MFT/3 MDF top warping

[PCROSSL1]

Does anyone have experience of using their MFT/3 in an outside unheated  workshop.  Does the MDF top warp under these conditions ?
I am contemplating purchasing an MFT/3 table after reading very many good reviews.  The only review which caused me concern was on the axminster.co.uk website – repeated below:-

"Keep it dry
……... More important is the it must be kept away from damp, otherwise the MDF top will warp alarmingly. Its something to bear in mind if its kept in an unheated garage or in site where there is a damp atmosphere."

I live in the UK and my workshop is a shed.  I heat the workshop only occasionally if I work in it in the really cold weather.  The shed is not damp but temperature will fluctuate (winter/summer)

 

[Roseland]

I looked into this a while ago.  It seems MDF doesn't mind some humidity, as long as it's constant.  It's changes in humidity that cause sagging.

And yes, I researched it because, like you, I live in the UK and my MFT is in my garage, albeit an integral garage and never heated.  Perhaps being only 300 yards from the sea my humidity problem is worse than yours.

I found my top had sagged significantly after about three years, when I flipped it over.  That must have been about three years ago and it's probably time for a change (or just flip it again!)

I think the answer may be to use an Axminster Valchromat ready made top, or to make your own using Peter Parfitt's jig from Medite Tricoya Extreme. http://www.architecturetoday.co.uk/taking-construction-storm/

I'm reluctant to brace the underside as it would compromise the positioning of clamps.

Festool have black tops in the MFTs they take on road shows, but they're not for sale.  I don't know it they are Valchromat or phenolic faced ply.

PM me if you would like any more info.

Andrew

 

[PCROSSL1]

Thanks Andrew.  Your experience is reassuring.  Like you I considered it but thought I would go ahead anyway.  Especially as I have an offcut of MDF which has been hanging around in my workshop for a while and seems OK.  The Axminister review just unnerved me a bit but given your reply and the fact that nobody else seems to have a problem I am going to give it a go and buy one.
Interesting to note that MDF does not like ‘change’ in humidity rather than the humidity
Paul

 

[Rob Z]

Paul, our MFT tops all got 'saggy' but I never knew if it was because of hard use on jobsites or because of a property of the MDF in the variable climate of being trucks, customers' garages, etc.    Now that I am doing workshop only work, with climate control, I am going to replace my tops and hopefully  they will stay flat.

Andrew--that is interesting info in that link you posted. 

 

[sancho57]

When I lived in the UK for 4 years (got backlast june) I kept my 3 MFTs (2 MFT3s and one Kapex MFT) in my unheated garage shop in Huntingdon-Cambs. I had no noticeable warpage on any of them.

Only heat i had in that shop was a small protable bench top heater I used when I was working in the shop during the winter.

 

[Gregor]

Now that I am doing workshop only work, with climate control, I am going to replace my tops and hopefully  they will stay flat.

MDF, while it has merits for certain applications, also has drawbacks - one of them is that it isn't stable when you have it horizontally, unsupported (which you have how it is used on the MFT) and is prone to sag with time.

I would suggest to simply flip the tops over when they start to sag, they'll likely straighten themselves out (till you have to turn them again)...

 

[Corwin]

Table sag was the first thing I asked about once I finally joined the FOG, and that was when the FOG was still on Yahoo. So, this is a common problem.

 

[Roseland]

Unless you only ever make vertical cuts (i.e. with the TS55 at 90°) the MFT tops are consumables.  Over time, as you cut different thicknesses and different angles the groove made by the blade gets progressively more ragged.

People have tried filling it, and then sanding it flat.  I routed a dado and made an insert in mine, but I'm not sure it was worth the effort.

My guess is that for anyone who uses theirs more intensively than a casual hobbyist will be changing or flipping the top before it sags anyway.

If you don't fancy buying a replacement from Festool, or a Valchromat one from Axminster, you can easily make your own.  You can use Peter Parfitt's jig, but if you only need one every few years that's a relatively expensive option.  I have used my MFT top as a routing template (using a copy bit) to make a replacement.

