What Is Wrong with my $4 MFT Square ?

[Dick Mahany]

I needed to re-square my MFT after flipping the table top. I decided to make a few MFT squares and see how well they would work.  I purchased a quarter sheet of 18mm MDF from my local home center for $15.  Then I used my trusty Parf dogs in the standard MFT holes to cut one straight edge and then a 90 degree corner.  A quick rearrangement of the dogs gave me the 45 degree orientation and voila, I had an MFT square of unknown squareness.

To check squareness I quickly made a second one and set the two side by side on the MFT table and checked every possible combination of 90 degree pairs looking for a gap somewhere with a bright light and a feeler gauge.  To my surprise, I couldn't get a 0.0015" feeler gauge in between them anywhere, and in any combination.

This is too simple to have actually worked.  What am I missing?  I realize that they're just MDF, but if I damage an edge, I can recut it square in about 2 minutes.  I can still cut two more out of that quarter sheet. Or I could laminate 2 pieces and make a tall one.

[attachimg=1]

[attachimg=2]
Any errors in squareness would appear magnified by 2x. Can't see any!

[attachimg=3]

 

[DynaGlide]

I did the exact same thing, but using a tso guide rail square to make mine

 

[mattdh]

dick- i figured out whats wrong with your $4 square. you still need to flush $96 down the toilet.  ;D

 

[Gregor]

dick- i figured out whats wrong with your $4 square. you still need to flush $96 down the toilet.  ;D

This nails it.

;D

 

[nclemmons]

Paint it red and put a price on it!

 

[Sparktrician]

My objection to 18mm, 19mm or 3/4" squares is that when the user has to square the rail to the fence for material with greater thickness than the square being used, one has to lower the rail, square up, then raise the rail, possibly inducing a minute error in squareness.  I prefer using the admittedly over-expensive Woodpeckers MFT square which is 1-1/8" high.  I've never yet needed to cut material over that height.  This gives me that ability to square the rail at the exact height I'll be cutting. 

 

[Dick Mahany]

My objection to 18mm, 19mm or 3/4" squares is that when the user has to square the rail to the fence for material with greater thickness than the square being used, one has to lower the rail, square up, then raise the rail, possibly inducing a minute error in squareness.  I prefer using the admittedly over-expensive Woodpeckers MFT square which is 1-1/8" high.  I've never yet needed to cut material over that height.  This gives me that ability to square the rail at the exact height I'll be cutting.

I share that concern.  I adopted the 8020 guide rail height track idea from [member=17701]Sean KS[/member] and [member=17453]Hal M[/member] here on the FOG, and I believe that has eliminated the squareness error due to rail height change.  Just to try it out, I think I will laminate two pieces of MDF for a total height of ~36mm on the square.  I'll have to light-weight it considerably, but I have the technology  [smile].

 

[nclemmons]

If you are worried about height, glue two together.  The squareness is still there and height is an easy challenge to solve.  You could even glue them up and then cut them to triangles...

 

[Dick Mahany]

I did the exact same thing, but using a tso guide rail square to make mine

Great alternative.  I like seeing new ways to solve problems and improve accuracy.  The rail square has the advantage of being able to use it on so many cuts whereas the MFT square that I made is pretty much a one trick pony.

 

[Svar]

Nothing wrong with it. I think woodworkers, particularly hobbyists, fetishize expensive squares.

 

[Master Carpenter]

Nice work !!! A $4 solution is un-Foglike but that square looks perfect.

I've always just used the framing square I own anyway, I've never seen the point of a special MFT square. I might make one like yours out of a scrap piece of MDF and see if it fits my workflow.

 

[Stone Message]

Try this one...


Peter

 

[DynaGlide]

I did the exact same thing, but using a tso guide rail square to make mine

Great alternative.  I like seeing new ways to solve problems and improve accuracy.  The rail square has the advantage of being able to use it on so many cuts whereas the MFT square that I made is pretty much a one trick pony.

I think you maybe misunderstood. I made a 18mm MDF square, using the TSO to cut it. I cut a perfect square 4 or 5 times, then split in in half diagonally to create two MFT squares. Then I drilled it out and used two bolts and wing nuts to hang it off the aluminum profile of one of my MFT's.

