Are your cuts square on your TS?

[Bill Huber]

Exactly, but in either case you still have a problem not only with cross cutting but with ripping also. The real answer is align the table (miter slots) to the blade, then you can set your miter gauge to the slots or the blade, any other way is just wrong. I don't know of any saw where you can't adjust the table, maybe a cheapy. But the tables on most (all?) cabinet saws can be easily adjusted- my Uni has Allen head bolts at each corner. Loosen the bolts a little, then use a dial indicator and a dead blow hammer- tap, tap, tap, the table into alignment- takes all of one minute. On saws where the trunion is mounted to the table it may be a little more difficult, but not much.

No you will not have a problem with ripping, the blade may burn or drag but you will still get a straight rip.

So you are telling me that your saw is set to .0000 front to back to the miter slot.

I have a very old contractor saw and have worked for many hours trying to get it set but I have never been about to get it less then .002 I am sure it is getting worn out, but my saw is not the only one that is not set perfect.

I would say that there are a lot of saws out there that are not perfect and I still say you should always use the miter slot to set the miter guide.

I guess will will just have to agree to disagree on this.

[Bruce Benjamin]

Loosen the bolts a little, then use a dial indicator and a dead blow hammer- tap, tap, tap, the table into alignment- takes all of one minute. On saws where the trunion is mounted to the table it may be a little more difficult, but not much.

"A little more difficult"??? I'm guessing you've never actually tried to align a contractor style saw before. It's not rocket science and it is possible to align the blade to the miter slot with a high degree of accuracy on a contractor saw. But I would never call it easy. I don't know how long it really takes to align a cabinet saw but I can tell you that I'm pretty handy mechanically speaking and it took me a lot longer than a minute. Trial and error, back and forth, I think it took me close to an hour and it's still not perfect. Close enough but not perfect. I don't think I'm in the minority either.

Another issue with aligning the fence with the blade is that sometimes blades aren't perfectly flat. In addition to that, the blade offers a much shorter surface to measure off of compared to the miter slot. Referencing the blade is the way to go to remove possible sources of error.

Bruce

[jim gossage]

bill,
what is the best way to align the miter gauge to the miter slot? it seems like you would want to register your square up against an edge rather than just eyeballing it. once the miter gauge is in the slot, you have lost the edge of the slot.

[Art Mann]

It does not present a problem with either ripping or cross cutting if the blade is slightly off from parallel to the miter slot. In fact, some texts on tablesaw setup say to tow out the back side of the blade by .003 or .005 with respect to the miter slot in order to reduce the possibility of binding between the blade and fence. I don't do it that way, at least on purpose, but lots of people do. Regardless, you should always reference the miter fence to the miter slot in which it slides rather than to the blade - if you want the best accuracy.

[Bruce Benjamin]

It does not present a problem with either ripping or cross cutting if the blade is slightly off from parallel to the miter slot. In fact, some texts on tablesaw setup say to tow out the back side of the blade by .003 or .005 with respect to the miter slot in order to reduce the possibility of binding between the blade and fence. I don't do it that way, at least on purpose, but lots of people do. Regardless, you should always reference the miter fence to the miter slot in which it slides rather than to the blade - if you want the best accuracy.

I don't think I've ever seen anything that said to purposely set the blade out of alignment to the miter slot. Are you sure you're not confusing that with setting the rip fence out by .003" to .005"? I've seen that a quite a few times. What you're suggesting would cause more binding between the blade and the fence, not less. At least as far as I can see.

Bruce

[Gary Keedwell]

A great way of squaring up your miter gage is by using a wixey digital gage by hanging your miter fence off the edge of table saw . Zero off the gage on the saw top and bring it over to the mite fence and tighten up when it registers 90º.
Gary

[glenn bradley]

I setup the blade to the miter slot, fence to the miter slot and square the miter gauge to the bar as you suggest. Works fine. Also, yet another handy use for your tilt gauge:

The pics are actually opposite of what I do but you get the idea.
Zero it on the bar Wixey-on-Miter-1.jpg

and adjust to 90* on the gauge headWixey-on-Miter-2.jpg

As long as your gauge is at 90* to it's own bar, the bar fits the slot without slop and your saw is setup to the slot . . . all is well.

[Bruce Benjamin]

Something to consider when squaring the miter gauge head to the miter bar is if the miter bar is actually sitting square in the miter slot. What I mean by that is, how tight does the bar fit in the slot and how did you get it that way? If you have a miter bar that has some adjustability in the form of ball plungers or eccentric disks you may have one section adjusted slightly differently than another section. While the miter bar may be snug in the slot as it slides along, it's not necessarily perfectly square in the slot. I'm not saying this is always a problem but it's worth checking.

I have two miter gauges, the stock General miter gauge and an Incra 1000SE. I have checked both by cutting a 90 deg. crosscut and checking it for square. That's the real proof. I then checked the head against the miter bar. Right now both gauge heads are square to the miter bar but I remember when I first got my General International saw I checked the cuts and the gauge head was square to the miter bar but the cut wasn't quite square. I did some thinking and it finally dawned on me that the bar wasn't adjusted quite evenly so the bar wasn't square in the miter slot. This won't happen to everyone but it's worth checking before making a critical cut on expensive stock.

