Difficult to remove these hinge screws.

[CarlH]

The attached photo is of a Hettich controller for the bifold action of a Nolte wardrobe door.

The controller in the photo is working normally, but another of the total four does not allow its bifold door to close without a second (human) hand to help it. If no second hand, it judders and jams.

This is because the leaf spring in the hinge of the controller arm has broken and fallen out.

I have been offered a new leaf spring. It's a powerful spring which has to bend into a U shape and have its two ends persuaded into slots. The controller is about 7 feet above floor level, so I want to remove the hinge/control arm unit from the door and hold the hinge socket in a vice.

Looks straightforward: unscrew the two screws which have Pozidrive # 2 heads (the most common Pozidrive head).

PROBLEM

It's not straightforward! The screws start to turn anticlockwise easily. After little more than a quarter of a turn they suddenly act as it they have hit an inviislble stop. Manual twisting harder on the screwdriver is futile. They won't move any further.

At this point, the hinge socket it slightly loose. So the problem does not seem to be something like the the tail of the screw coming hard up against the back of the socket.

I am very reluctant to try to force the screws to turn more. An excellent PZ#2 driver starts to "cam" and damage the screw head. The timber (some sort of fibreboard) of which the door is made is only 19 mm thick. The door in question has a mirror on its front face, apparently bonded into place.

Are these "screws" not what they seem, but some sort of fastener which goes into a socket fixed into the timber and turns to lock? If this were the answer you would think that the hinge socket could be wiggled out from the bore in the door once the heads have been turned up to the stop. But the socket is slightly loose and does not want to move outwards any further from how it is when the screw heads have been turned to the apparent maximum.

Has anyone else experienced, and solved, this problem? If so, HOW, please?

 

[Swwils]

It's a regular hinge screw. It's probably just jammed on the metal.

 

[pcaouolte]

Sometimes those screws start to bind into the metal hinge as you undo them. It may be necessary to undo each screw a small amount and keep alternating between screws so that they push the hinge out of the recess as you gradually undo them.

 

[Harry Bloomfield]

As above, undo both and tease the bracket out a little at a time, then undo a little more.

 

[JohnD]

There is a fixing that is not a screw, but has a sort of semi-circular profile. You give it a quarter turn and the larger side bites into the wood. Might possibly be them. A sort of cam or interrupted screw.

Test the "screws" on your other hinges to see if they do the same.

If so, the method is to quarter-turn the fixings to release, then pull out.

 

[CarlH]

Your suggestion is along the lines that had occurred to me, and that I mooted, but this does not release the control arm hinge mounting.

I guess the "screws" must be either what you suggest, or, as already advised, normal hinge screws, but possibly with a large diameter thread (like a chipboard screw) which only just passes through the hole in the metal, and can easily catch and jam against this when one attempts to undo it.

I'll try again. I have not (yet) been able to move the fixing beyond the point where it becomes very slightly loose after the two screws are turned a-c by a 1/4 turn. At that point the control arm hinge mounting has, so far, shown no willingness to be pulled out with the "screws" still in place.

In view of that, I will first try the method suggested by S, P and HB. If no go, then re-try your method.

Very many thanks to all who have so far tried to help.

I'll report back asap.

PS these control arms are nearer 8 than 7 feet above floor level. So removing the one with the missing spring in order to try to persuade a new spring into place is a priority!

 

[CarlH]

I have succeeded in removing the "guilty party" from the wardrobe door.

Despite their heads the "screws" have proved to be 1/4 turn fasteners.

When they are a 1/4-turn turned back to the stop point, the nylon sockets within which they turn are no longer expanded in their bores in the "monkey timber". The "screws" do not appear to be intended to be removed from the sockets or, if this is what should happen. they would require considerable force to extract them.

I found, with the "screws" turned the 1/4 turn back, that the socket would lever/prise out of the timber fairly easily. The holes for the nylon sockets may have been drilled a bit over-size.

The two sockets are connected by a substantial linking piece, which again suggests that they are intended to stay in place and allow the "screws" to be extracted. However, the "screws" have a coarse screw thread which is only on the surfaces of two quite thin diametrically opposed ribs, or cams. The rest of the diameter of the screw is cut back. The thread on the cams is to retain the "screws" in the internally threaded sockets. They cannot be unscrewed beyond the 1/4 turn needed to expand/free the divided ends of the sockets.

When these cams are turned a 1/4 turn clockwise they expand the solid parts of the nylon sockets, causing these hopefully) to jam in the timber bores

A 1/4 turn anticlockwise moves these these sections into matching slots in the nylon socket, which then become slack(ish) in the bore in the timber. The thread on the non-raised sections of the "screws" engages with a thread on the inside of the solid sections of the sockets. The "screws" can't be unscrewed because the their longitudinal ribs are trapped by the slots in the sockets.

The complete fastening system has to be pulled out with the controller swivel socket. Clearly. this must not be done more often than absolutely necessary because the bores for the sockets will wear (especially with particle board) so the sockets will end up not gripping the bores tightly enough to keep the controller firmly in place.

It is worth having been able to free the controller, though, because a removable U fastener for one end of the spring is now visible, and accessible for removing/replacing!