Picking things back up

[webby2]

Need to add that I have a means of adding in an internal potential, I am using rubber bands to add that potential.

I have been able to add the correct number of rubber bands so that when I hang the 90g mass on the 30mm side I can almost balance the arm, remember that the other side of the arm weighs approx. 20g so not much.

Within the range the internal potential holds, outside the range it does not. 

I took the whole system off the mount and and placed the central shaft in a set of bearings and with the rubber bands in place I needed to add 45g to the 30mm side to bring that lever level, so the whole system is balanced around the axle for the lever.

I just did something silly, I mounted the bearing block in my vise and then put the lever axle into that bearing block.  My spring scale weighs approx. 45g in total, the scale shows 30g when I hang it from the hook by itself.  So for 180 degrees of rotation that spring scale is almost enough weight to hold the lever level, (the scale shows 30g while hanging by itself), pull on it so about about 35g is showing and this comes to a peak, so from no extra needed up to about 5g extra and then back to no extra needed.  The other 180 degrees of rotation and I need to pick up on that spring scale a little bit, down to approx 25 and this is again from none needed up to a max and then back down to none needed.

[webby2]

This could be fun,,
I am printing out some test parts for the test-part that on paper shows a 1:1.314 in to out

I used pulleys on the first re-do and now I am using gears, making all those belts was a bother cause it is hard to get the tpu to fuse straight, and then to get the correct tension in it all.

[webby2]

Made some quick parts for some quick tests.

I am using both gears and pulleys.  The gears are 1:1 between systems but not to the go-between part, the pulleys are a 1:1 and connect all the gears together.

My input forces gears to move around the go-between part, that gear rotation is transferred to other gears which then rotate about the go-between part, the go-between part is the key.

Quick tests are looking very positive until the belt slips,, very annoying since now I am going to have to redesign things so that does not happen.

[webby2]

I will say that if I ignore the go-between part the math holds true that the if input side is a value of 1 then the output side is a value of 1.314, that is just mechanics at work.

So I am needing to test for the go-between part, which by itself is performing no added work, it is simply transferring the input to the output like a belt does for a pulley, or an idler gear,, and the like.

When the belt is not slipping it looks possible but when trying to load the belt slips and then no results to be had.

[webby2]

While I am trying to figure out how to design things I tried something silly and it has me a little confused.
I have holes in the pulleys so I can secure a string, I ran that string across the system to the other pulley and out through that hole so now I have a limited motion of no slipping.

I thought that I could use a weight for the input and output comparison,  and I thought that it should go one side heavier and one side lighter to balance.

The whole thing rotates around on a central shaft and when I have the weights equidistant from that shaft the weight value is opposite of what I thought.  What I have right now is  60g going down on one side of the shaft to 90g going up on the other side @the same distance of drop,,, roughly speaking.  Making the system shift either direction is actually rather easy and light feeling and it seems as though the path I choose the string to take has an impact as well.

I thought that the 90g going down should lift 90g and that to balance the forces I should add to the lift side where what I seem to have is that the lift side is taking less input,, maybe I am identifying the sides backwards??

[webby2]

just double checking things.
the lighter weight is 70g, the lighter weight is 50mm from the central shaft
the heavier weight is 90g, the heavier weight is 55mm from the central shaft

[webby2]

the systems are not equidistant from the shaft so I am thinking that it is the difference that is providing for this interaction, however to counter the one side adds a force into the whole system so I would need to counter each system relative to the central shaft.

[webby2]

I think I might of found the pathway that I need to interact with, it is not really the way I thought it would be.
I am printing off more slightly changed parts, I keep getting the slop and printer error and stuff a little off so I get into either a miss or a bind and keep making small changes to get each part to fit and work together, it was in going over all this so many times that I saw what might stop the system from doing what I wanted it to do, that is provide me with a 1:1.314 gain in work.

Now to print more parts and see what I see, then print more parts from there.

[webby2]

My setup needs some structural parts added but the functional parts are in place well enough for a few basic tests.

My spring scales are problematic in that I need to overload the system to get smooth readings and that drives the system out of sync so that a limiter I have in place comes into play and locks things.  While it is in this condition if I pull on the output with 1200g I only need to supply 900g to the input, however if I pull on the input with 900g I only need to supply 1000g to 1050g on the output.

I changed up to dropping weights, each are 90g.  When I reset so that the input and output are synced back up the input side has a very slight tendency to fall.  I add another 30g to the output side and it has a small tendency to fall.  If I give the system a spin it moves further one way more than the other, that is to say that the heavier side will continue to move down further than lifting it up.  If I put the 30g on the input side it falls without needing to spin.

