newb cabinetry questions

[markiej]

Hi all! I more or less finished my design, and have done some research on the assembly piece, but watching a ton of assembly videos and posts, I'm still a bit confused about a number of things. 

• Why 3/4"?  The total weight of components in my setup is maybe 30 pounds - it seems like most of the support is for the cabinet itself, which, if using 3/4", requires that much more support - would it be a terrible idea to use 1/2"? I'm asking because I really only want this thing to be as heavy and complex as it absolutely needs to be.
• Let's stick with an assumption of 3/4", because that's what I designed.  Would 1.5"x1.5" pieces of different length be adequate as support wood (battens?)?
• How are they employed?  From what I've seen, battens are glued/nailed into the sideboard.  Then it gets foggy for me - what other attachments are employed, and are different methods applied depending upon the circumstances?
  
• The top back panel doesn't need to be a door, but I would like it easily removable if I have to troubleshoot the monitor.  I think I'm hearing that MDF doesn't lend itself naturally to re-attaching things.
  
• I want to permanently attach the control deck to the small front piece, because I think a hinge there would make it easier to to get full access.  Is that dumb?

Thanks in advance for any and all responses, or no responses. Cheers!

[yotsuya]

Stick with 3/4 - the sturdiness will pay off in the end.

[Ond]

Some thoughts on using battens.  The size you mentioned sounds fine.  In your diagram, the blue "Screwed here?" indicator.  It's not a good idea to drive screws or nails directly into the edges of MDF even 3/4" thick. MDF splits really easily on its edges.
 
Driving screws into battens from the outside to the inside of the cabinet at the green and red arrows is recommended.  Just countersink the screws slightly so you can overfill the screw points with Bondo or similar.  Gluing and screwing using battens makes for strong joints.  Glued joints are very strong using white/Yellow water based MDF glue (once completely dry).  Scews in this case are mainly used for keeping the panels in position while the glue dries.

If you don't use glue you can still drive screws from the inside to out to keep your panel surfaces smooth but joints are not as strong.  See my Metropolis project thread on the main board for details on using battens, screws etc.

[markiej]

Stick with 3/4 - the sturdiness will pay off in the end.

OK, I'm sold - as I was poking around I realized that 1/2" tends to be for shorter, smaller things, especially MDF, which is relatively snappable.

[markiej]

Some thoughts on using battens.  The size you mentioned sounds fine.  In your diagram, the blue "Screwed here?" indicator.  It's not a good idea to drive screws or nails directly into the edges of MDF even 3/4" thick. MDF splits really easily on its edges.
 
Driving screws into battens from the outside to the inside of the cabinet at the green and red arrows is recommended.  Just countersink the screws slightly so you can overfill the screw points with Bondo or similar.  Gluing and screwing using battens makes for strong joints.  Glued joints are very strong using white/Yellow water based MDF glue (once completely dry).  Scews in this case are mainly used for keeping the panels in position while the glue dries.

If you don't use glue you can still drive screws from the inside to out to keep your panel surfaces smooth but joints are not as strong.  See my Metropolis project thread on the main board for details on using battens, screws etc.

Thanks so much for helping to clear this up for me! I'll definitely check out the metropolis thread.

[bperkins01]

MDF is essentially 3/4" thick paper..  It is not as structurally sound as plywood or a solid wood..  that is why it has challenges holding screws, etc..  Good stuff - just behaves differently

[Mike A]

I hate MDF.

Its heavy.

It doesn't hold screws.

It soaks up water like a sponge.

The only time I use it is when I need something that is flatter than flat.

[bperkins01]

I hate too..  I haven't used it in years...  There are a few good uses I suppose..  But for cabinet construction of any kind.. its pretty sucky..
Not bad for indoor painted signs 

[Ond]

MDF also produces dust which is a toxic respiratory irritant.   It's hard on tools, especially router bits.   It's all the things the other guys have said.  It's also still my preferred woodworking material for cabinet building.  It just has rules for joinery, surface finishing, health & safety.

[1-UP]

Totally agree with Mike A but I wouldn't rule out MDF. It's cheap, nice to paint and easy to join (permanentely) if you use a biscuit jointer. If you're using screws with MDF you'll most probably have to use battens. Joining MDF corner to corner with screws is possible but you'd have to have perfect pilot holes and countersink everything and have the right screws. Even then the joint will be weak simply because of the material itself. A slight twist and the screws will be useless.

I would only ever biscuit joint MDF and if you have plently clamps and good glue you can get really good, strong results. Just as strong as a ply built machine but thats only because its glued and permanent. Cam fixings, screws, nails, bluetac, anything like that and you'd be better with ply. Especially if you're building something you want to take apart to move it. Melamine is another option but the inside is chipboad and not as strong as ply. I use whatever I can get for free but for a beginner, either get a biscuter and learn how to use it or just use ply. The only two advantages to MDF are, its usually cheaper (might not matter to you) and its easier to paint the face (no wood grain).

Personally I don't really like battens. I know a lot of original cabs use battens but that was the quickest / cheapest method. There are other ways to fix a cabinet together. A lot of the flat pack arcade type things use cam locks which is probably cheaper nowadays.

Consider using a 'key' on each side panel to help strengthern CP and CP front plate. Similar to battening but easier to do if you have loads of small battening bits. Look at some old nintendo cab plans and you'll see what I mean.

Regarding the CP hinge. You might want to consider having it fully removable as you may want to have different CPs or work on the CP away from the machine.