# Routing MDF



## Zurt (Oct 27, 2010)

I tried to route some box joints on 1/2" mdf just to test the bits. The joints get falling apart so I assumed that box joints and possibly dovetails are not a good idea for mdf.

Is this something I'm doing wrong or is this something that's not possible?

I was thinking of veneering mdf and using that to make boxes as it would be a lot less expensive then using "real" wood.


Burt


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## Tempest (Jan 7, 2011)

The center core of MDF is very soft so I doubt dovetails would work with regularity. If the pins are larger than typical pins it might. Same goes for box joints.

I would use pins no less in size than the thickness of the material.

You will see the MDF core at the ends whether the face is veneered or not.


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## Tempest (Jan 7, 2011)

Forgot to add that you should be using high quality double grind MDF for this type of operation as it will have less tendency to powder and break.


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## Zurt (Oct 27, 2010)

Where do you get that and what's the cost like? Around here, I can only get the run of the mill Home Depot/Lowes stuff. Even then, Lowes rarely has MDF believe it or not.


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## jlord (Nov 16, 2009)

There's mdf & mdf light.


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## jschaben (Jun 21, 2009)

jlord said:


> There's mdf & mdf light.


I'm kinda the same boat as Burt... There's MDF-HD.... H(ome) D(epot) period. No idea what grade it is and asking anyone at the store gets a look like ya got a third eye or something. Any way of determining the difference?


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## bobj3 (Jan 17, 2006)

The light is the same as PLYWOOD, "thickness" just like the candy bar same price but less in the package..


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## jschaben (Jun 21, 2009)

bobj3 said:


> The light is the same as PLYWOOD, "thickness" just like the candy bar same price but less in the package..
> 
> 
> ===========


Hi Bob - the stuff I get calipers out to 3/4" when I buy 3/4" so I'm OK there. What got me wondering is using the sagulator link for determining shelf length or something, it has 3 choices for MDF; LD, MD and HD. It also has 8 variations of particle board. Nothing I've looked at seems to be labeled, at least in any way that I recognize as a grade..


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## Zurt (Oct 27, 2010)

I'm with John on this. Same exact results also with 1/2" & 1/4". For the most part, this stuff does what I need it to do. Making joints is something I'd like just for testing purposes.


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## Tempest (Jan 7, 2011)

Try and look up wood supply houses in your area that cater to cabinet shops. The Borgs won't carry the good stuff. My favorite is Plumb Creek MDF II which is a very nice double grind MDF. Dense and heavy, but strong for MDF. There are other brands out there as well.

MDF lite is less dense than typical MDF which makes it lighter but not as strong. It will be the same thickness as other MDF of a given size. Often used for vertical/ceiling paneling and other low wear areas. Also for CNC tables since it allows more air flow.


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## Phil P (Jul 25, 2010)

Quite frankly I cannot see the point of trying to make a box or for that matter a dovetail joint in MDF. The material simply doesn't have the structural strength to support such techniques, in fact much of its limited strength is in the skins where it is denser. MDF is a wonderful material, I use it almost every day in one form or another, but it is best jointed with simpler methods such as biscuits, screws, Domino loose tenons, loose tongues, etc where minimal disruption of the surface layers yields acceptable results 
ues


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## bobj3 (Jan 17, 2006)

Hi Phil

I use MDF for Box joints but not for dovetails, once it's glued up it's very strong 
I like to use it for small boxes/drawers ( 1/4" to 1/2" Thick MDF ) with the bit below.


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Phil P said:


> Quite frankly I cannot see the point of trying to make a box or for that matter a dovetail joint in MDF. The material simply doesn't have the structural strength to support such techniques, in fact much of its limited strength is in the skins where it is denser. MDF is a wonderful material, I use it almost every day in one form or another, but it is best jointed with simpler methods such as biscuits, screws, Domino loose tenons, loose tongues, etc where minimal disruption of the surface layers yields acceptable results
> ues


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## Zurt (Oct 27, 2010)

I have a lot of scrap mdf. I also have an Incra Ultra so I'd like to practice using the mdf scraps. That's what started this whole thread. I have a lot more mdf scraps than hardwood so it would be a lot easier then trying to dimension the various unmatched hardwoods.


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## Ralph Barker (Dec 15, 2008)

I'm not sure how to gauge the different MDF grades, either, but choose the finest particle size that's available. 

As for using MDF for practice, it's good to remember that MDF is tough on bits, due to the high glue content. Poplar may be a better choice for this purpose. Keep the MDF for jigs, templates, and such, where its properties are more consistent with the requirements.


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## paulfinlay (Jun 19, 2010)

hi mdf is to soft and will not work very well for box joints.


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## bobj3 (Jan 17, 2006)

Hi Paul

I have made many,many,many boxes (from 1/4" to 3/4" thick) with MDF and cabinet doors and face frames as well and it's very strong once it's glued up 

MLCS Raised Panel Carbide Tipped Router Bits 2
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paul finlay said:


> hi mdf is to soft and will not work very well for box joints.


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