Tablesaw alignment thought about a different way

[Mark Hennebury]

You don't need any jigs, calipers, dial indicators or custom machined super flat plates;
All you need is an understanding of what you are hoping to achieve, how to achieve it and a block of wood and a big hammer.
Cut the block of wood, examine it.
Smack the table with a hammer to adjust it. ( if its an expensive saw, use the block of wood in between the hammer and table)
Rinse and repeat until it cuts as accurately as you want it to.

[Don Crawford]

One year, I needed to spend some money on tools right at the end of the year, and one of the things I splurged on was the Master Plate. I don't know if it's worth the cost, but I was able to get all my table saws dead on with it much easier than trying to use a blade. I would buy one of those before making, or having made, something more elaborate.

http://mastergage.com/display_product.asp?id=4

This is actually close to what I am talking about right?

[Dan Friedrichs]

This is actually close to what I am talking about right?

It's just a (very) flat piece of metal that bolts onto the arbor. You still use a dial indicator mounted to something running in the miter slot to measure how parallel it is to the miter slot.

[David Buchhauser]

It's just a (very) flat piece of metal that bolts onto the arbor. You still use a dial indicator mounted to something running in the miter slot to measure how parallel it is to the miter slot.

Or you can install a straight, flat piece of aluminum bar into the miter slot, then take measurements with a pair of dial calipers (or digital calipers) at each end between the Master Plate and the aluminum bar.
David

[Andrew Hughes]

I have one of those and it works fine. But so does a combination square up against one side of the miter slot. Rubbing on the same tooth front and back.
Heres a pic just in case your a engineer

[David Buchhauser]

Nice Andrew! I like it. I think your method can get you to within 0.005" or less - plenty close for most work, or to use the "5-cut method" to fine tune it.
David

[Mark Hennebury]

I guess i just don't get it; why wouldn't you just clamp block of wood to your mitre fence and cut it and examine the cut surface. You can tell how well aligned it is by the resulting scratches from the teeth; if you leave the wood clamped and run it back and forth past the blade , you can tell by the feel , if its touching the front and back teeth, you can tell by the feel, you can tell by the sound, you can do it with the saw running or off, and run the block past the teeth just the same as your adjustable square or dial indicator. I don't see why you need anything.

The "5 cut method" will only determine the error in perpendicularity of the mitre fence to the axis of travel, it won't tell you anything about the alignment of the mitre slot to the blade. They are two different things. The scratch pattern of the teeth will tell you if the axis of travel is parallel to the face of the blade. If you have the mitre slot correctly aligned with the blade, you will have scratches going down, from the front of the sawblade and scratches going up from the back of the sawblade. If you have the slot misaligned one way the back teeth wont touch the cut wood, or misaligned the other way will burn the wood.

There is an easier and more accurate way of checking the miter perpendicularity; Simply cut a 40" long 2x2 in half and stand it on your saw table top, then slide the two pieces together you will see and can measure the error, it will be magnified 20 times. and as an added bonus, it will also tell you if your blade is perpendicular to your table top. So the one cut method gives you error readings in two dimensions and magnified 20 fold.

[Andrew Seemann]

Nice Andrew! I like it. I think your method can get you to within 0.005" or less - plenty close for most work, or to use the "5-cut method" to fine tune it.
David

I use a digital caliper from the miter slot (mostly for speed and convinience), but I check it with the combo square method. You set it so it just barely drags against one of the front right pointing teeth and run it against one of the back right pointing teeth and listen if the sound and feel of the drag is the same. That should get you within a few thou, which is really more accurate than the tolerance of the saw as a system. My guess is that it will match on some of the teeth but not all; again the method of measurement is probably more accurate than the arbor run out, arbor arm arc tolerance, blade run out, miter slot straightness, etc. taken all together.

And then after we get the blade to within a gnat's whisker of parallel to the miter slot, we go and bolt on huge @ss Biesemeyer fence extensions to the top, put it on a mobile base and bounce it around the shop floor, change the blade, run 8/4 white oak on it for a few hours, and then find all our parallelness and squareness we spent so much time on are all off by 5 thou here and 10 thou there, and yet, the saw works and cuts just fine. . . . .

[David Buchhauser]

Here is a nice video from Rockler on this subject.
David

https://www.youtube.com/watch?v=jvjZKFSXkNA

How to Align Table Saw Blade.jpg

[David Buchhauser]

The "5 cut method" will only determine the error in perpendicularity of the mitre fence to the axis of travel, it won't tell you anything about the alignment of the mitre slot to the blade. They are two different things.

Hi Mark,
Of course - you are exactly right. My mistake. I don't know what I was thinking - I guess I need to wear my "thinking cap" more often.
Thanks for you post.
David