Author Topic: Why MDF and not plywood? (Read 6249 times)

bigmoe · « **on:** July 10, 2003, 06:53:09 pm »

I didn't want to hijack Xynie's thread, but I've been wondering something similar.

Not being a builder or carpenter...is there some reason so many people use MDF over plywood? My initial thought would be that plywood would finish better (if you stain rather than cover it).

AlanS17 · « **Reply #1 on:** July 10, 2003, 07:01:45 pm »

I've found that MDF is uniform throughtout. Plywood has grain which can make cutting harder because the blade slips easier. Plus MDF is already smooth so it's easy to cover. It also cuts and drills VERY cleanly. If you've worked with it you would know.

If you plan on making a hardwood arcade machine that's more like a piece of furniture then go with the plywood. If you want a machine that's more like a real arcade machine, go with the MDF.

Howard_Casto · « **Reply #2 on:** July 10, 2003, 07:27:58 pm »

Quote from: AlanS17 on July 10, 2003, 07:01:45 pm

I've found that MDF is uniform throughtout. Plywood has grain which can make cutting harder because the blade slips easier. Plus MDF is already smooth so it's easy to cover. It also cuts and drills VERY cleanly. If you've worked with it you would know.

If you plan on making a hardwood arcade machine that's more like a piece of furniture then go with the plywood. If you want a machine that's more like a real arcade machine, go with the MDF.

That's not entirely true, classic cabs were made before mdf so they were usually laminated plywood or something similar.

Anyway the only benefit of mdf is it's easier to cut the groove for t-modling and it's smoother (in case all you planned on doing was paint the surface) other than that plywood is a much better building material and more resistant to moisture.

So your choice.

AlanS17 · « **Reply #3 on:** July 10, 2003, 07:30:02 pm »

NO! Don't listen to him! He only thinks he's right cuz he has a higher post count!

Howard_Casto · « **Reply #4 on:** July 10, 2003, 07:55:10 pm »

Quote from: AlanS17 on July 10, 2003, 07:30:02 pm

NO! Don't listen to him! He only thinks he's right cuz he has a higher post count!

Oh no are you gonna accuse me of insulting you now and threaten me with bodily harm.

Kids today... nice to see a few people around that still have a sense of humor.

paigeoliver · « **Reply #5 on:** July 10, 2003, 08:57:59 pm »

I also prefer plywood over MDF. It is much better, and lasts much longer, and is more sturdy.

matt888 · « **Reply #6 on:** July 10, 2003, 09:10:33 pm »

Use MDF!!! Plywood is not uniform and you can have areas that are split...or will split. The thicker the plywood, the safer you are though. Putting a nail or screw through the edge of plywood can be nasty- even with pre drilling a hole. About the only thing I'd ever use plywood on would be something that needs to give a bit...like a skateboard half pipe (yes, in the 80's I used to skate board

) Just another opinion here.

Cabinet = MDF!!!!

AlanS17 · « **Reply #7 on:** July 10, 2003, 09:12:50 pm »

Oh great. The only person on my side had a post count of 9!

j/k

I just like MDF cuz it's easier to work with. It's probably not as heavy-duty. I would consider using plywood for the sides and stuff, but I would build the control panel from MDF.

matt888 · « **Reply #8 on:** July 10, 2003, 09:30:11 pm »

Easy there. High post count may not = high intelligence! J/K

AlanS17 · « **Reply #9 on:** July 10, 2003, 09:31:08 pm »

I'll agree there. I think I've actually gotten dumber since my first post!

BobA · « **Reply #10 on:** July 10, 2003, 09:47:18 pm »

MDF is the composition of choice due to the fact that it is cheap and easy to paint. This also reduces cabinet cost. It cuts easily but the dust is very bad for your lungs. More people are on a budget so MDF wins the numbers game.

Really nice Plywood does not have voids and is also easy to paint or stain. For the furniture look the plywood veneers are beautiful when stained but the cost of VG plywood is very high. Not the stuff that you make skate board ramps out of.

You make your choice depending on what you are looking for.

BobA

TrickyFishy · « **Reply #11 on:** July 11, 2003, 12:28:58 am »

didn't see anyone mention particleboard...not as smooth as MDF but cheap and laminates well.

!! DOH !! Just saw the other thread...

AlanS17 · « **Reply #12 on:** July 11, 2003, 01:05:22 am »

Too bad laminate is prohibitively expensive unless you're building half a cabinet...

gndprx · « **Reply #13 on:** July 11, 2003, 09:15:10 am »

I built my cab 50/50 Ply and MDF.