I increased the drop mass to 190g and the system seems to be balanced, no tendency to move either way.  I add 30g to the output side and it drops fairly quickly, when I move the same 30g to the input side it drops very slowly and will stop moving until I give the system a little push.

Not the results I was hoping for, but not the results I was expecting.  I was expecting the system to stay balanced and behave in a normal fashion.

[webby2]

I upped the weight to 270g and things appeared to become more "normal".

Then I thought about the limiter, so I shifted the system one way and not much change then I shifted it the other way and now the output side having the extra 30g goes up, very slowly and I need to nudge things so I am thinking that what I thought was "synced" may be in the wrong place.

[webby2]

trying all sorts of little changes and at this point the one thing I have noticed is that when using the 190g weights the system behaves a little differently than when I use more or less.

I add 30g to the output side and the nudge the system and it will slowly fall down a little bit, put it on the input side and I do not have to nudge the system at all.  I have tried with my sync point moved, using CW and CCW rotation, switching the weights, so it seems that there is a preferred force direction of change, how much and why, not sure.

[webby2]

Found an issue with the build.

2 pulleys printed from the same printer and the same file gave me 2 slightly different diameters.  These are then walking around one another so that is what I think is showing the results I have been getting.

[webby2]

strange,
The shift is not always the same, it is as if the tension in the belt is interacting with everything.

[webby2]

if you have 2 levers and you use a spring to connect them together and you want to compress or stretch that spring you need to supply a force on each lever.  While the spring is potentialized then it does not matter which way the levers move, that is one side moving up while the other moves down or vice-versa, the needed forces on the ends of the levers remains the same.

My system has 2 reactionary levers, the input side and the output side, the input is 90mm and the output is 120mm.  These are locked into a 1:1 rotational value.  I supply the input side with some force and that force is transferred via a belt across the system to the output side at a 1:1 so the output side sees the same force.  All things, except for the reactionary lever arms, are 1:1.

It is my go-between parts that allows this to happen.  What I thought was the only reactionary force I needed to counter was easy enough.

I was expecting that if I supplied the input side with a force potential so that the belt was transferring 10N of force that the reactionary arm of 90mm would create the appropriate work potential and that with the 10N of force being provided to the output side it would produce its appropriate work potential that was 1\3 more than the input side, being the arm is 1\3 longer.

What I got was close enough to a 1:1 pass through when the input side also supplied the motion to call it a 1:1.

When I measured the system when the output side was providing the motion things were different, I had to supply more force than I was getting from the input side.  This is what I have been looking into.

I am slowly making parts to see if I am correct and to see if I can make a gain out of this, right now it does appear to be a sink, or a loss of work.

[webby2]

0.017453292519943
(2*PI)/360
PI/180
so for 90mm arm and 360 degrees the distance is
((π÷180)×90)×360
565.486677646
or any degree you wish to use
((π÷180)×120)×360
753.982236862

In my system I do not need to worry about any of that stuff because I set all things, except those arm lengths, to 1:1.  The input and output move the same distance, the force applied to the end of the arms moves the same distance,,,

In other words my belt needs to spin the identical pulleys so many times for the arms to make 1 complete revolution, it is not the length of the arms that counts.

I thought I only had to worry about 1 feedback loop that I easily took care of, however.

There is the lever relationship between the arms.
To simplify what I tested I will put it this way,
I applied a force into the connecting belt and measured the torque imparted into each arm without the rest of the system, so 10N of tension on the 90mm arm made 900Nmm of torque, 10N of tension applied to the 120mm arm made 1200Nmm of torque.

Then I started testing the steps, independent of the complete system looking for the other feedback loop that I missed.

I found the loop and it was not hiding at all I just missed it.  The system is collapsing the distance of change into an internal change, or conversion.  This feedback is between the go-between part and the output arm\pulley and it supplies a force of opposition to the change in position relative to the go-between parts that seems to mirror the change in distance of the arms, the output is 1.333 times the size of the input.

The force of opposition in my system then should look like 900g of pull on the input then goes across the system via the belt and drives the output arm to 1200g of force, then there is the internal force of opposition that reduces the available force down by 1\3 of 900 (the input force) or 300g of force leaving me with 900g of force on the output side.

The thing is that feedback oppositional thing is applied against the output and just like the spring between levers it does not matter which way the levers are moving that opposition is against the output arm.  This then would infer that for me to take 900g of force from the input side I would need to supply the output side with 900g + the 300g for a total of 1200g of force.

Force must be supplied to both sides, that is how things work after all.