Miter Saw: Blade Wobbles

If the blade bearing is bad, it will make a growling, grinding or a low moaning sound and will usually be accompanied by a vibration. The bearing will also have play in it because it is worn, which will cause the blade to have a wobble. Repair procedures will vary on models.
To replace the saw’s blade bearing, remove the outer flange, blade and inner flange. Remove any washers and bushings, followed by the spindle assembly by taking out the screws securing it to the saw. Once the spindle assembly has been removed, spin the bearings to determine which one is bad. Bearings should always be smooth and quiet. Use a bearing puller to remove the one bearing on the shaft.
Tap a new bearing in place on the shaft using a socket that only makes contact with the inner race of the bearing to avoid damage. For the bearing inside the sleeve, use a bearing puller to separate the sleeve from the spindle and then use a socket that only makes contact with the outer race of the bearing – tapping it free with a hammer.
Install the sleeve onto the shaft and then install the new bearing with a socket that only makes contact with the inner race of the bearing, to avoid damage. Tap it in place with a hammer. Install the arbor screw into the shaft and tap on it with a hammer to finish seating the bearing into the sleeve. Do not tap on the shaft itself as you can damage it. You may have to go back and forth between tapping on the inner race with a socket and the end of the shaft to seat the bearing.
Reinstall the spindle assembly into the saw. Reinstall any washers and bushings. Reattach the inner flange, blade and outer flange.

If the blade wobbles, it could be bent or warped. Blades warp from overheating. To check the blade to see if it is warped or bent, remove it from the saw and place it on a surface that is completely flat and then look at it from the side. You should be able to see if the blade is touching the surface all around. If it is not, then it is warped. You can also push down all around the edge of it with your finger. If the blade moves up and down, it is warped. Install a new blade if it warped or bent. 

Some models have blade clamps instead of blade flanges. If a clamp becomes worn or damaged it will cause the blade to wobble. Inspect the clamps carefully making sure they make contact with the blade all the way around. If you notice any gaps, replace the clamp. You can also remove the inner and outer clamp and lay them on a flat surface and inspect them side ways making sure they are flat. Touch them with your finger all around. If it moves up and down replace the clamp.

If a flange is worn, damaged, warped or bent, it will not make proper contact on the blade and will cause the blade to wobble. Inspect the flanges closely for a tight seal around the blade. If it is not making contact all around the blade, replace them. You can also remove the flanges and place them on a flat surface and look at them sideways to see if they are making 100 percent contact on the flat surface. If they are not, they need to be replaced. Touch them all around – if they move up and down, replace them.

If the blade washer becomes warped, it will cause the blade to wobble as it will produce a gap in the flat, joining surfaces. When something becomes warped, it is generally caused by overheating. To check the washer, remove the outer flange, blade and inner flange. Remove the washer and inspect it. Lay it on a flat surface and touch all around it – if it moves up and down, it is warped. Sometimes, on a small part, it may be hard to determine if the part is warped or not. Washers are inexpensive so replacing it would be a good idea regardless. If the blade still wobbles, you have a least eliminated the possibility of it being the washer.

A worn, or damaged, bushing will produce a wobble within the blade. Repair procedures will vary on models. To inspect the bushing, remove the outer flange, blade and inner flange, followed by the washer and bushing. Inspect the bushing for signs of wear. If it is cracked, chipped or if you see anything else out of the ordinary, replace it. Carefully inspect the edges; both inner and outer. If it is warped, replace it as well. Sometimes, it may be hard to see if it is warped. However, bushings are very inexpensive and they will wear out over time – replacing it is never a bad option, if you are unsure if it is still good or not. If the blade still wobbles afterwards, at least you have eliminated the possibility of the bushing being the cause. Install the new bushing, washer, inner flange, blade and outer flange.

If the base is wobbly, the wear plate is worn out. The wear plate is located between the base of the saw and the saw. The wear plate allows you to rotate the base freely. Over time, this part will wear and cause movement in the saw. The blade is attached to the saw, so this movement will appear as a wobble in the blade. To fix this problem, you will need to replace the wear plate. Begin by removing the fence, followed by the kerf plates. Take out the center bolt and all of the pieces attached to it, making note of the order they are in for reassembly purposes. Once removed, separate the saw from the base. Remove the wear plate, clean the entire area and install the new wear plate. Reattach the saw back onto the base and insert the bolt back in from underneath. Reinstall the washer, roller bearing, the washer on top and then nut. Tighten the nut enough so you can move it freely, but not too freely – it should have a little tension on it.