This is the fifth post in a series of Ryobi table saw alignment articles.
The sliding miter table comes with a large cross cut fence which is much larger than the stock miter gauge of a comparable table saws. This makes it easier to cut larger stock on the table saw without having to purchase or build jig. The Ryobi BT-3000 / BT-3100 does not come with a standard miter rail. However, I have seen templates for building a table insert that adds a standard sliding miter rail into the table top.
What are we trying to accomplish?
Get the cross cut fence 90 degrees to the direction of travel of the sliding miter table, not the table saw blade.
What is the effect when the sliding miter table is out of alignment?
Cross cuts that are supposed to result in a 90 degree cut end up either greater than or less than 90 degrees. This results in gaps when the cut piece is assembled into the finished project.
Alignment process
Checking the alignment
This is primarily a dynamic process where you will be making four cuts on a scrape piece of material. The five sided cut technique will be used to determine the squareness of the cross cut fence. The technique utilizes an error additive approach. This approach does not require any special jigs, just a micrometer. The beauty of this technique is that it is very accurate.
1) Select a piece of scrap stock that is in the around twelve inches square. The stock does not have to be a perfect square, it can be a rectangle. 3/4” plywood works really well for this. Add up the lengths of all four sides of the stock. This test effectively tests making a cross cut of a single piece of stock that is as wide as the sum of all four sides of the scrape stock.
2) Mark each side of the stock piece with a felt tip pen. On the first side mark it with the letter ‘A’, then in a counter clock wise mark the other sides ‘B’, ‘C’ and ‘D’. Place the letter markings about an inch in from the edge of each side.
3) Set the cross cut fence to 90 degrees using the ‘quick stop’ device.
4) Place the stock against the cross cut fence with the side ‘A’ to the right of the cross cut fence. So that side ‘A’ is the first side to be cut off. Cut off about 1/2 inch of material so that the saw blade is running as close as possible to normal.
5) Turn the stock so that side ‘A’ is up against the cross cut fence and side ‘B’ will now have a piece trimmed off. Repeat for ‘C’ and ‘D’ sides. Take extra care that there is no debris between the cross cut fence and the stock because it will throw off the test.
6) Now for the fifth cut. This will be the second cut on the ‘A’ side. Cut off a strip that is between 3/4” to 1” wide.
7) Determining how out of alignment the cross cut fence is. If you are going to be doing this by feel or by eye, break the piece in half. The difference between the two ends is the amount the cross cut fence is out of alignment.
Using a micrometer measure both ends and take the difference again this is the amount the cross cut fence is out of alignment.
Let’s put some numbers into an example to help demonstrate how this works out. Suppose the scrape stock was 12 inches square. The fifth cut off piece ends are 0.7852 inches and 0.8197 inches wide.
Total out of square is:
0.8197” – 0.7852” = 0.0345”
The effective cross cut width tested is:
12” x 4 = 48”
This is how wide of a stock we effectively cut with this test. For all practical purposes the sliding miter table can not cut a 48 inch wide stock. So we have been able to get a very clear image of the alignment of the cross cut fence.
The error is square to within 0.0345” (approximately 1/32”) over a distance of 48 inches.
How to adjust the alignment
1) Loosen the cross cut fence.
2) Loosen the ‘Quick stop’ cap nut all the while holding the cam screw in place with a screwdriver.
3) Rotate the cam a small amount.
4) Re-tighten the cam nut. Make sure that the tightening does not change the cam position.
5) Set the cross cut fence to the 90 degrees.
6) Perform the alignment test again
The cross cut fence should hold its alignment as long as none of the parts attached to it are moved. If any of the parts are moved, the accuracy should be rechecked.
