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Author Topic: 5-cut Calibration Method  (Read 16317 times)

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Offline Woodhack97

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5-cut Calibration Method
« on: January 25, 2012, 04:53 PM »
First off forgive my ineptitude.

Used the 5-cut method for the first time recently (It's amazing how much useful info is in the manual!). I measure the offcut with dial caliper and get the following:

Offcut at right measures .3725 in.

Offcut at left side measures .3680 in.

.3725 - .3680 = .0045

.0045 divided by 4 = .001125

So my saw is out about 1/1000th of an inch?   

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Offline waho6o9

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Re: 5-cut Calibration Method
« Reply #1 on: January 25, 2012, 05:03 PM »
I'd say that's perfect.

Offline Rick Christopherson

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Re: 5-cut Calibration Method
« Reply #2 on: January 25, 2012, 05:24 PM »
For more information that is directly applicable to your Kapex, you may want to look at the Supplimental manual. http://www.waterfront-woods.com/festool/Kapex_KS120.pdf It describes the methods and includes an angle calculator to help you interpret the results.

Oops. I was reading too fast and see that you did use the manual in your process.

I would suggest putting your numbers into the built-in calculator and looking at the "angular error" in deciding whether it is good or not. From what you posted above, I would venture to say that it is so close to perfect, that attempting to make it better will likely make it worse.
« Last Edit: January 25, 2012, 05:29 PM by Rick Christopherson »

Offline rdesigns

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Re: 5-cut Calibration Method
« Reply #3 on: January 25, 2012, 05:29 PM »
That's the thickness of a playing card.
If you were checking the bevel angle, I'd say, Good enough.
If it's the miter angle, you could do better. Use a playing card to gauge the distance you need to correct. (or a feeler gauge, of course.)

My Kapex' miter cuts were perfect according to the 5-cut method. I fussed over the bevel angle till it came out perfect too.

Love that Kapex!

Offline Rick Christopherson

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Re: 5-cut Calibration Method
« Reply #4 on: January 25, 2012, 05:33 PM »
That's the thickness of a playing card.
If you were checking the bevel angle, I'd say, Good enough.
If it's the miter angle, you could do better. Use a playing card to gauge the distance you need to correct. (or a feeler gauge, of course.)

My Kapex' miter cuts were perfect according to the 5-cut method. I fussed over the bevel angle till it came out perfect too.

Love that Kapex!

Actually, that is only 1/2 the thickness of a piece or paper. However, what is missing from the original posting is "How long was his cut". 0.001" over a 10" cut, for example, is a super-good value. 0.001 inches over 1" may not be that good. So this missing piece of information is important to know.

Offline Woodhack97

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Re: 5-cut Calibration Method
« Reply #5 on: January 25, 2012, 06:20 PM »
Oops forgot that piece of info.

I was checking the vertical bevel angle. The length of the offcut  was 3 15/16". Still good?

Offline Rick Christopherson

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Re: 5-cut Calibration Method
« Reply #6 on: January 25, 2012, 06:29 PM »
Oops forgot that piece of info.

I was checking the vertical bevel angle. The length of the offcut  was 3 15/16". Still good?

With the numbers you have provided, this gives you an angular error of 0.016 degrees too far to the left. For a bevel adjustment, that is very good and should not be touched.

This error is so close to perfect on a bevel that simply changing your hand positions and methods will give you different results. In other words, this is within the bounds of the "human factor" while operating the saw.

Offline woodie

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Re: 5-cut Calibration Method
« Reply #7 on: January 25, 2012, 08:39 PM »
I'm trying to figure this out for calibrating my MFT/3 as well. I entered my info in the PDF but it wont calculate an answer. I'm using a Mac so perhaps Preview won't allow it to work properly.  I just tried entering the formula on a calculator. Just to be sure I wasn't doing it wrong I entered the OP's info but my result is different than yours Rick. What am I doing wrong?

Here's a screen shot from the calculator.



So for the OP's info I'm getting -.00028 ?

My cut on the MFT/3 resulted in:
.505" Left
.5525" Right
10-7/16" Length

I'm getting -0.003. Is this right?


Green - MFT/3, FS 1080/2, FS 1400/2-LR32, FS 1900/2, FS 3000/2, Parallel Guide Set, CT 26E, CT MIDI, OF1400 EQ, LR32 Drilling Set, MFS 400 Set, MFS 700 Set, Domino DF700 Set, Domino DF500Q Set, C12 NiMH Set, T18+3 Set, 2011 Centrotec Set, RO150 FEQ, RTS400 EQ, LS130 EQ, Planex LHS225, and various accessories

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Offline Steve R

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Re: 5-cut Calibration Method
« Reply #8 on: January 25, 2012, 08:47 PM »
Can someone point me to the rules for this 5 cut competition? Never heard of it... did this just come out in Popular Woodworking? My goal is not to cut twice and still be too short...so five cuts seems like a really bad thing... [eek]

Cheers,
Steve
"A Festool is a tool, Marian; much better than any other tool: an axe, a shovel or anything. A Festool is still only as good or as bad as the man using it. Remember that.” ~ Ode to Shane (the movie)

Offline Rick Christopherson

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Re: 5-cut Calibration Method
« Reply #9 on: January 25, 2012, 08:51 PM »
Woodie,
If you are viewing the PDF embedded into a browser window, it is possible that the built-in calculator may not function. Try downloading the manual and open it directly in Acrobat.

