Sunday, August 22, 2010

Offcut Fence For MFT-1080 (wohoo!) Part Deux

In "Part Un", I blogged about a trivial but cool addition to my MFT-1080 that allows me to quickly get repeatable measured cuts on the off-cut side of the guide.  Thing is, this grand addition partly assumed you did the modification I did to add 4 1/2" of crosscut capacity to the MFT-1080.  Not everybody did that.  Shame on both of you. :)  VoilĂ , here, I'll show you how to create that handy detachable fence for use with the original MFT fence.

The idea of this modification is to replace the fence clamps with a block that locks into the MFT hole grid.  Here's a picture of the finished block with two 3/4" dowels in the block.  Note that the MFT holes are actually 20mm holes, but the 3/4" dowels forced to the outside edge of the MFT holes holds it very well.  The idea will be to put two #10 screws through the block laterally to grab a square nut in the back track of the fence shown behind the block (these screws grab the fence the same way the calibration block of Part Un did).  This will be clearer later.

I drilled the block by lining it up with two MFT holes under the block and the block itself being parallel to a row of holes.  Placement of the block isn't rocket science, but here's how you get the correct distance from that row of holes:
On your existing MFT fence, measure from the front of the fence to the front of the dog holes immediately behind it.  If you look carefully, I drew a pencil line at the front of those dogs.  Mine's about 52mm.

Measure the width of the extra fence you have; mine's about 35mm.  Mine is a Festool replacement from the EKAT system; read Part Un for details.  Note that it doesn't have to be a Festool fence; anything you can attach from behind will work although I had this and it uses the flag stop :)


Subtract the width of the fence from the distance in step 1. (17mm for me)

Subtract an extra 3mm (1/8"). (14mm for me)

The resulting measurement is the distance you want your block to be from that parallel row of holes.  Mark the face you have facing those holes; it will face the fence.

Use the MFT holes as a drill guide for your 3/4" Forstner bit; in this picture I show it from above.

Afterwards, push in two pieces of 3/4" dowel and glue in place.  This should be a snug it to the MFT top.

Lastly, drill holes through the block laterally for #10 screws and screw the fence in place.  Calibrate it in a similar way to the way I did it in Part Un except that you will place the block to the right of the fence, calibrate once, tighten the screws, then have a fence you can easily attach.

So the question is: why subtract the 1/8" fudge factor?  Well, it is for fudge... you don't want that fence to touch the stock in the horrible case that the fence isn't exactly coplanar and moves the stock skew to the real main fence.  By setting it back, the flag stop still engages the wood and you are good to go.

3 comments:

  • Markus said...
     

    I'm very interessted in watching your videos and reading your blog, thank you very much for sharing this information with us. One question to this: "The idea will be to put two #10 screws through the block laterally to grab a square nut in the back track of the fence shown behind the block" - Could you provide a picture to me? I don't understand how you couple the block to fence. Thank you very much and greetings from good old germany... :)

  • Paul-Marcel said...
     

    Hi, Markus,

    Well, I don't have a picture since that was to demonstrate how you could build the offcut fence for a different table like the MFT/3. I never built the block you are referring to (part one of this offcut series is the one I built and use on my table).

    All you need to do is drill 2 holes from the back of the block to the front. Next, put two #10 machine screws through the holes and thread them in to two square nuts that you've placed inside the T-track in the back of the fence. That will secure it to the block that has the dowels for insertion into the MFT table top. That's what the calculation was for: determining the size of the wooden block to get the offcut fence just slightly behind the plane of the main fence.

    Does that clear it up a bit? Sorry for not having a picture; again, those pictures were mock-ups to show how you could do it for an MFT/3 configuration; the older MFTs like mine can use the fence clamps as shown in part one.

  • Markus said...
     

    Thank you for your explanation, I think I got it now.

    Thank you again, have a nice day!