First Build - TV Cabinet In MDF

[Knottyboy]

Hey,

First off I'm new to the forums so hello everyone. I'm looking to make a custom TV cabinet to house all my bits and bobs nicely. Due to cost I'm looking to do this in MDF. Also as B&Q kindly cut everything to size (within reason) I was going to use these guys:


http://www.diy.com/nav/build/timber...mm/MDF-Board-L-2440-x-W-1220-x-T-18mm-9276268

http://www.diy.com/nav/build/timber...mm/MDF-Board-L-2440-x-W-1220-x-T-12mm-9276267

Here's my basic design (shelves in the middle bit may vary).

Lucky one of my best mates is a chippy that's willing to help me. Having said this I don't want to go in blind so was wondering if anyone could give me some tips on doing this.

If it's okay I have a random list of thoughts I'd like too see what people's opinion would be:

- Weight, if I was to move would you reckon this would be too heavy?
- Weight, would this cause a stability issue?
- Would it be best to put holes along the sides for the shelves, make it "changeable", and also if not fixed in this could reduce weight when moving.
- What would be the best drawer rollers?
- I appreciated this would be based on the rollers but what tolerances would be required with regards to the drawers? (2mm all round to the face + roller thickness to the width?)
- We were thinking about scribing the back allowing for 100mm "legs" to enable us to do this (to overcome the skirting in my living room). Should we "beef up" the legs?
- With regards to fixing it together I was thinking of using a few "MDF-Tite" screws with wood glue throughout. Would this hold or would we need better fixings?

For your information consoles and an HTPC will be going into this so there will be a considerable amount of weight in the cabinet. I am planning not to have anything on top of the unit though.

The dimensions of the cabinet is '936mm Tall' by '1808mm Wide', '600mm Deep'.

Thanks in advance.

 

[big-all]

heeelllooo and welcome Knottyboy

to tall to complexed really at that size far to heavy
you need to arrange it in 2 or 3 units placed together
you need at least 30% back to give strength to the structure
around 450mm is a better depth
i build many tv units and you will need at least 2" clearance top and sides and lots off airflow around some games consoles
so build 25-50mm overhang off the back with open ends to allow air circulation

movable shelves are fine as long as you have enough structural components

 

[Deleted member 174758]

- Weight, if I was to move would you reckon this would be too heavy?
- Weight, would this cause a stability issue?

I'd be concerned about a backless structure without a plinth ripping itself to pieces more than anything else. I therefore suggest building it in 2 or 3 pieces and bolting the pieces together with cab joiners

Edit! Bummer, BA beat me to the draw!!!

- Would it be best to put holes along the sides for the shelves, make it "changeable", and also if not fixed in this could reduce weight when moving.

Yes, but you also need to be aware that without a back or some form of bracing you need to consider having something like a single fixed shelf to brace the structure

- What would be the best drawer rollers?
- I appreciated this would be based on the rollers but what tolerances would be required with regards to the drawers? (2mm all round to the face + roller thickness to the width?)

Something like Blum Blumotion are brilliant (as well as invisible) for hravily used drawers. Hettich, Salice and Grass manufacture similar styles of runner. Accuracy is important so try to work as near to the dimension as you can. 2mm out of parallel fronr to back on a carcass can be packed out

- We were thinking about grooving the back allowing for 100mm legs to enable us to do this (to overcome the skirting in my living room). Should we "beef up" the legs?

Grooving? Surely you mean scribing out around the skirting? In which case yes, good idea. I wouldn't beef up the legs, in fact I wouldn't use legs atall. The gable end panels (i.e. the uprights) are strong enough to carry the entire structure and can be adjusted by adding adjustable feet either behind the upright panels or screwed into T-nuts in the bottoms of the upright panels - although simple plastic wedge packers are readily available and cost buttons

- With regards to fixing it together I was thinking of using a few "MDF-Tite" screws with wood glue throughout. Would this hold or would we need better fixings?

A few? Drill and countersink all joints properly with the right size of drill/countersink making sure that you clean out the pilot holes fully and to the full length. this is very important because if you don't do it right the end "grain" in the panels you are screwing into can and will split. the glue is much less important in the joint than having enough screws properly installed. And don't use PU (polyurethane, Gorilla) glue - sticjk to a good quality white PVA

Because you intend to carry weight I strongly recommend the following changes to your design:

1. Make the entire structure out of 18mm MDF, with the possible exception of the backs
2. Beneath the lowest shelves don't leave the structure open but incorporate a plinth at least at the rear
3. Where out of sight use 1 x 1in softwood cleats at the joints to add strength and rigidity to the structure (if you have a front plinth this is, of course even stronger with a cleat behind it
4. On the open units try to incorporate a 100mm or so deep cross brace (18mm) beneath the top as this will make the units considerably stronger and more rigid
5. Even in the drawer cabinets incorporate that 100mm deep brace at the back beneath the top for the same reason
6. A solid 18mm back screwed and glued inside the rear of the drawer cabinets will be more rigid than a 12mm back, albeit a bit heavier
7. To calculate the approximate weight work on the approximation that 20 sheets of 18mm 8 x 4ft MDF weighs about 1 tonne - or 50kg a pop (16.8kg/suare metre)

 

[Harbourwoodwork]

I recently used some MDF fixings from WORTH ,they have a drillbit point on the end of the screw and are designed to go into MDF end grain without splitting which they do (all these things have limits) I was very impressed with these fixings, in combination with biscuit joints will give good results that's my two pennorth

 

[foxhole]

So it's a TV cabinet with no TV?

 

[Knottyboy]

Thanks for your advice guys, especially JobAndKnock for your extensive answers.

I've re-sketched the cabinet and it now will look something like this:

I plan to follow J&K / Harbourwoodwork's advice and do this as 3 separate units then join them up. Would four fixings between cabinets suffice (ie top left/right, bottom left/right, between the cabinets).

Thanks for recommending the "Blum Blumotion", which I am sure would be perfect but at over £40 quid a pair a little out of my range (considering I'd need 8 pairs =S). I take it you would recommend against "cheap and nasty" £5 pairs from Screwfix but is there an in between option?

With regards to the number of screws to use, I said a few as I didn't want to put to many and in turn weaken the structure, is there a rule of thumb to follow here?

So it's a TV cabinet with no TV?

The TV will be mounted on the wall above.


Edit: I don't plan to leave the drawers at a .5mm increment.

 

[Harbourwoodwork]

Biscuit joint centres circa 5", screw's one each side of a biscuit and1.5"-2"away from the edges

 

[Deleted member 174758]

Much more robust and moveable! On your centre unit I'd suggest making the unit from two end panels, a top, a single bottom, a single top, two full length plinths (front and rear) and a single back. The centre uprights can then be slotted in and screwed in from top, rear and bottom (takes accurate measurement for the drillings, BTW. I'd suggest cutting a piece of MDF to act as a setting spacer or "rod" rather than trying to use a tape measure). That will be a lot stronger. The way you have drawn it it will still be fragile and likely to break if roughly handled (too many joints!)

Thanks for recommending the "Blum Blumotion", which I am sure would be perfect but at over £40 quid a pair a little out of my range (considering I'd need 8 pairs =S). I take it you would recommend against "cheap and nasty" £5 pairs from Screwfix but is there an in between option?

OK, in that case I'd opt for the knock-offs of the Blum Metabox style runners used in so many kitchen places. They are widely copied and if you scratch around there a few firms making them in silver/grey as well as white, ivory and brown. I used to deal with a firm who did them in black, however the recession saw them off. . Cheap and tolerant of "iffy" installation. Whatever else make sure you get screws the right length (16mm or 5/8in)

With regards to the number of screws to use, I said a few as I didn't want to put to many and in turn weaken the structure, is there a rule of thumb to follow here?

Yes, don't skimp on the screws (I'd go at 80 to 100mm centres) and use a pilot/countersink to drill the correct size holes making sure that you clean out the holes thoroughly. Don't go nearer than about 70 or so mm in from the edges and cramp up a side to a bottom, etc before drilling - you may need to buy a couple of carcass corner cramps, Small price to pay IMHO. Properly installed it's the plinths, braces and screws which give the strength to a unit like this

 

[big-all]

few more points
you havent allowed for full material thickness in your plans

the tv should b at a normal viewing height yours is to high for comfortable weiwing would suggest screen center at 1m to avoid discomfort but thats up to you

 

[foxhole]

Agree with BA, far to high unless you like neck pain.

 

[Knottyboy]

few more points
you havent allowed for full material thickness in your plans

the tv should b at a normal viewing height yours is to high for comfortable weiwing would suggest screen center at 1m to avoid discomfort but thats up to you

Damn it..


I just thought put it high and tilt it but... having said that never had a TV like that so you are probably right. Might have to consider a longer lower design.

Has anyone got their TV high up, tis a 42" so at best (lowest) the centre point will be 1.3m from the ground (TV is 71cm tall). Which doesn't seem too bad if I just wall mount it to hold the weight.

 

[big-all]

what height is your present tv??
if its quite high sit on the floor and watch it ??

 

[freddiemercurystwin]

Blimey!

Untitled

• freddiemercurystwin
• 13 Jul 2012
• 1

 

[Knottyboy]

Blimey!

Untitled

• freddiemercurystwin
• 13 Jul 2012
• 1

Don't think that's quite right as its about 100cm wide (30 cm larger than the middle bit).