Author Topic: What is a “reasonable” out of square angle?  (Read 2323 times)

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Offline Alt

  • Posts: 8
What is a “reasonable” out of square angle?
« on: April 09, 2019, 07:31 PM »
Hi,

I have a new MFT 3 and set it up with a Starrett combination square hardened steel head using he standard method (as per Festool’s video); I double-checked with an ECE square as well. When using the 5 cut method to check the square I was unable to do better then an 1.22 mm error in a 440 mm long cut.
Should I be concerned?

Thank you,

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Offline Dick Mahany

  • Posts: 547
Re: What is a “reasonable” out of square angle?
« Reply #1 on: April 09, 2019, 07:53 PM »
Is that 1.2mm before or after you divided the total error by 4 ? If it is before, then the total out of squareness is really 0.3 mm over 440mm.  In my experience with my MFT3, I had at least that amount of squareness error introduced simply by changing the height of the guide rail due to the design of the Festool brackets. 

A search through this forum will yield many discussions about optimizing and maintaining MFT3 squareness and many creative folks have developed solutions that are more repeatable than the OEM  Festool design will yield.  Your question on what is acceptable will really be dependent on what you are building.

BTW welcome to the FOG. Great helpful and a ton of experienced folks here  [welcome]


Offline ChuckM

  • Posts: 1318
Re: What is a “reasonable” out of square angle?
« Reply #2 on: April 09, 2019, 07:59 PM »
1.22m sounds way too much. If divided by 4, it gives 0.3mm or 0.012". This is what Gary Katz says about his error finding on his mitre saw:

"My DeWalt produced a piece that was off by .010 in., meaning that each cut would be out of square by .005 in. in a full length cut. Five thousandths of an inch might not sound like much, but a gap that size in a mitered casing joint is visible from four feet away."

Did you follow the calculations like this?



« Last Edit: April 09, 2019, 08:11 PM by ChuckM »

Offline Michael Kellough

  • Posts: 4312
Re: What is a “reasonable” out of square angle?
« Reply #3 on: April 09, 2019, 08:15 PM »
Is that 1.2mm before or after you divided the total error by 4 ? If it is before, then the total out of squareness is really 0.3 mm over 440mm.  In my experience with my MFT3, I had at least that amount of squareness error introduced simply by changing the height of the guide rail due to the design of the Festool brackets. 

A search through this forum will yield many discussions about optimizing and maintaining MFT3 squareness and many creative folks have developed solutions that are more repeatable than the OEM  Festool design will yield.  Your question on what is acceptable will really be dependent on what you are building.

BTW welcome to the FOG. Great helpful and a ton of experienced folks here  [welcome]

This is why someone like Anderson should make a thicker square, tall enough to maintain good contact with both the fence and an elevated guide rail.

To the OP, no matter how good your combination square is it simply doesn’t have enough contact with the fence and rail. Continue with the 4 cut process (use Rick’s calculator in the Kapex supplemental manual) until you get as close to dead square as you want. Then save that final square corner as your reference for setting the fence square to the rail in the future.

Offline Alt

  • Posts: 8
Re: What is a “reasonable” out of square angle?
« Reply #4 on: April 09, 2019, 08:28 PM »
Many thanks for the welcome and the quick reply!
It is 1.22 mm over 440 mm. This compares “poorly” with a very nice document prepared by William Ng on the 5 square cut check on the MFT.
Specifically, my error angle is much worse than what Ng obtains (my 0.22 degrees versus  his at 0.016 degrees). Thus, no matter what I build my error is just too much.

I am beginning to think that my Starrett square head does not have long enough sides and will try to borrow a Woodpecker 1281.

Best regards,

Offline Alt

  • Posts: 8
Re: What is a “reasonable” out of square angle?
« Reply #5 on: April 09, 2019, 08:39 PM »
1.22m sounds way too much. If divided by 4, it gives 0.3mm or 0.012". This is what Gary Katz says about his error finding on his mitre saw:

"My DeWalt produced a piece that was off by .010 in., meaning that each cut would be out of square by .005 in. in a full length cut. Five thousandths of an inch might not sound like much, but a gap that size in a mitered casing joint is visible from four feet away."

Did you follow the calculations like this?



William Ng’s document on 5 cut on the MFT, which I used, is identical. Thank you!

Offline pixelated

  • Posts: 185
Re: What is a “reasonable” out of square angle?
« Reply #6 on: April 09, 2019, 09:01 PM »
I just finished setting up my new MFT and making some test cuts. The best square I had on hand was my 12 inch Brown & Sharpe combination square, it worked fine for squaring the rail to the fence and my 4 cut test was accurate to less than 1mm.

