directly " I emailed ACM 3 weeks ago and still haven't heard from them.

[Kurtis Olson]

The switch is in working order. I have used this machine for over a year and it has never failed to start as long as you give the wheel a spin prior to turning the on/off switch. I'm not 100% sure what the difference between a push button switch and a centrifugal one, but I would aim to guess that it is centrifugal since it's a turn or twist style rather than a button. I'm pretty certain this is a bad start capacitor and not something else.

[Bill Dufour]

A centrifugal switch is inside the motor endbell with nothing outside the motor to see. It is closed at low rpm and opens up once the motor is up to speed. Many motors you will hear it snap closed as the motor coasts down when it is turned off.
Bill D

[Tom M King]

I was suggesting to test the windings to see if the motor was still good. If a short had developed, it does happen, it would blow the capacitor. It's not much trouble to check the windings. Also you can burn one up by using too small of a starting capacitor.

You use the same meter you checked the capacitor with. If the windings are bad, it's just wasted time beyond that trying to find the right capacitor. I do understand that capacitors go bad over time. I'm waiting for one to come in right now for a heat pump.

https://www.electricalengineeringtoolbox.com/2017/10/how-to-test-3-phase-motor-windings-with.html

I would try another motor repair shop, trying to find one where the guy that runs the shop is also the owner, and has gray hair. I'm fortunate to have such a shop. The guy has a great understanding of electric motors, is very quick at diagnosing a problem, quick to fix it, and very reasonable.

Also, check on the old iron forums. Maybe someone there has the same motor, and knows the correct answer.

[Bruce Wrenn]

On a dual capacitor motor, the start capacitor is placed in parallel with the run cap for starting. Motor comes up to speed, start cap drops out, leaving run cap in circuit.