Belt tension pulling blade out of alignment on my Craftsman 113 - why?

[Josh Saul]

Like so many people before me, I'm rehabbing my Grandpa's early 80's Craftsman 113 table saw. I've taken all the usual steps: PALS, link belt, new pulleys, and I've even picked up a new fence for it.

The problem is, after I align the blade and lock everything down tight, if I raise or lower the blade, the subtlest change in tension on the belt pulls blade significantly out of alignment. If I move the motor at all, that changes the alignment. If I grab the arbor shaft, and pull hard, there actually isn't a lot of play side to side, but I can measure a good bit of play up and down. Does this mean the saw needs new bearings, or is it something worse? The bearings aren't silent when I spin the blade, but there's not a lot of noise, either. I don't have a lot of experience with bearings, so you'll have to forgive me.

I'm not looking forward to changing the bearings, but if that will get this thing going, I guess I'll have to do it. If there's a bigger problem going on, I need to know so I stop throwing good money (and time) after bad.

[Lee Schierer]

I don't have that problem on my 113 saw. Check the motor mount and insure that the motor can pivot freely. The saw uses the weight of the motor to provide tension so the motor must pivot freely on the hinged bracket. Much of the tilt mechanism and parts of the carriage are aluminum, so it is possible there is wear. I've had noise from my bearings once in a while and I have added a bit of oil to the shields and they have quieted down. Also note that there are little plastic caps on the bearings on your motor that should be pulled and a few drops of oil put in to keep the motor bearings lubed.

[Josh Saul]

The motor is definitely able to pivot freely, so it's not that. I really just need to know what the source of all the play is so I can replace it. Do bad bearings move around that much?

[Ellery Becnel]

Josh,
If you can measure a good bit of movement up and down, it is the bearings. Not very costly, but a good investment. You have addressed and improved all other components in the
Drive system. I would go with a good quality bearing. It will make you life enjoyable. Check for wear in the bearing housing, where the outer race of the bearing fits. The normal
Tolerance is .0005 - .002 loose. You measure the outside of the bearing and the inside of the bearing housing. The inner race of the bearing to the shaft should be an interference
Fit. Normally, .0002 - .0005 tight. This will vary somewhat bases on the shaft diameters, bearing design, temperature, RPM, etc. That should be enough to make sure that there
Are not any worn parts. You do not want to change bearings and still have a problem, or have a premature bearing failure. I do not want to scare you with all of this, but it is important for the reliability of your hard work that you have done already. Keep us informed on you progress.

Ellery Becnel

[scott spencer]

IIRC, there are two 1/2"(12mm) bolts that hold the rods of the motor mount system in place at the rear of the saw. Those rods can be adjusted to allow for more or less lean of the motor, and are easy to reach from the back of the saw. You might experiment with that and see if it helps.

[Jerry Bruette]

If you can move your arbor up and down, which would be radial play, and your bearings don't make noise or are smooth when you rotate the arbor chances are you have excessive clearance in the bearing housing or the bearings don't fit tight to the arbor. You'll have to disassemble the saw to determine which condition you have. Repair parts are available but you'll have to decide if it's worth the cost to repair.

[Josh Saul]

Like I said, I think the belt tension is correct, and not really the problem, per se. If I even touch the motor, that will move the blade a measurable amount. And it'll really move the blade if I push on it. And even if I remove the belt & grab the arbor pulley and yank it, I can see about 10-15 thousandths of movement on my caliper. So, this is a symptom of shot bearings? If I rotate the blade by hand, it does make a sound. With the motor switched on, it's loud, but not deafening or anything - I just don't have much to compare it to. But it definitely sounds like more than just air rushing over the blade.

[Josh Saul]

Also - does up & down bearing play tend to mean something different than side to side? Thanks for all the help.

[Ellery Becnel]

Radial movement is up/down, side to side. Axial movement is in/out, or thrust. If you are measuring .010 to .015 (lift), bearings are history. As Jerry mentioned, it could be the bearing housings and or the shaft. You have to decide if it is worth the repair costs. Take a pry bar, or long screwdriver and place it against the bearing housing, then place the other end against your ear. Turn the arbor and listen to the sound transmitting through the pry bar. It is an easy way to hear the internal mess inside. It should be a smooth rotating sound of the bearing turning. Anything else, DEAD.

[Lee Schierer]

Okay, lets start over. First of all can you be more specific about the magnitude and directions of motion you are seeing. I suspect you have a missing thrust washer in the raise lower crank more than bad bearings if the blade is moving strictly up and down and not tilting. Remove the belt and blade from the arbor.

If your bearings are bad you should see/feel movement in any direction relative to the casting that holds the arbor when you try to move the arbor. If teh casting is moving your problem is elsewhere.

If you run the motor with out the belt in place listen to the noise it makes.

Then put the belt on and run the saw. If the noise is considerably louder you could have bad bearings or a link belt that is running backwards. If it is about the same or just slightly louder then your blade is creating the noise. Some blades will absolutely howl.

Using calipers to measure movement of the arbor in blade is the wrong tool for the job. You should be using a dial indicator. You can get one for $20 at Harbor freight that will be more than adequate for the job. You will need to mount it so it doesn't move and place the tip against what you are trying to measure.

Make sure the four bolts holding teh trunnions to the bottom of the table are all tight.

[Josh Saul]

I misspoke about the tool I am using to measure - I am using a dial indicator. Oh, and there's some side to side play, just more up & down if I pull hard on the arbor. I'm going to replace the bearings and report back. Thanks for your help.