MFT and Guide Rail Alignment

[Qwas]

I decided to flip the MDF top and started thinking (oh oh, trouble...). The MDF top is perfectly square and the holes are aligned perfectly in reference to the sides. So why not align the guide rail so it is square to the front side of the MDF top? It is easier to use a framers square here since the square's edge is slightly raised on the guide rail and sits above the radius bottom edge of the guide rail.

Better yet, you can use the holes in the table top to align the rail. Example is shown in another post further down in this subject.
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And now you can align the auxiliary fence to the guide rail (actually, you don't even need this fence anymore unless making angled cuts). Now everything on the table top is squared. I can now use bench dogs in a vertical row of holes (Rockler example) as a board stop and get a perfect parallel cut. Simply slide the guide rail down to where the cut needs to be made. Oh yeah, get rid of those guide rail clamp stops on the sides of the table (you know, the ones the factory says don't move).
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Or, I can make a parallelogram and make parallel cuts. Simply keep the  parallelogram closed and cut the first edge, open the parallelogram and make my second cut. My parallelogram was made out of some excess T rails I had sitting around (it is 8020 Inc. part numbers 25-5013 and 25-2514) and some aluminum bars with holes on 2 inch centers. The 1/4-20 bolts are slightly long so they go through the nut and bottom out in the stock rather than holding the top bar tight.

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While I had the top off, I decided to route a 1/4 inch dado into the top edges of the MDF top. I can put an aluminum bar into the slots and use these as an auxiliary fence. More on this later. I'm waiting on some parts to show up.
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Before this, I always aligned my guide rail to the aux fence but I knew the aux fence was not square or parallel to the table top. The holes were only good for clamping. But now, I see a whole new world opening up.

Is this setup something I missed when beginning, or did everyone else miss this too?

 

[cdconey]

From what I recall when I bought my MFT a while ago, I set up the guide rail parallell to the right edge of the MFT & squared the fence to the guide rail.  I still do it that way, and don't have many issues.  Makes sense to me, it's quick, accurate, and repeatable. 

 

[Dave Rudy]

Early on on the old forum there was extensive discussion about different ways to square the MFT.  Your ideas (especially the routed insert idea) are brilliant, as we have come to expect.

One question is this -- isn't the really important right angle in cutting that between the fence and the guide rail?  In other words, can't you cut in any orientation relative to the edges of the mft tabletop or exterior rails so long as the guide rail and fence are perpendicular?

Put it another way.  If the guide rail is exactly parallel to one edge of the MFT surface and exactly perpendicular to the other, but the fence is off slightly, you will still not get a square cut.  IIRC, that's where the discussion went a long time ago -- that repeatable squaring depended on two movable (adjustable) surfaces more than on referencing with respect to a known edge or fixed surface.  That's why the MFS (or your parallelogram) is such a help -- because it is an easy and quick way to achieve true square between fence and guide rail.

Have you thought about routing another groove at the top of the table (perpendicular to the one you already did)?  With two fences set to the table at exactly 90 degrees, it would be a simple matter to use the parallelogram to square the guide rail at any location along the table and have repeatable square cuts.

Dave

 

[Qwas]

One question is this -- isn't the really important right angle in cutting that between the fence and the guide rail?  In other words, can't you cut in any orientation relative to the edges of the mft tabletop or exterior rails so long as the guide rail and fence are perpendicular?

Dave

For the past year that is how I have been squaring - paying attention to the aux fence and ignoring the rest of the table. If I needed to crosscut a narrow board, it went up against the aux fence, bring down the guide rail, and stretch across the table to make the cut.

Now I keep the guide rail aligned with the table top. Slip a couple of bench dogs into some holes in the middle of the table (running parallel to the table front), bring down the guide rail, and make the cut. No stretching. The bench dogs can act as my aux fence wherever I put them.

Have you thought about routing another groove at the top of the table (perpendicular to the one you already did)?  With two fences set to the table at exactly 90 degrees, it would be a simple matter to use the parallelogram to square the guide rail at any location along the table and have repeatable square cuts.