I have used both the Wixey and the Beall angle gauges, (I kept the Beall) and they both claim an accuracy of + or - .1 degree. That doesn't automatically mean that every measurement is off by .1 degree but it does mean that you might want to do a test cut to find out if your gauge is really set where you want it to be. Two 44 degree or 46 degree miter corner cuts instead of 45 degree cuts will definitely be noticeable. That being said, I have used this method on my Incra gauge and the Beall matched the gauge's reading exactly and the cuts were dead-on.

Bruce

[Lonnie Cook]

Bill:

I'm sure that this thread has given a lot of woodworkers a better understanding of the geometry of a saw cut.

Even if your blade is slightly out of alignment with the miter slot, here is a fast, accurate, and cheap way to set your miter fence to make exact cuts.

Insert a nail into a tight-fit hole in the throat plate. Place your set-up reference (drafting triangle, Sliding T-Bevel, template, etc.) against the miter fence and the nail. Slide the miter gauge back and forth. Adjust the fence until the reference touches the nail along the entire path.

I prefer the 5-cut method to set the zero-deg stop, but a 90deg drafting triangle can be used against the nail, also.



Yep, it's a Ryobi with a sliding table, but this works on "old fashioned" saws with miter slots, too!

- Lonnie

[Art Mann]

I don't think I've ever seen anything that said to purposely set the blade out of alignment to the miter slot. Are you sure you're not confusing that with setting the rip fence out by .003" to .005"? I've seen that a quite a few times. What you're suggesting would cause more binding between the blade and the fence, not less. At least as far as I can see.

Bruce

Good catch. The rip fence should always be set exactly parallel to the miter slot from all I have read. But, you are right in that I said the wrong thing about the blade. What I meant to say was some authorities say to set the back edge of the blade out from the rip fence, not the miter slot. I thought one thing but typed out something else.

[Art Mann]

Lonnie, that is a neat trick. I also prefer the 5 cut method as it amplifies the error X4 so you can see it better.

Bruce, in your example, don't you mean 44.9 and 45.1 instead of 44 and 46? I'm not so sure this amount of error will be very noticeable. The gap produced varies like the sine of the angular error. The sine of 0.1 degree is about 0.0017. A miter cut that is 2 inches in length with a 0.1 degree error will produce a gap of about 3.4 thousandths. That is a little less than a dollar bill thickness. Of course, you have to multiply that by 2 for a mitered joint if both angles are out by 0.1 in the same direction. I used to check the blade after setting it with the Wixey using a machinist square, but I never found any difference. Test cuts are the only way to really know for sure if bevels are right. I use an Incra 1000se for cutting miters and after I calibrated it, the angles have always been right on the money. I don't do trial cuts every time with the Incra because I found it isn't necessary.

[Gary Keedwell]

Good catch. The rip fence should always be set exactly parallel to the miter slot from all I have read. But, you are right in that I said the wrong thing about the blade. What I meant to say was some authorities say to set the back edge of the blade out from the rip fence, not the miter slot. I thought one thing but typed out something else.

The Blade is always supposed to be parallel to the miter slot. What you should be saying is the fence is sometimes skewed out a few thousands on the back side of the saw.

Gary

[Bill Huber]

Bill:

I'm sure that this thread has given a lot of woodworkers a better understanding of the geometry of a saw cut.

Even if your blade is slightly out of alignment with the miter slot, here is a fast, accurate, and cheap way to set your miter fence to make exact cuts.

Insert a nail into a tight-fit hole in the throat plate. Place your set-up reference (drafting triangle, Sliding T-Bevel, template, etc.) against the miter fence and the nail. Slide the miter gauge back and forth. Adjust the fence until the reference touches the nail along the entire path.

I prefer the 5-cut method to set the zero-deg stop, but a 90deg drafting triangle can be used against the nail, also.
- Lonnie

Very neat idea, I like it......!!!

I tried it this afternoon and I used one of those On/Off magnets and it did just fine.

I used the 5 cut method to set the miter guide up to start and when I checked it with your method it checked out.

Thanks for the idea, this is a quick check, a little faster then the 5 cut.

[Bruce Benjamin]

Lonnie, that is a neat trick. I also prefer the 5 cut method as it amplifies the error X4 so you can see it better.

Bruce, in your example, don't you mean 44.9 and 45.1 instead of 44 and 46? I'm not so sure this amount of error will be very noticeable. The gap produced varies like the sine of the angular error. The sine of 0.1 degree is about 0.0017. A miter cut that is 2 inches in length with a 0.1 degree error will produce a gap of about 3.4 thousandths. That is a little less than a dollar bill thickness. Of course, you have to multiply that by 2 for a mitered joint if both angles are out by 0.1 in the same direction. I used to check the blade after setting it with the Wixey using a machinist square, but I never found any difference. Test cuts are the only way to really know for sure if bevels are right. I use an Incra 1000se for cutting miters and after I calibrated it, the angles have always been right on the money. I don't do trial cuts every time with the Incra because I found it isn't necessary.

As you said to me in a previous post, Good catch, Art. Yes, that is what I meant but not what I typed. However, a .003" gap is easily visible even to my tired eyes and a .007" gap should be visible to anyone's eyes.

As I said, my Beall gauge has been dead on when compared to any other tool or method I have, including the all important, "Does the part actually fit test". But that doesn't mean that people should just automatically discount the margin for error listed by both Beall and Wixey. I would suggest that everyone test their gauge once in a while just to see where it is.

My Incra 1000SE is attached to Incra's miter sled. It has been dead on right out of the box but I still checked it to make sure. I'm really impressed with Incra.

Bruce