Securing and Squaring an MDF top to the MFT table frame

[Hotwheels]

So, I had a replacement top made for my MFT 1080 by a cabinet shop that used a CNC machine.  I unscrewed the old top, put the new one in place and used the same screws that came out of the old top to secure the new top to the frame.    After a day or so I needed to move the table and I noticed the top moving around inside the table frame.  The screws were in as far as they could penetrate the MDF, but they were not holding the top securely.  I found some other screws and those held somewhat better, but now the holes have too much play in them and the top still moves. I don't work with MDF so I am assuming I should have used some special mdf compatible screw.

It seems necessary for the top to be square to the frame and not move or else cuts will not be square. To fix this and make it work the plan is to drill and countersink a hole from the top of the table and use machine screws and a nut that will allow me to position the top square to the frame.  On the 1080 tables there is slot where the screw insets and that slot has enough play so that I should be able to adjust the top square to the frame.

Does this make sense?

 

[jeffinsgf]

If you read the manual for the 1080 (and for that matter, the MFT/3) you'll find no mention of using the dog holes to line anything up for sawing. I'm not saying you don't want your table secure, but it isn't necessary for the grid to be perfectly aligned to the frame. There's a procedure to align the fence and rail to each other. No dogs necessary.

 

[Vtshopdog]

If I'm reading right you are attaching the new top to frame with wood screws in the MDF???  Machined inserts would be stock in factory top.

For MDF try using threaded inserts (I've always called them "Hurricane Nuts"). Fairly common and should be available in multiple lengths and various machine threads.  My recollection is stock MFT uses M8 thread
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[Hotwheels]

Good suggestion about the hurricane nut things.  I just used the screws that came out of the old MFT 1080 to attach the new MDF top and those clearly were not the right screws. So, the original top is something other than MDF, maybe MDO or HDF.  I wasn't thinking, just trying to get the top secured so I can do some work.  Thanks for the help.

 

[Frank-Jan]

The mft3 tops have the threaded inserts, similar to those hurricane nuts, the older mft1080 and mft800 came attached with woodscrews (I have a mft3 and a mft800 that came with my kapex-set).

 

[Hotwheels]

It looks as if the MFT 3 uses a 15mm long Rampa M6 threaded insert, no flange.  I have not found a Rampa source in the US, but I would guess some of the E-Z LOK inserts for MDF/soft wood will work?

I have never seen an MFT 3 in person. Are the screws inserted from the underside of the table into the threaded insert?

I also discovered that apparently the hole size in the MFT 1080 and the MFT3 are not the same. At least one dog supplier indicates some of their dogs only work with the MFT3 tables.

 

[Birdhunter]

I have 2 MFT 3 tables. Mine feature 20mm holes. The top is fastened to the frame with bolts that feed from the top down to the frame. I don’t have the 1080 but I have read that it also has 20mm holes. You could Google Parf dogs and Qwas dogs to see if they are both suitable for both tables. Those are the dog brands I use.

 

[Frank-Jan]

I only have 1 mft3, according to the festool work app it's purchase date is sept 2008, they might have changed it at some point, but the top on mine is attached with bolts from the bottom into the rampa nuts in the top.

 

[Oldwood]

I think the OEM top has 6 mm inserts but these from Lee Valley, or if you could find them locally would work. They are 1/4".
https://www.leevalley.com/en-ca/sho...-quick-connect-plain-insert-nuts?item=00N1113

They have no flange, so you can run them down past flush from the top.

 

[Hotwheels]

I have an "MFT Kapex", not sure of the vintage, but it is older. Making some cuts today I noticed it has the "v" profiles along the edges and the table is secured apparently the same way as the MFT3: there are 5mm/25mm hex head screws with a lock nut that thread into a recessed flanged threaded insert from the bottom side of the table top.  The screw goes through a hole in the aluminum profile. On the MFT 1080 the screw fits into a slot that is built into the profile.  I can make this work using recessed threaded inserts and screws that are 25 or so mm.

The holes on the MFT Kapex (and I assume the MFT 3) are larger than the ones on the MFT 1080. My 1080 holes range from 19.86 to about 19.9xmm where as the MFT Kapex holes range from 19.96 to 20.01 or so.  The older Veritas Parf dogs I have measure about 19.86mm and have enough play in the MFT Kapex holes that it would be fine for clamping but not for alignment.  But, those same dogs fit snugly into the new tops I had made based on the original 1080 tops.

For me it means finding dogs that fit the 1080 size holes so I can have the option of using rail dogs, anchor dogs, and regular dogs for setting up cross cuts.

Thanks for the Lee Valley link, I will check out that option.

 

[Vtshopdog]

I wonder if the UJK parf 20mm reamer might solve your issue of differing hole sizes?
https://tsoproducts.com/tools-equipment/ujk-parf-system-reamer-for-20mm-holes/

 

[Hotwheels]

I wonder if the UJK parf 20mm reamer might solve your issue of differing hole sizes?
https://tsoproducts.com/tools-equipment/ujk-parf-system-reamer-for-20mm-holes/

I thought about a 20mm hand reamer, but there is always the possibility of introducing some error using that method.  The UJK reamer seems to have fewer human error possibilities. The other option is to just have the CNC shop make a couple more tops using the specifications for the MFT3 20mm holes.  That might be cheaper than paying for the cost of milling custom dogs or accumulating dogs that don't quite fit.

 

[Michael Kellough]

Movement of the top within the frame is a problem with the MFT1080 and 800. I never bought an MFT3 so don’t know if the stronger fastening method solved that problem. When the older style MFT is moved you do need to check square once again since the fence is attached to the MDF and the rail is attached to the frame. I just make sure to always pry the top into the same corner, then check square again if that’s important.

Seems you’re on the right track to secure the top (I think the screws held in the old top because Festool uses a better grade of MDF) but if using dogs between both tables is important I’d get the Parf reamer and use Parf dogs.