Electrically operated door bolts. How can I do this?

Solenoid operated bolts of the type you describe are certainly available - the motorised gates at work have them. Not sure where they came from, but shouldn't be too difficult to find a supplier of these motorised gates.

A traditional solenoid might not be quite suitable, depending upon how much "play" there is with the up-and-over door (your call on this one, I'm afraid) since the "throw" of the solenoid bolt tends to be rather low - usually 15mm or less, and the pull strengths can be a little low for this application. You might find solenoids specifically for this application

What with this being a DIY group, have you considered the merits of a series of motors, each driving a threaded piece of studding, then welding a locking "bolt" to a nut that sits on the threaded studding to provide a cheaper solution? (ok, a bit heath-robinson, but an interesting idea if you want to dabble)

Electric door locking is more usually done by purpose-made electromagnets. Unlike bolts, they can easily accommodate misalignements. RS Components list them, but I would be surprised if you could not find them cheaper.

Colin Bignell

Instead of draw bolts you need two Magnet Door Locks. We fit them all the time on these types of things. You can even have them on battery back-up in case of power cuts. They are much safer if fire occurs as well.

Have a look at these:

cheaper, and 12 volt, so you could rig up a battery backup system.

Tom

on a few projects. They're very cheap, and pretty good for both pushing and pulling.

Strong enough for this type of job though?

I think it will depend a lot on the alignment of the bolt with the hole. If it is reasonably well aligned, not requiring too much force, then yes, these motors will do fine.

They are pretty simple rack/pinion arrangements, so can deliver a reasonable amount of force - maybe ~20N - over 30mm travel.

How often do you get this on a door bolt, and for how long?

I know what you mean, but I do think it's doable. It may be necessary to use slightly oversized bolt holes to allow for misalignment.

I'm sure magnetic catches are a better option for this application, I was just mentioning that I've used these motors in similar applications with good results.

They're actually a direct mechanical replacement for the ones on my SD1 (and probably other BL cars too) at a fraction of the price. The connectors need to be changed, though.

The complete kit they offer is excellent value, but suffers from voltage drop due to undersized connectors and cable as supplied. Probably ok for many apps, but beefing these up allow the motors to develop their full torque.