# MDF router table, warping, continuing saga



## phillip.c (Aug 9, 2012)

Hello,

I would like to build a router table out of MDF. I already started, actually, with some difficulties. 

First, naturally, the MDF was not perfectly flat. This was a pain at first, but I soon resolved to simply flatten it using my router and skis. It was flat, for about one day. 

How should I seal the MDF to prevent warping?

After I apply this seal, can I use this as a ready-surface?

I know that formica is often used, but I can only buy the stuff locally in a 4x8 sheet, and I'm really not hot on that idea. 

Last, can I plan to plunge route the exact height of my mounting plate? I REALLY don't want to use leveling screws, they have the habit of working their way out of level. 

Thanks,

Phillip


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## Semipro (Mar 22, 2013)

Welcome to the forum Phillip
First not big fan of mdf for table top,you did not say what thickness you are using?
If it was me I would glue two pieces together and make top 1 1/4" to 1 1/2" thick,next seal both top and bottom of mdf . You may router the insert correctly but mdf is still a wood product so it will swell and move ,you may still need to adjust the insert will have no way to do it ( this is only my opinion it by no means it is the only way)


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## phillip.c (Aug 9, 2012)

What should I use instead of MDF? I am frankly very unhappy with my results thus far and I am pleased to try some other material.

If I used cabinet grade plywood, would it swell and shift like the MDF does? To what degree?


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## JOAT (Apr 9, 2010)

phillipdanbury said:


> What should I use instead of MDF? I am frankly very unhappy with my results thus far and I am pleased to try some other material.


I think if I were making another, from scratch, I'd probably prefer a solid core door. But I'm not, so I'll stick with what I've got - my table is over 10 years old, the top is 1/2" plywood, and the router plate the same. No problem with warping. However, under is a virtual spiderweb of 2X4 pieces, so it is very well supported. All glued together with Titebond II, except for the bolts holding it to a shelf, at a height I can sit using it. Nothing fancy, no bells, no whistles, no T-tracks, no train tracks, just the top. If I need a fence for something, that's what 2X4s and clamps are for. I tried MDF for a project, once, and decided I didn't want to mess with it again.


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## Cherryville Chuck (Sep 28, 2010)

I made my table top out of 5/8" melamine coated particle board with grooves in it for t-track but I put cross pieces like Theo did and after 3 years it is still dead flat. If you have milled your mdf to uneven thicknesses I would toss it and start over but attach to a good support frame with cross supports as close to the router as is practical.


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## Mike (Nov 22, 2004)

Phillip, have you read the sticky threads at the top of this section?


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## phillip.c (Aug 9, 2012)

Indeed I have, just wanted to see if members have had particular problems with warping and sealing, and if these problems have simple solutions. 

From what I gather from both the stickies and feedback, I may be better off using birch plywood rather than MDF.


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## mpIX (May 30, 2013)

phillipdanbury said:


> Indeed I have, just wanted to see if members have had particular problems with warping and sealing, and if these problems have simple solutions.
> 
> From what I gather from both the stickies and feedback, I may be better off using birch plywood rather than MDF.


I must admit i haven't read the sticky's however i do use a high grade multi ply Russian Baltic Birch for loudspeaker cabinet building. Some of the backloaded horn designs have a labyrinth of passageways and can be quite complicated builds. The one thing i always have to go above and beyond to control is warpage of my stash of 5'x5' sheets i like to keep on hand. Baltic Birch Plywood will warp fast if not stored right. we prefer BB ply because the quality stuff is dense, void free, it also is very stiff for given amount of material vs. MDF, i.e. to reach the level of stiffness of one 18mm BB panel out of MDF would require 1.5" thick MDF (we almost all agree MDF is crap, we'd sooner use chip board). Many like minded builders are accomplished professional cabinet makers, we're not just making this up as we go along.

The Birch plywood from Home Depot is a mixed bag and def lower quality. Some has many ply's others don't. The inner ply's are poplar not birch. The stuff from Lowe's is even worse. 

States Industries Apple Ply is also a high quality product, kind of the american equivalent of Baltic Birch ply, but at a premium. the stuff is crazy expensive. 

I think as others already said, if using a wood product a engineering system of bracing will be your best bet. 

Good luck with your table.


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## rwbaker (Feb 25, 2010)

Nothing wrong with MDF as long as, all exposed surfaces, are sprayed/brushed with a water proofer such as shellac before working it. After a 1/2 dozen tables, for a 1/2 dozen people, (3/4" shellaced, glued to 1 1/2" and Formica or aluminum tops) all sold by word of mouth, I have never had one warp and it has rained the last 21 straight days in Matthews, NC. MDF like all bonded wood products including marine plywood and Masonite are hydroscopic and must be protected from moisture (humidity) in a non-stable shop environment. I order 8 sheets at a time and the first chore is to spray / brush / roll a 3 pound cut on all exposed surfaces, do this and avoid water based glues on MDF and you will not have any issues. Like Mike, this comes up on a regular basis and has been answered several times and should be under the tabs.

