Vibrating jointer - Off to see the wizard

Rennie Heuer

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My DJ-20 has a vibration that is getting worse. I've opened it up and it seems that the source of the vibration might be the belt. However, the belt seems in good condition. What could be causing the vibration? Belt too old? too tight? Too loose? Misaligned?:dunno::huh:
I don't see anything wrong with the sheaves and the motor runs smoothly - no bearing noise, etc.
 
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Everything ok with the cutterhead? Nothing loose there I trust?

Could always try one of those link belts. I used one on my bucket mortar mixer and it works pretty well there. They are supposed to help eliminate vibration, so if it's the belt, that would be a quick fix.
 
OK - Dug a little deeper. Removed the belt, still vibrating. Removed the sheave, motor runs smooth. So, I'm guessing its the sheave. Now, can't see any damage and there is evidence it has been balanced. So - what's next? Can I take this someplace to be balanced again?
 
OK - Dug a little deeper. Removed the belt, still vibrating. Removed the sheave, motor runs smooth. So, I'm guessing its the sheave. Now, can't see any damage and there is evidence it has been balanced. So - what's next? Can I take this someplace to be balanced again?
Look in the yellow pages for electric motor rewind shops. The have balancing equiptment...:thumb:
 
OK - Dug a little deeper. Removed the belt, still vibrating. Removed the sheave, motor runs smooth. So, I'm guessing its the sheave. Now, can't see any damage and there is evidence it has been balanced. So - what's next? Can I take this someplace to be balanced again?

I don't know how the sheaves are balanced. But, if weights were used, it may be possible a weight fell off.
Have you swept the floor recently?
 
OK. Another bit for the craniacs among us.I replaced the belt and took the sheave (which is balance by taking material away, not adding to - so, no need to sweep the floor) to the machine shop and checked the balance. Not perfect but within tolerances. I realigned everything and tensioned the belt and it still vibrates.... but only under load. As soon as the power is turned off the vibration disappears and it spins down quietly.

So, all of you electrical wizards out there - could I have wired it incorrectly? It's single phase 220. Could the winding be at fault?

Added - I did a little research on the web and found a number of references to rotor issues if the vibration is only when power is applied. Also looked at some replacement prices. Yikes.
 
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In my experience some vibration issues may be solved by making sure the pulleys are properly seated and the set screws are tight. Sounds like you have taken care of that on the motor. How about on the cutterhead?? I know of nothing that would cause that kind of vibration that is a wiring issue. If the motor spins the correct direction, it's wired right.
 
My $o.02 worth . Bearings? loose bearings will show up under load where it seems smooth otherwise. Could be bearings in motor or in the cutter head. Could be a dry bearing from the dust etc. Disconnect (and all those safety issues) turn (spin) and if you feel ANYTHING, there is a problem...

Could be belt: I'm not sold on link belts but I do like segmented belts. they are much more flexible than standard belts. If it has been a while sense last use, some belts get stiff in time.
Real question is if you can feel the vibrations on the tables or are you talking about shaking the plaster type of vibration. Fast or slow? Slow, I would look at the belt, as it indicates a slap. Faster points to a rotating object.

My thoughts on the matter. Will be interesting to find the answer.
 
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OK, so we are somewhat confident that the motor spins smoothly but, is that just because there is no "leverage". Do you have another sheave around you could put on that shaft? Where I'm going with this is . . . I have a spindle sander in the shop right now. It developed a shudder on the up-stroke. I went through pretty great pains to isolate it.

Turns out I was deceived. The motor, which I thought turned smooth since it behaved with a bare shaft, was the culprit. Bearings and a shaft issue didn't show at all until it was attached to other mechanisms that emphasized the undetectable movement (the guy at the shop had to show me that, I missed it and gave up).
 
What about, not sitting properly on the ground, a slight difference would pass unoticed under no load but would be enhanced under pressure.

Harmonics, due to a not so sharp blade maybe another possibility and if they are they can destroy you machine.

I'm no expert at all but I when everything fails I tend to look at the most weird or simple things and many times the problem is there.
 