MDF is probably the most versatile wood available. The major benifits are that it's generally perfectly flat (plywood can be warped when you buy it), it mills up very clean and easy (plywood gives you tear out if you are using the wrong blade or try to cut to fast, or if there's voids, etc...) and it paints very easy with commercial paints if you primer/seal first.

I used marine grade birch and oak plywood for the exterior of the cabinet because I was staining it to be a piece of furniture in the house rather than an authentic cabinet. And at $45/sheet for the good plywood, MDF was a better choice for the parts you won't see.

2 sheets of ply, full sheet of MDF and 2 half sheets of 1/2" mdf for the back and misc...small pieces such as shelves.

hyiu · « **Reply #14 on:** July 11, 2003, 10:02:16 am »

my $0.0002 cents....

if you want to paint it to some color....
I would say.... MDF....
it takes paints easy...

but if you're going for the furniture look....
(with wood grains...) plywood it is....

I believe plywood can take more stress then MDF....
if you're covering your CP with artwork and lexan...
I would suggest using plywood....

and yes..... nice plywood is more expensive....

I'm building mine with brich plywood.... (if it matters...)
and it cost $40+ a piece (4 x

....

good luck.....

Sasquatch! · « **Reply #15 on:** July 11, 2003, 06:06:14 pm »

I'll echo what most people said. If you intend for the wood to show at all, go with plywood. If you don't (if you're going to paint or laminate), I'd say go with MDF. You will want to make sure that your MDF is "braced" in some manner though. At the very least, use 1x1 corner braces to join the pieces - don't drill directly into the side of MDF, as it will likely split.

Brax · « **Reply #16 on:** July 11, 2003, 06:29:39 pm »

Oh and if you never plan on lifting the monster go with MDF. Go to Home Depot and lift a 3/4" 4X8 sheet of MDF, then go do the same with a sheet of plywood. There's your answer.

It's stonger, more resistant to damage and moisture. The few voids you encounter certainly won't affect the grip of your t-molding and even if it does there's such a thing as hot glue. I didn't find the low end grades of plywood too much different than MDF. The first time you have to go or down a flight of stairs with that monster you won't be patting yourself on the back for saving $20 by buying MDF. The thing is going to cost you 1k, even saving 50 or 60 bucks is small potatoes imo. If you're painting then seal it first and you won't see any wood grain. If theres a few knots then fill them. It's a little labour but it's worth it in the end. Look at Frosty's paint finishes and tell me it can't look good.

MiKman · « **Reply #17 on:** August 03, 2003, 08:53:21 pm »

Quote from: Brax on July 11, 2003, 06:29:39 pm

Oh and if you never plan on lifting the monster go with MDF. Go to Home Depot and lift a 3/4" 4X8 sheet of MDF, then go do the same with a sheet of plywood. There's your answer.

It's stonger, more resistant to damage and moisture. The few voids you encounter certainly won't affect the grip of your t-molding and even if it does there's such a thing as hot glue. I didn't find the low end grades of plywood too much different than MDF. The first time you have to go or down a flight of stairs with that monster you won't be patting yourself on the back for saving $20 by buying MDF. The thing is going to cost you 1k, even saving 50 or 60 bucks is small potatoes imo. If you're painting then seal it first and you won't see any wood grain. If theres a few knots then fill them. It's a little labour but it's worth it in the end. Look at Frosty's paint finishes and tell me it can't look good.

Even if you plan on lifting the monster you could still go with MDF, just make the cabinet so it can split into two peices like mine

shmokes · « **Reply #18 on:** August 03, 2003, 09:22:07 pm »

Quote from: matt888 on July 10, 2003, 09:30:11 pm

Easy there. High post count may not = high intelligence! J/K

I disagree. I feel myself get physically smarter with each post.

edit: Ah....I felt that.

SirPoonga · « **Reply #19 on:** August 03, 2003, 09:38:39 pm »

MDF is pretty good. If you take care of it right the negatives people say don't exist. You just need to prime MDF well then it will last a long time. MDF is particular to moisture so that's a big reason to prime well.

Drilling into the end of either can cause a split. Always predrill any hole.

MDF is VERY sturdy. Note many subwoofer cabinets are in MDF. You know how much stress subs put on a cabinet, especially with 300+ watts of power? My sub is 4 years old and it's just like it was hen I built it.

Tailgunner · « **Reply #20 on:** August 03, 2003, 10:32:47 pm »

Quote from: SirPoonga on August 03, 2003, 09:38:39 pm

MDF is pretty good. If you take care of it right the negatives people say don't exist. You just need to prime MDF well then it will last a long time. MDF is particular to moisture so that's a big reason to prime well.