It is not the MDF with the problem, if it did not work then why would so many manufactures use it - Baker


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## harrysin (Jan 15, 2007)

Like Richard I always seal MDF with Shellac if I'm not going to laminate it. Kitchen cabinet shops usually have a skip out the back and it's surprising the size of some of the off-cuts of Laminex plus other goodies.


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## DaninVan (Jan 1, 2012)

"It is not the MDF with the problem, if it did not work then why would so many manufactures use it - Baker"

-It's cheap
-no grain
-the surface is smooth and defect free
-did I mention that it's cheap(er)?


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## MikeMa (Jul 27, 2006)

If you are going to go with "birch" plywood, I STRONGLY recommend Baltic Birch Plywood. You may need to shop around for it in your area as Lowes and Home Depot tend not to carry it. The stuff is a much higher quality, including typically being very flat, and a true 3/4" thickness. It also tends to be heavier as well (almost as heavy as MDF) which is beneficial for a RT top as well.


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## Willway (Aug 16, 2012)

Any table will have a tendency to warp even cast iron if it is unsupported. The best way to stop warping is proper support, and sealing all surfaces. If you just look at the Router Workshop table that Mike keeps mentioning the design itself shows why it doesn't warp. This table could be built entirely out of MDF without warping, if it was entirely sealed.The same is true with a router table cabinet. If properly designed it will provide full support and make it almost impossible for the top to warp. It is easy to pull warp out of an existing piece of MDF or plywood with level and true support under the table. Even some cast iron tops use angle iron underneath not only for mounting but to also provide support. When using MDF you have to seal every bare surface and try to use a non water based glue. The cutout for the router can be sealed and hardened with HotStuff CA glue. This stuff is not expensive around $10 for 2oz. on Amazon, which is a heck of a lot of super glue. For a comparison a bottle of LocTite from Lowe's or Home Depot is $5 and only contains *.14oz*.. This stuff will stop any kind of wear on MDF, like keeping the leveling screws from eating into the MDF. Just something to think about when building a table.


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## retired doug (Oct 10, 2010)

*another material option*

I made my router table top out of 2 pieces of 3/4" mdf laminated together, sealed with shellac and topped with 1/2" Corian sheet. A member of our scroll saw club gets pick up loads of Corian cut offs free and distributes them to the members. You could even laminate 3 or 4 sheets of Corian for a solid plastic top. Remained dead flat for the last 6 months in Coastal southern California.


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## Cherryville Chuck (Sep 28, 2010)

Willway said:


> Any table will have a tendency to warp even cast iron if it is unsupported. The best way to stop warping is proper support, and sealing all surfaces.


Exactly right. Any type panel will bow if it is unsupported over too far a span, even with no extra weight applied. They weren't engineered to do that. Even mounted vertically they can bow between 24" centers. I don't necessarily agree with the need to seal the panels although I don't live where it is very humid all the time. If the panel is securely attached to a good support frame with short spans between supports then I don't know how it can warp. I attached my 5/8" particle board top to a 1 x 4 pine frame with glue and biscuits and it has stayed dead flat.


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## MAFoElffen (Jun 8, 2012)

NiceG316 said:


> If you are going to go with "birch" plywood, I STRONGLY recommend Baltic Birch Plywood. You may need to shop around for it in your area as Lowes and Home Depot tend not to carry it. The stuff is a much higher quality, including typically being very flat, and a true 3/4" thickness. It also tends to be heavier as well (almost as heavy as MDF) which is beneficial for a RT top as well.


Just a thought. I use 3/4" marine plywood for my machine tables. The kind I get is with a synthetic layer on the shell plys (top & bottom). lots of layers (11 plys for 3/4"). Not bothered by moisture. Strong. Never had one warp.

My router table is 1 layer 3/4". My worksite multi-tool table is single ply 3/4". My RAS Table is 2 ply 3/4" each + a 3/8" sacrificial.

Very slick surface if waxed. Still slick if not... and it wears well.


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## Mike (Nov 22, 2004)

I think Formica is the best surface for a router table because it wears well, wipes clean with a rag and a shot of window cleaner, and most importantly will not transfer to your wood which creates problems when you stain/finish. It seems most major router table manufacturers agree with this.


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## MAFoElffen (Jun 8, 2012)

Mike said:


> I think Formica is the best surface for a router table because it wears well, wipes clean with a rag and a shot of window cleaner, and most importantly will not transfer to your wood which creates problems when you stain/finish. It seems most major router table manufacturers agree with this.


I have to agree with you Mike. I would have said Marine was the same, just as good... But...

I get alot of mine as salvage and if new, there's a lot of shipyards around here and a mill close. I just looked at prices out of this area... Boy, twice as expensive. I couldn't afford to do that if not where I am. Formica on birch would be my choice then.


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## charles543 (Jan 19, 2013)

How about a torsion box table top?


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## phillip.c (Aug 9, 2012)

I'm not sure what a torsion box table top is, perhaps you would post a link?

I have actually resolved to use a different material. I have a couple boxes of leftover hardwood flooring from a friend's project that I will be gluing together and surfacing. I will also support the top sufficiently to prevent weigh-dependent sagging. 

Thanks,


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