How square is the face of your table on your table saw to the mitre slot ?

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Forum topic by Icer posted 03-22-2012 01:37 AM 1764 views 1 time favorited 16 replies Add to Favorites Watch
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9 posts in 2228 days

03-22-2012 01:37 AM

Just did some checking on my old Grizzly TS-10 and it seems to be out of square by 3/64’s” .

I set up a straight edge and an angle plate with a 1/4 electric die grinder with a 2” long stone and it is now closer to .030 out so still working it back .

Next will be to do the rear of the table . :)

Reason I asked is I read the blog Hutch has on the extruded aluminum fence he built and am in the prossess of getting that set up on my saw .

Doing all this should get me a little better surface to bolt the new rails to the saw or it should . LOL

Thank Everyone for your input .


16 replies so far

View BlankMan's profile


1490 posts in 3319 days

#1 posted 03-22-2012 02:39 AM

Boy I never thought of checking that. But I can picture how that could throw the fence rail off, skewed on an angle from the miter slots and therefore blade. But you’d maybe never know it because the fence would be adjusted to be parallel to the blade.

I’m going to have to check that out of curiosity.

-- -Curt, Milwaukee, WI

View ajosephg's profile


1880 posts in 3527 days

#2 posted 03-22-2012 02:52 AM

The table doesn’t have to be exactly square to the miter slot, nor does the fence rail. The fence is adjusted to be parallel to the miter slot, and if the rail is straight (duh) the fence will be parallel to the miter slot no irrespective of where it is located. Draw a picture if you can’t see it in your mind.

-- Joe

View Sawkerf's profile


1730 posts in 3035 days

#3 posted 03-22-2012 03:14 AM

I’ve never checked and can’t see why I would. If the blade is parallel to the miter slot and the fence is parallel to the blade what else do I need?

-- Adversity doesn't build reveals it.

View GrandpaLen's profile


1650 posts in 2239 days

#4 posted 03-22-2012 03:41 AM

I believe you’re over thinking this Table Saw tune-up.

If you bolt your new rail onto your saw and the rail is .030” out of square to the miter slot, you’re finished with that step. There is plenty of adjustment available on the trunions and fence to compensate for that.

Move on to adjusting your saw blade parallel to the miter slot and adjust your fence parallel to the blade.

Good Luck

-- Mother Nature should be proud of what you've done with her tree. - Len ...just north of a stone's throw from the oHIo, river that is, in So. Indiana.

View hhhopks's profile


651 posts in 2344 days

#5 posted 03-22-2012 04:12 AM

Shouldn’t the front and back edge of the TS be perpendicular to the slot?
I have always assume that is so and use it to reset my miter gauge back to 90 deg with it.

Since I have never checked, I guess I am just liucky.

-- I'll be a woodworker when I grow up. HHHOPKS

View BlankMan's profile


1490 posts in 3319 days

#6 posted 03-22-2012 04:48 AM

Joe, I can picture it in my mind, that’s why I want to check it.

And this is why I want to check it and it’s not only about the fence being parallel to the miter slot or blade.

If the fence rail goes off on an angle and the extension table is square and extends true, at the end of the fence rail there could be a gap or the rail is pushing the table back. So it could be torqued. And you align the fence to be parallel to the blade and miter slot right by the blade and miter slot not 52” away at the end of the fence rail. So it could be off there.

The really extreme downside to that would be when cutting something that wide could lead to pinching and kickback. Extreme longshot, but safety is foremost, and I’m not going to overlook anything that could be potentially dangerous once I’m aware of it.

One could say in a tug of war between the fence rail and the extension table the rail would win, but maybe not with my extension table. The frame under it is made of 2”x1/4” angle iron, same thickness as the fence’s angle iron so it might be a draw.

-- -Curt, Milwaukee, WI

View brtech's profile


1028 posts in 2889 days

#7 posted 03-22-2012 02:07 PM

Most T square fences have two components in the front rail, and the back rail is only a surface to run against. On the front rail, you mount a piece of angle iron to the table. Then you mount a square tube to the angle iron. When you do the latter, you adjust the square tube so the fence has an equal gap on both ends. There is over 3/64 of play on both fences I have worked on lately. That’s why it doesn’t matter much.

View ajosephg's profile


1880 posts in 3527 days

#8 posted 03-22-2012 03:36 PM

Curt -
Brtech explains it well.

