MFT3 table not cutting square--not even close

[paulhtremblay]

"The saw is not cutting consistently. After each cut, I put a square against the new cut. For example, for one test, I got nearly perfectly square cuts for the first three cuts. Then for the fourth, the cut was way out of square for no reason. "

You know that can't be true.

There are only two ways the saw could cut inconsistently.

1. The blade is loose. In that case you'd never get a good cut so it can't be that...

2. The jibs are loose so the saw is not snug on the spine of the rail allowing you to change the toe-in
    as the saw cuts. If the jibs are loose you can torque the saw clockwise or counter as you go.

If the toe adjustment is off too much you'll get measurable differences in the width of the piece if the entire blade did not pass all the way past the work. If the blade was not fully plunged before entering the work you can also get measurable differences. Keep in mind measurable does not necessarily mean significant.

Of course there is a scientific reason. I mean to say, I haven't done anything different, since I still very carefully snug the board to the fence, make sure my saw is flat on the rail, etc. The jibs are snug (checked them more than a few times), and of course, the blade isn't loose.

I have read else where that you must make sure the blade goes all the way past the work, which I think means past the second jib (green knob). If you didn't, would you leave a chunk at the end of the board?

 

[grbmds]

I doubt the blade must go all the way past the work. The cut must obviously be complete before stopping the saw and/or raising the blade.

The inconsistency would indicate some inconsistency in technique (no offense meant) or that, in the case of the bad result, movement of the wood. Was that piece smaller? Was it at least as wide as the guide rail? As I said before, I've had great success with installing additional rubber strips on the underside of the guide rail. With these, I can more easily cut pieces that are somewhat narrower than the guide rail without danger of the piece moving. Plus, the strips keep the guide rail flat on the wood if the piece is narrower than the guide rail.

I just have not experienced your problem and get consistency on my cuts. When I don't get a square cut it's because I wasn't careful about making sure the guide rail is laying tight on the wood's surface or the wood is just too narrow to cut without some other accessory like Rip Stops or additional clamping.

Try doing a simple project that that requires reasonable accuracy and squareness, maybe just a test face frame, and see what the result is. I'm a firm believer in practicing on a tool I'm not familiar with first anyway just to see what the end result really is. You may be concerned about something that doesn't affect the end result.

 

[JonSchuck]

I would say that the saw should not go all the way past the cut.  There is supposed to be a .006" toe-in so the back of the blade shouldn't be cutting anything anyway and if you go past the cut and the green jib gets beyond the end of the guide rail the saw will wiggle.

My TS55 quickly got dull and was burning the wood.  I checked the toe-in and found out I had a toe-out of .029".  No, I had never dropped the saw.  I had to fix the toe-in, get my blade sharpened and move over and re-cut all my splinter guards.

 

[Michael Kellough]

"I have read else where that you must make sure the blade goes all the way past the work, which I think means past the second jib (green knob)."

The relationship between the blade and the jibs varies with the depth setting.

There must be some inconsistency with your technique to get inconsistent results.

The jibs could be the part of the problem. If the jib is off the rail at either end of the cut then it's as if the jib setting suddenly became 2mm too large and the saw can pivot.

Are you sure the jib never left the guide rail?

Another change since the original MFT is the change in the circular saws. The old ATF saws had a continuous slot in the steel shoe and jibs that kept the side of the slot against the rail. With care you could keep the saw perfectly aligned with the guide rail even if it was cantilevered several inches off the end of the rail. This allowed you to make accurate cuts even when the guide rail was only a little longer than the work piece.

This isn't possible with the TS saws. Both jibs must stay on the rail at all times or the saw won't track correctly.

I don't think the guide rail supplied with the new MFT is any longer than the old version. If it's the same length then the actual cutting capacity (when used with the TS saw) is less than the old MFT.

 

[Michael Kellough]

I would say that the saw should not go all the way past the cut.  There is supposed to be a .006" toe-in so the back of the blade shouldn't be cutting anything anyway and if you go past the cut and the green jib gets beyond the end of the guide rail the saw will wiggle.

My TS55 quickly got dull and was burning the wood.  I checked the toe-in and found out I had a toe-out of .029".  No, I had never dropped the saw.  I had to fix the toe-in, get my blade sharpened and move over and re-cut all my splinter guards.

You are right, properly adjusted toe-in is very slight. Even if there is too much too much toe-in the cut should still be even as long as the front of the blade started the cut off the work.

If a saw has too much toe-in and the cut begins with a plunge cut then the first cut end of the board will be a little under cut. It will measure long and if it is turned to the fence as part of the 4 (or 5) cut procedure it will skew the results.

 

[Tinker]

I'm out of ideas, and don't want to start making cabinets until I am sure my cuts will come out square enough so I won't have to sweat during glue up.

