Hello, I’m back with another question. I purchased a Jet 8″ jointer last December (or was it January). Anyway, I had been using it pretty heavily during the first month when I began to hear a bad noise.
I checked it out the noise and discovered that the pully on the cutter head shaft was loose and missing the set screws. Since it was under warrantee, I got another pulley and tightened those set screws as best I could.
Then, about 2 weeks ago it happened again. Silly me, when it happened the first time I had assumed that the factory had neglected to put in the set screws. I now realized that they fell out just like the replacement ones did. I have again ordered a replacement pulley under warrantee.
So, I called Jet and asked if I should use locktight to prevent a third recurrance of this problem. They said that locktight would void the warrantee. (I don’t understand why since there is a locktight that will allow the screw to be removed.) When I went to the woodcraft store yesterday, I mentioned this problem. They suggested that vibration could cause the pulley to break loose and convinced me to buy a special vibration free adjustable belt.
I am not sure what is causing this problem. All I can think to do is put locktight on and periodically check the set screws for tightness. Not so sure about the fancy belts. They are pieces that are looped together and it does not appear that it will do what they claim.
Sorry this is so long – Any words of wisdom would be appreciated.
Thanks – David
Replies
Sounds like the person at Woodcraft was just trying to make a buck rather than help with the real problem. The 'special belt' is a Link Belt and they work well. V-belts have a memory that can and does cause vibration that may be more noticeable on some machines than others. I've used a Link Belt on a contractor saw and it took the vibration to almost non-existent.
I have a Jet 6" jointer and have never had a problem like you describe -- seems to be vibration free and was right out of the box. I'd suggest pushing your Jet representative to get the problem fixed before the warranty runs out.
Bill Arnold
Food for Thought: The Ark was built by amateurs; the Titanic by professionals.
Put Locklite on the screw.
Like Bill, I have a 6" Jet jointer which has gotten regular use over the past two and a half years, and has been vibration free. I agree with Bill to have the problem corrected before your warranty is void. Loctite may hold the screws in, but my guess is the vibration is still there.
Dave,
The ordinary vibration of a belt driving a pulley shouldn't cause a set screw to loosen. Unless there is some out of the ordinary vibration, I'd look for other causes of the problem and there are a few possibilities.
The most likely cause is the tolerances of either the set screw or the threaded hole, or both, are off leading to poor engagement of the threads. While Jet, in general, has good quality control it would be easy to miss this problem. Asian woodworking machinery is built to fairly loose tolerances for ease of assembly, and to save money, and this can lead to these kinds of problems later.
The second possibility is that the first loose pulley chewed up the end of the shaft and now the pulley can wobble a bit which will cause a set screw to back off eventually. The only good fix for this would be to have Jet give you another cutter head and a new pulley.
Along the same line either the hole in the pulley or the diameter of the shaft could be out of tolerance, or the key could be a loose fit, again leading to wobble that could cause the set screw to loosen. The pulley should be a snug fit on the shaft with no play even with the set screw backed off. Again if the fit is loose, Jet should give you new parts.
If the pulley is a good fit on the shaft, there are a few things you can try to keep the set screw from backing off. First you could try the removable Loctite, how will Jet ever know that you used it? Be sure to clean off the threads of both the screw and the pulley with solvent to make sure the Loctite bonds well.
If the pulley doesn't have a key to align the shaft and the pulley, make sure that the set screw is tightening against the center of the flat on the shaft. If the set screw isn't exactly centered on the flat, the pulley will rotate a bit later and the set screw will loosen.
You probably would have noticed this, but check for a second set screw on the pulley, sometimes one is on the hub and a second one is down in the vee of the pulley, obviously both should be tightened.
If the there is enough thread length in the pulley's set screw hole, you can stack two short set screws one on top of the other. Tighten the first screw against the shaft and then put the second screw in and tighten it against the top of the first screw to lock the bottom screw in place. The threads are probably metric but you should be able to find a hardware store that stocks metric screws.
Hope this helps, John W.
Edited 8/7/2004 6:36 pm ET by JohnW
Thanks for the detailed response. Jet, in fact, attributed my problem to a set screw with threads that were poorly matched to the threads in the pulley. What is the best way to determine if the shaft has been damaged?
Thanks - David
Dave,
If the shaft is damaged, you'll be able to see and feel that the surface is rough or out of round. When the shaft was new the finish on it would have looked like the shank of a new drill bit.
Lengthwise scratches from changing the pulley are to be expected but damage that goes all the way around the shaft because the pulley spun or wobbled suggests that the shaft has been damaged.
John W.
"Not so sure about the fancy belts. They are pieces that are looped together and it does not appear that it will do what they claim." Regardless of what the source of the original problem turns out to be, don't underestimate the joy of using a link belt. They work very, very well!
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Another proud member of the "I Rocked With ToolDoc Club" .... :>)
You might want to check the motor shaft and drive pully.
Cast pullies are not always concentric and will cause viberation.
Just a thought.
Leo
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