How to Fix the Wobbling Table Saw Arbor

Fixing the wobble in a table saw arbor

4/15/2013 12:54:21 PMhttp://woodgears.ca/saw_arbor/index.html

Fixing the wobble in a table saw arborI had been thinking of buying myself a contractor saw, when I saw the Delta hybridsaw (model 36-655C) at Home Depot wiht two promotions on it at the same time. Itwas a good deal.

When I set up the saw, I found everything on it to be ok, except that it did not producereally clean cuts. The included blade was not exactly finishing blade grade, so I wentand bought a good finishing blade, the kind that costs around $50.

Even with the good finishing blade installed, it still didn't produce the sort of cuts thatone would consider finishing cuts. So I investigated further.

It turns out that the problem was the arbor of my saw - It had a slight wobble to it.

The nice people at Home Depot offered to take the saw back, but the prospect of hauling it back out of my basement and to thestore was not appealing. Besides, the saw wasn't really defective. After all, I didn't spend the sort of money one would spend on agood cabinet maker saw, so why would I expect it to cut like one?

I figured I'd just have to buy a new arbor, as I had done with my previous table saw. But before doing that, I decided to do a bit ofexperimenting . As a result , I figured out a cheap and elegant way to fix the problem. So if you have a saw with a similar problem,you might want to try this procedure.

Checking the arborThe first step is to make sure the problem is due to arbor wobble. Get agood finishing blade, and start by cutting just a millimeter off the edgeof a piece of lumber. Then, stop the saw, slide the lumber back againstthe edge of the blade, as shown, and turn the blade by hand to seewhere in the rotation it rubs against the piece of lumber.

In the position where it rubs the most, mark the arbor shaft with apermanent marker. After doing this, loosen the nut for the blade, turnthe blade a quarter turn, and re-tighten. Again, check where it rubs(previous step). Do this a few times. If the place it rubs stays roughly atthe same point of rotation of the arbor, then it's the arbor that has aneccentricity. If the rubbing moves with the blade, then it's mostly yourblade, and you should replace that first.



If you have a dial indicator, it's fun to measure the wobble. At about 1"from the tips of the teeth .002" variation or less is good. But .005"variation or more won't give a clean cut.

But just touching the blade to turn it will deflect it. It's best to take thebelt off, and just spin it by grabbing the arbor for this measurement.

If you don't have a dial indicator, skip this step. It's not really necessary.

On the arbor, the variation should be less than .001". In fact, if you canmeasure it at all, its too much. Even at the unacceptable level of wobblethat my saw had, it was still less than .001".

This step should also be done with the belt off, as pulling on the belt willdeflect the arbor more than .001"

But really, measuring this is unnecessary . It's mainly for the analretentive who happen to own a displacement indicator.

Grinding the wobble outClamp a grinding stone at a 45 degree angle to the heaviest piece ofhardwood you have. A piece of 2"x2" angle iron would be even betterthan a piece of wood, but use what you have handy.

With the saw running (with the belt back on), lightly push the stoneagainst the disk part of the arbor. Ideally, push it so lightly that it onlymakes contact with the arbor intermittently. As its rubbing against thedisc part of the arbor, move the stone forwards and backwards (awayand towards you in the photo). After a minute, unmount the stone, andflip it over, as the stone tends to get clogged from doing this.

You may also see the occasional spark as you do this. This is ok. Justdon't let the arbor get too hot, as that might affect the accuracy of theoperation. If you see continuous sparks, you are pushing way too hard.

The ends of the stone do get full of metal this way, but seeing that thispart of the stone is not used for sharpening , it doesn't really matter. Acoarse stone is better than a fine stone because it takes longer to clog.In the mean time, the saw arbor should end up being almost mirrorsmooth, even with a relatively coarse stone.



The whole procedure is rather iterative. I think I spent a total of about5-10 minutes of actual grinding until I was satisfied with the results. ButI went back and mounted the blade again and again for checking if it

was good enough.

Truing the arbor flangeThe arbor flange itself is often just a stamped piece of metal, and the flange may not be all that flat either. I think the idea is that theflange flexes to conform to the blade and arbor, but I would imagine its much better for accuracy if the flange were flat to begin with.

You can check the flatness of the flange by putting it on a flat surface,and pushing it along every spot along the edge. If it rocks up ever soslightly from doing this, then it's not really flat. It's a good idea to have afinger straddle the table and flange on the other side, and push firmly onthe opposite side. It's easier to feel small displacements with the fingeron the opposite side than it is to see it rock up. A displacement of just.001" can very distinctively be felt if your finger is in contact with boththe flange and the table.

If the flange is not flat, put some fine sandpaper grain up on the table,and just sand the flange flat. Use circular strokes, and push with a fingerin the middle of the hole. With pressure applied to the middle of thedisk, and the disk rubbing against a flat surface it should get flat. Turnthe disk by 90 degrees every once in a while as you do this.

As you can see from the varying width of the sanded surface, my flangewas not completely flat.



Next, I checked to see if the surface where the nut touches the flangewas parallel to the wide side of the flange. Turns out mine varied byabout .005".

You do need a displacement indicator for this step, unfortunately .Although I'm not sure how useful this step is, because I got my saw tocut quite clean before I did this. So if you don't have a dial indicator,don't worry about this step and the next.

Sanding the nut side of the flange parallel is an iterative process. Onceit's established where the high spot is, put pressure on that part whilesanding. Sand for a bit, then measure again and repeat until thevariation is somewhere less than .002". I don't think this part is overlycritical.

And finally, a comparison of cuts. I didn't have any pieces left that I'd cutwith the saw before fixing it, but the cut on the left is with a finishingblade, and the cut on the right is with the included blade. Before fixing it,the finishing blade didn't cut any cleaner than the included blade, so itgives you an idea how much of a difference this can make.

Note that the light on the photo at left is at a low angle, to bring out anytexture in the cut. Also, these cuts are in maple. I find its easier to get aclean cut out of hard woods than soft woods. My guess is that theharder woods end up helping to guide the blade, seeing that it onlytakes a small amount of force to deflect the blade by a few thousand'thsof an inch.

My saw is still not perfect. With my good blade, I still get about .002" ofwobble near the theeth of the blade.

Charles Wood writes about trying this method:Hello there!



Table saw alignment More about my tablesaw

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I used you guide on how to do that, and it works great!

I bought a 1977 Craftsman 10" table saw, solid chuck ofrust, it turned, but with major force. $60

After tearing everything apart, cleaning it and oiling, I getit going and the worst - it cuts like a dull chainsaw.Horrible wobble in the blade. I was depressed since I onlyspent another $26 on it so far (pulley, belt, oil, bolts). Iwas hoping for a low dollar end result, and getting a new

arbor, bearings (might as well), and such would end up with a long delay and more money.

Then I ran across your article! Attached is a picture of my jig I used to hone them back to perfect.

I have the calipers and the stone on the miter device. I lift the miter and i can go back and fourth, and apply pressure in the wiggleroom of the width of the miter slot.

Final verification of "perfect" was done by setting the calipers measuring stick pretty tight against a piece of paper on the arbor,then remove the paper. Shine a flash light from behind to bounce between the two. Spin arbor by manually turning the backside(no belt). Variations in brightness indicated the same in distance. When I was finished - You couldn't see any difference, wasperfect.

Put a brand new 7.25" blade in there, and make a cut. It's garbage. ??? I forgot to remove the sticker from the blade before Imounted it. Cleaned that off, polish with steel wool and presto - almost perfect cut, can barely tell it was cut with a saw as opposedto on the jointer.

Thank you!

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How to Fix the Wobbling Table Saw Arbor

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