5 Cut Method - What is it & How to do it?

[david blakelock]

This might be a really stupid question, but in reading previous posts about building a crosscut sled I saw multiple references to the "5 Cut Method". I gather it involved making 5 cuts to measure the accuracy of your sled, but that is about as far as I got. Could someone please explain the process and how/when to use it?

Thanks!!

David

[David Prince]

There are several good ways to check the accuracy of a crosscut fence on a saw; the Five Sided Cut process is one of those methods. This method is commonly used with sliding table saws. The benefit of this method is that it is "error additive", fairly easy to do, and gives the tester a useable measure of accuracy. The process can also be used on standard table saws and other machines. The Process


1. Select a piece of stock to use for the test, something about16" to 24" square is a good size that will give the test a decent amount of resolution. The stock material should be stable and flat for the best results, ¾" Melamine, plywood, or MDF is a good choice. You'll need to measure some fairly small variations in this stock, the best way to do this is with calipers or some similar tool but it is possible to perform the test by "feel".

2. Set the fence perpendicular to the blade (reading ninety or zero degrees as dictated by your machine).
3. Place the stock against the crosscut fence and cut off about ¼" to ½" of material. Note, it is a good idea to have some reasonable amount material on the "waste" side of the blade. This ensures that the blade is in a stable state and that the test is being conducted under "normal" conditions.
4. Rotate the stock 90 degrees by placing the fresh cut edge against the crosscut fence and make another cut. Repeat this step until you have rotated the stock back to the original position. Note, extra care should be taken to ensure that there is nothing between the stock and the crosscut fence to throw off the cut angle even a little as it will affect the test.
5. Make another cut in this position (this is the fifth cut) and save the off cut.

6. Take THIS off cut and mark one end F for forward (this edge was cut first by the blade), and A for aft in the correct positions.
7. Compare the difference in width between the F and A ends; the difference IS the accuracy. For example if one end is 1/8" thicker than the other then the fence is out of square by an amount of about 1/8" over the sum of the sides that were cut. If a ~24" square test piece was used, the fence is out of square by 1/8" over 96" in length (24 x 4 = 96). The method creates an additive error each time the stock is rotated and cut.

You can use this information to determine how much to move the fence to bring the cut more into square. In the case of a 24" square test piece, the fence would be moved about 0.03" measured at a point on the fence 24" away from the blade (1/8" divided by 4 is about 0.03").
Once the new reference is set, the five sided cut test should be performed again to see how close to square the system is with a new correction. It must be understood that at some point in the alignment process it becomes a waste of time trying to dial out a small error, it is an exercise in futility. This is because of the nature of wood to begin with (which changes shape based on its environment), the basic accuracy of machines and blades, the problems in creating a repeatable setup, and trying to reliably measure such small differences in width.

[Tom Hintz]

I have a story on the 5-cut method with photos and a video that might be helpful. See the link below.

The 5-Cut Method (http://www.newwoodworker.com/basic/5cut.html)

[David Nelson1]

Thanks for the post fellows. I have seen and heard the method before but didnt know the proper name or the site.:D

[david blakelock]

David - thanks for the detailed explanation!
Tom - thanks for the link to your website!
It makes much more sense now.

David

[Jim Becker]

I will note that this method is also important to those of us who use sliders to insure that our outriggers and cross-cut facilities are exactly perpendicular to the slider wagon.

[Ruhi Arslan]

... In the case of a 24" square test piece, the fence would be moved about 0.03" measured at a point on the fence 24" away from the blade (1/8" divided by 4 is about 0.03")

Is it divided by four (4) or five (5)? Since the measured piece is the fifth cut, error is magnified five times, right?

[pat warner]

Sir: "David Prince"
I am very impressed with your prose, method, attention to detail, and your plan of attack here.
You sir, would be the instructor I'd like to turn too. (M.E.?).
I'd would only add that the inspection of the edge after each cut is equally paramount.
Moreover, a chip anywhere (practical), slop in the sled, a strange saw signature (excessive blade warp under load due a feed rate faster than the practical consumption rate e.g.), mishapen stock with no ground straight edge to compare (face or edge to), could add some unexpected and independent (to your cutting method) error.
Folks are happy with the 5 cut example too, but all I contend is:
That given 1 straight flat stick (verified), and one slice (x-cut), you can get a pretty good signature on the sled and saw mechanics. And maybe zero in on the error faster. & there is always some error!

[Neil Brooks]

Sir: "David Prince"
I am very impressed with your prose, method, attention to detail, and your plan of attack here.
You sir, would be the instructor I'd like to turn too. (M.E.?).


The credit is rightfully due to Phil Bumbalough -- the actual author of that information (and a ton of other useful info) !

http://benchmark.20m.com/articles/TheFiveSidedCut/TheFiveSidedCut.html

[David Prince]

I am not claiming that I wrote the description. I didn't. I just cut and pasted the info I found on the Web to address the OP's question. Please don't attibute my response as my words. It was described in a very simple format and didn't require me to rewrite the description.

I wasn't too concerned about the word for word method to it because it is a description of a process that we all use and isn't some secret recipe. In this case it is just his description. I would have used his name and source, but that was all that showed up when I cut and pasted it. I wasn't trying to plagiarize, but rather to get out an answer to the OP.

I didn't think it was an issue of where the information came from, but rather how to preform the task.

In the future I will keep this in mind and give credit if needed.

[Jim Becker]

I am sure there was no intentional lack of attribution here, folks, and David explained what happened. That said, we should all try to give attribution when it's appropriate to do so...it's just a good courteous practice.

Jim
SMC Moderator

[Gary Curtis]

Near Christmas of 2008 I was asked to demonstrate my sliding tablesaw to a Swiss gentleman living near San Francisco. The company dealers in California didn't have a model to show.

When the fellow came up to my little mountain town, I decided to demonstrate the accuracy of the crosscut fence. So I went through the drill of the 5-Cut Method on a 2-foot square of laminated MDF. At the conclusion we were left with a test strip that registered a tolerance of about .006" over an 8-foot length.

My visitor was so impressed with the tolerances and calibrations on the machine, he talked me into selling it. It was 20-months old and I had realized that it was more of a machine than I needed. Regular cabinet saws don't have a Crosscut Fence. But the 5-cut method will tell you if your rip fence, your blade or even your Miter Gauge or anything other than 90-degrees to each other.

Nice stuff to know.

[glenn bradley]

I do this: http://www.thewoodshop.20m.com/five_cut_method_swf.htm