Built-in bookcase project - some questions

[Rich_Z]

Hi all, first off thanks for the great advice on the forum - I've been mining it for help for about a year now, it's brilliant.

There's a couple of things I'd like some advice on that I haven't been able to find by searching. I'm currently working on a project building a large bookcase running the whole length of an 8m hallway (one side) and, as I have a tendency to do, I think I may have bitten off a bit more than I can chew, designing a bit beyond my manageable level, at least in terms of getting it done in a reasonable amount of time.

My first question is about steam bending. I'm using walnut veneered mdf with some flat walnut lipping in some places and in others, lipping with a routed profile. I have one shelf at the end of the bookcase extending round the corner a few 100mm, and would like to make this curved, trimmed with steam-bent profiled lipping. In cross-section the walnut edge would look like a 'P', with the total thickness 12mm, and the projection at the top 4mm. This will be my first attempt at steam-bending... So, my question is - should I rout out the profile before or after steam-bending? It seems easier to rout a straight piece of wood, but I'm worried about fibers splitting on the projection when bending it.

Elsewhere, on this behemoth... With the main shelving, which will be 19mm thick, I'm hoping to have recessed LED strip lights on their underside, near the front. The strip lights will be housed in an aluminium LED profile, set in so that it's perspex top will be flush with the shelf surface. Now there are profiles that are shallow enough that would only need 7mm groove, however LEDs need to be a far enough away from the perspex to even out the light so that it looks like a solid bar of light. I've been told the 15mm profile would enable this. Now obviously a 15mm deep groove in 19mm thick material is asking for trouble but do you suppose the aluminium structure of the profile, glued inside the groove with cyanoacrylate, would support the structure? I've a feeling it might, but not sure enough to go ahead with the purchase.

The LED profile:

Any thoughts appreciated!

Thanks,
Rich

 

[Myfordman]

You clearly like a challenge !!!!

I'd bend and fit to the shelf before profiling otherwise the the wood will twist due to the different thickness through the profile. Do a trial bend first to judge the degree of spring back, then modify your bending jig to compensate. Try and pick the section of walnut used for the bend to have as straight a grain as possible in the area of the bend and 6" or so either side of the bend. Have everything to hand for the jig including spare clamps before you bring the wood out of the steamer then work quickly as the jig will pull heat out of the walnut quite quickly.

Cutting 15mm deep into 19mm veneered MDF will be quite weak to handle and I fear will show through the veneer in time even if the aluminium will return some strength to the edge.

MDF is a poor choice for book shelves when loaded and you will need a substantial edge lipping to resist bending. So why not beef up the edges of the shelves with a thick lipping sat 25-30mm deep and then hide the lighting strip in that. Make the lipping, fit the extrusion then lastly fit to the shelf edge to minimise any tendency of the deep groove showing through.

Good Luck

 

[MMUK]

LEDs are one of my specialities, if you need any help or advice give ma a shout.

FWIW though, if they aren't going to be seen, use a self adhesive strip of SMD LEDs. You could incorporate a small power supply somewhere to run them on 12vDC. If that's too bright, ramp the voltage down a little (don't drop below 10v though or they won't work).

 

[Myfordman]

LEDs are one of my specialities, if you need any help or advice give ma a shout.

FWIW though, if they aren't going to be seen, use a self adhesive strip of SMD LEDs. You could incorporate a small power supply somewhere to run them on 12vDC. If that's too bright, ramp the voltage down a little (don't drop below 10v though or they won't work).

Can you tell me what the electrical configuration of these led strips is please.
I assume is has to be some sort of series/parallel arrangement. Do they have a current limiting resistor built in.
As an electronic engineer I understand single indicator Leds with a near constant Vf which varies for different colours but not up to speed about led dice used for lighting/decorative applications.

TIA

MM

 

[Myfordman]

Just bumping this in the hope that MMUK sees it and can shed some led on my query above.
TIA

 

[pablo823]

Hi Rich
I think your over complicating it, either laminate the sections in 2mm till you get your desired thickness
making sure its done out of the same piece, or do the curved section out of solid on the spindle or router
table with a template then but the front straight section up to it

Paul

 

[Mr T]

Hi Rich

I would favour Paul's suggestion of laminating the lipping between male and female formers then machining afterwards. I think you said there was only one curved shelf, but if you needed multiple lippings you could laminate a wide section then cut it into strips of the required width.

Chris

 

[MMUK]

LEDs are one of my specialities, if you need any help or advice give ma a shout.

FWIW though, if they aren't going to be seen, use a self adhesive strip of SMD LEDs. You could incorporate a small power supply somewhere to run them on 12vDC. If that's too bright, ramp the voltage down a little (don't drop below 10v though or they won't work).

Can you tell me what the electrical configuration of these led strips is please.
I assume is has to be some sort of series/parallel arrangement. Do they have a current limiting resistor built in.
As an electronic engineer I understand single indicator Leds with a near constant Vf which varies for different colours but not up to speed about led dice used for lighting/decorative applications.

TIA

MM

Sorry only just seen this.

The strips I supply are designed for 12vDC. They are wired as one resistor per three LEDs and can be cut to length every third lamp. The strips are about 8mm wide and stand only 2mm-3mm high. They are backed with 3M adhesive on a 5m strip. In white I can supply warm (approx 3200K) or cool (approx 6000K).

All you need is a regulated 12vDC power supply. One 5m strip draws around 5A @ 12vDC.
I use a 300w PC PSU in my workshop. The 12v rail is rated at 17A but maximum draw on the mains is 1.25A @ 240vAC at full load.

 

[Myfordman]

Thanks. Sounds interesting.
OK so DC input is 1 amp/12w per metre approx?
Can you tell me the cutting pitch please? i.e. the length of strip for 3 leds & associated resistor or how many leds per metre if that is easier.

Thanks
MM

 

[MMUK]

60 LEDs per metre, 300 total in 5m strip. Cutable approx every 55mm.

 

[petermillard]

I've used these self-adhesive LED strips and they're terrific - great for accent lighting, pelmet lights, shelf lights etc...
Recommended.