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31

General stuff / Re: Picking things back up

« Last post by webby2 on March 02, 2024, 08:28:12 am »

I have rebuilt my test-part, I have made it smaller and with only 4 subsystems.

They all are mounted in bearings on a frame and they are all connected to each other with a single common part.  They are all connected so that there rotational change is the same and in the same direction as each other.

I have test pulleys that are 31mm radius and are mounted on each subsystem shaft.  I am using these to test input and output stuff so that I can identify and follow what the feedback systems are within the whole system.

On one pulley I have wrapped a string with a 180g mass hanging on it, well I can not find my other 180g mass right now so on another pulley that is opposite the first one I have wrapped a string with a 250g mass hanging on it.

The drop and lift distances are the same due to the pulley radius being the same and the angle change being the same.

There are force changes within the systems and in one point of view that can be viewed as a 3:1 and this is where the feedback part is that I am looking into, it should cancel that advantage.

So,, I start the first test with the 180g mass low and the 250g mass high, let the system slip through my fingers and the 250g goes down and the 180g goes up nicely for a 180 degree rotation.  Now I reset my system for the other 180 degrees of rotation but I set the 180g mass high and the 250g mass low.

I use Mr. Finger to help the 180g mass to move down, a small amount of rotation and the 250g mass will drop back down, go past that value and the 250g mass no longer can lift the 180g mass, Mr. Finger is noticing a "heavy sluggish" feel but it is the same for either direction of rotation, keep rotating and Mr. Finger notices this "feeling" is reducing until there is a point where it is very easy to rotate the system in either direction a little bit, 10-20 degrees.

I tried to add 70g to the 180g mass to see if it would lift the 250g mass, well it did not work so well and the sluggish feeling got much worse.

I have to improve a few parts and then make sure that I have not created an artificial force potential with the setup, nothing like loading a spring without realizing it to mess with things.

32

General stuff / Re: Picking things back up

« Last post by webby2 on February 14, 2024, 08:34:01 am »

not really useful for much but an interesting method.

33

General stuff / Re: Picking things back up

« Last post by webby2 on February 12, 2024, 07:28:22 am »

I have drawn up something that is a little confusing.

I have a fixed input distance of 120mm
I have an angle of change at a constant 3.65 degrees for the input.  I think this means my input work is going to be the same amount for any of the transfer system lengths.


the output is 45 degrees of rotation on a 10mm arm.
the longer I make the transfer system components the interactive angle between the input and output changes, ie: at one set of length values (468mm) the range goes from 106.01 to 74.83, many times longer (12m) the range goes from 115.8 to 71.37.  This is in consideration that a 90 degree interaction angle would be the best force transfer.

I think that this could be a kind of non-rotating lever (NRL) in that my input distance is always the same.

34

General stuff / Re: Picking things back up

« Last post by webby2 on January 20, 2024, 04:52:38 am »

sidetrack:
I have my multi-systems interacting with the input, so named because that is the way I have been viewing it to distinguish direction of throughput not as the ONLY way of using it.

My input and the multi are connected as such that one rotation of one drives one rotation of the other, they are a 1:1 rotation.
In looking for alternative methods of adding a constraint to stop the massive deflection of shafts and stuff I can up with a way but it has an interesting issue.  The direction of rotation of the multi can go either CW or CCW but the input always rotates in the same direction CCW.

In one view then they are a 1:1 but in the other they are a 2:1, that is I can rotate the multi in the opposite direction of the input and one rotation is still one rotation which means that between them there are 2 revolutions.
This is not all new stuff, at least to me and I am guessing that it will end up leading to nowhere, but it is kind of fun.

35

General stuff / Re: Picking things back up

« Last post by webby2 on January 11, 2024, 02:44:00 am »

so my chain and sprockets are adding more losses than I thought.  If I only use them to transfer between 2 sprockets I have an increase from about 0.5N up to about 3.5N.  To take up all the slack and just start the motion of transfer is close to the drop weight value but to get the system to move more than that takes initially a lot more and then it drops down while motion is maintained,, somewhat due to Mr. Hand not being really good for this.

I took all that off and used one of my alignment jigs instead of the chain and things were interesting.  I increased the drop weight to 4.5N and, depending on where in the rotation I measure, the input force goes from about 3.2N up to over 6N.

Watching the test-part bend and twist with all this is a bit of an eye opener as to how much constraint is going to be required.

36

General stuff / Re: Picking things back up

« Last post by webby2 on January 07, 2024, 06:06:35 am »

simple solutions are good.

I am however having significant issues with the plastic parts deforming and not providing for a smooth interaction, when I use force the parts are almost grating by each other instead of sliding and rolling smoothly.  I have one small spot where the input force to start things moving is less than 2.4N but then things get sticky and it takes over 4N to move but then the system kind of shoots forward and stops again until I pull further on the input.

It would seem that I need to use hard surfaces instead of plastic ones.

37

General stuff / Re: Picking things back up

« Last post by webby2 on January 06, 2024, 03:11:58 am »

I have made some parts strong enough so that I can actually see what the parts look like as they are interacting, those are the input arm and the interactive drive unit.  This allows me to see what the lever system is doing as the forces are being applied and transferred from one area to another.

I have a pivot shaft that is supposed to be rigid but even with a small amount of force being transferred those rigid pivots are bending.

I am aware of these forces but I did not appreciate the reality of how large they become so I need to constrain that reactionary force issue before I can proceed.

38

General stuff / Re: Picking things back up

« Last post by webby2 on January 05, 2024, 04:44:57 am »

I have checked the mass and force on the drop weight, 2.5N.  I have that connected to a string and am running that string over a pulley so it applies its force horizontal into the system.  I have taken that pulley and used the other spring scale on the other side and it shows the same 2.5N even when I am raising and lowering the drop weight.

Moving slowly I have to apply from 3.2N to 3.6N of force to raise the drop weight, this is when the drop weight is on the output side.  It is almost the same for the other side, but there are some spots where the force required jumps up to almost 7N when a part transitions its orientation.

39

General stuff / Re: Picking things back up

« Last post by webby2 on January 05, 2024, 03:11:19 am »

Just throwing this out there.

Using this design setup to cause the system to move, on the output side I need to apply approx. 1.5N of pull then to use the input side to move the system I need to apply approx. 1N of pull.

40

General stuff / Re: Picking things back up

« Last post by webby2 on January 05, 2024, 03:03:37 am »

I am testing out a design change and have an interesting thing.

I have reduced the input\output radius, with that I can now apply approx. 15N of force on each side and nothing moves.  If I want the system to rotate with this consideration in place I need to increase the force up to approx. 20N on whichever side I wish to be the driving side to move the other side at approx. 15N.

This could just be me not applying and moving things correctly but the same relationship appears to happen with more or less force being used.

I tried another one but the part was rather flexible and under force it would flex changing the rate of angular change side to side and showed a growth in force when I used the input side but the input side, due to the flex, moved a larger angle than the output side.