Squaring up my Old Grizzly Table Saw

[Glenn Samuels]

I have a 3HP Grizzly table saw that is approximately 25 years old. Just changed all the bearings and it runs like a dream. I recently moved so I am setting it up in my new home. I raised the blade as far as it would go and checked to make sure it was 90 degrees. One side is exactly 90 degrees and the same spot on the other side (not front to back) is .8 degrees off. When I square up the side that is off, then the other side is off. Then I broke out my machinists square and got the same results. I did however replace the geared bearing housing which had broken while taking it apart. If it was machined slightly differently from the original, could that be the cause?

It has a cast iron top and extremely heavy so I don't think that it warped. The steel straight edge shows it to be flat. Why would one side be a perfect 90 degrees and the opposite side be off? Any suggestions would be appreciated.

[Terry Beadle]

IF...big IF...the table dead flat as measured with out the blade in between. Then I would check the thickness of the saw blade for uniformity. Ie...is the blade wedge shaped?
The second thing I would check is the drive shaft flange for run out.

Last, 8 tenths of a degree on a saw blade kerf cut is not a show stopper in wood working. IMO

After you put it all together, I would adjust the blade 90 setting via a dynamic cut on 8 qtr or bigger stock. In other words, adjust the blade given the circumstances to it's nearest 90 setting with favoritism towards the side of the table you most often have the finished piece placed on.

These are suggestions.

For me, I just use my Grizzly TS to rough cut stock and do final squaring, thicknessing etc. with my hand planes.

[Phil Thien]

Only two possibilities:

(1) Your measurements are wrong.

(2) Something isn't flat (blade and/or table).

I suspect a combination of #1 and #2.

[glenn bradley]

I'll add that cast iron is softer than you think. If you rotate the blade does the side that is dead-on stay dead-on. How about the side that is .8 off?

[Bill Space]

First thought at this end is: What are you using as the reference to determine the error on each side of the blade?

Are you using the miter slots? If so, then they are likely not parallel to each other.

I would align the top with the blade using the miter slot that I would be using most if not all of the time.

The rip fence would be a different animal...would be aligned with the blade independent of the miter slots.

This is what I would do anyway...YMMV.

Hope this helps....

Bill

Edit: whoops! Upon rereading the question I see I misunderstood the what was being asked...:eek:

[Glenn Samuels]

Glenn, Yes, the measurements are exactly the same as I rotate the blade.

I did however replace the geared bearing housing which had broken while taking it apart. I will contact Grizzly to see if replacing it could effect the right angles.

[Mikail Khan]

I suspect that you are using a wixey or equivalent to measure the blade angle to measure the 0.8 deg off.

What you are saying is the table is flat - that is 180 degrees. When you raise the blade and you divide that 180 degrees into two you are getting one segment with 90 degrees and one which is 80.2 (or 90.8) degrees. This should not be possible.

When using an angle cube to ensure the blade is perpendicular you have to change the reference surface from side to the next when moving form one side to the next. Try using the same side of the cube for both sides of the blade and go to the back of the saw to see the second measurement.

If you are using a digital protractor and you are getting 90 on one side and something other than 90 on the other side then your table may not be perfectly flat (no table ever is) or the blade insert cutout may be affecting the accuracy of you reading.


I would suggest that you do some quick checks for flatness, using one side of the blade set the saw blade to 90 and start cutting some wood.

If you have a lot of free time on your hands joint one face of a 2" thick block of wood about 12" long. Then joint the 2 nearest faces to square them up. With the first jointed face flat on the table saw rip 1/8" from each of the sides. If the blade is not square and you look at the block edge on you will now have a trapezium. Measure the with of the face that was on the table and the opposite face with a vernier. The difference will be twice the error you get when you use the saw. If the block was 2" thick divide by 2 and you will get your error for every inch of blade height.


MK

[glenn bradley]

Glenn, Yes, the measurements are exactly the same as I rotate the blade.

I did however replace the geared bearing housing which had broken while taking it apart. I will contact Grizzly to see if replacing it could effect the right angles.

OK, cool. Are we lucky enough that you checked this same thing prior to breakdown? If so, the work/parts are our primary suspect. However, the fact that the deviation is fairly consistent with rotation sounds more like the blade is being distorted under pressure. If you loosen the arbor nut and washer slightly, does the deviation vary?

[Glenn Samuels]

After all is said and done, it looks like the primary cast iron top has warped. Didn't think that it was possible but I now know that it is. Thanks for all the good suggestions.

[Mikail Khan]

Did you remove/reinstall the top when you did he repairs. Try slackening the bolts that hold the top to the cabinet to see if the flatness changes. I have read about people improving the flatness of their tops by using shims between the top and the cabinet.

All is not lost.

MK