The penultimate fence for a MFT 1080 (or two)

[greymann]

Why "penultimate"?  As I searched the previous FOG postings I found that "ultimate" seems to be taken for most any situation one could imagine.  I also want to leave room for inevitable improvements to be made by others.

I was just recently able to find a second MFT 1080 which works great in my shop.  While trying to adapt the great single MFT setup work done by Steve Adams and Paul Marcel and others to work with two MFTs that I showed in two earlier posts, I made an accidental discovery that only works on the MFT 1080.  If this is already known, I apologize in advance but I couldn't find any reference to it on the FOG.  I had both 40 series and 60 series aluminum extrusions for testing and almost by accident set the 40 series on the MFT top rail.  I noticed that the The slots almost perfectly lined up.  It turns out that it is the almost that makes all the difference. 

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Here you can see, if you look very closely, that the lip of the extrusion closest to the table top just extends over the edge of the MFT slot. 

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When a fastener is tightened, the extrusion is pushed tightly against the the edge of the top which is just as precisely and squarely cut as are the holes.

The closest analogy I can think of is like drawboring a peg to tighten a tenon, back before the domino that is.  The point is that the extrusion is now referenced to the edge of the top and not to the table rails which are most usually not square to the top.

The process of putting this together involved drilling some holes in the extrusion.  I initially intended to fasten only to the MFT that held the guide rail but later found that the implications of this application went much further.

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Here I show the holes and fasteners I used. 

The tricky part is lining the fasteners with the holes in the extrusion. 

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Sliding them on one at a time and securing them each with a screwdriver as I went worked for me.

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Because the edge is as parallel/perpendicular as are the holes, this results in a fence as square to the rail as I can measure. 

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My remaining problem was that I couldn't find a commercial flip stop to work with that setup.  A metalworking friend replaced the too long arm on this Rockler flip stop with this and I additionally have a threaded hole to make a micro adjuster.

Now, at least for me, it really gets interesting.  Since as I said, I had just gotten my second 1080 I drilled more holes in the extrusion and connected it also.  I also added a second extrusion on the other side of the MFTs and pulled them together with a few clamps underneath.    I got out my dogs and started checking the result.

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I found that the second table was also square with both fences and that a floating bar crossing both tables was square to the rail anywhere it was placed.  To me it seems that the tables are not merely connected, they are joined.  This leaves me with the largest cutting area I think I can get from two tables.  I think this will also be very useful as an assembly table for squaring up parts.

A final use for the bars on opposite sides of the table is shown below.

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Here you see the chop saw I use while waiting for it to die so I can drink more Festool cool-aid.  I often want to make additional use of the MFT surface but don't like to leave something this heavy sitting on the MDF for very long.  Now I don't have to.  It is just sitting unsecured in this photo but I now have a number of more permanent jigs planned.

I know most of you have moved on to the MFT/3 but I hope there are still some of you who will find this interesting.

Dick

 

[Theshipstore]

Dick. This is a great idea and awesome usage of 1080 stock. I like the idea a lot and I am going to try and implemented this on a pair of MFT's. I use 1080 materials a lot on my MFT's,  one of mine is setup strictly for door assemblies .
Thank You for this idea

Sal

 

[Corwin]

One problem some of us have had is that the side profiles are not plumb with the top, requiring that anything bolted to the profiles be shimmed...  I gather that your tables do not have this issue.

 

[greymann]

Corwin, Maybe I didn't say it well but the relation of the profiles on my tables to their tops is no different than yours or I suspect anyone else's. The point is that the extrusion is forced against the top and is therefore plumb with it and doesn't depend on the relation of the profiles to the top.  Its what I'm trying to show in the first and second image and also in the eighth and ninth.  The tightening of the bolts makes the gap disappear.

Dick

 

[Qwas]

Corwin is right, on my MFT, in the upper right corner, there was an 1/8" gap between the side profiles and the MDF top. The rear profile and a side profile were too long. I disassembled the entire MFT to remove the profiles and cut about 1/2" off them and re-installed. It took several hours to accomplish and I'm not sure it was worth the effort but at least now I know my top and profiles are aligned.

