# MDF vs. Plywood for jigs, table tops etc.



## roer

Hi

All of us want the table top for our router table to be dead flat and our jigs and fences to be 100% straight. For that we need stable wood that remains as stable as possible under different humidity. The preferred material seems to by birch plywood, but why is MDF (or laminated MDF) so seldom the preferred choise ? As I know MDF is should be even more stable than birch plywood, or ???


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## Cosmicsniper

Actually, MDF is probably preferred by more people for such things than plywood just because of cost. High quality birch plywood is great if you can afford it, but MDF works very well too. Unless your workshop is underwater, the MDF should be plenty stable.

I think some people avoid MDF because of the nasty dust it generates when you cut it…not because of stability issues.


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## Bertha

I use MDF sandwiches because the edges are friable. Nothing wrong with MDF in my book!


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## LeeBarker

And the dust issue is blown way out of proportion. Yes, the dust is bad, but simple precautions are all that's required. It's a great product, widely available, reasonably priced, easy to work, and usually delightfully flat. Put on the mask and cut, that's my thinking.

Kindly,

Lee


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## woodklutz

The problem I find is attaching it. What method do you guys use to joint. I use dry wall screws and they tear out.


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## DrDirt

I like the stability of the MDF - perhaps weight factors in as well - but jigs and templates stay nice and flat. I have a tablesaw sled made from birch ply and it warped a bit - - just enough that there is a "bump" or ridge between the left and right sides of the kerf.
Next one will be MDF - but it always seems that more attention is spent to make the NEW stuff than going back and remaking the old.


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## jonasramus

Both plywood and MDF have there pro's and con's. Generally the best idea is to pick the one appropriate for the application.

MDF Pro's: very stable, very flat, less expensive than high quality plywood
MDF Con's: it is not as strong as plywood of the same thickness, it does not hold screws well, it swells terribly if it gets wet, the edges get easily damaged, it's damn heavy.

Plywood Pro's: is usually stable but can cup or warp, it can be purchased in a wide variety of veneers to match you project, it hold screws very well
Plywood Con's: it's very expensive if you buy the good stuff, it needs it's edges covered if the pc is for show


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## Bertha

Clutz, I usually glue and pneumatically pin it for jigs. If I need screws, I usually use fine Kregs. I have a tendency to use Kreg screws for a lot of non-pocket applications.


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## GregD

I have problems keeping the moisture off MDF jigs. It gets hot in my garage (Houston) and sweat becomes an issue. Things I care about get a coat or two of poly or I start with melamine and edge band any exposed edges.

IMHO MDF is more flexible than flat, so I usually plan for some structure to give it good support.

woodklutz - I use Kreg's pocket hole screws mostly and drill a pilot hole at least part way. I also do the final tightening slowly by hand - they go from tight to blown out real fast. I don't expect MDF to conform nicely to a flathead screw, so I would drill a countersink and use a conventional flathead wood screw before trying drywall screws.


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## LeeBarker

MDF glues easily. I would not recommend screws into the edge. Perhaps a staple as a clamp. Biscuits work splendidly. Or you can cut a kerf and make 1/8" spline stock out of plywood.

As soon as you try a mechanical fastener in the edge, you're running a strong risk of changing that dimension.

Performax screws are the right ones if you insist, but then you gotta buy the $25 bit.

Kindly,

Lee


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## LeeBarker

Confirmat, not Performax!


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## Bertha

Lee's got drumsanders on the brain


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## LeeBarker

It's the constant drumming, not the sanding, that makes me weird, Al.


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## NBeener

With MDF, I've had great luck using Spax screws.


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## azor

Does anyone make a confirmat or spax screw in a 1 1/4" length, #8, 7, 6


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## BillWhite

I have used Extera (exterior grade) MDF with great success. More expensive than the regular stuff, but is almost bullet proof. I even used it on porch columns of a home. Won't work UNDER water, but it sure does not vary with humidity.
Check it out.
Bill


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## 000

I don't like it because router bearings start to compress into the edge and get deeper with each pass. I usually will band an edge when possible. I have no problem screwing to the face, I never try to screw into the edge.

5 year old thread to look for confirmat screws, but whatever. :>/


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## ThomasChippendale

Looking at the expansion coefficient, MDF is less stable than birch or maple plywood and its been my experience. It is also vulnerable to water exposure and acts like a sponge. I use it mainly for single use templates because its cheap but each time I use it I dislike the dust and the fragility and promise myself I will never use it again, but I do because I cannot find anything cheaper.


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## Finn

I use MDF


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## lateralus819

Having worked in an enviroment where my employer goes through at least 15,000 sheets a year, and seeing how prone it is to failure, I use it very minimally.

If you're going to build something to just sit or one time use its fine but other than that it is plywood for me!

I've actually had good luck with some ply from HD being stable. Others not so much.


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## bondogaposis

I use MDF a lot, my entire router table is built from it I also have several workbenches where it is used for the top. It is a great vibration dampener and that is why I used it for my router table. I live in a dry climate so moisture has not been a problem for me. It has great compression strength but not so much tensile strength, it has it's place in the right application.


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