Slab front drawers question?

[leverb01507]

Hi guys, I've got some face frames for some built ins to make, pretty standard face frame construction, although no traditional beaded edge profile that's the usual. The problem I'm having is that the slab drawer fronts and slab doors are being specified as 36mm thick. I normally use MR MDF for painted slab drawer fronts but the thickest I've ever used is 30mm, and I'm not sure that 36mm is available in MR. My question is, if it was you would you use 36mm standard mdf, or laminate 2x 18 MR pieces together to make up the thickness? The whole lot is being spray finished in a super high gloss white finish (not by me), and the carcasses are formed from polished concrete. My gut says stick with MR and laminate, but it's going to be hard to get an even pressure over the larger areas without a big hydolyic press, I would imagine a vacuum press would be short on pressure? Thanks on advance,
Ben.

 

[Chrispy]

Yes you could do that very easily in a vacuum press, but they are going to be very heavy doors! Could you make them hollow if you could get the use of a plattern press, what hinges are you using not many will work with such thick doors?

 

[RobinBHM]

It sounds a contemporary style, so would imagine you will be using concealed blum hinges. As Chrispy says such hinges wont clear on such a thick door, without a massive gap. I would suggest testing the hinges on a strip of scrap that thickness before deciding on material.

Is there a reason why it is being specified that thick? Is it a client choice or maybe architects drawings -often material or design details are specified without knowledge of construction techniques and some persuasion may allow a change of spec to your preferred thickness, say 25mm. I often receive drawings with timber section spec'd at say 50mm or 75mm, these can usually be changed once Ive explained 45mm or 68mm thick will be much less wasteful on timber and hence less expensive

 

[leverb01507]

I have a sample of the hinges already, they are 4" bearing butt hinges, brushed look. Strangely they are only 40mm wide, and are being set so that the back of the leaf finishes flush with the back of the door. There is to be a 30mm wide stopped groove in the hinge side of the door 30mm deep to take a solid wood strip to take the hinge screws. The idea is if any movement occurs in the solid wood it won't affect the finish of the front like a lipping would. I will probably domino the strip in as well in light of the weight of the doors. I did say to him about the weight, I thought skinning a frame would save a lot of problems, but the chap wants "a feeling of mass". As you can imagine it all looks rather industrial in the drawings. Thanks,
Ben.

 

[leverb01507]

It sounds a contemporary style, so would imagine you will be using concealed blum hinges. As Chrispy says such hinges wont clear on such a thick door, without a massive gap. I would suggest testing the hinges on a strip of scrap that thickness before deciding on material.

Is there a reason why it is being specified that thick? Is it a client choice or maybe architects drawings -often material or design details are specified without knowledge of construction techniques and some persuasion may allow a change of spec to your preferred thickness, say 25mm. I often receive drawings with timber section spec'd at say 50mm or 75mm, these can usually be changed once Ive explained 45mm or 68mm thick will be much less wasteful on timber and hence less expensive

The client is infact an architect himself, to be fair he has produced some lonely drawings, I've never had so much detail in a plan. It is for his own house, in his office.

 

[Jacob]

Tell him about the construction problems - designing and making should be a joint effort - a two way process. It's quite possible to make lovely drawings of things impossible to make.

 

[AndyT]

Possibly part of the problem here is that MDF is pretty dense stuff compared to most timbers and many other manufactured boards. Could you use something else easily available in big thick bits such as solid fire door blanks instead of MDF?

 

[RogerBoyle]

A vacuum press will work well as Chrispy has already said

Other than the weight I really don't see a problem
You will have to gap/Shoot the doors to fit the frame so they open properly as you would any other door and gap the drawers to suit the doors.
Advise the Client that at this thickness you would need to leave a bigger gap for clearance.
If he needs an idea of the gap, point him to a normal internal house door (similar thickness)
He will then either say yea or nay but at least then you both will be working together to sort the issue .

Or am I missing something :duno:

 

[Max Power]

I would have thought 4" butts with bearings would easily carry the weight of those doors providing there's no excessively wide ones. They are usually used on heavy external doors so should be fine. Sounds a very straight-forward job so why not give him what he wants. The only thing Id watch out for is the set of the hinges as there's only going to be a 4 mm projection at the front so part of the radius of the knuckle may be inside the door so you may need to scribe this to avoid a gap

 

[Max Power]

No reason he couldn't fit them tight Roger providing they have a relief angle on the leading edge, which wont be seen when closed

 

[Max Power]

What size is the biggest door ?

 

[leverb01507]

I don't really have any problems with the brief, although it's a little unconventional it is pretty straight forward stuff, and shooting in the doors with little relief angle will allow me to get a perfectly respectable shut line. My question was more about whether using standard mdf instead of MR was asking for problems later on. I pretty much only use MR, do I have little experience of how the normal mdf would a, hold up long term an b, take a fairly unforgiving finish.

The hinges will need a very slight scribe, but nothing too bad, and I think he said he would go up to a 45mm, which I think would visually look better.

The largest doors are no bigger than 0.75m2 so I don't think that's an issue.

I think I will probably just laminate 2x 18mm MR together, that was my initial thought, I was just concerned about getting them pressed together tight enough over the 0.75m2 doors, but if everyone is confident a vacuum bag would have enough pressure I will stick to that.

 

[Chrispy]

That's the good thing about a vacuum bag press, the pressing force per square inch inch stays the same, whether you are gluing up a chess board or a table top the only difference is it will take longer to suck the air out of a larger bag.

 

[Phil Pascoe]

What do the "lonely drawings" look like ? Sad?

 

[leverb01507]

Incredibly sad, there's a longing in their eyes for the drawings they once knew!

 

[leverb01507]

That's the good thing about a vacuum bag press, the pressing force per square inch inch stays the same, whether you are gluing up a chess board or a table top the only difference is it will take longer to suck the air out of a larger bag.

I think I was concerned more about the two surfaces being so flat and smooth that there would be potential for air pockets to form in the glue, a bit like an air hockey table. I suppose thin even glue application would eliminate that issue though. Thanks for the help.

 

[Giff]

I have made similar with a 20mm timber frame (better for hinges) and 9mm MR MDF, all the edges are then planed off and skinned with paintable edge banding http://www.edgeband.co.uk/paintable-edg ... glued.html then professionally sprayed.

 

[doctor Bob]

If it's being finished professionally in a high gloss it will be waterproof, go with 38mm standard MDF. if you laminate you will get movement between the 2 boards