Drilling into the end of either can cause a split. Always predrill any hole.

MDF is VERY sturdy. Note many subwoofer cabinets are in MDF. You know how much stress subs put on a cabinet, especially with 300+ watts of power? My sub is 4 years old and it's just like it was hen I built it.

MDF is prefered for speaker cabinet construction because of it's density and lack of a grain structure. Acoustically it's a "dead" substance, where plywood or solid wood will resonate at preticular frequencies.

SirPoonga · « **Reply #21 on:** August 03, 2003, 10:35:11 pm »

Quote from: Tailgunner on August 03, 2003, 10:32:47 pm

Quote from: SirPoonga on August 03, 2003, 09:38:39 pm
MDF is pretty good. If you take care of it right the negatives people say don't exist. You just need to prime MDF well then it will last a long time. MDF is particular to moisture so that's a big reason to prime well.

Drilling into the end of either can cause a split. Always predrill any hole.

MDF is VERY sturdy. Note many subwoofer cabinets are in MDF. You know how much stress subs put on a cabinet, especially with 300+ watts of power? My sub is 4 years old and it's just like it was hen I built it.

MDF is prefered for speaker cabinet construction because of it's density and lack of a grain structure. Acoustically it's a "dead" substance, where plywood or solid wood will resonate at preticular frequencies.

Yep

Had to add what others said. MDF is really easy to work with. A dremel cuts up MDF fairly easily.

Tailgunner · « **Reply #22 on:** August 03, 2003, 11:07:14 pm »

http://www.lungster.com/l/speakers/mdffaq/mdf.html

I found this and thought someone might find it useful. It's written more for speaker cabinet construction, but the basics of building stuff out of MDF are covered rather well.

Apollo · « **Reply #23 on:** August 04, 2003, 12:08:06 am »

Hmmmmm, always predrill any hole eh, anyone else see the difficulty in doing such a thing?

SirPoonga · « **Reply #24 on:** August 04, 2003, 12:51:02 am »

Quote from: Apollo on August 04, 2003, 12:08:06 am

Hmmmmm, always predrill any hole eh, anyone else see the difficulty in doing such a thing?

Nope, did that for both my arcade cabinet AND my sub cabinet.

Tailgunner · « **Reply #25 on:** August 04, 2003, 03:53:07 am »

I predrill and then countersink first. Multiple drills come in handy as it's quicker to switch drills instead of continously swapping out toolbits.

Homebrew · « **Reply #26 on:** August 04, 2003, 05:47:34 am »

Personally i think the way to go is an all Carbon Fiber Cab. But only if you have more many than you know what to do with. In which case you can send me a few sheets while your at it.

-Kevin

Brax · « **Reply #27 on:** August 04, 2003, 08:17:53 am »

Quote from: Apollo on August 04, 2003, 12:08:06 am

Hmmmmm, always predrill any hole eh, anyone else see the difficulty in doing such a thing?

I always predrill as well. My cabinet is made from 5/8" MDF and I was able to put #8 screws into the edges using this method. Not one crack or split.

Wienerdog · « **Reply #28 on:** August 04, 2003, 12:01:40 pm »

Quote from: Brax on July 11, 2003, 06:29:39 pm

Oh and if you never plan on lifting the monster go with MDF. Go to Home Depot and lift a 3/4" 4X8 sheet of MDF, then go do the same with a sheet of plywood. There's your answer.

LOL, I've gone to Home Depot twice to buy 3/4" MDF. Both times I couldn't beleive how heavy it was, and I ended up not buying it. In the Chicago area, Menards carries MDO. It has a MDF veneer over a plywood core. You get the smooth surface to for painting, but the strength and light weight of plywood.

I'll be using birch or oak plywood for my cab since I'm staining it.

MiKman · « **Reply #29 on:** August 04, 2003, 01:56:38 pm »

I dunno my personal feeling is that plywood might be too light and while playing a very heated battle with 4 players could rock the cabinet around alot. You won't have this problem with MDF. Of course you could put some bricks in the bottom of a plywood cabinet to make it heavier so it doesn't move around while playing hard...

Frostillicus · « **Reply #30 on:** August 04, 2003, 02:07:50 pm »

Quote from: MiKman on August 04, 2003, 01:56:38 pm

I dunno my personal feeling is that plywood might be too light and while playing a very heated battle with 4 players could rock the cabinet around alot. You won't have this problem with MDF. Of course you could put some bricks in the bottom of a plywood cabinet to make it heavier so it doesn't move around while playing hard...

