# Using MDF



## spike1 (Sep 24, 2015)

I intend to use a 1" flush trim bit on 3/4' MDF. Am I setting myself up for failure or disappointment with the results?


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## RainMan 2.0 (May 6, 2014)

Welcome to the forum . I'm are the resident experts will have an answer for you shortly .
All I know is wear a good quality mask when working with mdf


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## honesttjohn (Feb 17, 2015)

+1

The only thing I've found a use for MDF is as a spoilboard on the 
CNC machine. That stuff is terrible to work with and has virtually no strength and crumbles and breaks and is heavy and ........

It was a major disappointment when I tried to work with it.

HJ

And I got 2 sheets of it in the basement


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## spike1 (Sep 24, 2015)

Thanks for the input. I wanted to use stuff I had laying around my shop and save $ on new purchases. i figured if I was careful with pilot holes and glue, that the spare MDF I had might be a decent substitute for plywood. The project is a shop vac/dust cyclone cart which won't receive a lot of abuse. We'll see. Thanks again.


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## Cherryville Chuck (Sep 28, 2010)

Mdf has it's uses but in that one I think you would be better off with ply. One of the biggest problems you would have with that is the screws holding the wheels on. It also wouldn't take bumps that well.


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## old55 (Aug 11, 2013)

Welcome to the forum.


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## Shop guy (Nov 22, 2012)

Using mdf for most things is just an invitation to disaster. I like to save money as much as the next guy and some say more than most but Mdf is not the way. So save yourself some frustration and bite bullet and buy plywood.


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## hawkeye10 (Jul 28, 2015)

This mantle clock is 100% MDF. It cuts and routs very good but when it comes to finishing there is where I had problems. It soaks up finish like crazy, especially where you rout and cut with a saw. I used Zinsser Bulls Eye 1-2-3 to prime with. You might prime twice or three times before putting on a top coat. Try testing on some scrap. If I had known about how much you need to prime MDF my finishing would have gone a lot better. I am sure you know that they have been making routed cabinet doors from MDF for years.

Zinsser Bulls Eye 1-2-3 1 gal. White Water Based Interior/Exterior Primer and Sealer-2001 - The Home Depot

You can also get this primer in a rattle can and spray it.


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## The Hobbyist (Apr 25, 2015)

honesttjohn said:


> +1
> 
> The only thing I've found a use for MDF is as a spoilboard on the
> CNC machine.


Have you tried this large sheets of flat (blue or pink) high density foam as a spoil board? They work GREAT, they save the tool, they do not add a load to the CNC machine, and they are really CHEAP when you want to do a test run in a wood-like material to make a prototype of whatever you are going to cut out of the more expensive material afterward.


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## Quillman (Aug 16, 2010)

If your 1" cutter is the standard 1/2"D trimmer with an R-3 (3/16 x 1/2) bearing on it, you are looking for trouble. Whilst that cutter is capable of wasting a lot of MDF, it will chatter the work; it deflects. Use a bigger cutter, at least 3/4"D.
Most chip/dust collectors will clog, do this outside.
In my view, it will hold fasteners acceptably, work as lab surfaces and is useful for first run templets.
Uses MDF for all sorts of applications.


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## honesttjohn (Feb 17, 2015)

The Hobbyist said:


> Have you tried this large sheets of flat (blue or pink) high density foam as a spoil board? They work GREAT, they save the tool, they do not add a load to the CNC machine, and they are really CHEAP when you want to do a test run in a wood-like material to make a prototype of whatever you are going to cut out of the more expensive material afterward.



That makes a lot of sense. Will have to try it. But I still got some scrap ply and those MDF sheets that I got to do something with. One is 1 1/4" thick.

My hunting partner had his kitchen cabinet doors made from MDF - lasted about 10 years and the edges started crumbling.

Quillman - how close to Detroit do you live? lol

HJ

Hates MDF and all that goes with it.


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## spike1 (Sep 24, 2015)

You are right.I tried it this morning and it was a disaster. i quickly decided not to let MDF touch my router bits any more. I'm buying the ply wood and dumping the MDF. Thanks.


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## Stick486 (Jan 4, 2013)

spike1 said:


> You are right.I tried it this morning and it was a disaster. i quickly decided not to let MDF touch my router bits any more. I'm buying the ply wood and dumping the MDF. Thanks.


Smart move Fred...


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## bobditts (Jan 5, 2015)

MDF routes very easy. I use it for car audio stuff all the time. You do have to have nice sharp bits though.


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## The Hobbyist (Apr 25, 2015)

bobditts said:


> MDF routes very easy. I use it for car audio stuff all the time. You do have to have nice sharp bits though.


Car audio stuff? Are you confusing MDF with particle board? They aren't the same thing.