One thing that I found helpful in the process was after checking and adjusting things with the square, I made measured rise and run marks on the rail and fence then measured the diagonal and compared that with the calculated value. Doing 3, 4, 5 makes it simple, but I used an arbitrary number set with a story stick. (I have a calculator that has the calculation programmed). Doing that gives you a larger "virtual" square.

Did you check your square for squareness before starting?

Offline kevinculle

  • Posts: 301
Re: What is a “reasonable” out of square angle?
« Reply #7 on: April 10, 2019, 09:03 AM »
I assume you have checked your squares by drawing a line perpendicular to a straightedge, flipping the square and drawing a second line very close to the first.  The lines should be parallel and you can easily see even a minute deviation from parallelism.  I have seen postings suggesting that even Starrett squares have been found to be out of square new and should be checked.

Offline Alt

  • Posts: 8
Update - Re: What is a “reasonable” out of square angle?
« Reply #8 on: April 11, 2019, 02:22 PM »
Hi,

I have a new MFT 3 and set it up with a Starrett combination square hardened steel head using he standard method (as per Festool’s video); I double-checked with an ECE square as well. When using the 5 cut method to check the square I was unable to do better then an 1.22 mm error in a 440 mm long cut.
Should I be concerned?

Thank you,

In retrospect the problem may have been a combination of over-analysis and error on my part.

Rick writes in the Kapex supplemental manual:

"The factory calibration threshold is ±0.16°, but this calibration procedure is capable of measuring errors as low as ±0.001°, which is nearly impossible to obtain in actual practice." My expectations were immediately reset.

I redid the alignment and the 4-cut square checking.
My "new" measurements yielded -0.05 degrees, compared to William's 0.0158 degrees.
Also, it felt like a bonus, I got the same accuracy when using Festool's bench dogs instead of the MFT/3 fence.

Thank you all for helping me out!

Offline grbmds

  • Posts: 1929
Re: What is a “reasonable” out of square angle?
« Reply #9 on: April 12, 2019, 09:46 PM »
One thing I always keep in mind is that, if I check a 90 degree corner with a square I trust and can't detect any noticeable out of squareness, it's  square. If I can't see it using my Woodpeckers squares, then it most likely won't make a difference when I'm assembling a box, cabinet, or piece of furniture. The wood will move depending on different levels of moisture in the environment in which it finally sits.
Randy

Offline TheSergeant

  • Posts: 100
Re: What is a “reasonable” out of square angle?
« Reply #10 on: April 13, 2019, 12:09 AM »
I'd recommend buying a slop top for your guide rail.  It removes the play where the track meets the locating pin.

People don't mention this frequently enough but you need to re-square everytime you adjust the height.  Also, check your fence and make sure it's straight.  I've had 3 MFTS and one had a bowed fence.  If you use a small square to square it, it'll look square but then when you cut a longer panel it won't be.

To be honest though the Festool system isn't ideal.  There's a user here that was making/selling a nice kit but it escapes me at the moment.  There's also a very nice DIY solution using dovetails in the MTFC thread.  It's maybe 4-5 pages from the end.  You'll have to scroll through.


Offline Jiggy Joiner

  • Posts: 822
Re: What is a “reasonable” out of square angle?
« Reply #11 on: April 13, 2019, 07:34 AM »
Acceptance if something being out of square really depends on what’s being built?
If it’s a section of stud work or boxing in etc, probably not the end of the world but, with cabinets, boxes and furniture etc, no, well at least not for me anyway.

The MFT is designed so that set up properly, it will give square cuts, or at least very close to how square precision work commands.
If I go to the trouble of cutting rough sawn timber, planing it, and running it through a thicknesser, when it lands on the MFT, I want to know my cut will be square.

It only takes minutes to square up the MFT, so don’t settle for less.

Offline Sanderxpander

  • Posts: 397
Re: What is a “reasonable” out of square angle?
« Reply #12 on: April 13, 2019, 10:51 AM »
It's all a matter of degree, literally. Nothing physical is ever truly square in the mathematical sense.

Offline Peter Parfitt

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Re: What is a “reasonable” out of square angle?
« Reply #13 on: April 13, 2019, 12:26 PM »
Hi @Alt

Festool make no claim for the accuracy of the size of the holes in the MFT3 nor the accuracy of the layout. As far as they are concerned it is a work holding and jig fixing bench with quite separate arrangements for cutting using a tracksaw.

It was the variation across a range of MFT3s that drew me to conceiving the Parf Guide System in order to have an accurate layout and consistent hole size suitable for tracksaw with guide rail againt tall dogs type cutting.

