Squaring the front and back edges of a crosscut sled

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Forum topic by jstewart posted 09-16-2007 03:40 AM 2013 views 4 times favorited 7 replies Add to Favorites Watch
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141 posts in 4084 days

09-16-2007 03:40 AM

Topic tags/keywords: crosscut sled square

I’ve seen lots of great looking crosscut sleds on the site. I’ve been wanting to build one for myself, but haven’t got around to it. I have one question about the process. Are there any tricks to making sure the back and front crossboards are absolutely square to the blade/mitre track? Being a crosscut sled, it’s useless if it’s not square.

-- Joshua, Olathe, Kansas

7 replies so far

View Karson's profile


35120 posts in 4393 days

#1 posted 09-16-2007 04:20 AM

Joshua, your right on it being useless and I’ve seen something in the last month about making sure it was square. I’ll try to find it.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware soon moving to Virginia †

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141 posts in 4084 days

#2 posted 09-16-2007 04:24 AM

I just found this one another site:

It describes what they call the 5-cut method for squaring a crosscut sled fence. I basically boils down to setting the fence, making some cuts, determining if the fence is currently correct and resetting the fence.

Are there any methods to ensure the first “guess” is VERY close to square? I know I need to run some test pieces and check for square after I’ve set the fence. I just don’t want to set it, test, reset, retest, reset, retest (you get the idea).

-- Joshua, Olathe, Kansas

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13754 posts in 4090 days

#3 posted 09-16-2007 04:32 AM

Check out this post by Niki

-- We must guard our enthusiasm as we would our life - James Krenov

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Thos. Angle

4444 posts in 3955 days

#4 posted 09-16-2007 04:33 AM

Niki did a blog about a week ago with 40 some photos of building a sled. That would be a good place to start. I don’t think he did any 5 cut method. It was pretty straight forward. Seems like I set my back fence with a framing square, running a line from the first cut both ways. I’ve seen some with a slot on one end so the fence can be adjusted until it is correct.

-- Thos. Angle, Jordan Valley, Oregon

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Douglas Bordner

4024 posts in 4057 days

#5 posted 09-16-2007 05:25 AM

The front standard is not so important, but the back fence needs to be square to the cut (and presumably the blade is square to the table/miter slot. There was a recent FWW article about building a sled, and the interesting variation was that the fence wasn’t screwed first to the sled, but rather through bolted with the nut in a pocket under the sled on one side. With one side stable you can swing the fence until it is square to the cut, and then secure it. I used Niki’s 45-45-90 triangle trick to layout the fence position. Works great.

-- "Bordnerizing" perfectly good lumber for over a decade.

View slaphitter's profile


50 posts in 3919 days

#6 posted 09-17-2007 04:26 AM

You can get very, very close on the first try by using good old high school math.

Make the sled (without the rear fence), and run it carefully through the saw to establish the kerfline. Then use trigonometry. If you have a right triangle where one leg is 3 and the other is 4, then the hypotenuse (the diagonal) is always 5.

So measure up the kerf 6 inches. Then use two rulers (or draw pencil marks by trial-and-error and use one ruler), until the perpendicular line measures 8 and the diagonal measures 10. If you measure carefully, when all 3 lines are just right you will have VERY close to square.

View Sawdust2's profile


1466 posts in 4081 days

#7 posted 09-17-2007 04:40 AM

Take a compass, or is you don’t have a compass take a ruler and drill holes at 8” and 10” to put a pencil in.
(or 1” for the pivot and 9” and 11” for the other points)

Lay an arc with the 8” hole from the corner and lay an arc with the 10” hole from the end point of your first line.
Where they cross is exactly where you need your last point. (A thick pencil lead will put you off a little)

-- No piece is cut too short. It was meant for a smaller project.

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