Dave

Exactly. I have routed the groove on both sides and the back side of the table where the old aux fence would be. Now I can cut boards up to 29 inches wide by not having the MFT aux fence on the table top. On the far back corner (farthest from where the guide rail normally goes) I can have that exact 90 degree corner. This corner can also be used for gluing up cabinets or anything else requiring a perfect 90 degrees.

Also, I can use any set of holes, my bench dogs and parallelogram, to square up the guide rail.

On the table side with the rail guide close by is where I prefer to use the parallelogram. And by using the parallelogram (or sliding an extrusion onto) with the aluminum strip, I can rip boards and know they have a parallel edges. Before cutting I remove the parallelogram (and/or extrusion) so I don't have to worry about trapping a board and have it come shooting out at me. My next to last picture shows an example with an extrusion on the aluminum strip.

 

[Qwas]

Here is an example of crosscutting using the bench dogs in the middle of the table.

 

[mhch]

    Isn't this a  bit similar to the MFT squaring jig described by Jerry Work in his "Getting the most from Festool MFT".
    Two kind of wooden arms,

    .    one kind can be attached anywhere on the MFT thanks to the 20mm holes,
        This is not different from using bench dogs fitted in the MFT holes

    .  the other kind can be attached to the upper T track of the MFT side rails.
        This is a bit like fences sliding in the routed dados.

  Same idea, different implementations ?
   
 

 

[Qwas]

Yes, it is a similar idea but it goes much farther. I have used Jerry's idea (thanks Jerry) and that was some of the inspiration.

But this is a whole way of thinking of the table. The holes are no longer a "convenience" for clamping, but useful for for cutting and holding boards for cutting.

Perhaps my next post will help.

 

[Qwas]

Perfect Miter Cuts!

Need some quick, good miter cuts? Just install the bench dogs into holes at 45 degrees.

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Cut your board.

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Move your bench dogs to the opposing 45 degrees and cut.

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Very quick and very near perfect.

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No stumbling on setup, or measuring of angles. Just fast, simple and easy. This took about 1 minute.

Try it for yourself, you will be surprised!

 

[mhch]

  That's the great idea: using the hole pattern in a different way !!
  60 and 30 degree angles also become easy (use a 2 x 1 ratio).

 

[Qwas]

Yes, you're catching on! We're not paying $86 for a piece of MDF, but for precisely aligned holes and perfectly square corners. We need to take advantage of that.

I thought the same thing about the 30 and 60 degrees but when I measured the angles it came out to something like 25 and 72 degrees. I need to look into that one some more. Might have been something in my setup.

The more I think about it, the aux fence becomes an obsolete item, rarely needed anymore.

 

[mhch]

    When posting a few minutes ago I hesitated mentionning that the angle accuracy
    could be impacted by the fact that bench dogs have a size and thus the side of
    wood pieces is not exactly located at the center of the MFT hole,

    I was going to make an experiment, but your measurements confirm the issue.

 

[Qwas]

My mind is reeling with ideas. I'm having to break away from the old ways of doing things.

Here is one of them - I no longer need a square when working with the table. When I need to align the guide rail, simply stick some bench dogs in a set of holes (as an example let's say the 3rd set of holes in from the right), loosen the guide rail clamps, slide the guide rail against the bench dogs, tighten the guide rail clamps. I can remove the bench dogs and use them in another set of holes (running horizontally) to make a perfect crosscuts or perfect 45 degree miters. In fact, this might be more accurate than trying to use a square to set the guide rail.

And my squares can be checked at any time by placing it in a corner of the MDF top or by using bench dogs set up in an "L" shape.

I have run into some dried up glue in my holes so I always prefer to use 3 dogs to verify any edge.

 

[mhch]

  Further on this thread of ideas, I' ll modify my homemade wooden
  arms, similar to those suggested by Jerry Work using the threaded
  rod connectors, so that each will have 3 connectors properly
  located (for either parallel installl to the MFT sides and for
  the 45 degree angle install).

  Plug the arm, position the rail, unplug the arm.

  While on this topic ....
  Jerry suggests to use standard bolts with a epoxied washer to
  screw the connectors from below the MFT. I found that starred
  plastic bolts M10x30 with a 60mm threaded rod are available
  from online vendors. They are very similar with those provided by
  Festool to install the fence, and are perfect to solidly fix those
  arms to the MFT.

