New 8" jointer sounds like head bearings are bad

[Glen Butler]

I turned on my brand new Powermatic PJ-882HH jointer at it sounds bad. It sounds like metal rubbing on metal or as if a bearing that has just a little bit of play and no grease so it vibrates violently. I removed the belt and ran just the motor, and it ran quiet. The head spins nicely by hand, but it must be what is making the aweful noise at high speeds. The bearings are sealed so I don't know what to do. Any ideas? Is there any possibility the noise will go away after the machine is "broken in" if there is such a thing with these machines?

The belt doesn't look like I imagined it would. It is a regular v-pulley belt but it has notches almost as if to fit splines on the inside circumference and the belt says something about it being for an automobile. Could the belt be making the screaching because of the notches? I have checked belt tension. I am wondering if it might be harmonic.

Any experts out there?

[Mike Bensema]

The problem you describe does not sound like a bearing. Metal on metal scraping could be the pulleys rubbing as it comes up to speed. First thing to check is make sure both pulleys are tight on the shafts and not too close to the machine. There is most likely a setscrew holding them on that might have come loose. I had this problem on a table saw years ago.

The belts do not need to be overly tight, you should be able to deflect them at center span about 1/2" with 20 pounds force, about what you can do by pressing a straight finger into the belt. If the belt is too loose, it will most likely squeal, too tight will put too much force on the bearings and could cause problems down the road. If the pulleys are significanly misaligned, the belts might squeal as well. To check alignment, use a straight edge across the pulleys and see if they are coplaner.

The belts you have should work fine, but they will vibrate differently then solid belts. It is very possible you are developing a resonance with these belts. I did a test on a contractor saw several years ago and the type of belt you have had significantly more vibration then a solid belt on that machine. Increasing the tension reduced the vibration, but you need to make sure you do not overtighten and cause problems with the bearings later on. On my saw, I ended up going back to the solid belts to reduce the vibration, you could try the same or use Link Belts which should have a different resonant frequency then the cogged belt you have now.

[Rob Cunningham]

Check that the motor pulley is not rubbing on the cover. On mine, the setscrew had backed out enough to allow the pulley to slide on the motor shaft and rub.

[CPeter James]

This is an article I wrote for our Guild Journal. It is long, but addresses your belt issue. I have seen other "new: Powermatic jointers with belt issues.