 

[clark_fork]

We can comment all day about squares but the problem is more fundamental and that is the MFT/3 drop down rail wanders. We all consciously or unconsciously adopt... " square twice and cut once." and go on the search for a squaring solution. ($$$) Simple question... Is the installation of the modified TSO GRS-16 solving rail wander? Since, with my Parf Guide System, I have other custom MFT's and the dog clips, I find myself using my MFT/3 less often because of the unreliablity of the drop down rail. I have installed that small plastic add-on to the rail that centers the front pin and that helps but I still have rail wander. What are other solutions to the fundamental problem other than this constant search for the right square?

 

[Cheese]

We can comment all day about squares but the problem is more fundamental and that is the MFT/3 drop down rail wanders.

I find myself using my MFT/3 less often because of the unreliablity of the drop down rail.

That's the reason I never bought into the idea of using an MFT as an accurate cutting station. I'd use it as a clamping, work holding, assembly station instead.

For short pieces I use a Kapex, for long pieces I use a TS, TSC or a HKC on a rail.  [smile]

 

[Svar]

We can comment all day about squares but the problem is more fundamental and that is the MFT/3 drop down rail wanders. What are other solutions to the fundamental problem other than this constant search for the right square?

This:http://festoolownersgroup.com/festo...e-rail-support-unit-rsu2/msg534256/#msg534256

 

[Michael Kellough]

We can comment all day about squares but the problem is more fundamental and that is the MFT/3 drop down rail wanders. We all consciously or unconsciously adopt... " square twice and cut once." and go on the search for a squaring solution. ($$$) Simple question... Is the installation of the modified TSO GRS-16 solving rail wander? Since, with my Parf Guide System, I have other custom MFT's and the dog clips, I find myself using my MFT/3 less often because of the unreliablity of the drop down rail. I have installed that small plastic add-on to the rail that centers the front pin and that helps but I still have rail wander. What are other solutions to the fundamental problem other than this constant search for the right square?

It should since it go wherever the rail goes.

If your concern is the slack fit of the pin in the rail slot (front rail support) then maybe the rail isn’t set up right. The rail should be sprung to the left so it fits snugly against the left side of the pin. (It can’t fit tight against both sides of the pin at the same time or it will be too tight and/or wear out the rail slot)

When I bought my first MFT 15 years ago I was surprised that the rail was installed crookedly on the hinged riser. Before proceeding further I loosened the bolts and made it parallel to the hardware. Then I slid the front riser into place against the stop in the t-slot and lowered to rail only to find it could not meet the pin.

Probably spent at least 2 hours understanding and undoing my mistakes.

Now that I understand the subtlety brilliant way Festool (rather an unknown mechanical engineer) managed 20 years ago to maximize the utility of some very simple hardware I am able to get very accurate results using the MFT for cutting.

It is a pain to have to re-square every time the height of the work changes significantly but that doen’t happen all that often. And my very old homemade square (similar to the square above) makes it pretty quick. I still check the actual cut. Even when the setup seems perfect some unknown factor can make the result a little off (depends on how picky you are) and a little shimming of the fence makes it right.

 

[Mario Turcot]

I would add a few recess magnets to hold both squares together for thicker boards. Or... I'll take Square #2  [tongue]

 

[Dick Mahany]

I would add a few recess magnets to hold both squares together for thicker boards. Or... I'll take Square #2  [tongue]

[member=66597]Mario Turcot[/member], GREAT idea!  Magnets would allow the squares to be easily separated or combined when the extra thickness is needed.  I just realized that I have a long lost assortment of rare earth magnets from Lee Valley that I can finally put to use. (Just hope I get the polarizations correct when I epoxy them into the squares  [embarassed])  Thanks for the idea!

 

[Cheese]

We can comment all day about squares but the problem is more fundamental and that is the MFT/3 drop down rail wanders.
I find myself using my MFT/3 less often because of the unreliablity of the drop down rail. I have installed that small plastic add-on to the rail that centers the front pin and that helps but I still have rail wander.

It is a pain to have to re-square every time the height of the work changes significantly but that doen’t happen all that often.
Even when the setup seems perfect some unknown factor can make the result a little off (depends on how picky you are) and a little shimming of the fence makes it right.

So for the sake of discussion, if you owned any brand chop/mitre/slider saw and every time you changed the material thickness, you’d also have to check the squareness of the chop/mitre/slider saw would that be an aggravation or just business as usual?

Seems to me that there are a lot easier ways to cut varying thicknesses of materials accurately than on a MFT.