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By Teejay
#1277475
Can someone please tell me whether it is better to use MR MDF or Plywood for this type of job?

Also, what thickness is standard in these cases and what size face frames do you tend to use?

What material and thickness is best for the doors?

This is a rough design of what I have planned:

Image
By oakfield
#1277669
18mm mdf would be the normal choice for the cabinets.
I always use moisture resistant as it’s a better quality material and takes paint better.
I like to use 22mm mdf for the doors - it gives a more solid feel than 18mm.
I normally do face frame at 38mm as it allows 1mm overhang either side when joining 2 cabinets together.
I sometimes do sides and bottom rail of faceframe at 45mm. You may need to go bigger than that if the walls are really out of level and need scribing too.
Hope that helps a little bit.
Mark.
By Teejay
#1277690
oakfield wrote:18mm mdf would be the normal choice for the cabinets.
I always use moisture resistant as it’s a better quality material and takes paint better.
I like to use 22mm mdf for the doors - it gives a more solid feel than 18mm.
I normally do face frame at 38mm as it allows 1mm overhang either side when joining 2 cabinets together.
I sometimes do sides and bottom rail of faceframe at 45mm. You may need to go bigger than that if the walls are really out of level and need scribing too.
Hope that helps a little bit.
Mark.



Thanks for your reply Mark. I am suprised that people are constructing the whole lot from MR MDF. That's some seriously heavy construction!

What do you use for the face frames? Material, thickness etc?

Do you have plans and photos of something designed in the way that you have described above so that I can visualise it please?

Is there a standard allowance within the measurements from wall to wall to figure out the maximum size of cabinets without them being able to fit squarely?

In our design, we need to make cabinets for two alcoves around the central fireplace. What do you think about the front of the cabinet overlapping the front face of the fireplace for the two cabinets whose ends touch that wall?

Very rough idea: Image
User avatar
By porker
#1277710
I always use 18mm MDF for the carcasses, thicker for the doors, maybe 6mm for backs. Now use Medite MR for everything as it leaves nicer edges. Rarely use ply for this type of application. Sure it is heavier but does that matter? I use redwood or tulipwood for the faceframes. I don't see a problem with the units protruding in front of the fireplace but you will need to think how you close the gap as you can't use normal face frame scribing. What I have done in the past is to scribe a side panel on perpendicular to the fireplace front and cover the whole edge with the faceframe. Worth looking at what Peter Millard does on YT (10minuteworkshop) as he does this stuff for a living.
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By custard
#1277826
I make freestanding furniture rather than fitted pieces, so I'll defer to others on the forum who are more experienced than me.

Just to say the spans on your shelves look to be about 900-1000mm wide. If they'll be loaded with books then you really want to be careful about sagging.

Resources like "the sagulator" (really useful by the way),
https://www.woodbin.com/calcs/sagulator/

will suggest that 3mm of sag on these shelves is okay, a tolerance that's widely accepted. But personally I hate any hint of saggy shelves and when I'm making stuff for myself I work to a maximum 1mm sag tolerance. Here are some bookcases and alcove units that I made for my house,

Bookshelves-FR.jpg


Alcove-Units-01.jpg


Alcove-Units-02.jpg


These all have similar shelf spans to your project. Even if you were to use 30mm thick MDF you could only have a light loading of paperbacks before you'd be at the 3mm sag limit, and you'd have no chance of hitting my 1mm sag limit. But I want a maximum of 1mm of sag even with a shelf packed with heavy hardback books (which averages out at about 15- 20Kg per 300mm), and I don't want shelves thicker than 30mm.

Consequently you'll have to either use whopping great lippings front and back made from a stiff hardwood like Beech, or you'll have to use solid softwood or fully 30mm ply, or if you want a lighter construction you can use a hollow core/torsion box principle.

I use plenty of hollow cores for floating shelves. Here for example are some 60mm thick floating shelves I made for my kitchen,
Floating-Shelves-01.jpg


Floating-Shelves-02.jpg


Floating-Shelves-03.jpg


These can be just 6mm Birch ply separated by softwood dividers, they'll weigh nothing yet if designed and made accurately they're phenomenally stiff.

And if you've got the budget you can go even further. A workshop where I was working once made some collectors storage cabinets for a client in the USA, to keep shipping weight down they were made from an aluminium honeycomb composite that was skinned with 3mm MDF then veneered with saw cut 1.2mm veneers. The whole thing weighed nothing but you could have parked a locomotive on it!
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By petermillard
#1279543
+1 to what the guys said above. 18mm MR MDF for the carcasses, 22mm for the doors with either 6 or 9mm panels (depends on size) and 6mm backs on the carcasses.

Shelves are usually 22mm MR MDF with a solid timber lipping if the span is >750mm; if they’re adjustable and you know they’ll be heavily loaded then consider lipping front & back, or making them fixed.

I did an older 5-part video series on alcove units, starts video #094. Link in the sig.

HTH P.
By Just4Fun
#1279616
Are there any regulations in the UK about having flammable materials like MDF or wood near a fireplace? I know over here there are rules that I had to bide by when refurbishing my kitchen, so I could not put cabinets right next to the Aga-style oven.
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By porker
#1279664
Have a look at the HETAS guidelines and Building Regulations Approved Document J. They are mostly about flues etc. but there are rules about proximity to combustibles. Not too difficult to follow and sensible IMO.
By Teejay
#1279694
Thanks so much for your replies, that's a lot of information to digest. I've been sidetracked at the moment and haven't had the time to dedicate to seriously thinking about what you have said and apply it in reality.

At the moment I'm really not sure whether I want to go for fixed shelves or not and don't know what spacing would be best. I don't plan on putting books on them but you never know in the future!

Also, I don't know how to decide whether to have the corners of the cupboards overlap the front of the mantelpiece slightly or meet at the point the two would meet (the cupboards will sit forward of the mantelpiece slightly). I haven't seen anything that I can use as reference for approaching using this method either.
By johnnyb
#1290249
just to add a different opinion i like 15mm birch ply for carcases. in fact for diy ply has many advantages. i like either beaded pine matchboard or reeded mdf for backs. this is for painting. tulip is a lovely buttry timber for face frames and details. nicer than pine. do not use farrow and ball paint its way soft btw. better to use pre cat.