Are MFT 20mm holes subject to degrading ? ?

[Slappy]

would the MDF in a MFT top 20mm holes  degrade in size  (wow out or enlarge ) the more the holes are used with these  Qwas , Parf , Ripdog,  type of dogs, the Festool low profile clamp as well  ? 
MDF is Not the most stable product for repeated pressure applied to it's  edges .
I always wondered what the " Use Of Life Range" of the holes would be  under constant use  ?  ?
as certain holes on the top would be always used more than others . 
Is the MDF in a Festool  MFT top different than just typical MDF ? OR is it HDF instead ?
I was gonna ask this in the Rip Dog Redux thread but didn't want to Hi-Jack the thread .

So to be polite I ask the question  here  [cool]

 

[Qwas]

After 5 years of use, I've not seen any degradation. I've mounted dogs to 80/20 extrusions to use as a fence and then smacked them 2x4s, 2x6s, and even 2x12 lumber. No signs of degradation or turning into ovals. I have not seen the holes change due to using just the dogs with the same abuse either.

I'm sure if someone tried long enough and hard enough, they could succeed but normal use, or heavy use, should not be an issue.

Some of these auto-adjust Bessey clamps can put some tremendous force in a concentrated area. I've played with putting dogs on these clamps but I haven't been happy with the looks of the holes afterward. If you want to use that style clamp, I recommend using the Seneca Woodworking MFT Clamp Dog. Senaca Woodworking

To be honest, I don't use the same holes all the time. If my workpiece is only 12 inches wide, I move the dogs down closer to the bottom of the table so I don't have to stretch as far for each cut. Also, I spread the dogs as for apart as possible, so a short board might have a dog under the guide rail and another dog 1 or 2 columns away, and for a long board I will move the dog down to the far left column. That's the beauty of the dogs, they are so easy to move.

There have been discussion about the grade of MDF used on the MFT. I've heard it's a special grade but have no way to prove it. I don't know anything about the different grades either. I do know the MDF is pretty much temperature and humidity stable and I have not seen the holes change size at all.

 

[rmwarren]

Great question. Based on a quick test it looks to me like there is a slight enlargement. The first/last hole is the one I commonly use for the rip dog.


Probably not enough to impart any noticeable error when the dog is secured with a knob.

My use could probably be considered "normal" and I have used the rip dogs exclusively for almost 2 years.

RMW

 

[Qwas]

The video doesn't prove much, that change could be less than 1/2 of .001" and you would get that result. I've never been fond of tall dogs because they can act as a lever and forces applied to the top of the dog will be multiplied at the bottom of the dog.

 

[rmwarren]

I didn't say it proved anything, rather it seems to indicate that hole is slightly larger than every adjoining hole.

RMW

 

[Steve248]

I believe that the MFT uses HDF which is their own special recipe manufactured for them.

I have read this somewhere in the forum but unfortunately do not have the thread.

 

[GarryMartin]

It's been mentioned several times in different threads, but I believe the original source of the comment on a "special mix" similar to HDF is ccarrolladams - see http://festoolownersgroup.com/festool-jigs-tool-enhancements/where-can-i-get-custom-cnc-mft-top-in-s-new-jersey/ for one example thread.

 

[grbmds]

I guess you'd expect there to be wear with constant use. It's metal rubbing against "wood". It didn't seem like there was enough wear in the video to make a difference in accuracy. It would be like any tool. If it's used continuously or frequently, there will be wear on parts which are wearable.

 

[rmwarren]

I guess you'd expect there to be wear with constant use. It's metal rubbing against "wood". It didn't seem like there was enough wear in the video to make a difference in accuracy. It would be like any tool. If it's used continuously or frequently, there will be wear on parts which are wearable.

I think in my case it is likely the lever action Qwas mentioned below, but that is a guess. When the tall dogs are secured from below I have not noticed any effect on the cuts made using them to position the guide rail.

For the record I am not an engineer, machinist, or otherwise expert in any of this, I just play one on internet forums...  [doh]

RMW

 

[leer]

For holes that get repeated use, you could swab fine CA (cyanoacrylate, or Super Glue) in the holes to toughen them.  Any roughness that might cause a dog to not slide in easily can be removed with a rolled piece of sandpaper. Use a Q-tip to swab the hole.  If you try to apply thin CA vertically down the hole, it will be like pouring water into the hole, and will run everywhere.

I use CA to toughen spalted wood to be turned on a lathe.  I've saturated pieces that felt light as balsa and would crumble in your hand if squeezed.  After applying CA and allowing to harden, I turned them like a normal chuck of wood.