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## jschaben (Jun 21, 2009)

Hi Fred
I've used MDF on several projects and, like most things, has it's advantages and disadvantages. Biggest disadvantage is likely the dust the stuff leaves and the tool wear. Biggest advantage is that the unmachined surfaces takes paint very well. Machined surfaces need a good coat of primer (I use Zinserr Cover stain usually) followed by a light sanding with a 180 or 220 sanding sponge and another coat of primer. 
Realizing that MDF has little or no structural strength, I won't use it for drawer or tool boxes but will use it for drawer fronts. I also like it for paint project raised panels but usually use poplar for the door rails and stiles. The advantage here is that you don't have the expansion/contraction issues you do with solid wood nor the edge grain/edge grain and inevitable void issues you have with plywood. By eliminating the expansion/contraction problems the panels can be glued right to the rails and stiles eliminating panel rattling and resulting in an extremely strong door unit.
I guess, in my view anyway, it is like picking the right tool for the job and also picking the right material. :smile:
hawkeye's clock is a great example of an appropriate use for MDF.


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## jschaben (Jun 21, 2009)

The Hobbyist said:


> Car audio stuff? Are you confusing MDF with particle board? They aren't the same thing.


I've made car speaker enclosures and even a custom shift insert from 1/4" MDF. Haven't found much use for particle board other than the occasional template or making as test fitting a piece and using that as a setup jig. :smile:


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## RainMan 2.0 (May 6, 2014)

The Hobbyist said:


> Car audio stuff? Are you confusing MDF with particle board? They aren't the same thing.


I doubt there's any place for particle board in car audio , at least I pray not .
This is the beginning of an amp rack I was building using MDF



These door pods I built are made from mdf and bondo wrapped with vinyl .


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## rcp612 (Oct 22, 2008)

I guess I must disagree with most. All but one of my mobile bases are MDF with no regrets. 
If you "size" the ends with 50/50 water/glue, and, use a lower torque on your drivers when screwing, the MDF will work very well for. And is much cheaper than plywood for shop fixtures. 
Oh, BTW, I also drilled pilot holes for all screws and added 1 or 2 drops of thin CA for extra strength.
Attached is a pic of my first shop "furniture" which, sadly had to be replaced during my downsizing. That is entirely 3/4" MDF except for 3/4" poplar blocks in each corner of the base for caster installation.
The person that bought this is still using it today making that project about 10 years old by now.


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## RainMan 2.0 (May 6, 2014)

rcp612 said:


> I guess I must disagree with most. All but one of my mobile bases are MDF with no regrets.
> If you "size" the ends with 50/50 water/glue, and, use a lower torque on your drivers when screwing, the MDF will work very well for. And is much cheaper than plywood for shop fixtures.
> Oh, BTW, I also drilled pilot holes for all screws and added 1 or 2 drops of thin CA for extra strength.
> Attached is a pic of my first shop "furniture" which, sadly had to be replaced during my downsizing. That is entirely 3/4" MDF except for 3/4" poplar blocks in each corner of the base for caster installation.
> The person that bought this is still using it today making that project about 10 years old by now.


Nice job Roger . I use 1" mdf for my work bench tops . They get sales on 4'/5' 1" mdf once in a while and it's worked great for me . I was going to use it for a router top but the guys here convinced me otherwise . I think it would be fine as long as it has support underneith to stop it from flexing , and isn't in a humid climate . 
I'm a Baltic Birch guy now though , just love the stuff !


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## honesttjohn (Feb 17, 2015)

MDF doesn't even make good insulation, any way you apply it.

HJ

+1 on the Baltic Birch


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## RainMan 2.0 (May 6, 2014)

honesttjohn said:


> MDF doesn't even make good insulation, any way you apply it.
> 
> HJ
> 
> +1 on the Baltic Birch


I wonder if I just bought one bundle , if that would quite it down a notch ? :|


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## honesttjohn (Feb 17, 2015)

RainMan1 said:


> I wonder if I just bought one bundle , if that would quite it down a notch ? :|


Nah - - that would just make us egg you on to put it up, buy more, and finish the job.

HJ


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## RainMan 2.0 (May 6, 2014)

honesttjohn said:


> Nah - - that would just make us egg you on to put it up, buy more, and finish the job.
> 
> HJ


Yes that's my concern to


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## subtleaccents (Nov 5, 2011)

For those of you that have to work with or have worked with in the past as I have, here are some small suggestions to help make it easier to complete the project. As stated by some of the members it does shorten the life of the cutting tools, makes dust collection nothing short of a nightmare and the surfaces that were machined are as porous as you can get. You can't or should I say shouldn't run fasteners into the edges (end grain if you please) because it will split even with predrilling if you are looking for the fasteners to hold.

I always used biscuits and glue at mating edes and when finishing the project I had excellent results with Sherwin Williams Sher-Wood Vinyl Sealer 24% solids. Stock codes T67 F 3 and 520-3997.
This sealed the MDF exceptionally well as a base for the top coat. 
Now mind you, this stuff is expensive. Depending on where you can get this sealer it can cost between $55 and $65 per gallon. But if you need to finish MDF this is good stuff.

If you don't have to work with this material, I would suggest not to start but you don't know when there is no choice.


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## bobditts (Jan 5, 2015)

The Hobbyist said:


> Car audio stuff? Are you confusing MDF with particle board? They aren't the same thing.



not confusing them at all. definitely well aware of the differences. MDF is popular in the car audio world for building speaker enclosures due to its low cost, density, and strength.

here is a link to a man who sells router bits that are primarily made to be used on MDF in the car audio world. http://www.12vtools.com/


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