2nd prototypes have arrived and the first stage of evaluation has been done. I've made a short video which I've attached and which is worth looking at to get the context for my notes below.
This design was a radical change from the first prototype and also from the concept after thinking about what to change.
Looking at the video you will see that I have integrated the cable guide into the base of the handle. With a separate cable guide the costs were rising to an unacceptable level. In the video you can see the cable threaded through the cable guide. This works well but for me there is a tad too much friction so I will redesign the cable guide so that it will accept a brake cable Teflon / PTFE liner and I'll also smooth the curve at the Z3 lock lever end.
The cable was intended to pass through a hole in the M5 thread at the end of the door handle lever such that a lock nut could be fastened down on the cable to keep it in place. Unfortunately the hole made the threaded rod too weak to run a die down whilst creating a clean thread so I'll replace that with an eye at the end of the lever which will take a normal M4 or M5 bolt which can be used to clamp the cable.
This will also allow me to strengthen the handle lever, it'll now be something like a 6mm bar with the eye at the end.
The video shows that the push button action is separated from the lever action. The way that this now works (and works well) is that the push button has the task of moving up and down in the handle well by around 5-6mm and in so doing operates the handle causing it to open by around 15 -18 degrees, the same as the original. The handle is then latched in this position by the spring loaded sliding bolt and the push button returns to its original position under the tension of the spring which you can see in the well of the handle. The centre of the push button slides through a slot in the base of the handle well, this minimises the tendency of the push button to rock backwards and forwards. It can be made to jam by pushing at the front or rear end but it can also be released from the jam by pressing at the other end.
The spring loaded sliding bolt is of similar design to the original but whereas the original would allow you to return the handle from this half cocked position this design does not allow that. It will be necessary to fully operate the handle through to 45 degrees before it will return under the tension of the spring in the Z3 lock (or manually). The reason for this is that the tension of the spring in the Z3 handle is greater than the holding strength of the original bolt so if the button was pressed and released then the handle would close again. I know that it would be simple to grasp the handle whilst it was still open but the other effect of allowing this would be that it could cause the push button to jam and to do so with more force than would be comfortable to release. Because the lever action of the handle is all at the front of the push button and because of the amount of leverage that pushing the handle can impose I think it is best to avoid the risk of jamming the handle under that leverage.
For the same thread cleaning issues as mentioned above I will replace the front M6 threaded rod with a female M6 fastening (similar to the original). It will allow around 6mm of fixing which will probably leave it a millimeter or so proud of the inside of the door panel. I would expect that one or two M10 penny washers will slip over the protrusion before an M6 penny washer can be used to fix it down. In the original they supplied a bridge type of fixing...
Other than that there are a couple of tolerancing issues to improve. Last one was too tight, this one a bit too slack in places so now I know where to land
If you look at the video you will notice that there is a key slot in the top of the push button. This will accept the Z3 key (or a screw driver) and will rest in either the open position or, if turned through 90 degrees, in the locked position. This feature will be optional and is a simple mechanism to prevent the handle from being operated by casual passers-by. I will also have a simple push button without the key lock feature which will be the standard offering, the turn key option will probably add £15-20 per side.
All I have to do now is implement the modifications and go through what I hope will be a final phase of prototypes. The changes will take around 2 weeks and the production another 3 or so weeks after that. Beyond that, if everything goes well then I will be happy to polish and sell that prototype if anyone (Piran?) is keen to get their hands on one otherwise it will be another 4 or so weeks after the evaluation before polished products become available.
In the next week or so I will mount one of these prototypes on the door and connect it to the lever so that I can see more accurately where the handle needs to be positioned to ensure that the cable guide is in the right place. I'll need to do this before I finalise the changes to the cable guide and so before I order the next models.
I've added a 2nd video which shows the operation of the push button lock. you have probably noticed that the handle is a bit floppy in these videos, that's only because I haven't included the sliding bolt which keeps everything tethered in place.
Let me know if you have any questions / comments.
Cheers
Russell
. Is it just me or is there a difference between the drivers and passengers door skin (in the way they go on they were quite different) so there will need to be enough adjustment to compensate for the differences.
