Unit Construction

[MooreToolsPlease]

Evening all,
got a job coming up for a customer who wants an island unit for her kitchen. i've added a couple of drawings of what she wants.
The only difference is there will be another shelf in the side where the bottom shelf has grooves.
I've got a few reservations here, one being that with a huge slab of granite on top, and no back as such to keep it all square, there might be some movement in the whole piece.
Second is that she wants it all out of solid oak, no mdf anywhere except for drawer construction.
How would the forum go about joining the bottom shelf to the sides allowing for wood movement?

 

[Oryxdesign]

I think if you're not putting backs in it you'll have to do a framed construction. It seems a bit extravagant to make the panels out of solid oak but I guess the customer is always right (and sometimes ill informed). If it was me I might consider putting a panel in high up, so you can see it, that we increase rigidity.
Simon

 

[CWatters]

I'd add a vertical or two under the bottom shelf.

 

[BradNaylor]

You seem to have drawn the bottom shelves with the grain running from back to front. This isn't going to work - on many levels.

I would run the grain on the shelves from side to side and dado (trench) them into the carcass sides and central upright. Wood movement will not then be a problem.

I presume that the drawers are opened from one side only. If so I would brace the whole structure with sturdy 20mm panels disguised as dummy drawer fronts on the 'back' side. Veneered MDF would be perfect here but if you have to make do with solid oak so be it!

Cheers
Dan

 

[MooreToolsPlease]

Thanks for the replies folks,
The grain on the shelves will indeed run from left to right, sketchups paint bucket tool was having an off day.
there are 4 drawers, 2 from each side. between the drawers I as going to add a tight fitting back piece to try and add to the ridgidity, same between the legs too down the middle.
Wont be able to see it unless they are down on their hands and knees.
I was either going to use the domino or run them in grooves, but I'm not too sure on what mechanical fixings I can use to hold it all together?

 

[chippy1970]

Pocket hole screws maybe ?

they can be hidden out of sight.

 

[Steve Maskery]

Solid oak for carcases and MDF for drawers? Wrong way round. Really, wrong way round.
S

 

[MooreToolsPlease]

I wouldnt really call it a carcass, as the customers see it more as a piece of furniture.
I always make drawers out of MDF. The way I normally work is that if it is out of sight then veneered MDF will be fine.
The customer wants and has paid for solid oak on all the seen surfaces so thats what I need to give them.

 

[jasonB]

The draws are going to be very short, if the work surface is 900 high then draws from each side look like they will only be 300 max front to back, I would go with two draws that can open from both sides and make them from anything but MDF.

If its not drawn to scale then a panel mid way as you suggest will give a lot of strength, I'm just about to make an island 1500x1100 with six draws from each side, this will have a 19mm panel down the center to keep it all square. ( granite top & down the two short sides)

As said pocket hole screws will add piece of mind if you don't want to just have a glued joint.

Jason

 

[lathepilot]

Matt, I would think that your major movement issue would revolve around cupping and twisting in the oak boards. Even well seasoned material moves in time.

Consider placing fixings pretty darn close to the front of each side to ensure that gaps can't open up. Using relatively narrow planks, alternated up-down, will mitigate the worst of the cupping, but if you glue-up your boards with the outer ones set so that they would cup inwards (towards the shelves) that might help.

Setting the shelves back by a couple of mm would help to ensure that any movement in the sides doesn't meant that the joint comes conspicuously out of alignment.

I have done carcass work with dry joints in the past- using biscuits for alignment and cams for connection- no glue! Loose tongues and pocket screws could work in a similar way.

I would consider some additional battening of some sort to maintain flatness. Or, as noted above, a framed construction could work. Think suitably chunky frame with a full thickness loose panel and perhaps just a shadow line rebate of 2-3mm rather than a full panel raising.

Finally, I have had good success with Birch ply for drawer carcasses. Takes a bit of finishing work but they are strong. 8)

Good luck!
Thom

 

[BradNaylor]

Just a word in favour of using MDF for drawer boxes;

I use 18mm veneered MDF lipped with about 20mm of solid wood for most of my drawers, but only where they are being used with concealed runners. You have to rebate away 5-6mm of the thickness of the MDF below the drawer bottom to make it work. I biscuit joint the drawer boxes together.

I've never had a single problem - my drawers are plenty strong enough for heavy use, and it is a great way of using up all those long strips of veneered MDF that always seem to accumulate!

For traditional drawers without metal runners I use solid wood of course, as the drawer is taking a lot more stress in use.

Everyone wants Blumotion type soft-close drawer runners these days, though.

Cheers
Dan

 

[Oryxdesign]

Just a word in favour of using MDF for drawer boxes;

I use 18mm veneered MDF lipped with about 20mm of solid wood for most of my drawers, but only where they are being used with concealed runners. You have to rebate away 5-6mm of the thickness of the MDF below the drawer bottom to make it work. I biscuit joint the drawer boxes together.

I've never had a single problem - my drawers are plenty strong enough for heavy use, and it is a great way of using up all those long strips of veneered MDF that always seem to accumulate!

For traditional drawers without metal runners I use solid wood of course, as the drawer is taking a lot more stress in use.

Everyone wants Blumotion type soft-close drawer runners these days, though.

Cheers
Dan

This is pretty much what I do as well, you get really strong hardwearing drawers, I finish with Rustins Plastic Coating which seals the Veneered MDF excellently. I think this would be good for the sides and bases too especially if they go for a framed design,

Simon