Beap52 1,390 #1 Posted June 19 My 9 year old miter saw has gotten nearly impossible to slide on the two rails to the point it was getting dangerous. I tried blowing air and lubricating the twin tubes with dry lube but with no success. I was almost to the point of buying a new one and trashing this one but decided "what the heck, if I try to repair and ruin it, it's headed for the dump anyway." I took it apart and after cleaning of what I call the bearings, it's once again sliding like new. I drove out the bearing unit with a wooden dowel Then I used a pick and tested each set of ball bearings. They were supposed to move freely some of the were frozen with small pieces of sawdust. Two or three of them took quite a bit of effort to move but slowly working back and forth with shots of air gun finally freed them. I then worked dry graphite into each roll of ball bearings. In fact, my air gun would make them rotate. I made this cover to hopefully help keep the two rail tubes protected from sawdust. 2 2 Share this post Link to post Share on other sites
ebinmaine 72,365 #2 Posted June 19 3 minutes ago, Beap52 said: decided "what the heck, if I try to repair and ruin it, it's headed for the dump anyway Love a good "no lose" situation. Good save! 1 1 Share this post Link to post Share on other sites
8ntruck 7,772 #3 Posted June 19 Probably got gummed up with really fine saw dust. 2 Share this post Link to post Share on other sites
ri702bill 9,335 #4 Posted June 19 (edited) Those are recirculating ball bushings. Two things they do not like - ultrafine dry dust and frost on the rail. There are drop-in ceramic coated solid replacements available for most common sides that are unaffected by both. The IGUS IGLIDE is such a type. Note that the balls are meant to recirculate and need about 1.5 x their body length of motion to do so. That helps keep them cleaned out of debris.Worst usage is repeated very short oscillating motion where the balls just roll a tiny bit. That leads to fretting damage on the shafts...... Edited June 20 by ri702bill 1 1 Share this post Link to post Share on other sites
lynnmor 7,788 #5 Posted June 20 It appears that there are wipers that haven’t been keeping the dirt out, see if you can get new or better ones. 2 Share this post Link to post Share on other sites
Beap52 1,390 #6 Posted June 20 14 hours ago, lynnmor said: It appears that there are wipers that haven’t been keeping the dirt out, see if you can get new or better ones. Agree that the wipers are not doing their job. It's a Kobalt saw so it's not high quality but has served me well. Now that I know how to clean the bearings and it doesn't take that long I can monitor for "stickiness" in the sliding. My homemade shield surely does help keep a lot of the dust at bay. Of course it is the fine stuff that is going to be a challenge. I'm learning on this one. I've never seen or heard of recirculating bearings before. 1 Share this post Link to post Share on other sites
kpinnc 14,569 #7 Posted June 22 (edited) On 6/20/2025 at 7:42 PM, Beap52 said: never seen or heard of recirculating bearings before. AKA linear bearings. As has already been said, the seals are extremely important. It's the age-old fight between cleanliness and lubrication. Each affects the other in a negative way. Hard to tell from your pictures, but you may have space for extra seals. In this case, two might work better than one. Edited June 22 by kpinnc 1 Share this post Link to post Share on other sites
