Unisaw owners - check your keys!

[Larry Fox]

I have a Unisaw that is a few years old (X5) and last night I needed to raise the blade further than I normally do. I turned the saw on and was greeted with an aweful noise. I immediately stopped and unplugged the saw and set about investigating. To make a long story short the key that holds the pulley to the motor shaft had worked it's way loose to where it was sticking out and contacting the rod that raises / lowers the trunion.

A couple of quick and gentle taps with a tack hammer resolved the issue but I thought I would share it so you can be on the lookout for it.

L

[Josiah Bartlett]

You might want to pull the pulley off the shaft and replace the key. It should not be a loose enough fit that the key works its way out, that can result in a keyway that gets beat up.

I had this happen to a harmonic balancer on an engine once, on a long trip. I had changed the timing belt a few weeks earlier and then drove up I-5 on labor day weekend. I suddenly felt a jolt and saw my harmonic balancer bouncing down the road behind my car. Fortunately I was able to collect all the pieces, and the tow truck driver let me use his shop and tools to repair it in exchange for double milage on the tow. The key had slipped out, sheared in half, and then the harmonic vibrations caused by running at exactly the right RPM for hundreds of miles had loosened the locktited crank bolt and the whole thing fell off at 75 mph.

[Pete Bradley]

There should be something that holds that key in there. If it's a straight key, there's most likely a set screw in the pulley that goes in right above the keyway. See if it's there and replace and/or tighten.

Pete

[Brian Ross]

I have an old model Unisaw and it developed a rattling noise which I thought were the bearings as the saw is about 25 years old.When taking it apart I discovered that the set screw that holds the keyway in place had come loose. Same as your pulley. I checked the shaft for wear and it was OK. Replaced the key and tightened the set screw and good as new. As someone else stated the set screw is above the top of the key. When replacing the top of saw try and get it in exactly same place as when you took it apart. If you don't you will have to make new zero clearance throat plates. Don't ask how I know.
Good luck
Brian

[Larry Fox]

Thanks for the replies - I never thought to look for a setscrew. I will do-so tomorrow.

[Kyle Kraft]

Put a drop of blue loctite on the setscrew or if the threaded hole is deep enough, put another setscrew on top of the first one.