3/4" plywood is not light. Not as heavy as MDF but we aint' talking balsa wood here. It takes considerable effort to move just a 2-player cab made of 3/4" birch plywood - a huge 4 player would be that much heavier. If somebody is whacking the controls hard enough to move a cab, I'd pray for the joystick not to break first.

Sanding sealer on birch plywood is a good combo for painting - I prefer plywood since it looks nicer, and c'mon it smells great after you cut and route it

Quote from: Brax on August 04, 2003, 01:56:38 pm

Look at Frosty's paint finishes and tell me it can't look good.

thanks

Scottula · « **Reply #31 on:** August 05, 2003, 09:41:17 am »

I've been working on my cab over the last couple of days and used 5/8" plywood and the reason was the weight. 3 sheets of 5/8" ply is not light by any means and it would take significant effort to move the sucker, especially once you get all the components in it (I have a 70lb monitor to go in still).

Only complaint is the finishing. I've spent far too much time with the wood putty and sander trying to smooth it all out before finishing. It'll be worth it once it is done!

ErikRuud · « **Reply #32 on:** August 05, 2003, 10:10:07 am »

All of the quality issues that have been attributed to plywood can be solved by buying better plywood. Of cousre that will cost at least twice as much as MDF!

Frostillicus · « **Reply #33 on:** August 05, 2003, 02:10:03 pm »

Quote from: ErikRuud on August 05, 2003, 10:10:07 am

All of the quality issues that have been attributed to plywood can be solved by buying better plywood. Of cousre that will cost at least twice as much as MDF!

This is true - good plywood is like 40$ a sheet or so. That 9 dollar panelling plywood really sucks, if that's what people are using.

ErikRuud · « **Reply #34 on:** August 05, 2003, 02:49:40 pm »

A sheet of 3/4" MDF is usually around $20.00. Pros: It is flat, consistent, and has a smooth surface for painting. Cons: It is heavy, prone to water damage, and the dust is more toxic.

A really good sheet of 3/4" plywood will cost at leats $40.00. It will be even more if is furniture grade. "BC" grade probably won't be good enough, and don't even think about "CD" grade. Pros: More rigid than the same thickness of MDF, Lighter, sawdust is less toxic. Cons: More expensive, surface needs to be sealed and sanded before painting.

Grasshopper · « **Reply #35 on:** August 05, 2003, 03:23:09 pm »

Personally I consider Plywood to be superior for all the reasons given - it's stronger, lighter, less susceptible to moisture damage etc.

Also, the impression I get (and this is based on what I have read on the BYOAC website and not on any hard evidence) is that MDF causes router bits to wear out more quickly. As router bits are seriously expensive this is something else that you may wish to take into account.

SirPoonga · « **Reply #36 on:** August 05, 2003, 03:45:26 pm »

Hmm, I used only one router bit on my cabinet. And only two dremel bits for the fine stuff.

MDF is prone to moisture, that's why you prime it well:)
But plywood has nasty cons too, like if not treated it will warp through humidity changes.

I'd have to say, in this application, MDF is just as strong as plywood. But because of plywood's layer contruction I put my monitor on a plywood shelf than an mdf shelf.

Hey, MDF is heavier, it's more dense (hence it being so strong). If you don't want your cabinet on wheels, either way it will be tough. I have a double dragon II cab with no monitor. That is STILL a pain the the arse to move.

ErikRuud · « **Reply #37 on:** August 05, 2003, 03:56:40 pm »

SP,

You are correct.

3/4 MDF is perfect for arcade cabs. Just don't count on primeing to solve all the moisture problems.

Good 3/4" plywood with 5 or more layers should not warp, but sealing plywood with a good polyurethane should prevent any warpage.

GrassHopper,

The resin/glue that is used to make MDF and particale board is the reason it tends to wear out bits faster. There is more friction, which means more heat. Heat is bad for sharp edges.

SirPoonga · « **Reply #38 on:** August 05, 2003, 03:59:14 pm »

Quote from: ErikRuud on August 05, 2003, 03:56:40 pm

3/4 MDF is perfect for arcade cabs. Just don't count on primeing to solve all the moisture problems.

I haven't had any probs with moisture yet and all I hav done is a coat of primer, sand, and another coat of primer.

Though getting a sealant wouldn't hurt.

ErikRuud · « **Reply #39 on:** August 05, 2003, 04:09:54 pm »

Oridnary humidty in the air should not affect the MDF.

But if it should be exposed to water, such as a leaky basement, it can swell at least 50%. I have seen it happen to a laminated counter top.


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