CPeter

"Have you ever brought home that shiny new tool from the tool store and after you carefully set it up, plugged it in and turned it on, had a terrible vibration that gave you buyer’s remorse? I have. There are many causes for this vibration, but two of the most common are the belts and pulleys. Most of the stationary tools used in woodworking have a belt and pulley drive system. Until John Gates developed the v-belt in 1917, most of the belting used was flat leather with a few small machines using a round leather belt. Flat belts could transmit large amounts of power but required careful alignment and tensioning. Early woodworking shops used a system of line shafts to drive the machines from a central power source, either water power or a steam engine. This system had long shafts hung from the ceiling and powered the individual machines with flat belts. One of the largest manufacturers of flat belts was Page Belting located in Concord, NH. Another was Tilton Endless Belts in Tilton.
After Gates’ v-belt was introduced and electric motors became more economical, the use of the line shaft and central power was greatly reduced. By the early 1930s, most machines being produced were using v-belts and individual motors. This allowed for flexibility in locating machines in the shop and also, the introduction of portable machines. The changes even went so far as to use separate motors for different functions on an individual machine, such as a four sided planer or a dual arbor, dual motor table saw like an Oliver 260D.
Along with the introduction of v-belts, came the general use of die cast pulleys made of aluminum or zinc. They were inexpensive and relatively easy to make and the quality could range from poor to good. They came into widespread use, especially on multiple or stepped pulley applications like multi speed lathes and drill presses. In slower speed applications, they proved to be adequate, but the inaccuracies in manufacture caused the pulleys to be less than perfectly round. This out of roundness introduced vibration into higher speed applications such as table saws, lathes, and belt driven grinders. For the hobbyist this might be acceptable, but for others, it was not and the use of machined cast iron or steel pulleys as either standard on upscale machines or as an aftermarket addition became popular. The most recent change in belt drive systems is the use of the Poly V-belt. This is the type of belt used in automotive serpentine configurations and now becoming common on some woodworking machines, especially those that use small diameter pulleys.
The most efficient method of transmitting power from a motor to a machine is to have the blade or arbor made as part of the motor shaft. Any system that transmits the power from the motor to a separate shaft will have some power loss and the potential of introducing vibration due to irregularities in the parts of the system. Quality control can reduce both the power loss and vibration, but comes at a monetary cost. This cost/quality is balanced by the manufacturers trying to satisfy both the market and their bottom line.
Replacing stock belts and pulleys with aftermarket upgrades can greatly improve the performance of woodworking machines, but there is a point of easiest and least expensive upgrade that will probably yield the greatest improvement. There are several options. One of the most touted is the use of link belts, introduced by Fenner as PowerTwist. This belting is available at most woodworking suppliers and also from any bearing supplier. It is a good choice if the machine must be disassembled to replace a belt. One of the biggest advantages of the PowerTwist belt is that it doesn’t take a set. Standard v-belts tend to want to return to an oval shape and also because of the materials used in their construction, they tend to acquire the shape that the belt was in when the machine was shut off. PowerTwist belt is not the answer to all problems, however. First of all, it is expensive, about $8.00 per foot, so a 5 foot piece for jointer would run $40. Second, it is directional. It must be run in one direction only, so can’t be used on machines that can be reversed such as a shaper. Third, because it is made from links that are a fabric/urethane composition, it is hard and somewhat abrasive and will wear soft die cast aluminum/zinc pulleys. And forth, because it rides high in the v pulley grooves, there may be clearance problems. In spite of these issues, because it does not take a set, it is very effective in transmitting power smoothly and can reduce vibration in many cases.
Another option that is being used more and more often is the “AX” series of v-belts. These are sometimes called cogged v-belts because the inside surface has a series of side to side cuts which results in a series of teeth or cogs. These cuts allow the belt to more easily bend on small diameter pulleys and reduce its tendency to take a set. One other factor that separates the “AX” series of v-belts is that the sides are machined to an even surface. This makes for smoother running. The cost is about 25% more than a standard hardware store or original equipment belt. It is often being used on higher end new equipment. These are available locally from bearing supply houses or on the internet from suppliers like McMaster Carr and MSC Direct. This upgrade might be worthwhile on any new or new-to-you piece of equipment.
While on the subject of replacing belts, most machines will benefit from a new high quality American made belt. The original equipment belts on most imported machines are generally of low quality and older belts dry out and become hard and stiff.
Good quality machined and balanced replacement cast iron pulleys are another inexpensive upgrade. One brand commonly available is Browning. It is not necessary to buy the expensive machined steel sets that are sold by the various woodworking suppliers. Many machines will benefit from this upgrade; however there are some machines that use a proprietary pulley made especially for that machine and only direct replacement pulleys should be used. The Delta DJ20 jointer is an example of this. When mounting and aligning the pulleys, if possible, it is desirable to mount the pulley with the v- groove next to the motor and the set screw on the outside. This gets the belt load as close to the motor bearing as possible and puts the least strain on the motor bearing resulting in longer bearing life.
Another factor that can cause vibration in belt driven equipment is belt tension. A belt that is too loose can vibrate just as the strings on a guitar vibrate. Also, a loose belt may slip under load. A belt that is too tight will cause premature bearing failure, so the key is finding the correct tension. Generally speaking, you should be able to deflect the belt ½” with reasonable finger pressure at a point half way between the pulleys. While there are many variables in this test, it will generally get you into the right area. A more modern method uses a frequency meter to measure the vibrations of the belt as it is plucked, the same way a stringed instrument is tuned.
In summary, machine vibrations can be caused by low quality, stiff or worn out belts, out of round pulleys, or incorrect belt tension. Usually these problems can be corrected by the average woodworker and at a small cost. The improvement in the quality of the cuts can be dramatic."

[Frank Drew]

Thanks for posting that article, CPeter, and I learned something -- I didn't know that link belts were supposed to be uni-directional. I put one on my lathe and often reversed the rotation for sanding, etc., but can't remember if power transmission was affected.

[Glen Butler]

Thank you for that article, but the belt I have is already "AX" and I have tried several different tensions and the noise persists. I don't have such a noise on my planer which has regular v-belts. Could the noise be the whirring of the grooves on the AX belt that is causing the noise. I wish I could get my computer mike close to it so you could hear it. It sounds aweful, and a little discomforting. As I said before, it may not be the belt. It sound like metal on metal or the rapid vibration of a loose bearing.

[CPeter James]

It could be a bad bearing. I believe that is a Chinese made machine and there could be a dry or defective bearing. Do you have a mechanic's stethoscope? I find that they are invaluable in trying to run down noises like that. I have much better luck with one of those than the screwdriver method that others use. The long probe is easy to get into places that have moving parts and you can be safely out of the way.

CPeter

http://www.tooltopia.com/ProductImages/lis-mo/LIS-52500.jpg

[glenn bradley]

If it is brand new what does Powermatic tech support have to say? That is a premium priced machine and I would expect excellent customer care to be built into that price. If you get a tech support guy on the phone he may be able to pinpoint the issue from his experience and get you fixed up toot-sweet.

[Robert Chapman]

Glen is right. Powermatic provides excellent customer service and contacting them should be your first step and hopefully your last step. In my experience they are very good and should be able to solve your problem.

[Glen Butler]

Contacting them is definitely my next step. I scoured that machine. I took the head out so I could feel the bearings spin and one of them feels dry, and there is some unsmoothness to it. I tensioned the belt, untensioned the belt, made sure the pulleys lined up, even to the point of shimming the motor to get perfect alignment, still the noise persists.

I will need to get me one of those stethoscopes. I have always used a garden hose and an ear plug in the other ear. Didn't have my hose with me today so I cannot pinpoint where the noise is coming from but it is either the bearing on the fan end of the motor, or it is the bearing on the user side of the cutter head.