Sorry to come and spoil the atmosphere and harass you again with my thoughts on the efforts...
I come back to the principle of the cam frame acting on the lower plate through fingers... No problem when climbing, since the assembly will have been carried out/adjusted with care, the 4 fingers are in contact and the mobile plate remains parallel to the cam, therefore to the fixed plate. The behavior can be different on the descent since it is the springs (and gravity) that will cause the movement, and will be responsible for maintaining the contact of the fingers on the inclined ramps. From the point of view of forces, the cylinder is not the driving force in this movement, it just has a brake role in charge of managing the speed of descent. Quote from Bernard in his first message: "a small shock (...) on the profile structure is enough for the system to start jerking." At the risk of sounding pessimistic, I think that if such a phenomenon begins for any reason, the plateau may not go down. Same type of problem (but less critical) for the "cam" frame, which is only held by a shoulder + Teflon washer downwards.
Increasing the preload of the springs goes in the direction of improving the behavior since the contact action of the fingers on the cam will be greater. Another possibility is to make bilateral connections: - at the level of the cams by a block of parallelepiped shape and grooves + pin, - at the frame level by shoulders + washers in both directions . Is this reasonable? It's up to each of us to judge...
Bertrand, For my part, I would have preferred you to modify the following points:
The shape of the follower (pusher) and add the rounding to have a linear contact not punctual, and if you want to improve it even more, I recommend not a ball finger, but rather a roller follower.
Reinforce the shoulder of the cylinder
Bring the cylinder shaft as close as possible with the cam support in order to minimize eccentricities and have a smoosmooth movement (in my video I positioned it outside, but if the size doesn't allow it, maybe it would be possible inside)
M.Blt , on the subject of the efforts for the descent. There should be no problem for the machined part with the slopes, it will be driven by the cylinder in both directions. But so that the part that supports the fingers is always in contact with the slopes, I have provided 4 return springs in each corner of the supports that will be used to support the workpiece.
1. Allows you to always have your fingers flat on the slopes.
2. To balance the forces applied by the springs of the probes which do not have a perfectly homogeneous distribution on the surface (each small hole on the plexiglass plate is a probe location).
3. The problem with these return springs is that they have to fit within the maximum 180N that the cylinder supplied (otherwise I will have to supply another one). Your solution will solve this problem, but I am not sure that it fits into the available space. See my last 3D in previous post where the clutter is indicated.
Lynkoa15, Yes for the shape of the finger, and especially for the "roller follower ", I'll go and see it on the net. Unless I make these two elements in a POM C type material ?
When you talk about reforming the shoulder of the cylinder, is it on the length to enlarge the contact surface and the fixings of the part that holds the rod of the cylinder?
The position of the cylinder can be raised a little, but I have a 25 mm footprint between the IC (green part mounted on the moving part) for the electronic components and the cylinder I see what is possible to do.
Thank you all for your help and I continue on my side too.
Following your various tips that I tried to apply, I modified my 3D and I just posted it.
I still have my fingers to work, I'm looking for a rubber roller guide , but I haven't found what I'm looking for yet.
I have a few questions:
My brass bearings will have an inner diameter of 14 mm, what should be the diameter of the pins and their precision?
What should be the diameter of the housing of the pins below?. (see my remark below for these accommodations
On my old assemblies, the pins were fixed by screws and were blocked in their housing, I wonder if the fact of having fixed my axes at both ends did not already cause alignment problems and therefore blockages. In this setup, the pins are only fixed on the CI EZ support (so at the top), and the rest of the assembly is suspended by these pins. To make sure that the pins are perfectly aligned with the brass bearings, rather than using a screw to lock the axles, I imagine adding a bit of play (5/10) in the housing of the pins in the CI EZ mount. And fix the pins with a spring key to give them a little freedom and so that the pins align themselves with the brass bearings. What do you think of this idea, it could improve the system and the movement or on the contrary add constraints and problems? and therefore block the axes.
On the Cam Support part, where the slopes are, I purposely enlarged the slotted holes so that they don't rub on the axes during horizontal travel. The piece is guided by the 6 fingers that move the whole vertically. Does this seem correct to you or should I also use the axes for the guidance and therefore put self-lubricating rings?
Here is for tonight, looking forward to reading you.
