Soft Start for TS motors?

[Dennis Peacock]

My Jet Cabinet Saw starts really hard. I was wondering if there was a way to "help" it start with less of a <b>JOLT!</B> Ya know, push the botton and <b>BAM!!!!!</B> shes up and spinning before you can twitch an eyebrow......The whole saw jolts when the switch is flipped on. No wonder the set screws on the saw arbor work loose!!!! Is there a way to put a "softer start" on a 220V 3HP saw?

Just askin'......

[Jim Becker]

Mine did that when I originally bought it...generally the first few starts of the day. In the cooler night air, the hard belts were taking a "set". Replacing the factory belts with PowerTwist link belts solved it for good. Now it just starts as I would expect it would and runs slightly quieter...although that's way too subjective to be proven without lab gear!

[Dennis McDonaugh]

Jim, did you put link belts on a cabinet saw? I'd thought about that, but I'd been told that you shouldn't use link belts to replace multiple matched belts. Maybe that's an urban (woodworking) legend, but I didn't do it. My Jet starts hard too--no bang, just an abrupt start. There's enough of a jolt to feel it through the table. The MM16 with a 3.5 hp motor and the 3hp Jet planer don't start as violently.

[Jim Becker]

I've heard some folks talk about the "matched sets" but when you think about how link belts work...they are self-matching, IMHO. I have not stalled the saw at any time using them and they have been in operation for about two years now. About a month or so after installing them, I had to re-tension, but that is normal for link belts as they will stretch a little bit when new. The saw runs smoothly and without any hint of vibration.

I have the link belts on every tool that can take them excepting my DP...never got around to that one as I don't use it all that much. The jointer and bandsaw really benefited from the vibration-dampening properties of these belts, too.

The number "38" sticks in my mind when it comes to the number of links for the saw, but it may be slightly different...two years was a long time ago!

[Phil B]

I have a soft start feature on my saw, it's a kind of neat thing to have. The way the feature is implemented on mine is via the addition of more start capacitance when the "go" button is pressed, it takes about 2sec or so to spool the blade up.

There is no reason I know of that you couldn't do the same for your saw if you wanted it that bad.

PMB
http://benchmark.20m.com

[Lee Schierer]

Originally posted by Dennis Peacock
No wonder the set screws on the saw arbor work loose!!!!



I can't help on the soft start, but try Loctite on the set screws. They make a product called 242 that is perfect for screws that tend to loosen from vibration. It can be broken when a wrench is applied.

[Jeff Cybulski]

Dennis - Remember when we we're at Bob Lasley's house his Shopfox made a "shrill" when it started. Bob said it was blade deflection if I remember correctly. Does it sound the same as Bob's?

Jeff

[Dennis Peacock]

Jeff,

I remember that....nope....mine sounds more like a knocking sound when the saw is only powering down.

I did get it fixed and the set screws "felt" tight, but I tweaked them a little bit and now the knocking sound is gone.

If it happens again, those set screws will get the Blue Loctite Treatment..!!!

[David Rose]

pulley(s). If they get a little sloppy on the key that fits in them, it will be hard to keep the screws tight enough to avoid a "slap" when spinning up or down. I had a pulley on my old jointer that had been shimmed around the key. It gave me the same effect. I flattened the top of a piece of key stock (removed from the shaft) with a hammer until it was snug. It worked a few times, but I still replaced the pulley.

David

[Rob Russell]

Phil B - adding more capacitance will bring the motor up to speed faster. A "soft start" would cut the amount of capacitance in the start circuit. If that's a permanent part of the saw and not an optional "push 1 button for fast start and push another button for soft start", I'd say the manufacturer found a way to shave a couple of $$$ by using a smaller capacitor and giving it a marketing name. If there is a second button you push for soft start, I'd guess that adds a resistor that cuts the current flowing through the start cap.