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-   -   233 telescoping arms how do they work? (http://www.chiefdelphi.com/forums/showthread.php?t=116765)

Steven Donow 10-05-2013 09:52

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by Nemo (Post 1273874)
To the people who have posted in this thread: I just want you to know that after the school year ends, I'm going to devour the information in this thread, including both the pictures and written explanations. I am looking forward to trying to figure out the guts of one of these arms and working with some students to create a model of something we could build. Thanks very much for all of the posts.

If only it were possible for Pink or 254 to send everyone here an arm :D

Lil' Lavery 10-05-2013 10:15

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by DevenStonow (Post 1273877)
If only it were possible for Pink or 254 to send everyone here an arm :D

I think the postal service might question why disembodied limbs are being shipped around the country.

Triple B 10-05-2013 10:55

Re: 233 telescoping arms how do they work?
 
good one Sean, and you are correct on your earlier post about the passive drive of the third stage on pinks tower.

roystur44 10-05-2013 11:08

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by smart1 (Post 1273383)
i have seen pictures but i still can't figure how they work. I want to know how to make one this summer. any pics or cad would be great.

Take a look at how 1986 did their arm. They used heavy duty drawer slides and a cascaded cable and pulley system. It was simple, elegant, easy to manufacture and did the job.

smart1 10-05-2013 13:24

Re: 233 telescoping arms how do they work?
 
we have done many lift's with bosch 20 series with custom sliders and cable but that has it's limitations, mainly strength and weight.

M. Mellott 10-05-2013 17:33

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by Nemo (Post 1273874)
To the people who have posted in this thread: I just want you to know that after the school year ends, I'm going to devour the information in this thread, including both the pictures and written explanations. I am looking forward to trying to figure out the guts of one of these arms and working with some students to create a model of something we could build. Thanks very much for all of the posts.


Seconded. These are some great idea to digest! Many thanks as well!

craigboez 11-05-2013 20:13

Quote:

Originally Posted by Triple B (Post 1273873)
In our application we use the constant force springs to assist the extend function only.

Mike D "233 for life"

Would you mind elaborating on which constant force springs you use?

EDIT: I ask because I'm only familiar with the coil style constant force springs and if you used those I'm curious how they were implemented.

Chinmay 11-05-2013 22:17

Re: 233 telescoping arms how do they work?
 
Try looking up negator spring or constant force spring motor. It's a really nicely packed solution to the counterbalance problem. Ill update this when I'm at a computer with some links Ect.

craigboez 12-05-2013 01:14

Re: 233 telescoping arms how do they work?
 
1 Attachment(s)
Quote:

Originally Posted by Triple B (Post 1273697)
I can only speak for the 233 arm on this topic. First off, a gearbox is attatched to the outside of the largest box (4d0 x 4d0 x d125 al box) at the bottom of the tower. It has a shaft that transfers power to a sprocket on the inside of the box. At the top of the box is an idler sprocket which is also the tensioner for this chain. We will call this chain 1. Chain 1 is attatched to the outside of the next box (2d5 x 2d5 x d125 al box) thru what I call the "chain anchor". The motor/gearbox drives this stage in and out directly.
The gearbox has a 10 turn pot attatched which controls the limits and also the PID control for ramping up and down the power as the tower nears its limits at each end of its travel. Now here is where it gets a little tricky, the opposite side if the 2d5 box has a shaft in the bottom with a sporcket on the inside and the outside, this is what drives the final stage of the tower. It also has an idler at the top which also acts as the tensioner for these 2 chains.
The chains both have a "chain anchor". The chain on the inside of 2d5 box is attached to the bottom of the final stage (1d0 x 1d0 x d125 al box). The chain on the outside of the box is attatched to the inside of the 4do box. The key is that the anchors are on opposite sides of the chain, this allows the second stage to use the anchor to drive the chain which extends the final stage at the same time. This is a very lengthy post and I may not of explained the subject completely but it has started an open line of communication. Ask any questions you may have and i can explain why Charlie did not like the delrin bearing blocks from 2k10.

Mike D "233 for life"

After some analysis, this is my understanding of what Mike describes.

EDIT: would someone familiar with the 254 system we willing to describe or diagram that system? From looking at all the pictures, I believe they use a different concept.

R1ffSurf3r 12-05-2013 06:48

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by craigboez (Post 1274179)
Would you mind elaborating on which constant force springs you use?

EDIT: I ask because I'm only familiar with the coil style constant force springs and if you used those I'm curious how they were implemented.

look at post 18, and the second picture

smart1 13-05-2013 21:19

Re: 233 telescoping arms how do they work?
 
Thanks for all of the helpful insight.

craigboez 17-05-2013 15:53

Re: 233 telescoping arms how do they work?
 
1 Attachment(s)
After looking through the pictures referenced earlier in the thread, I was able to better understand the 254 telescopic arm. It is conceptually very different from the 233 arm.
  • 254 used a single piece of belt routed continuously through the assembly and then pinned to the final stage at each end of the belt. See attached for a diagram.
  • 233 used two loops of chain, one to drive the first stage and then in a cascading fashion used the first stage to drive the second stage. See my previous post 39 for a diagram.
Both elegant solutions to a similar problem, and as you can see from the pics, the hardest part of building one of these is in the packaging.

We attempted to build a nylon strap driven arm, similar in concept to the 254 design, and found it very difficult to get all the rollers, idler pulleys, and pieces of slippery UHMW from colliding with each other. In the end we ran out of time, kept the first stage, and just implemented a first level hanger.

The devil is definitely in the details with these mechanisms.

Travis Covington 17-05-2013 16:18

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by craigboez (Post 1275615)
After looking through the pictures referenced earlier in the thread, I was able to better understand the 254 telescopic arm. It is conceptually very different from the 233 arm.
  • 254 used a single piece of belt routed continuously through the assembly and then pinned to the final stage at each end of the belt. See attached for a diagram.
  • 233 used two loops of chain, one to drive the first stage and then in a cascading fashion used the first stage to drive the second stage. See my previous post 39 for a diagram.


The devil is definitely in the details with these mechanisms.

This is correct. Thanks for illustrating this for others.

smart1 17-05-2013 21:58

Re: 233 telescoping arms how do they work?
 
Quote:

Originally Posted by craigboez (Post 1275615)
After looking through the pictures referenced earlier in the thread, I was able to better understand the 254 telescopic arm. It is conceptually very different from the 233 arm.
  • 254 used a single piece of belt routed continuously through the assembly and then pinned to the final stage at each end of the belt. See attached for a diagram.
  • 233 used two loops of chain, one to drive the first stage and then in a cascading fashion used the first stage to drive the second stage. See my previous post 39 for a diagram.
Both elegant solutions to a similar problem, and as you can see from the pics, the hardest part of building one of these is in the packaging.

We attempted to build a nylon strap driven arm, similar in concept to the 254 design, and found it very difficult to get all the rollers, idler pulleys, and pieces of slippery UHMW from colliding with each other. In the end we ran out of time, kept the first stage, and just implemented a first level hanger.

The devil is definitely in the details with these mechanisms.

Thanks again.

fr05ty27355 21-10-2013 11:37

Re: 233 telescoping arms how do they work?
 
What did 254 and 233 do to pin the chain/belt to a stage? I'm wondering if they put bolts through the chain/belt, pinched the chain/belt against a toothed surface, or did something else. I'm guessing they might have had different methods since 254 used a belt and 233 used chain.


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