...you're kidding...unbelievable.
Just make a cabinet and you will see that .05 degree is inconsequential.

Tim

There's no need to use the perimeter, just the length of the side. So you have 2 mm error over 570 mm length, or .5 mm actual error (.2 degree error before dividing by 4, or .05 degree actual error).

Your rip test at the end of the post shows some pretty good results. I would adjust for a .2 mm error and then you have a +/- .1 mm error. I really doubt you can get much better than that. Here are some things you can check for to remove any errors.

It sounds like something is moving between tests. We can rule out the fence because you are seeing movement when using dogs too. The first suspect should be the MDF top, verify it cannot move around inside the aluminum frame that holds it. Then check the clamps that hold the guide rail to the table's side. Make sure they are locked down and not slipping. Check that pin on the front one and make sure it is fitting the guide rail slot with no slop (if there is slop, try taping it for now). Next make sure the soft rubber under the guide rail is clean and gripping the test piece good. Then check the jib adjustments on the saw and be sure it is tight enough that the saw can't move sideways on the guide rail. Also verify that your saw base is sitting solidly on there guide rail and it is not rocking.  Check with a square and verify your saw blade is coming down at a true 90 degrees. Check and be sure your saw blade is mounted tight.

If all of that checks good, then I'm out of ideas. You can check with Festool to see if they have any other ideas.

I did all those tests already. (The saw went back already because of an out-of-alignment bevel; the bevel is now perfect.) I'm out of ideas, and don't want to start making cabinets until I am sure my cuts will come out square enough so I won't have to sweat during glue up.

Don't you know the Navahos, who weave some of he very finest blankets deliberately put an imperfection somewhere in their blankets.  They feel only their God can be perfect.  Mere man can never be perfect.

I like that philosophy  [smile]
Tinker

 

[NEW2FES]

I am still not sure I am buying into someone getting "0" difference in any saw with the 5 cut method. I use the 5cut to set up my miter saws as that is when it usually comes into play. When you make miter corners to make say a frame in the end the 4 cuts will form a perfect or near perfect square.

When cutting a sheet or piece of lumber rarely will you be aligning 4 or more side to make a perfect square. In ripping or crosscutting I can't think of to many cuts that would be used in that manner. You want one end to be as close in width to the other as possible.

I would simply make a cut then reverse the panel or measure edge to edge to see if there is a variance unless the cut piece is small enough to put in your caliper.

As far as getting a perfect cut well there are some fudge numbers there also. First off there is operator error or even bias as to what they are trying to find. When using a caliper on a piece of MDF or wood one can easily squeeze the piece to alter the numbers. You are also probably using a $13 Harbor Freight caliper which is somewhat accutarate but has variances. Your square also has variances. Simply walk up to your MFT and grab the rail and it moves slightly in many directions. The saw also moves on the rail.  The dogs can compress the mdf slightly. The wood can move while being cut, etc, etc

Just adding up the variances in the measuring tools would eliminate a "0" outcome in measuring. There is a huge difference in measuring a piece of aluminum in heavy dedicated fixtures where accuracy can be achieved repeatedly. There is not one time I have done a 5 cut test on a miter saw that the outcome wasn't difference in the end. The idea is to get as close as possible as due to all the variables you aren't hitting "0" every time.

No argument but sometimes guys go a little overboard with the Festool love. I do not even think Festool themselves would make the claim that the MFT can be set up to a "0" repeatable cut. There are guys chasing that with $25k 2000lb sliders.

The MFT can be set up to do very accurate repeatable cuts. Put the caliper away and simply measure end against end. By the way the humidity alone can change that measurement.

Buy a good square and understand you bought a great tool for portable cuts not a cabinet saw.

 

[tjbnwi]

It's not a 14$ caliper and it gets tested and approved by a calibration lab. I've used these measuring devices for years (at least 40) and know the feel of them.

Often in this thread I have recommended the Slop Stop, eliminates a variable.

No reason why zero can't be achieved. Is it necessary ion what we do- not really, but, the closer you are the less the error while cutting during every day tasks.

Tom

 

[wrightwoodwork]

Why no just get on a build the thing you want to do. I've never done a 5 cut test and I've got no interest in doing it. All I do is check I'm getting a square cut. That's it as long as over the distance I need does not show any light between the square and edge it's square as far as I'm concerned. Then I will cut the rest and make it up. When I make it up I will just dry assemble and as long as no visible vaults draw my eyes to that area it's fine. My guess is you are going plus or minus past the 0 point.

