mdf or plywood

[Nefesis]

i am planning on building a cab next week and wondering whether to get mdf or plywood. i heard 3/4" mdf was really heavy, so i was wondering whether
1. does it have to be 3/4"
2. is plywood lighter than mdf and as sturdy?

[FractalWalk]

MDF isn't heavy, it is EXTREMELY FREAKIN' heavy. It doesn't have to be 3/4" but even 5/8" is ridiculously massive.  

Plywood is sronger and much lighter than MDF, but it can be little bit harder to work with depending upon what you're doing.  It's also easier to finish MDF (i.e. paint, laminate).

I like MDF for small projects, but If I were to build another cab, I'd use plywood.

[Sylentwulf]

What I'm planning, personally, is 1 sheet of 3/4" MDF, and 2 sheets of 3/4" finished grade plywood.

The MDF is going to be for the control panel, and misc. stuff, the plywood is going to be the side and as much other easier stuff I can do with it.

[Nefesis]

Sylentwulf: are all of the sheets 4' x 8'? i might do 1 sheet 4 x 8 of mdf and the other two of plywood, or else all 3 plywood. have some scraps of plywood lying araound, but it's probably only 1/2".  thank you.

[OSCAR]

I wouldn't build an entire cab out of 3/4" MDF again.  It was way too heavy and I didn't find much benefit to using it over plywood other than the initial cost of the wood.

Most people that complain about working with plywood are likely referring to cheap pine plywood that has a rough finish.  That leads to either lots of sanding and primer coats to get a halfway decent paint finish, or you figure in the cost of laminate and skip the paint.  What I've used on a couple cabs is a good birch/maple plywood (~ $30 for a 4'x8' sheet) that has a very smooth finish which is easy to paint and leaves a great finish with very little work.  I've also found that a good oil based enamel leaves the best finish with a roller because it takes longer to dry and self levels quite a bit better than water based.

Here is a pic of a cab that is made of 3/4" birch plywood with 1 coat of primer and 1 coat of yellow enamel.  I didn't have to prep the wood surface at all other than run over it real quick with 400 grit sand paper prior to the primer coat.  It turned out with an incredibly smooth finish and is probably the best paint job I've ever achieved on a cab.

[JustMichael]

Where's the sideart?  

[Apollo]

You're right I used plywood which was a great choice but I had constuction grade lying around already so I used that. I can't get the surface as smooth as I wanted it so next time I would buy furniture grade plywood. MDF is a pain in the ass IMHO.

[OSCAR]

Where's the sideart?  

On my to-do list...  I haven't had it printed yet.  

It's ready to go and on a CD, I just haven't sent it out.

[Nefesis]

i will probably be using plywood then.

[REBIRTH]

I would recomend plywood as well - a good maple/birch plywood (cabinet grade) as Oscar suggests.  Plywood is actually easier to use (just drill/screw away, MDF you have to make sure you pilot hole every screw, etc), is lighter than MDF, and will last longer than MDF (if the cabinter is going to get banged by vacuum cleaners/kids/etc).  Not that MDF is bad, but I would go plywood every time.  

[MonitorGuru]

Actually, my local Menards sells both oak laminated pine plywood as well as oak laminated MDF.  The plywood is about 72# per sheet (48x96) and the MDF is 96# per sheet (49x97).  So it's about 32% heavier.

[Nefesis]

does anyone know if 3 sheets of 1/2" plywood would work?

[paigeoliver]

You don't want to use 1/2", as I don't think they make t-molding to fit that size. Use 3/4".

I actually recently started building a cabinet from scratch (yes me, the eternal convertor is actually building a cabinet from scratch).

Despite the fact that I always scream about using plywood, I looked at furniture grade plywood at the hardware store, and then looked at the price of MDF, and ended up buying MDF.

Man, is it heavy. But it was fairly easy to deal with. We cut my side panels both at the same time using a cordless saw. Had to clean one part up a bit (gave me an excuse to buy a sander anyway), but overall the sides came out great. Routed them for molding with my new router. I used an 1/8" 3 wing slot cutter, mainly because I got that bit in a set of bits which only costs me $10 for the set, while the correct slot bit is like $30 and has to be special ordered. I will have to glue my t-molding in, but it is going to work just fine.

I used a design loosely based on Defender, with one major on purpose change, and several minor differences.

Funny thing is that I am actually building this cab to house a REAL PCB and monitor (either Uo Poko or City Connection), and Mame.

[TaaJ]

Plywood here is $23.00 more per sheet than MDF.

I don't really mind anything heavy.

[Nefesis]

so weight is the problem for mdf and cost is the problem for plywood...crap.

[Apollo]

Don't use crap it's smelly and hard to sand.

[Nefesis]

how would you know it's hard to sand?

[Witchboard]

I'm in the same boat.  I'm trying to decide which to use, MDF or plywood.  MDF is cheaper and heavier.  Furnature grade plywood is more expensive, but lighter and stronger.  The shape I'm doing my cab I think I'll be dropping the extra $ for plywood.  It would just make me feel safer.

How ever, I will be making my CP out of MDF.

[Apollo]

I'm guessing you haven't seen my first cab attempt? "SCATCADE"

Unfortunately shortly after completing the project my basement flooded, you can guess the rest.

[CIA_Guy]

does anyone know if 3 sheets of 1/2" plywood would work?

I'm building with 1/2" since I am concerned about weight more than anything else since I have to move on a regular basis.  I've got 1"x2" reinforcements.  I'm using a Defender-style design with a 19" monitor and it seems to be sturdy enough.  (Two sheets and some scraps were enough.)