 

[Corwin]

Corwin is right, on my MFT, in the upper right corner, there was an 1/8" gap between the side profiles and the MDF top. The rear profile and a side profile were too long. I disassembled the entire MFT to remove the profiles and cut about 1/2" off them and re-installed. It took several hours to accomplish and I'm not sure it was worth the effort but at least now I know my top and profiles are aligned.

While my top(s) also have this gap around their perimeter, that was not what I was referring to.  Both of the 1080s and my 800 all have profiles that do not sit plumb with the top.  The cast corner pieces were not formed accurately enough where the profiles bolted up.  This inaccuracy causes all of the profiles to bolt up such that they are out of plumb -- they all lean outward.  While not a big deal for most uses, it did prevent me from wanting to mount my Incra Incremental Track directly to the profiles in a similar fashion to what Dick has done here. 

Dick, I see now what you were trying to describe, and am rather surprised that you can tighten up the mounting bolts and have your fence align to the edge of the top rather than to the top of the profile.  It has been some 5 or 6 years since I have attempted to mount a fence to the top of the profiles, but as I recall, this mounting location proved less than ideal when working with larger (heavier) pieces as they could knock the fence out of alignment -- but then, that is problematic no matter how you mount a fence to the MFT.

 

[greymann]

I consider this a happy accident that it works for me.  I also have a gap along all edges between the profile and the top.  Both of mine seem to be closer to 1/16" and fairly consistent all around.  It is the amount that the 80/20 40 series extrusion overlaps the table profile and the size of its T-slot in relation to the MFT profile slot that makes this work.  As I thought more about how to describe why it works, I came up with this.

Suppose that you took the MDF top off and repeated the experiment.  Now the 80/20 would be free to tighten down and would stay aligned with the table profile below.  If you measured the distance between the two extrusion inner edges you should find that the distance is slightly less than the dimension of the MDF top.  However with the MDF back in place the extrusions are constrained to just snug up against it and therefore be plumb to it rather than the profile below.

In my experiments I found for my table how near a thing it was in that if I rotated the extrusion 180 and had a T-slot facing inward, there was a small but measurable lack of squareness.  The only explanation I can come up with for it is the fact that the T-slot edges are beveled inward 2 degrees and that small difference makes the method fail.  I also would be skeptical about any other brand of extrusion, or even the 80/20 15 series working here as the tolerance is so close.  Maybe someone else can try.

Corwin,  I found the fence to be remarkably secure.  I think it has to do with using the 80/20 fasteners instead of a M8 nut in the Festool profile.  If you look at the second photo I think you can just see the sides of the fastener protrude through the thin dimension of the Festool profile and contact the 80/20 slot edges.  Also the M8 flat head bolts nearly fill the top of the 80/20 slot.  For instance, I don't think an M6 bolt would work.  Finally, I stayed away from the "light" versions of the extrusion.  I wanted as much strength and rigidity in the extrusion as possible.

Dick

 

[suds]

Wonderful.  I have two 1080's and a small area to work in so these will come in handy.  Thanks for sharing.

 

[greymann]

Suds and Sal

I hope this works for each of you as well.  I'm very interested in knowing if this is one off or works in general.  I only have my tables to play with.  Also since I got into this game late, well after the 1080 was discontinued, my tables gotten through the aftermarket are probably very late production runs.  My first 1080 was on consignment at my local dealer and looked like it had the original top flipped once and the second table from a FOG member was almost pristine.  It might be that earlier tables that the longer term members have may have had QC problems later corrected.

Please let me know either by posting or PM how it went.

Dick

 

[suds]

Where did you purchase the aluminum extrusions?

 

[greymann]

There are two sources for surplus.  They are the only ones I've found that sell single pieces.  Search for "80/20 ebay" and "80/20 amazon" and you will find them.  The stock at each is different and varies from time to time.  When you get the extrusions, make sure to get any connectors (and bolts if you don't have a local source) you need at the same time.  Otherwise shipping costs will kill you on the small parts.  After some experimenting, I've stayed with the M8 x 1.25 thread size as it is the largest that will fit the 40 series and therefore forces the parts to center better.

Hope this helps.

Dick