As for your calculator, the reason for the difference is because your calculator is working in Radians instead of degrees. If you convert your 0.0002857 radians to degrees, you get 0.016 degrees. Spreadsheets like Excel do the same thing by default. You have to tell them you want degrees.

Offline Rick Christopherson

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Re: 5-cut Calibration Method
« Reply #10 on: January 25, 2012, 09:02 PM »
Can someone point me to the rules for this 5 cut competition? Never heard of it... did this just come out in Popular Woodworking? My goal is not to cut twice and still be too short...so five cuts seems like a really bad thing... [eek]

Cheers,
Steve

First off, the name "5-cut" comes from a math error made in a magazine article years ago, but has unfortunately stuck. It is really only 4-cuts that are necessary.

Secondly, 4-cut (or 5-cut, if you prefer) is the name of a calibration method of compounding an error 4-times to make it more accurate to measure that error. If you have a really small dimension that you need to measure, you multiply that dimension by 4-times to make it easier (more accurate) to measure.

As for the background for this discussion, go to the Kapex manual link in my first posting above, and go to pages 24 through 27 for a complete explanation about it. It is a common calibration procedure that can be used for many of your tools, not just a miter saw.

P.S. If it helps, here is the core image pertaining to that discussion in the manual. Notice how each of the successive offcuts is getting worse and worse in their error (1x, 2x, 3x, & 4x). However, any cut made beyond the 4th cut will still remain at 4-times the original error. So making more than 4 cuts does not make it more accurate. This will make more sense after you read the discussion in the manual.

46874-0
« Last Edit: January 25, 2012, 09:16 PM by Rick Christopherson »

Offline Rick Christopherson

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Re: 5-cut Calibration Method
« Reply #11 on: January 25, 2012, 09:30 PM »

My cut on the MFT/3 resulted in:
.505" Left
.5525" Right
10-7/16" Length


I'm sorry, I missed this part earlier. These numbers plugged into the PDF's built-in calculator result in an error of 0.065 degrees to the left. For an MFT setup, I would not consider this to be acceptable. On something as long as the fence on an MFT, you should be down in the 0.010 degree range (or lower if you wish). When precision is critical, you should be able to calibrate your MFT down to 0.001 degrees, but this is such high precision that simply moving your fence would require a new calibration.

The longer the length, the more accurate the cut could/should be calibrated.
« Last Edit: January 25, 2012, 09:33 PM by Rick Christopherson »

Offline woodie

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Re: 5-cut Calibration Method
« Reply #12 on: January 25, 2012, 11:07 PM »
Thanks! I was able to get my MFT to 0.016 before calling it a night [smile].
Green - MFT/3, FS 1080/2, FS 1400/2-LR32, FS 1900/2, FS 3000/2, Parallel Guide Set, CT 26E, CT MIDI, OF1400 EQ, LR32 Drilling Set, MFS 400 Set, MFS 700 Set, Domino DF700 Set, Domino DF500Q Set, C12 NiMH Set, T18+3 Set, 2011 Centrotec Set, RO150 FEQ, RTS400 EQ, LS130 EQ, Planex LHS225, and various accessories

Red - KSS80 EC/370, MT55cc, P1cc, F160, F110 and Aerofix Guide Rails.

Offline Deansocial

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Re: 5-cut Calibration Method
« Reply #13 on: January 26, 2012, 02:33 AM »
i thought the idea behind 5 cuts was that your first cut gives a nice straight edge to put against the fence to start the 4 cut and it is also the cut to measure off

Offline Hans Mertens

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Re: 5-cut Calibration Method
« Reply #14 on: January 26, 2012, 04:02 AM »
I was taught not to measure the difference but to see/feel the difference.  When you do the 4th cut, that piece should be perfect parallel if you have a 90° cut.  When you break that piece in two and put the two ends at your flat machine table you can see/feel if there's any difference.  That way you can test the squareness of your machine even when you don't have a caliper at hand.