  I'm not sure the URL of my french provider is of interest here,
  but I can provide it for those interested.

 
 

 

[Qwas]

    When posting a few minutes ago I hesitated mentionning that the angle accuracy
    could be impacted by the fact that bench dogs have a size and thus the side of
    wood pieces is not exactly located at the center of the MFT hole,

    I was going to make an experiment, but your measurements confirm the issue.

I checked everything today and used a trigonometry calculator. The correct angle should be 26.5 degrees and that is what I got. It would be 30 degree if the longest leg is 2.

I also confirmed that I can use the bench dogs to align the guide rail. Worked perfectly!

Let me know how you make out with the wooden arms. I'm thinking of using a t-slot instead of the wooden arm.

 

[mhch]

I checked everything today and used a trigonometry calculator. The correct angle should be 26.5 degrees and that is what I got. It would be 30 degree if the longest leg is 2

Let me know how you make out with the wooden arms. I'm thinking of using a t-slot instead of the wooden arm.

Could you please elaborate a little bit. I'm not too sure
I understand the 26.5 degrees and 30 degrees stories in your sentence.

 

[Qwas]

The wooden arms? That was from your post,

   Further on this thread of ideas, I' ll modify my homemade wooden
   arms, similar to those suggested by Jerry Work using the threaded
   rod connectors, so that each will have 3 connectors properly
   located (for either parallel installl to the MFT sides and for
   the 45 degree angle install).

   Plug the arm, position the rail, unplug the arm.

   While on this topic ....
   Jerry suggests to use standard bolts with a epoxied washer to
   screw the connectors from below the MFT. I found that starred
   plastic bolts M10x30 with a 60mm threaded rod are available
   from online vendors. They are very similar with those provided by
   Festool to install the fence, and are perfect to solidly fix those
   arms to the MFT.

   I'm not sure the URL of my french provider is of interest here,
   but I can provide it for those interested.

I was curious how that worked out for you.

 

[Michael Kellough]

Perfect Miter Cuts!

Need some quick, good miter cuts? Just install the bench dogs into holes at 45 degrees.

I applaud what you are trying to do, it's a very good idea to align the guide rail to the holes so you can make use of the grid for alignment of the fence or work pieces, but I have a couple of concerns.

1. Those Rockler bench dogs have posts that are just under 3/4", extremely loose in the 20mm holes of the MFT. I don't think I could trust that kind of fit for alignment.

2. I've never found a carpenters square that was really square, inside and outside edges, simultaneously.

But it is working for you anyway?

 

[Qwas]

I applaud what you are trying to do, it's a very good idea to align the guide rail to the holes so you can make use of the grid for alignment of the fence or work pieces, but I have a couple of concerns.

1. Those Rockler bench dogs have posts that are just under 3/4", extremely loose in the 20mm holes of the MFT. I don't think I could trust that kind of fit for alignment.

2. I've never found a carpenters square that was really square, inside and outside edges, simultaneously.

But it is working for you anyway?

I'm not pleased with the Rockler bench dogs but they have been working extremely well. Even though they fit loose, when you press a board against them they don't rock like you think they would. I'm trying to find something closer to 20 mm (like a bolt). The picture of the 2 cut miter boards put together didn't come out real good, but you can slide a paper into the joint about an inch. I blame that on the Rockler bench dogs. Also, at that time I was still learning. I think by using the bench dogs to align the rail to a set of vertical holes before making the miter cuts would have helped also.

I have 2 carpenters squares that seem to be dead on. I learned to take a machinist square into the store and compare before buying. I had to go through about 20 squares before I found a good one.

I can't believe how well this is working out and why I never thought of it before. I think it needs some fine tuning (like better fitting bench dogs) but I see a day when everyone will be using this method.

 

[Steve Jones]

The fixed part of the clamping elements are great bench dogs for the MFT, it's worth having a couple of sets 'cause you get four clamps out of the deal too. (of course at $84.00 a pair they're a bit steep)

 

[Qwas]

Thanks Steve. I have 4 of them sitting here.

I will need to measure the distance the face sits out from the hole and make sure it is consistent, but I'm sure it will be.