Andrew

 

[Michael Kellough]

The MFT is designed to be a portable work table. It is expected to spend much if not most of the time folded and vertical so the mdf surface would avoid the constant strain of gravity.

If you leave it horizontal for a long time the mdf will sag. Just flip it.

 

[cabin1914@msn.com]

Yes, the mfd is junk, we replaced ours after the first job with hdf. It costs a little more but is well worth it. If you don't have a cnc and want the full use, go to a cnc shop and have them make you one. Once they have it in their library, they will be easy to replace on a regular basis.

 

[Kimbo]

The MFT is designed to be a portable work table. It is expected to spend much if not most of the time folded and vertical so the mdf surface would avoid the constant strain of gravity.

If you leave it horizontal for a long time the mdf will sag. Just flip it.

My MFT is only a couple of  years old, but has spent most of its life folded and standing on a long edge in my unheated garage.  Unfortunately, here in the soggy Northwest, it has nevertheless warped.  My point is that storing it in a vertical position still subjects it to the strain of gravity.

 

[Bob D.]

The MFT is designed to be a portable work table. It is expected to spend much if not most of the time folded and vertical so the mdf surface would avoid the constant strain of gravity.

If you leave it horizontal for a long time the mdf will sag. Just flip it.

My MFT is only a couple of  years old, but has spent most of its life folded and standing on a long edge in my unheated garage.  Unfortunately, here in the soggy Northwest, it has nevertheless warped.  My point is that storing it in a vertical position still subjects it to the strain of gravity.

Maybe we could talk Woodpeckers into making a top with the standard layout of 20mm holes to fit the MFT from the same phenolic material they use on their router table tops. It should only cost a few hundred.  [eek]

I've haven't checked mine for any sag, but I have been thinking about adding some support, maybe a length of angle across the width or two pieces front to back might be better. Shorter spans would be stiffer given the same material. They might interfere with clamping but other than that I can't think of any issues. I have some 1-1/2 x 2 x 1/4" aluminum angle that might work. Thinking of drilling and tapping the leg under the top to have some jack screws or just use shims if needed to flatten it out.

 

[Jiggy Joiner]

My MFT tops and home made work tops are coated with Osmo which helps. I don’t worry too much though, when they get beaten up, I make new ones with the PGS.
Warping isn’t something I have suffered so far. My tops are used on cold wet sites, stored unheated or left in vans.
I have seen MDF tops sag but, that’s more to do with heavy items perched on them for long periods, as opposed to moisture.

 

[gronax]

My top of about 2 years old sagged which caused my cross cuts not to be square.  [mad]

I ended up flipping the top and coating with some wipe on poly.  Hopefully, that'll stop the problem from getting any worse.  Side note:  That top really soaks up the poly.  Have plenty on hand!

Square cross cuts were important for me as I was cutting cabinet pieces to length and I needed the accuracy so that gaps didn't show on the joints.

What I ended up doing that worked really well was to make 3D printed dogs that hold the work piece off the top with little EVA foam pads.  That seemingly averaged out the sag and the pads are compliant enough to give a square cut on a flat MDF work piece.  Totally solved the problem for me.  Here's my thing:https://www.thingiverse.com/thing:3749873

Subsequently I found these dogs really useful for rip cuts on the MFT.  I can lift the piece off the top and not worry about cutting up the top or more importantly the aluminum profiles  [scared].  The dogs are sacrificial and are easily reprinted if needed.

 

[jamanjeval]

My MFT is kept in a north eastern (USA) garage, vertically hanging on a wall, and I haven’t experienced any sagging of the top.

The top is indeed more sensitive to humidity than I’d like. When it was new, simply putting my forearms on the top caused it to swell significantly. It was extremely warm and my arms sweaty, but it was not like I left a standing puddle of water on it. On the advice of Peter Parfitt, I applied Osmo (I believe the one intended for floors) to the top, bottom and in the holes and I haven’t had the swelling happen again. Festool should have had a coating like this applied to the top directly from the factory.

When I replace the top, I’m going to see if I can make it out of some sort of solid surface countertop material like Corian.

 

[ear3]

I just flipped mine after 4 years, as there had developed a convex bowing on top.