I too make 5-cuts, the first to be sure I have a straight edge to start with against the fence.
« Last Edit: January 26, 2012, 04:06 AM by Mettes »

Offline Rick Christopherson

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Re: 5-cut Calibration Method
« Reply #15 on: January 26, 2012, 10:52 AM »
i thought the idea behind 5 cuts was that your first cut gives a nice straight edge to put against the fence to start the 4 cut and it is also the cut to measure off

That would be a matter of stock preparation, not part of the calibration. Unless you're picking through scraps at the bandsaw, they should already have at least one straight edge.  If nothing else, it's a jointer operation. You should never cut a piece of wood on the miter saw if it doesn't have a straight edge against the fence.

Offline BCConstruction

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Re: 5-cut Calibration Method
« Reply #16 on: April 09, 2014, 11:01 AM »
hey guys im trying to calibrate my saw.

Im still confused after reading this thread

i have

0.292" to the left cut
0.299" to the right cut
total length is 8"

problem is the festool PDF calculator is not telling me how much im out in degrees

Offline Rick Christopherson

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Re: 5-cut Calibration Method
« Reply #17 on: April 09, 2014, 12:05 PM »
It gives me -0.013 for your numbers.

Offline BCConstruction

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Re: 5-cut Calibration Method
« Reply #18 on: April 09, 2014, 12:49 PM »
It gives me -0.013 for your numbers.

So is that's pretty much square then.

Offline Rick Christopherson

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Re: 5-cut Calibration Method
« Reply #19 on: April 09, 2014, 12:52 PM »
Yes. A 1/100 of a degree on a miter saw is very good and probably not worth tweaking.

Offline gkaiseril

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Re: 5-cut Calibration Method
« Reply #20 on: April 09, 2014, 05:18 PM »
See  The Five Sided Cut Method.

The first cut is to establish as straight as possible edge, eliminate the manufacturers edge. And rotate the square workpiece 4 more time so the last cut is performed on the established straight edge of the first cut. Then measure the the thickness of the cut off piece and the difference between the fore and aft ends of the cutoff is distance of the error. Because there are 4 cuts to make the square divide the difference by 4.

Remember the fist cut was to establish the saws straight edge.

You might want to check that and the other cuts with a straight edge to make sure you are getting straight cuts.

As to the calculation in the Kapex manual, make sure one is using Acrobat or Adobe Reader with JavaScript enabled on a full computer not a mobile device.

Many mobile devices' apps that can read a PDF cannot process a PDF form and even less can handle JavaScript within the form. Adobe Mobile PDF Reader and q PDF notes  work fine.
« Last Edit: April 09, 2014, 05:41 PM by gkaiseril »
George Kaiser

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Offline BCConstruction

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Re: 5-cut Calibration Method
« Reply #21 on: April 09, 2014, 05:55 PM »
Thanks guys.

Offline WoodTender

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Re: 5-cut Calibration Method
« Reply #22 on: December 06, 2016, 04:03 PM »
Festool's Kapex manual isn't clear on how to factor the length of the offcut when manually performing the mathematical equation. It just says to enter the length in the embedded pdf calculator, which doesn't work on my end.

Can anyone explain how to math works, when factoring the length into the equation?

My measurements:

Left - .374"
Right - .360"
Length - 11"

My math w/out length factored shows a .0035 error. I arrived at this by (.374 - .360 ÷ 4)

Thanks,
Joshua



Offline Rick Christopherson

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Re: 5-cut Calibration Method
« Reply #23 on: December 06, 2016, 04:25 PM »
The equation is written right above the calculator. You tried to solve it using some other calculation.

Offline Peter Parfitt

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Re: 5-cut Calibration Method
« Reply #24 on: December 07, 2016, 11:53 AM »
I would doubt that anyone would be left wondering what the 5 (sometimes called 4) cut test is about after reading Rick's excellent work in the Kapex US Supplemental Manual.

For those who prefer a demo here is one I did not long ago:



I just end up with the ratio rather than the angle error.

Peter

Offline WoodTender

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Re: 5-cut Calibration Method
« Reply #25 on: December 07, 2016, 02:51 PM »
Thanks to Rick and Peter!

Peter, your video helped to clarify what I believed to be the correct method.

In looking at my original math above, it appears that my Kapex's error is .0853

This is below the factory calibration threshold of .16, correct?

Offline Peter Parfitt

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Re: 5-cut Calibration Method
« Reply #26 on: December 07, 2016, 03:02 PM »
Thanks to Rick and Peter!

Peter, your video helped to clarify what I believed to be the correct method.

In looking at my original math above, it appears that my Kapex's error is .0853

This is below the factory calibration threshold of .16, correct?

Yes, the smaller the figure the better. I do not believe that the factory calibration is very demanding and most users should be able to set theirs up a little better - it may take a few practice goes. Just follow Rick's excellent instructions.

By the way - before I made my first Festool purchase (Kapex and CTL26 from Axminster) I did loads of research and one of the huge plus factors for the Kapex and several other Festool tools that I have purchased were Rick's supplemental manuals which included so many super tips.

Peter