Belt sander Craftsman 315.117150 The spring-loaded bolt that adjusts the front roller has an eye hole into which a spring is fastened to the roller. The eye has broken, consequently I am in need of a new adjuster knob bolt. I know this is an old machine but is a replacement adjuster bolt with eye is still available? Where?

have you checked the wire that works the drive pulley it may need to be adjusted or replaced

I don't think there IS an adjustment. That is what prompted me to construct a tensioner device to add just that little more tension needed. This was MY fix after trying a new belt and spring.
My Craftsman mower lost the self propel feature. The small pulley on the top of the transmission would slip under load, There was just not enough tension on the belt to over come it. Tried a new belt and also replaced the tensioner spring...still slipping when going uphill or with full bag. Possible pulleys worn...not wanting to gamble more time and labor, I bought a 4" 1/4" cap screw with extra nuts and flat washers, a 3"16 eye bolt as well. Drill a 1/4" hole in the bracket that holds the trans activation cable in place and a 3/16" hole in the mower deck so the holes are in alignment with each other. Put the cap screw through the 1/4" hole with the threads facing toward the front of the mower. Fasten the eye bolt into the 3/16" hole in the mower deck locking it in place with one nut on each side of the metal. Now you have the 1/4" bole protruding through the eye bolt. Using a flat washer and nut, tighten then nut easily and when there is room put a second nut on it. When you have tightened it up to the desired belt tension lock the two nuts together using two wrenches. Note...do NOT make the belt incredibly tight or you will destroy the trans in a short time. Go a little at a time till the drive does not slip under load. Good luck hope this helps. Oh....you will have to trim the plastic cover that covers the transmission so the added bolt will clear it and you can put the cover back in it's proper place.

The front roller (usually a metal cylinder) is spring loaded. The rear roller (usually a rubber cylinder) is fixed and is driven by a belt from the motor. You need to push the front roller against a fixed object (like a benchtop) pretty hard to compress the spring about 1/2 inch. It should "catch" in the compressed position. Belt will now be loose and easy to reeplace. Then, to "un-catch" it, on most models, just stick a screwdriver behind the front roller bracket and pry it forward. It should pop right back into place. Good luck.

Your problem is at other end . Engagement problem is probably due to a loose belt. Make adjustment in that area of mower. GOOD LUCK.

You need to adjust the tracking knob which is by the front handle that looks like a triangle head screw. Make sure the belt tension leaver is tight and the belt has enough tension on it. Quickly press and release the start switch and note the centering of the belt. It should be in the center of the bottom platen. If it is not, adjust the tracking knob and bump the switch again. If the belt is going in the wrong direction turn the knob the other direction. Once you are close the center of the platen, press the power switch to turn the unit on and lock the trigger. Firmly hold the unit vertically from the front handle. Fine adjust the tension knob to center the belt and make sure the belt is not hitting the case which will cause damage. You should be able to use the belt sander without the belt slipping off. Let the sander do the work, do not push down and limit the side to side motion. If the belt will not stay on then the belt is too large or the torsion spring needs to be adjusted to applying more tension on the belt and drive roller.

I checked Searspartsdirect.com for that model number and they listed that number, but with an extra 0 at the right end. I couldn't find a belt release lever illustrated anywhere like that on my old Craftsman belt sander. On mine, you just flipped the lever either forward or back to release and tighten the belt. (still works great) There is a spring that pushes the front roller assembly forward when the lever is operated.

Do you know anyone with a metal lathe or that works in a machine shop? If you do ask them if they can make the rollers for you out of metal. Or else find a machine shop and ask them to make you new rollers.

On my model 315.11720 3"x21" Craftsman belt sander to change out sanding belts you push the front roller in until it clicks to lock in its retracted position (a pry bar may help here), switch out sanding belts then unscrew the tracking tensioner a bit on the opposite side with a allen wrench until the roller snaps back in place. I never remember anything about using a screw driver to force it back forward position again. Then readjust the tracking if necessary with a few short sanding load tests and you're good to go. Oil is dropped in the front roller center by removing the flat head screw - it should say "Oil Here" around the screw.

Check first that you have retensioned the belt... i.e. when you removed the other belt, you would have had to pull on a spring-loaded lever to remove the belt tension before you added the new one... make sure the tension lever is flipped back in to ensure the new belt is tensioned...

Next, and the likely problem you are having, is belt tracking... There should be an adjustment knob up near the front of the sander near the front roller, either on top of the front part of the sander, or to the side near the front roller... When you turn this knob, it makes the belt track either left or right over the sander's base. This knob will allow your belt to run square and true and not spin off to one side...You need to adjust the tracking using this knob while the belt sander is running and with the new belt tensioned and in place, so turn the sander upside down, and power it on with one hand, then turn the knob with the other hand whichever way is needed to have the belt track square and in the middle of the rollers. Make small adjustments on the tracking knob to begin with. They can be sensitive at times.

That should stop your belt spinning off to one side.

Try removing the adjustment screws and applying some Teflon thread sealant. That should prevent the screws from turning on their own. Another thing you can do it check the pulleys with calipers and make sure it is still cylindrical. I have seen ones that become worn on one side. Finally, roughly check the belt tension on both sides and make sure they are approximately the same tension.

Good Luck!

Ben Steigerwald