MFT/3 Calibration - Weird Situation

[endostrat]

I am new to the FOG, but have been a Festool Owner for some time.  Recently purchased and MFT/3 and Qwas Dogs for setup and calibration.  Here is the issue that I run into:  When I use the dogs to align the fence, I never get a square cut, there is always a small amount of rocking in the board when checking for square.  I recheck alignment and nothing has changed or moved.  I wonder if my fence is bent or something?  I then take my square and align the fence to the rail, and all the cuts are square.  What gives?  Also, when I just use the dogs and eliminate the fence variable the cuts comes out square. 

Does anyone have any idea what could be going on, or what I may be doing wrong?  Thanks for any and all advice.

 

[sancho57]

I don't know what's going on in your situation. I always use a precision square to set up my MFT. That way I feel I'm getting a more accurate set up as I'm physically setting up the fence and the rail at 90.

That is what I would do is use a square as a starting point tosee if you get the same results or get square cuts.

 

[wow]

If I read your post correctly, it sounds like your MFT holes aren't square to the rail? It's easy enough to check that out, and maybe you've already done that and I just missed it?

 

[peter halle]

I am new to the FOG, but have been a Festool Owner for some time.  Recently purchased and MFT/3 and Qwas Dogs for setup and calibration.  Here is the issue that I run into:  When I use the dogs to align the fence, I never get a square cut, there is always a small amount of rocking in the board when checking for square.  I recheck alignment and nothing has changed or moved.  I wonder if my fence is bent or something?  I then take my square and align the fence to the rail, and all the cuts are square.  What gives?  Also, when I just use the dogs and eliminate the fence variable the cuts comes out square. 

Does anyone have any idea what could be going on, or what I may be doing wrong?  Thanks for any and all advice.

First, welcome to the FOG!  If I read your post correctly I don't see that when you use the Qwas dogs to align the rear fence that you then also align the rail to the Dogs in a vertical row.  If not, then that is your issue.  There is no guarantee that the hole pattern is square or parallel to the side profiles. 

There are tons of videos and ways to set up your MFT.  I will always advise that users who have dogs either use the holes for indexing and setup (Dog way) or ignore the holes and not use the Dogs (the Festool way) but not try to combine.

Here is a link to a video that I shot a while ago that some members have said helped them out:



Peter

 

[festoolviking]

Great video Peter!

I have not seen it before. I will definately try this method, thanks.

Great pun with the green cool-aid at the end.  [big grin]  [big grin]

Festoolviking

 

[papasmurff]

If you are in doubt of your square or just wish to have a verification,  take a piece of plywood approximately 14x14 trim 1 edge, then put your trimed edge to the fence and trim the next edge, continue in this manner until all 4 edges are trimmed.  Then measure your diagonals, if they are both the same you have a true square setup.

 

[ear3]

Even with the dogs there can be some imprecision, because the points of contact between the rear fence and the dogs is so small, and because the dogs can actually shift slightly when under pressure.  Also note that the rear fence can be sensitive as well.  Make sure that when you are securing the left end of the fence with the fence stop that this doesn't throw the fence out of alignment.  The fence stop has a plastic tab that fits into the back side of the fence, and if this is too close or too far away it can push/pull the fence when tightening it down.

If you have the capacity to make precise measurements, one fix would be to cut a narrow strip (1/2" to 1") whose consistent measurements you could double check with digital calipers or something, and then use that as a spacer to align the rear fence to the dogs.  This way you are assured the fence is touching all points of the horizontal line with equal pressure.

What I do now is I just have a scrap board the depth of the table with a scribe line made by a precision t-square.  Put this on the table and adjust the rail to the line. 
 

 

[endostrat]

Thanks for the quick response.  From what I can tell, is that the holes are not perfectly parallel with the sides, and it was throwing it off just that much.  I have it all aligned with the square and it is dead on.  I am not going to mess with the dogs for right now.

 

[sancho57]

Just make sure your square is a known good square like a woodpecckers square. You'll be hatin life if its not.
Dont ask me how I know that

 

[mclaeys]

This is how I ended up calibrating my table--I ended up taking a bit from everybody to set it up. I moved the 1080 guide rail supports set against parf dogs to take the "slop" out of the rail alignment. Doing this allowed me to secure with the presumption of the grid being true instead of focusing on the protractor, which I don't need.

I used Paul Marcel's idea of using the fence set back--I'll be using my table against a wall too. You'll see that I also threw on a tape that I'll use for quick setup with the flag stop and have Qwas dogs ready to go.

The main weakness here is that the fence clamps used to support the rail are not designed and meant to be used in this way and are difficult not to end up with play in them. So many that buy this table do not set it up the way Festool designed it to be used, which I assume, is that the tabletop holes are not registration points, only a method for clamping and securing work. I'd like to see Festool create a new fence clamp that will accurately secure the fence with out the angle unit.

 

[Grasshopper]

Here is a link to my method:

http://festoolownersgroup.com/festool-how-to/simple-mft3-fence-squaring-procedure/msg353938/#msg353938