Wednesday, 3 May 2017

Converting an old Pine Bedstead to an Electric Bed ...

We have a very solid old pine bed frame, 1,500 mm (5') wide which in the UK is generally called 'kingsize' although in the US I believe it would be a queen.

For various health & comfort reasons, we were looking at replacing it with an electric bed of the same size, with independently adjustable mechanisms, i.e. basically two 2' 6" frames fixed side-by-side.  Such beds are common enough these days and readily available to buy new, and they start at around £600 and go on all the way up to several thousand.  

However, we couldn't find a suitable version with an open base that stands well clear of the floor on four legs in the same way our existing bed does, and which allows us to store all sorts of crap under there.   In addition, all the other furniture in the bedroom is quite substantial and also made from pine, so a modern lightweight fabric-covered bed base just wouldn't feel right in there.

Therefore, I decided to convert our own pine bedstead to electrically-adjustable operation rather than buying a new bed version in a different style.  

There are one or two European vendors I found that sell the articulating slatted assemblies on their own, complete with the actuators and controllers etc but without the rest of the bed frame.   One place stocks them at around £225 each ex-VAT, i.e. £590 in total including £50 delivery.  Allowing £150 each for two new mattresses would have brought the total to around £900, so still around the price of a new mid-range version.

However, I managed instead to find a used electric bed base to use as a 'donor' for the conversion, at £225.  By stripping the mechanisms off this old bed base, we would save nearly four hundred quid.

the donor bed delivered ...

The donor bed comprised two independent 2' 6" bases which clipped together to form the kingsize bed.  I'd bought this bed sight unseen and, although it was advertised as fully working, when I tested it in the garden I found one of the mechanisms wasn't operating at all.   

After first cursing the seller, I checked the plug fuse which was OK, confirmed the controller worked with the other bed, also OK, and so there was nothing for it except to remove and dismantle the dual actuator unit.

inside the actuator casing ...

With the multimeter, I had 240V on the transformer primary, >24V ac on the secondary and >24V dc on the rectifier board, i.e. everything as it should be, and so that just left the actuator motor control board.  When I removed a few parts for access, I spotted a fuseholder tucked away on a corner of this board, and when I checked for continuity I found that the fuse had blown for some reason.  

the fuse ...

Luckily, I had a few of these 20 mm fuses from my machine tool spares, and this 'fixed' the problem, although I still don't know why the old one had blown.   Anyway, after repeated up-and-down testing it didn't blow again, so this meant that both bed units now seemed to working.

testing after repairs ...

After having a good play around with the controls, I removed both mechanical assemblies from the base units, i.e. the metal framework, slats and actuators, and tucked them away in the workshop overnight.  Because this project was based on modifying our existing bed, I couldn't proceed further without being confident I could complete the works in one day and we could use the bed immediately after the conversion, albeit with the old mattress laid on top, otherwise we would have had to spend a night in the recliners or on the sofa !

Next day, I stripped the bed and removed the slats under the mattress.   There was already a length of timber for longitudinal support on the centreline, but I formed a much stronger beam by adding another piece of wood as a web and using this existing length as the flange.  These pieces were glued and screwed together, for maximum strength.

After an initial trial fit of the adjustable platforms, I added extra timber cross-members at the head and foot of the bedframe, where the ends of the moving frames land when the mechanism lays the bed flat.

I also had to make spacers to take up the gaps at the sides between the outer metal frames of the articulating assemblies and the deep wooden rails forming the sides of the bed.

I carried out a final fit of both assemblies, made a few last minute adjustments, and then drilled through the bed side rails and central beam with the metalwork still in situ, using the bolt holes as a template.  It then just needed nine M8 screws and nuts fitted and tightened to complete the job.

no-load testing after completion of the conversion ...

The new mattresses arrived a few days later.  They were unpacked and laid on the bed, and then the systems were tested under load.  Neither of us could exactly be described as sylphlike, but the actuators seem to have plenty of grunt, and the motors and mechanisms operate quietly and smoothly.

So overall, we're quite pleased with the conversion, although an electric bed takes a bit of getting used to ...

Each controller has three pairs of buttons; head-end up / down, foot-end up / down and both together up / down.   They are all momentary switches, i.e. they only continue to operate when the buttons are kept pressed, so the movements can be halted at any required bed position.  It's also a safety feature of course, to help prevent trapping of fingers etc in the mechanism.

And there was very little waste from the donor bed.  The sides and ends of the bases are from 22 mm plywood, so they've been dismantled and the boards stored in the shed for future projects.  I've also kept the castors and other hardware, too.

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