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Author Topic: Picking things back up  (Read 46843 times)

webby2

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Re: Picking things back up
« Reply #75 on: February 10, 2023, 07:11:47 am »
I am getting myself rather all mixed up and on top of that my base keeps wanting to spin but it supposed to be fixed in place.  I was kind of lazy and decided to not "fix it in place" so I could just spin the whole system instead of getting up and out of my chair to look at things from all angles,, time to just lock it to the vise on my desk.

I can choose the interactions and change the behavior of those interactions by adjusting them,, that part is what I thought should happen so now to get things adjusted and see what works and what does not.

webby2

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Re: Picking things back up
« Reply #76 on: February 16, 2023, 06:08:27 am »
Things are getting frustrating, annoying, exciting, interesting,,

I have made for a fair amount of adjustability and that creates a few issues and one part that I did not make adjustable, per say, needs to be made adjustable.

The part that is not so adjustable is held by rubber bands, my thought was that I could see if the forces I think should be there are if that part shifted against the pull of the rubber bands, that does happen.

I have 2 parts that are supposed to have free movement in one direction but due to poor craftsmanship they are a little sticky and that creates issues.  I set things in place with what I think the alignments should be, or close to it, and nothing happens easily, I tap on the table or test-bed and the vibrations allow the sticky parts to move as I think they should and things change as I think they should change.

This leads me to believe that the force interactions and motions I am looking for might be present within the test-bed.

I think this is all looking very promising :)

Now to design the next parts

webby2

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Re: Picking things back up
« Reply #77 on: February 18, 2023, 06:25:54 am »
This is a little perplexing.
What is supposed to happen is that I have two sources of force that are the same, the interaction via the device allows for the reactionary forces to be dissimilar and so to balance the reactionary condition I should be adding more force to one side.  I am using mass and gravity for the source.

The thing is I am adding a lot more mass to the one side than I think I should and even still the light side is advancing the system and lifting the heavy side.

The drop to lift is also not as I thought which might be the reason for the increase in mass needed to balance, my thoughts were that it should be 1:1.4 but the distance change is more like almost 4:1.

I have not designed the parts to allow for to much change from a setup relationship.

webby2

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Re: Picking things back up
« Reply #78 on: March 14, 2023, 06:30:37 pm »
I did not like the actual physical contact that two parts were having so I have been re-designing  that contact, well I decided I wanted it to mirror another part interaction so I finally got a configuration that I think will do that for me, I am printing off the rough parts now to check on the setup.

webby2

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Re: Picking things back up
« Reply #79 on: March 30, 2023, 03:46:51 am »
Just going back over older setups and decided to actually run a force measurement,, a crude one but it is not what I thought it would be.
I have 2 parts that are not the same but they move at a 1:1 rotation value.
One connection point for my scale was at 90mm from its axle and I applied 2N of force.
The other connection point for my other scale was at 145mm from its axle and I matched the pull of the other by applying 1.8N of force.

I used other force values,, 3 to 2,, 6 to 8.4 and through some parts of the exchange it is almost a 1 to 1

My interaction is not a constant thing so there is variation of the exchange distance between parts which is why I chose distances from the associated axle instead of the ends of the parts, trying for an actual leverage or torque value as seen by the axles.

webby2

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Re: Picking things back up
« Reply #80 on: March 30, 2023, 05:08:40 am »
I did not design one of the parts to move, it is actually sitting on a table and the other part pushes down on it while things are in motion so that part has more frictional losses than it needs to. 
That part is the one with the 90mm measurement point.

I am a little annoyed that the system looks like it might work this way, I did not think it could and went the other way with my build.

By the way the larger force numbers go with the 90mm point and the smaller ones with the 145mm point and both points rotate.

webby2

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Re: Picking things back up
« Reply #81 on: March 30, 2023, 02:18:40 pm »
so I pulled the test-bed apart and put it back together so the one part was on bearings.
I changed the measuring points and got them closer in length.

I ran the pull tests using one scale on one side and the other on the other then I switched the scales and did them again.

135mm to 155mm
 
300  320
600  680
1.2  1.45

200  240
600  680
1.2  1.48

webby2

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Re: Picking things back up
« Reply #82 on: March 30, 2023, 07:16:33 pm »
I was playing with the variance by position and I almost got it down to 2000 to 2000, so very close to a 1:1 but then I also had it at close to 1600 to 2200, again that is on 135mm to 155mm

Now to think about maybe redesigning this setup to work this way.  I am not sure if the small gain I have is worth the effort,, it looks like it might average out to something like 120% to 130%, then again when going full rotary it might end up at 0 gain.

webby2

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Re: Picking things back up
« Reply #83 on: April 04, 2023, 10:17:16 am »
Just playing some more.

I think I have another method for interacting with the base unit that may even be better than the 125% way of interacting with it.

webby2

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Re: Picking things back up
« Reply #84 on: April 05, 2023, 04:22:13 am »
Very frustrated,,,,
I have to figure out again how to make a part so that I can print it, it was a convoluted process of making this this way and then taking that and making it something else and then being able to make the part so that I can print it,,,,

In the meantime I remeasured my pull points and this time set them almost identical to between approx. 150mm to 155mm for each point.
These points are showing approx. 133% out compared to the in.

Anyway,, once I can make my part again then I am going to downsize the build a little bit and design it for this actual usage and try and remove most of the slop.

webby2

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Re: Picking things back up
« Reply #85 on: April 05, 2023, 04:44:12 am »
I just did some basic math to see if what I have measured is reasonable.
The range of relationship I should have goes between 1.26:1 and 1.41:1 so an average of 1.33:1 which is close to the range of values I am measuring using simple spring pull force scales.

webby2

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Re: Picking things back up
« Reply #86 on: April 12, 2023, 06:15:40 am »
I am redoing the base system to be used this way and I am increasing the multiplication up to almost 2:1.
I will have a small issue with the structure of the system being rigid enough to withstand some of the force values,, in other words I might break it fairly quickly.

I am looking at several days or more of print time and I am hesitating because after so much print time if I break it before I can get some usable data maybe I should try and make it more robust, or maybe it will be just fine,,, or ????/

webby2

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Re: Picking things back up
« Reply #87 on: April 12, 2023, 06:31:06 am »
A small note,
I am using my existing test-bed to look into these forces.  I have added a part to that test-bed to help hold things together but I can not keep them held so well and I have been moving my lock pieces even tho I am using 2 lock screws per lock part as well as my parts start to deflect, or bend.

I am thinking that I might be able to use just enough force so that the frictional losses are not a very large part of the transfer work part.

webby2

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Re: Picking things back up
« Reply #88 on: April 13, 2023, 04:03:12 am »
some days I think I sit and spin because part of me knows a better solution.

After thinking about my setup I came up with a simple way to remove these pesky force issues,, a very simple solution.  This solution does not require too much re-design and only a few more parts per system.

Leverage and torque are ratios of force and distance, so 1Nm is 1 newton of force at a distance of 1 meter, this relationship then has 2 extremes that do not play nice, those are, an infinite force with no distance or an infinite distance with no force.  I am going to use these conditions to my advantage :)

webby2

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Re: Picking things back up
« Reply #89 on: April 15, 2023, 01:20:01 am »
Designing my parts one way,,
I need three of the same parts in this setup and one way I can go with those parts will take me 65hrs of print time per part!

I think I will go another way :)

 

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