Regarding a tug of war between the rail and the extension table, I’d say it would be good practice to add washers or shims on the extensions to insure a generally linear surface to mount the rail to. If the extension table is too long it should be shortened.

My saw is a Taiwan knock-off of a Delta contractor saw to which I retrofitted a Delta T2 fence. It came with 2 cast iron wings. The holes in the wings did not line up with the holes in the angle iron rails, so I didn’t bolt the angle iron to the wings, so the fence rails are only supported with the bolts in the main table. After several years of use I haven’t had any problems. I added a shop built extension table to the right side made from plywood and aluminum angles bolted to the fence rail. I made sure that there was some slop in the holes of the aluminum to minimize any bending stress on the rails, however with the rails being made out of 1/4 inch steel, not much is going to bend them. Therefore, in my situation the main table is supporting the fence rails, and the rails are supporting the extension table. The cast iron wings are bolted to the sides of the main table and have no mechanical connection to the fence rails.

-- Joe

View Icer's profile


9 posts in 2228 days

#9 posted 03-22-2012 05:00 PM

Thanks for the input guys .

I understand the shimming of the rail system , must be that I’m a die maker by trade and work with tollarances of less than .002 mm all the time and .003 in so with my mind set anything over .010 in is huge . LOL

I’ll keep working on it till I’m satisfied with it . :)


View dbhost's profile


5705 posts in 3198 days

#10 posted 03-22-2012 05:07 PM

Never thought of measuring squareness of slot to table top, just slot to blade. Not sure why it would matter all that much. FWIW, My saw uses a sliding miter table, AND slots, the slots were an add on accessory, and I have slots, and SMT aligned to the blade within .001”, and everything seems nice and tight to me…

-- Please like and subscribe to my YouTube Channel

View Kenny 's profile


260 posts in 2414 days

#11 posted 03-22-2012 05:23 PM

Wow, and I thought I was anal!

I can understand though. My dad is a machinist and he drilled precision deep into my brain for years. I have been known to go way overboard with set-ups myself, but I’ve never considered grinding the front of my table to be parallel with the miter slot. That’s what shims are for!

I wouldn’t worry about it. Shim it or adjust the fence. If you have a straight tube for the fence to ride on, your all set. You can simply shim it to get that square with the miter slot.

Anyway, have you checked to see how straight the miter slot is milled? What if it’s not dead straight for the length of the table and your milling the faces to be square to something that itself isn’t straight?

Good luck.

-- Kenny

View Icer's profile


9 posts in 2228 days

#12 posted 03-23-2012 12:23 AM

Hi Kenny,

Yes I did check the mitre slots and I picked the better of the two to be the master slot . LOL

I have the front to within .010 of being square so a little more grinding tomarrow and the front should be good to go for me . Then it’s to the back side of the table to see if it’s as bad as the front was .

When I’m done with squaring the table I hope I won’t have to shim very much to get my rails square . :)


View MoshupTrail's profile


304 posts in 2447 days

#13 posted 03-23-2012 12:44 AM

Nope. There is no reason the table of the table saw needs to be square, and no reason the miter slots need to be square to front edge of the table. All that is important is that the miter slots are parallel to each other, parallel to the blade, and parallel to the fence. If the front face of the table is a little out of square it just means the fence will move closer to the blade as it goes back and forth. If we are talking less than 1/4” you’ll never notice.

To see this, draw an exaggerated picture of a table saw table. Draw it out of square on all 4 sides. Then draw two parallel miter slots and a blade slot parallel in between. Then draw a fence parallel to them. Now imagine what happens as the fence slides back and forth. Yup, it stays parallel! The tube needs to be straight though.

-- Some problems are best solved with an optimistic approach. Optimism shines a light on alternatives that are otherwise not visible.

View Moron's profile


5032 posts in 3860 days

#14 posted 03-23-2012 12:45 AM

everything starts from “square”……..without it, the exponent of error continues to grow

-- "Good artists borrow, great artists steal”…..Picasso

View Icer's profile


9 posts in 2228 days

#15 posted 03-24-2012 08:15 PM

Update ,

I have the front of the table(the to areas that will be the mounting ares for the nwe fence system) to within .003 in. the space between the 2 points is 30 ins. so I happy with that .

Still a bow in the center of the table of about .010 in, but I can live with that . hehe

Now to start on the back side .

This should give me a good base to mount the new fence system to as it is setup with front and rear bearings so any shimming need should be minamal .


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