Valley in table saw arbor

[David Huston]

I must have a valley in the arbor of my table saw. Was cutting some tongues for some doors last weekend and notice a very slight lip right next to the shoulder. Shouldnt be too much to sand of chisel off but would like to find a way to fix the arbor so I dont have to do that. Any thought on the best way to fix the problem?

[Jeff Erbele]

Hi David,
I am a machinist by trade. I read your post a couple of times, trying to grasp the problem. I was confusing valley and lip; one being below the surface, the other being above the surface. Got it; the valley is on the arbor, resulting in a lip on your work piece; correct?

Before you fix or replace the wrong thing, or half of the problem, ask why did this happen.
I suspect a loose arbor nut at some point, or maybe jamming the blade by accident, maybe in a ripping operation where the back of the saw fence is closer to the blade on the out-feed end than on the in-feed side of the table.
You may have one or more saw blades, having a worn arbor hole. Toss those as they are going to cause more problems forever, progressively worsening.

Several solutions come to mind. All include dismantling your table saw and removing the arbor.
In the machine shop, a machinist would chuck it in a lathe and dial it in, on two surfaces, two locations on the diameter, or on the outside diameter of the arbor furthest from the chuck and on the shoulder - the face where your blade mounts against, to ensure it is running straight and true.
If the arbor has the original center hole in the end, that suffices to line up one end, the other is done with the lathe chuck.

From there it depends on what equipment the machine shop has.
One could undercut the arbor, then either

1. make a sleeve that is a press fit fitting the undercut diameter of the arbor.
It could be installed 2 or 3 ways, cold, in a hydraulic or arbor press, or heating the sleeve on a bearing induction heater, or heating it with another heat source - a gas torch, usually an ox-acetylene torch. The heat expands the sleeve I.D. When it cools on the arbor O.D. it contracts and holds itself in place.
Sleeving is my preference for this situation.

2. if the machine shop has metal spaying capabilities, the machinist builds up the arbor, oversize, allows the arbor to cool, then turns it to the final diameter.

3. alternatively it could be built up by welding. It could done but that might create all kinds of other things to deal with, warping, splatter, hardening, brittleness, etc. depending on the skill of the machinist-welder.

Welding would be my last choice of repair options. After the arbor is built up, the machinist lost at least one critical reference surface to ensure the arbor is running straight and true in the lathe after welding and tempering. There are possible alternatives and solutions for that, each depending on the saw arbor design.

The problem with all of these options is economics. That is what changed the repair sector (my career) in the machine shop business. That is economical, mass production (read emerging markets and developing countries here), overseas. For less cost you probably can buy a new arbor and a bunch of new saw blades.

Going forward make sure your arbor nut is tightened properly. Your owners manual, if you have one, maybe states something in foot-pounds. One could be inclined to exceed that, making it extra-tight. If so, there is the risk of striping the threads, and you are faced with loosening it next time you change saw blades.

Sorry this happened. Good luck with it.

[Chris Rosenberger]

Depending on the age & kind of saw, you replace the arbor with a new one. Another option is to take it to a machine shop to see if they could repair it.

[Richard Coers]

You think you have a groove in the arbor and the blade is now off center? At the rpm the blade is turning, it won't make any difference in the cut. It will send the blade off center and change the balance, but not the cut. I would suspect the table insert is not flush, or something else mechanical.

[Jeff Erbele]

You think you have a groove in the arbor and the blade is now off center? At the rpm the blade is turning, it won't make any difference in the cut. It will send the blade off center and change the balance, but not the cut. I would suspect the table insert is not flush, or something else mechanical.

Excellent Point. If there is any combination of wear on the arbor and blade, the outside diameter of the blade would have run out. One tooth would be higher than the rest, cutting bigger wood chips than the one opposite tooth, 180 degrees from it, but sill rotating in a perfect circle.

RE O.P.: "notice a very slight lip right next to the shoulder"
Inspect the blade for chipped or dinged saw teeth. If so, all of them would be on the same side of the blade, all on the left or right blade set.