See this video from 12 minutes 40 seconds for a 5 cut test that gives a result of 0.00016 radians (0.0092 degrees):



Peter

Offline jobsworth

  • Posts: 5925
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Re: What is a “reasonable” out of square angle?
« Reply #14 on: April 13, 2019, 12:45 PM »
@Peter Parfitt

Peter ya need to have a dab of mustard on your shirt to look more professional

Offline fshanno

  • Posts: 984
Re: What is a “reasonable” out of square angle?
« Reply #15 on: April 13, 2019, 01:50 PM »
I have an idea.  Go buy a small manufactured RTA cabinet, maybe from the dent and scratch section at Ikea.  Then use one of the sides of that to set up your MFT.  That should settle it.  Your MFT setup will be based on squareness good enough for case work.
The one thing we learn from history is that we never learn from history.

Online Cheese

  • Posts: 6622
Re: What is a “reasonable” out of square angle?
« Reply #16 on: April 13, 2019, 03:10 PM »

Festool make no claim for the accuracy of the size of the holes in the MFT3 nor the accuracy of the layout. As far as they are concerned it is a work holding and jig fixing bench with quite separate arrangements for cutting using a tracksaw.

It was the variation across a range of MFT3s that drew me to conceiving the Parf Guide System in order to have an accurate layout and consistent hole size suitable for tracksaw with guide rail againt tall dogs type cutting.


This is exactly the conclusion one of the Woodpeckers engineers came to. He took 2 MFT tops he owned and he also purchased a new Festool MFT top, placed each one of them on their in-house Vision System and measured the diameter of the holes and the location of the holes. He remarked he was very surprised how much the 3 MFT tops varied dimensionally. He told me he considered the top useful for clamping purposes only.  [sad]

Offline Jiggy Joiner

  • Posts: 822
Re: What is a “reasonable” out of square angle?
« Reply #17 on: April 13, 2019, 06:27 PM »
When/if using the protractor set with the MFT, I use a thick assembly square and check with a rule using the 3-4-5 method. This usually produces square cuts, well at least acceptable square, as I’m relying on the square actually being square, and the rule markings being accurate.

As for the dog holes, when I do square cross cuts or rips, I use the extra offset holes on both edges, that I added, as in Peter’s video also with the PGS. I also have a few cutting station tops I knocked up with the PGS, they mostly just have a few holes for straight cuts, and basic angles.
I also have the TSO guide rail square set, GRS-16 and GRS-16 PE. They make life a lot easier too, very quick to set up, and remove any doubt.

Offline grbmds

  • Posts: 1929
Re: What is a “reasonable” out of square angle?
« Reply #18 on: April 13, 2019, 11:47 PM »
One thing I always keep in mind is that, if I check a 90 degree corner with a square I trust and can't detect any noticeable out of squareness, it's  square. If I can't see it using my Woodpeckers squares, then it most likely won't make a difference when I'm assembling a box, cabinet, or piece of furniture. The wood will move depending on different levels of moisture in the environment in which it finally sits.

Anything that is checked with a Woodpeckers square that is square is square and I use either a 1281 or my MFT Square to check square. If I can't see any gaps with those squares it's square and that is certainly good enough for cabinets, square joints in furniture, and any other precise, accurate woodwork.

While the MFT and miter fence are certainly not perfect, I check those for squareness before making any final cuts with my MFT Square and the result is as square as I've ever gotten with any other method; "squarer".
Randy

Online Cheese

  • Posts: 6622
Re: What is a “reasonable” out of square angle?
« Reply #19 on: April 14, 2019, 12:14 AM »
Anything that is checked with a Woodpeckers square that is square is square and I use either a 1281 or my MFT Square to check square. If I can't see any gaps with those squares it's square and that is certainly good enough for cabinets, square joints in furniture, and any other precise, accurate woodwork.

As long as the Woodpeckers square has been previously checked against a known standard. I have had a couple of their products that weren’t spot on. They were sent back and the situation was immediately remedied. Great customer service.  [thumbs up]

I keep a Starrett 12” master square as a standard that I perform a quick QA check on any new precision measuring instruments that I purchase.

Offline Alt

  • Posts: 8
Re: What is a “reasonable” out of square angle?
« Reply #20 on: April 14, 2019, 12:53 AM »
I'd recommend buying a slop top for your guide rail.  It removes the play where the track meets the locating pin.

People don't mention this frequently enough but you need to re-square everytime you adjust the height.  Also, check your fence and make sure it's straight.  I've had 3 MFTS and one had a bowed fence.  If you use a small square to square it, it'll look square but then when you cut a longer panel it won't be.

To be honest though the Festool system isn't ideal.  There's a user here that was making/selling a nice kit but it escapes me at the moment.  There's also a very nice DIY solution using dovetails in the MTFC thread.  It's maybe 4-5 pages from the end.  You'll have to scroll through.
Thank you for the suggestions! I forgot to mention that the slop-stop was already installed. Also, I did use the Starrett to check that the fence is straight. I did hear about the need for re-squaring upon height adjustment but, so far, after careful checking, I have not experienced it. My 4-cut test piece is 17"x17", which I understand, should be sufficient. My main concern is mitered joints for edges on the order of 18".