 

[grbmds]

Why no just get on a build the thing you want to do. I've never done a 5 cut test and I've got no interest in doing it. All I do is check I'm getting a square cut. That's it as long as over the distance I need does not show any light between the square and edge it's square as far as I'm concerned. Then I will cut the rest and make it up. When I make it up I will just dry assemble and as long as no visible vaults draw my eyes to that area it's fine. My guess is you are going plus or minus past the 0 point.

Good points. I have not found the TS55/MFT combo with fence and guide rail to be a problem with accuracy. In fact, I've found my cuts are more accurate, precise, and square that at almost any point since I started woodworking many years ago. I do check the squareness of the guide rail to the fence periodically and usually end up adjusting it, but then it's good for awhile and, so far, I have not had any problems. The same was true with my dados using the OF1400 on the guide rail with guide stops. I found the result better than any other method I've used. The only way to get used to the tools and get better at using them is to actually use them. Everybody makes mistakes and learns from them. I've found it's harder to make mistakes with the MFT and other Festools.

 

[paulhtremblay]

Update: I did two more 5-cut tests. Both tests showed the system off by .6 mm over about 600 mm. This amount than my original tests, and acceptable (maybe even good), so I wanted to update the thread.

But before I do that, I did notice something interesting. Both tests were off the same way, with the final strip wider on the non fence side. When I look at a board I have just cut, I notice that a very small amount of board (probably .1 mm) sticks out beyond the plastic cutting edge of the guide, on the non fence side. This could account for the small inaccuracy.

I wonder what causes that? I guess it is possible I tip the saw slightly to the left when I begin my cut.

 

[BUTTER]

I wonder what causes that? I guess it is possible I tip the saw slightly to the left when I begin my cut.

Even when one properly tightens the rail guides on the saw, (tighten until the saw doesn't move, and loosen JUST till it moves freely again,) the rail can flex or the user can torque the plane.  Nothing is foolproof, but this is a reminder that body mechanics play a huge role in accuracy for most things.

 

[paulhtremblay]

Even when one properly tightens the rail guides on the saw, (tighten until the saw doesn't move, and loosen JUST till it moves freely again,) the rail can flex or the user can torque the plane.  Nothing is foolproof, but this is a reminder that body mechanics play a huge role in accuracy for most things.

Very good point. I think my cuts are better now because I use a consistent, relaxed motion when sawing, avoiding excessive force in either direction.

You can only get so much accuracy. I'm half tempted to use shims and move the rail .15mm to see if I can get a perfect cut just for the sake of investigation, but fear I chase after the Holy Grail of squareness.

 

[hammer6048]

I have spent countless hours on this problem.  My thinking is that this is an inherent inaccurate tool, as when the guide is down there is slop in the slot and the tab it sets in.  I have tried to square this with precision squares, woodpecker triangle and Starrette builders square, all with unsatisfactory results.  My table is an orphan and sits in the corner, next step is to sell, sorry to say.  Using a sled on the Saw Stop for precision cuts. 

 

[grbmds]

I have spent countless hours on this problem.  My thinking is that this is an inherent inaccurate tool, as when the guide is down there is slop in the slot and the tab it sets in.  I have tried to square this with precision squares, woodpecker triangle and Starrette builders square, all with unsatisfactory results.  My table is an orphan and sits in the corner, next step is to sell, sorry to say.  Using a sled on the Saw Stop for precision cuts.

You might want to read the rest of this thread plus view some YouTube videos on the subject. The "slop stop" insert (might have the name wrong) for the guide rail is a good investment. Other than that, I have never really experienced these problems, even using a much less accurate square than a Woodpecker. Any of the dogs may help, especially lining up the fence as the first step so that everything is square to the MFT holes. Others have great advice in this thread and other threads on the FOG. I must admit I'm puzzled by your problem as the MFT coupled with the fence and guide rail is one of the most accurate tools I've ever used.

 

[Tinker]

I have a Hitachi 8-1/2" SCMS. It takes me longer to check and align that than it takes to align my ATF 55.  Now I have a new TS 55REQ, I seem to have little problem when making picture frames.
With the SCMS, I sometimes need to pinch in the last corner with clamping.  I have only made one picture frame since I got the TS 55 and that seemed to be dead on at the last corner. With the MFT and RMW's dogs.

Maybe it was just luck. My Dear Aunt used to tell me, "Ignorance is bliss."  Maybe she was right
Tinker

 

[grbmds]

I don't think any luck was involved. I did a picture frame using a set of dogs (not RMW) as a fence for the 45's,  cut with the guide rail which was set square to the fence on the MFT/3. They were the most perfect mites I've ever done. I also used a Hitachi 12" SCMS with digital read-out for many years. The miters were never that good even with periodic squaring. I'm always mystified when I see posts concerning out of square cuts. Are they perfect? I don't know, but my eyes and assemblies don't see the difference between perfect and the actual so I  believe the amount out-of-square is so small it's undetectable.