OK. Another bit for the craniacs among us.I replaced the belt and took the sheave (which is balance by taking material away, not adding to - so, no need to sweep the floor) to the machine shop and checked the balance. Not perfect but within tolerances. I realigned everything and tensioned the belt and it still vibrates.... but only under load. As soon as the power is turned off the vibration disappears and it spins down quietly.

So, all of you electrical wizards out there - could I have wired it incorrectly? It's single phase 220. Could the winding be at fault?

Added - I did a little research on the web and found a number of references to rotor issues if the vibration is only when power is applied. Also looked at some replacement prices. Yikes.
I don't see how it could be your wiring. I might change the motor bearings or have them changed or at least checked. Is there a really good old school motor shop in the area. Any looseness anywhere shows up more under load. I usually suspect belt first but you have already been there..
 
I don't see how it could be your wiring. I might change the motor bearings or have them changed or at least checked. Is there a really good old school motor shop in the area. Any looseness anywhere shows up more under load. I usually suspect belt first but you have already been there..
Yep - replaced the belt with a new, industrial quality (costs twice as much as a regular fan belt) one. No change.

Had the sheave run on another moter at the motor shop (a good 'old school shop'). Very little vibration.

The shaft seems tight, no slop.

So, here's what I've found so far. Without the sheave and belt hooked up the motor runs smoothly. Put on the sheave and the motor vibrates under power, but smooths out as soon as power is turned off. The same thing happens if the belt is on - just amplified. The vibration really sets the belt dancing, but everything smooths out completely as soon as power is turned off.

What I've found Googling is that this can sometimes be traced to the rotor. Either it has shifted in some way or a problem in the way it uses power - don't ask me to explain. This, like much of my brain, is virgin territory.:rofl:

I've removed the motor and I'm heading over to the motor shop to have someone who knows a lot more than me look at it.:wave:
 
Rennie, You have gotten good advice here so far. I would be suspicious of a motor bearing. I think Bill mentioned that sometimes the vibration only shows up under load.

When I used to work for money I worked at a very large industrial manufacturing Corp. We had a couple of guys , machine repairmen, on special assignment whose sole job was to do rotational vibration analysis of machines in the factory. When they had a baseline reading of a machine they could pick up and pinpoint problems before there was a breakdown. It was money well spent and saved the company big $ by allowing us to schedule preventative maintenance.

I don't know if it would help but you could stick a dowel or broom handle on the motor and put the end too your ear. If you could SAFELY put it near first the rear bearing and then near the front you might detect a difference in sound. You might hear a ticking or some oscillation more pronounced at one end versus the other. This is subjective because vibration is transmitted throughout a machine. Also if the bore of your sheave is even slightly out -of -round it will cause vibration. I would also take the cutter head apart and check for something causing an out of balance condition. If you think about where normal wear would occur I would think the cutter head sees the most strain from impact with the wood.

One of the tricks of successful trouble shooting is to go back to the last thing you (someone) did to a machine. I found that 75% of problems were ultimately traceable to the last occurrence. Good luck and BE SAFE.

One more thing to check is the motor mounts. My jointer had a similar vibration and it was a loose mount.
 
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Thanks everyone for the advice and guidance. Just got back from the motor shop where we ran the motor and sheave. It ran fine with minimal vibration. I am totally flummoxed. I'm beginning to think the minimal vibration is being amplified by, IMHO, a truly flimsy mounting system in the jointer base. So, my next step will be to reinstall the motor and align everything as best I can. Then I'll see if some bracing of the mounting struts improves performance. If not, I might just learn to live with it.
 
Got everything back in place - very carefully aligned. Added some nuts and bolts to the base in places where it looked as though they'd been left out for some reason (holes were there?).

It's running much better. Maybe I'm just too picky.:dunno:
 
Hmmmmmmm? Perhaps it is a flexing base. I used a 2" thick wood base between the BS and flimbsy metal stand... Made the BS run smooth, perhaps it wil smooth out your Joiner. Don't know from experience as when I set up my joiner I used a wood stand....
 
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