# MDF Board Routing Question



## aandc2005

Hello, I'm going try to build a guitar speaker cabinet out of MDF in 3/4 I was going to use Baltic birch but the cost in a little to high for me anyway my question is can rout the edge of MDF board once its all together using a round over bit? or will it chip up or splinter? I ask this because I want a round edge to apply the tolex and not a square edge. many thanks in advance!:thumbsup:


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## Marv

Due to the composition of MDF it will not splinter and you will get a very smooth edge using a sharp roundover bit (I build speaker cabinets in my spare time to support my car audio habit and routinely use an 1/8" roundover bit to ease the edges of the MDF with excellent results).

http://s29.photobucket.com/albums/c258/MrMarv/?


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## aandc2005

Thanks! Those speaker cabs look great good job!!!:thumbsup::thumbsup: are all of them in mdf? also what bit should I use for the inside of the speaker hole so that rests flush?



Marv said:


> Due to the composition of MDF it will not splinter and you will get a very smooth edge using a sharp roundover bit (I build speaker cabinets in my spare time to support my car audio habit and routinely use an 1/8" roundover bit to ease the edges of the MDF with excellent results).
> 
> http://s29.photobucket.com/albums/c258/MrMarv/?


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## Marv

No problem and thanks for the compliment! Most are MDF however some are Finnish or Baltic Birch and a few are pre-veneered MDF. To make the recess for flush mounting I use either a rabbet bit or a straight bit with a circle cutting jig.


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## aandc2005

OK I'll have to get a couple of bits for the router also I went over to Lowe's to check out what they had for MDF and they have some big sheets of it I think it was 5x8 or something like that for about 27.00, not to bad:thumbsup: I wish they had some ones that were thicker like 1 3/4 what thickness are you working with? it is possible to get MDF in a thicker amount? also where are buying your Baltic birch originally I was going to use that but the price was a little to high...I still need some of that for the front of the cab



Marv said:


> No problem and thanks for the compliment! Most are MDF however some are Finnish or Baltic Birch and a few are pre-veneered MDF. To make the recess for flush mounting I use either a rabbet bit or a straight bit with a circle cutting jig.


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## Marv

I can get up to 1 1/4" MDF from my commercial supplier (as well as Finnish or Baltic Birch) and the thickness I use depends on the application. 3/4" with a 1" baffle is sufficient for most lower power/smaller cabinets however if more strength is needed and you can't get thicker MDF you can glue 2 pieces together and/or add internal bracing.


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## red

You can route mdf and get a beautiful edge, but the dust is wicked! I hope you can hook a vac up to your router.

Red


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## aandc2005

Gluing two 3/4 pieces together? should I cut my sizes first then sand one side then glue together and use clamps? or should I just glue one sheet together(alot of glue:blink will they stay glued together? Should I glue and use mdf screws also? which glue tightbond? sumo urethane? I heard that urethane glue was a better choice for mdf...??



Marv said:


> I can get up to 1 1/4" MDF from my commercial supplier (as well as Finnish or Baltic Birch) and the thickness I use depends on the application. 3/4" with a 1" baffle is sufficient for most lower power/smaller cabinets however if more strength is needed and you can't get thicker MDF you can glue 2 pieces together and/or add internal bracing.


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## Marv

aandc2005 said:


> Gluing two 3/4 pieces together? should I cut my sizes first then sand one side then glue together and use clamps? or should I just glue one sheet together(alot of glue:blink will they stay glued together? Should I glue and use mdf screws also? which glue tightbond? sumo urethane? I heard that urethane glue was a better choice for mdf...??


I typically cut my pieces a little over size, roll on the glue (I use Elmers or Tightbond), brad nail a couple of corners to keep the pieces from sliding (marking where the brads are to keep from hitting them with blade/bit later ), stack them on a flat surface, pile more MDF/other heavy stuff on top and after sitting overnight I cut them to finished size.


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## Gerry KIERNAN

red said:


> You can route mdf and get a beautiful edge, but the dust is wicked! I hope you can hook a vac up to your router.
> 
> Red


Definitely wear a dust mask. The dust from the wood products and the binding agents are very bad for the lungs.

Gerry


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## aandc2005

Yes thanks I will be useing a sas painters mask:thumbsup:



Gerry KIERNAN said:


> Definitely wear a dust mask. The dust from the wood products and the binding agents are very bad for the lungs.
> 
> Gerry


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## woodnthings

1234


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## aandc2005

*1234*

1234?


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## rrich

One other tidbit about MDF. Rub Spackle into the routed corner and sand lightly before painting. This will yield a glass smooth finish.


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## Johnny Yuma

rrich said:


> One other tidbit about MDF. Rub Spackle into the routed corner and sand lightly before painting. This will yield a glass smooth finish.


If you are going to paint it, use oil based paint!!!!!

As for thickness? 3/4 is plenty for a guitar cabinet.
For a bass cabinet or a stack, you might want to double up the baffle.


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## Colt W. Knight

I know this is an old thread, but 3/4 or 1 inch thick MDF seems like it would be a heavy guitar speaker cabinet.


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## mdlbldrmatt135

Colt W. Knight said:


> I know this is an old thread, but 3/4 or 1 inch thick MDF seems like it would be a heavy guitar speaker cabinet.


 
Ya ever picked thwem up???? they're pretty heavy


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## Burnt_Blade

Johnny Yuma said:


> If you are going to paint it, use oil based paint!!!!!


I have found that Zinsser BIN is really great stuff to seal mdf and PB with. It is a shellac based primer that you can get in either an areasol or brush on. Two coats of it on the main surfaces, more on edges, or use the drywall compound on edges...and then you can use regular water based paint and get good results.


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## Colt W. Knight

mdlbldrmatt135 said:


> Ya ever picked thwem up???? they're pretty heavy


Yes, my tube amps weigh a ton. Ive contemplated building my own amps, and I was planning on trying to use some quality joined pine or mid weight hardwood to make the cabinet to try and save on some weight. 

Nothing worse than dragging a bunch of heavy stuff on/off stage to your truck.


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## Marv

Colt W. Knight said:


> Yes, my tube amps weigh a ton. Ive contemplated building my own amps, and I was planning on trying to use some quality joined pine or mid weight hardwood to make the cabinet to try and save on some weight.
> 
> Nothing worse than dragging a bunch of heavy stuff on/off stage to your truck.


In situations where I need to reduce the weight of the cabinet I use 12-13 mm void free Baltic Birch (doubled up or 17-18mm for the baffle) and brace the panels inside to eliminate resonance. This will save you about 30% over 3/4" MDF and will be a much better choice than solid wood IMO.


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## Colt W. Knight

That looks nice.


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## Marv

Colt W. Knight said:


> That looks nice.


Thanks! :smile:


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