Now, having said that, the 1/2" creates another problem -- finding a sheet that is flat to begin with.  Sure, it looks flat, but as soon as you cut out the large parts (sides, back door, etc.), you'll start to see warp.  That can be taken out as you screw things down to the reinforcements, but it might be better to use a little thicker plywood and accept some weight increase.  Like I said, weight was the biggest driver for me.

BTW, I'm using a thin wood strip along the edge instead of t-molding.  It'll paint up nicely and hide the tell-tale plywood edge.  It'd prefer t-molding, but I didn't find it in that small of a size.

Picture attached....be kind -- it's my first attempt!

[CIA_Guy]

and another view of the 1/2" plywood cabinet

[pocketbikez]

i like working with mdf more than plywood. mdf is easy to sculpt with a sander or router and it stays ultra smooth and silky. the extra heft of the mdf makes the cabinet feel sturdy and the only downside is that it takes a little extra muscle to move the cab.

[REBIRTH]

does anyone know if 3 sheets of 1/2" plywood would work?

I'm building with 1/2" since I am concerned about weight more than anything else since I have to move on a regular basis.  I've got 1"x2" reinforcements.  I'm using a Defender-style design with a 19" monitor and it seems to be sturdy enough.  (Two sheets and some scraps were enough.)

Now, having said that, the 1/2" creates another problem -- finding a sheet that is flat to begin with.  Sure, it looks flat, but as soon as you cut out the large parts (sides, back door, etc.), you'll start to see warp.  

Two things:

(1) The thinner sheet will warp more obviously, but if you have to use 1/2 then nothing you can do about that

(2) Looking at your picture it does not look like you are using a birch/maple cabinet quality sheet of plywood.  A birch/maple cabinet quality sheet of plywood has very little grain to it - the surface is pretty much a completely uniform color like an MDF.  Your picture it looks like you used an "normal" sheet of plywood, which has strong grain to it.  I also have made furnature/cabinets with plywood and almost every time I have found that birch/maple cabinet quality wood doesn't warp at all - I mean no warp at all - but standard quality plywood literally almost warps every time.  I never usually use that stuff due to the warp.  The warping comes a lot from that grain, the grain is normally not completely dry (not that yopu can feel that it is damp, but it is), so it warps often.  Again though, a birch/maple cabinet quality (about $40-$45 a 3/4" sheet) I have never had any warp at all.  nice Defender style cab though, looks like it is coming along well.  Defender rules!

When I was originally deciding between MDF and plywood, I also had trouble finding the right type of MDF - the MDF in the Home Depots by me is not the "correct" type of MDF, at least from reading these boards and what people did/didn't have success with.  There are many different types/qualitys of MDF and the Home Depots only carried the low-end type which people found to be troublesome.  They make an MDF called Superlight (I think that is the name) that is supposedly much stronger and more durable than standard MDF, and much lighter as well - but when I finally tracked this down it was as much or more than good plywood.  

[AlexSledge]

For those worrying about the excess expense of plywood, consider how long you plan to own the machine. The small extra expense now ill pay off in the long run. The main reason original machine manufacturer's used MDF is purely a matter of cost, it was cheaper, they made more profit.

Also, if you are going to laminate, or use full side decals, you can opt for the cheaper non-smooth forms of plywood. Though this isn't really an inexpensive hobby to be a part of.

[RandyT]

When I was originally deciding between MDF and plywood, I also had trouble finding the right type of MDF - the MDF in the Home Depots by me is not the "correct" type of MDF, at least from reading these boards and what people did/didn't have success with.  There are many different types/qualitys of MDF and the Home Depots only carried the low-end type which people found to be troublesome.  They make an MDF called Superlight (I think that is the name) that is supposedly much stronger and more durable than standard MDF, and much lighter as well - but when I finally tracked this down it was as much or more than good plywood.  

I use a *lot* of MDF in my shop and pretty much buy it all at the "depot".    

I don't know when the last time was that most here purchased MDF from them, but about 4 months ago the price jumped about $4 a sheet and it's now different.

The color is more of a "straw" color and it's much lighter in weight.  It still has great strength, machinability and surface properties.

Based on the price, color and other properties, I think this is the "good stuff".  The old material was actually made out of wood fibers and had a darker "hardboard" look to it.  The "good stuff" is lighter and stronger because it's made of straw fiber.  It's also nicer to the trees because it doesn't use them.  Because it's a relatively new process, it costs a little more to produce.  But since it uses an easily replenishable material, the prices should come down on it eventually.

But I could be wrong


RandyT

[RandyT]

For those worrying about the excess expense of plywood, consider how long you plan to own the machine. The small extra expense now ill pay off in the long run. The main reason original machine manufacturer's used MDF is purely a matter of cost, it was cheaper, they made more profit.

I don't know about all OEM's, but my Defender cabinet is made out of *good 2 sides* 3/4 inch MDO (Medium Density Overlay).  As an FYI, this goes for about $70 a sheet.

Most here aren't making "family heirlooms" and MDF holds up wonderfully as long as you don't saturate it with water before you seal it.  Use the $150 difference for something that will have an impact on your enjoyment of the machine, like a better monitor, faster processor, etc....

Also, if you are going to laminate, or use full side decals, you can opt for the cheaper non-smooth forms of plywood. Though this isn't really an inexpensive hobby to be a part of.

No, it's not.  But it doesn't have break the bank either, as long as you make some good decisions about what is really necessary to get you where you want to be.  There are many ways to skin the proverbial cat, some costing more than others.  But as long as you have a cat-skin hat at the end of the day, how you got there isn't as important as some would have you believe.

Just my opinion.
 
RandyT

(PS. No cats were harmed in the writing of this message   )